What is 26NiCrMoV14-5 steel?

26NiCrMoV14-5 (EN material number 1.6957) is a high-strength low-alloy steel grade per DIN/EN standards, specifically engineered for gas and steam turbine rotor shafts and other critical high-temperature components. It contains approximately 3.4–3.8% Nickel, 1.4–1.8% Chromium, 0.3–0.45% Molybdenum, and ≤0.15% Vanadium, giving it excellent strength, toughness, hardenability, and temperature resistance up to 450°C.

What are the mechanical properties of 26NiCrMoV14-5 (1.6957) steel?

26NiCrMoV14-5 (1.6957) steel has the following minimum room-temperature mechanical properties: 0.2% Yield Strength ≥ 730 N/mm² (typical 780 N/mm²), Tensile Strength ≥ 830 N/mm² (typical 920 N/mm²), Elongation ≥ 15%, Reduction of Area ≥ 50%, and Charpy V-notch Impact Strength ≥ 100 J (typical 135 J). The steel can operate at temperatures up to 450°C.

📍 Jiangyin, Jiangsu – China's Premier Forging Industry Hub

26NiCrMoV14-5 (1.6957) Forging Parts | Jiangsu Liangyi China

Q: What is the maximum size of 26NiCrMoV14-5 forgings you can produce?

Jiangsu Liangyi can manufacture 26NiCrMoV14-5 forgings up to 30,000 kg in single-piece weight. For round bars, the maximum diameter is 2,000 mm. For seamless rolled rings, the maximum diameter is 6,000 mm. For turbine rotor shafts, the maximum length is 15 meters.

Q: What certifications do you provide for 1.6957 forgings?

Jiangsu Liangyi provides EN 10204 3.1 mill test certificates as standard with every order. EN 10204 3.2 certificates — which require countersignature by an independent third-party inspector — are available when buyers arrange and commission inspection by bodies such as TÜV Rheinland, DNV GL, ABS, LR, or BV. Our factory fully supports and cooperates with third-party witness inspection. Our facility holds ISO 9001:2015 certification.

Q: Can you provide machining services for 1.6957 forgings?

Yes, Jiangsu Liangyi provides complete CNC machining services in-house. We can supply 26NiCrMoV14-5 forgings in rough machined, semi-finished, or fully finished condition according to your drawings. We also provide heat treatment and surface treatment services.

Q: What industries use 26NiCrMoV14-5 forgings?

26NiCrMoV14-5 (1.6957) forgings are primarily used in: power generation (gas turbines, steam turbines, generator rotors), oil and gas (compressor turbines, high-pressure valves, pump shafts), marine propulsion (naval vessel turbines, marine gas turbines), and heavy industrial machinery. Power generation accounts for approximately 60% of Jiangsu Liangyi's 26NiCrMoV14-5 production.

26NiCrMoV14-5 (1.6957) Forging – Quick Reference

Steel Grade: 26NiCrMoV14-5 / EN 1.6957 (DIN/EN standard, high-strength low-alloy steel)

Manufacturer: Jiangsu Liangyi Co., Limited – Jiangyin, Jiangsu, China (est. 1997)

Yield Strength: ≥ 730 N/mm² (typical 780 N/mm²)

Tensile Strength: ≥ 830 N/mm² (typical 920 N/mm²)

Max Temperature: Up to 450°C (ideal for gas and steam turbines)

Max Piece Weight: 30,000 kg (30 tonnes) single-piece

Max Ring Diameter: 6,000 mm (seamless rolled rings)

Certifications: ISO 9001:2015 · EN 10204-3.1 (standard) · EN 10204-3.2 via third-party witness inspection available on request

Applications: Turbine rotors, rings, bars, valve spindles, fasteners (power, oil & gas, marine)

Export Markets: 50+ countries worldwide – quote within 24 hours

Jiangsu Liangyi Co., Limited, established in 1997 and located in Jiangyin City, Jiangsu Province – the heart of China's forging industry, is a professional ISO 9001:2015 certified manufacturer of 26NiCrMoV14-5 (1.6957) open die forging parts and forged steel gas/steam turbine generator rotor shafts. With over 25 years of specialized experience, we produce high-quality 26NiCrMoV14-5 components for power generation, oil & gas, marine, and heavy industrial applications across more than 50 countries worldwide.

Our 1.6957 forgings are manufactured to strict international standards (DIN, EN, ASTM, API 6A) and our factory fully supports witness inspection by globally recognized third-party organizations including TÜV Rheinland, DNV GL, ABS, LR, and BV. We provide EN 10204-3.1 mill test certificates as standard with every order. EN 10204-3.2 certificates — which require countersignature by a buyer-commissioned independent inspector — are available when buyers arrange third-party witness inspection, ensuring complete traceability and quality assurance.

What is 26NiCrMoV14-5 (1.6957) Steel?

26NiCrMoV14-5 (EN material number 1.6957) is a high-strength, low-alloy (HSLA) Nickel-Chromium-Molybdenum-Vanadium steel per DIN and EN standards. The designation encodes its key alloying elements: approximately 3.4–3.8% Nickel for outstanding toughness and hardenability, 1.4–1.8% Chromium for corrosion resistance and hardness, 0.30–0.45% Molybdenum for elevated-temperature strength, and ≤0.15% Vanadium for fine grain structure. It is the benchmark steel grade for large gas and steam turbine rotor shafts operating at temperatures up to 450°C and is equivalent to ASTM A470 Class 8 and comparable grades in major international standards.

26NiCrMoV14-5 turbine rotor shafts manufactured by Jiangsu Liangyi in Jiangyin China

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Why Choose 26NiCrMoV14-5 (1.6957) Steel Forgings?

26NiCrMoV14-5 (material number 1.6957) is a strong, low-alloy steel that is used in important applications that need to work at high temperatures and pressures. This high-quality steel grade has great mechanical properties, which makes it the best choice for turbine parts and other heavy-duty industrial parts:

Outstanding Strength & Toughness: Excellent balance of high yield strength (730–830 N/mm²) and superior impact toughness, even at low temperatures
High Temperature Resistance: Maintains mechanical properties at elevated temperatures up to 450°C, ideal for turbine applications
Excellent Fatigue Resistance: Superior resistance to cyclic loading, ensuring long service life in rotating equipment
Good Hardenability: Achieves uniform hardness throughout large cross-sections, critical for heavy turbine rotors
Excellent Machinability: Good workability after proper heat treatment, reducing machining costs

Compared to other common turbine steels like 30CrMoNiV5-11, 26NiCrMoV14-5 offers better low-temperature toughness and higher fatigue strength, making it particularly suitable for high-speed gas and steam turbine rotors operating under demanding conditions.

Complete Range of 26NiCrMoV14-5 (1.6957) Forged Products

As a top 26NiCrMoV14-5 China manufacturer, Jiangsu Liangyi produces a full range of forged parts in all kinds of shapes and sizes, and our parts are up to 30 tons in single-piece weight. We have advanced forging equipment to make custom parts according to your drawings and technical specifications. Following are our complete product range for more options.

Turbine Parts

Gas/steam turbine rotor shafts
High/intermediate pressure rotors
Monobloc rotors and shaft ends
Turbine blades, vanes and guide rings
Seal rings and labyrinth rings

Forged Bars & Rods

Round bars, square bars, flat bars
Rectangular bars and rods
Max diameter up to 2,000 mm
Single-piece weight up to 30 tons
Custom lengths and dimensions

Forged Rings & Discs

Seamless rolled rings up to 6,000 mm diameter
Contoured rings and flanged rings
Discs, blocks and plates
Diaphragm and seal rings
Rotor end rings and casing rings

Valve & Fastener Parts

Valve spindles, stems and rods
Valve seats and valve bodies
Double-headed studs and bolts
Custom fasteners and hardware
NACE MR0175 sour service options

Hollow & Cylindrical Parts

Hollow shafts and hollow bars
Hubs, housings and shells
Sleeves, bushes and casings
Pipes, tubes and heavy wall cylinders
Outer diameter up to 3,000 mm

Custom Forgings

Custom shapes per customer drawings
Precision CNC machining available
Full in-house heat treatment
100% NDT inspection
Third-party witness inspection

Advanced 26NiCrMoV14-5 (1.6957) Manufacturing Process

At our Jiangyin forging factory, we follow a rigorous manufacturing process to make sure every 26NiCrMoV14-5 forging meets the highest quality standards. Our integrated production facility covers the entire process from steel melting to final inspection and testing. View our advanced forging equipment for more details.

Jiangsu Liangyi advanced open die forging factory with hydraulic press equipment in Jiangyin Jiangsu China

4.1 Melting and Forging Process

Our 26NiCrMoV14-5 forged steel steam and gas turbine rotor shafts are produced via premium vacuum degassed steel with low silicon content (VCD steel) or electroslag remelted (ESR) steel for important applications. All materials are thoroughly forged using our 2000T, 4000T, and 6300T hydraulic forging presses, 1–5T electro-hydraulic hammers, and 5M seamless ring rolling machines to break down the cast matrix and guarantee consistent grain flow throughout the part. We keep strict control over forging temperature, reduction ratio, and deformation rate to get improved mechanical properties. Any additional secondary steel treatments (such as CAB) are agreed upon in advance with the purchaser on a case-by-case basis.

4.2 Precision Heat Treatment Process

Heat treatment is an important step for high-quality 1.6957 forgings. Our state-of-the-art heat treatment facilities guarantee precise control over temperature and cooling rates to get the needed microstructure and mechanical properties. 26NiCrMoV14-5 forged parts are given liquid quenching (immersed in water or water spray) to get the needed hardness and strength.Surplus material is retained at the transition from the body to the journals, especially where the trepan core will be removed, to prevent distortion during quenching.The rotor shaft is quenched or sprayed until the center temperature of the rotor body drops below 80°C.We document the complete quenching/spraying process, including duration and final temperatures at both the rotor body surface and journals, for full traceability. Tempering is performed at a minimum temperature of 600°C, carefully chosen to achieve the specified 0.2% yield strength while maximizing toughness. The tempering duration and controlled cooling rate are improved to minimize residual stresses. Final heat treatment follows strict parameters: heating speed less than 40°C/h and cooling speed down to 300°C less than 20°C/h. This makes sure residual compressive stresses do not exceed 60 N/mm² at any point on the surface, preventing premature failure in service.

26NiCrMoV14-5 (1.6957) Chemical Composition

The precise chemical composition of 26NiCrMoV14-5 (1.6957) steel is strictly controlled during the melting process to guarantee consistent mechanical properties. Our in-house chemical analysis laboratory verifies the composition of every heat before forging begins. Check our full material catalog for other steel grades.

Table 1: 26NiCrMoV14-5 (1.6957) Chemical Composition (Weight %)
Element	Weight % Range	Function in Steel
Carbon (C)	≤ 0.28	Improves hardness and strength
Silicon (Si)	≤ 0.25	Deoxidizer, improves strength
Manganese (Mn)	≤ 0.40	Improves hardenability and toughness
Phosphorus (P)	≤ 0.010	Impurity, minimized for toughness
Sulfur (S)	≤ 0.010	Impurity, minimized for toughness
Chromium (Cr)	1.40 – 1.80	Improves hardenability and corrosion resistance
Molybdenum (Mo)	0.30 – 0.45	Improves high-temperature strength and toughness
Nickel (Ni)	3.40 – 3.80	Significantly improves toughness and hardenability
Vanadium (V)	≤ 0.15	Refines grain structure, improves strength
Total Aluminum (Al_tot)	≤ 0.025	Deoxidizer, refines grain structure

26NiCrMoV14-5 (1.6957) Mechanical Properties

All mechanical properties are tested using specimens taken from locations specified on the drawing. Tangential test specimens are used for rotor shafts to accurately represent the properties in the direction of maximum stress. The difference between individual values of 0.2% yield strength and tensile strength may not exceed 50 N/mm².

Test rings are not cut free before quality heat treatment, and all tensile and impact specimens are taken at least 40 mm from heat-treated surfaces to avoid measuring the decarburized layer.

Key Mechanical Properties at a Glance

26NiCrMoV14-5 (1.6957) minimum room-temperature properties per EN/DIN standard: Yield Strength ≥ 730 N/mm² · Tensile Strength ≥ 830 N/mm² · Elongation ≥ 15% · Reduction of Area ≥ 50% · Charpy V Impact ≥ 100 J · FATT ≤ −10°C (axial) / ≤ +10°C (radial). These values apply at room temperature (20°C); the steel is rated for service up to 450°C.

Room Temperature Mechanical Properties

Table 2: 26NiCrMoV14-5 Room Temperature Mechanical Properties
Property	Minimum Value	Typical Value	Test Standard
0.2% Yield Strength (N/mm²)	730	780	EN ISO 6892-1
Tensile Strength (N/mm²)	830	920	EN ISO 6892-1
Reduction of Area (%)	50	58	EN ISO 6892-1
Elongation (l₀=5d) (%)	15	19	EN ISO 6892-1
Charpy V-notch Impact Strength (J)	100	135	EN ISO 148-1

Axial Core Properties (Exciter End)

An axial core of at least ∅60 mm is taken from the journal area at the bottom (exciter) end of all turbine rotor shafts. This core is used to verify the mechanical properties at the center of the shaft, which is the most critical location for large rotors.

The purchaser reserves the right to extend the axial core up to below the barrel, which will be based on an altered drawing. All axial cores are clearly marked to ensure traceability to their original position on the shaft.

Table 3: Axial Core Properties (Exciter End)
Property	Minimum Value
0.2% Yield Strength (N/mm²)	≥ 730
Fracture Appearance Transition Temperature (FATT) (°C)	≤ −10
Charpy V-notch Impact Strength (J)	≥ 100

* Average of 3 Charpy V-notch specimens

Barrel Area Radial Properties

Table 4: Barrel Area Radial Properties
Property	Minimum Value
0.2% Yield Strength (N/mm²)	≥ 730
Fracture Appearance Transition Temperature (FATT) (°C)	≤ +10
Charpy V-notch Impact Strength (J)	≥ 70

* Average of 3 Charpy V-notch specimens

26NiCrMoV14-5 (1.6957) Physical & Thermal Properties

While mechanical strength dominates specification sheets, it is the physical and thermal properties of 26NiCrMoV14-5 that govern how a turbine rotor actually performs inside a running machine. Our engineering team works directly with turbine OEMs to ensure these properties align with assembly clearances, thermal growth calculations, and heat flow models — details that are invisible in a standard mill certificate but critical to long-term rotor reliability.

Table 5: 26NiCrMoV14-5 (1.6957) Physical & Thermal Properties (Typical Values at 20°C)
Property	Value	Unit	Engineering Significance
Density	7.84 – 7.86	g/cm³	Critical for rotor mass balance and inertia calculations
Young's Modulus (Elastic Modulus)	206 – 210	GPa	Governs rotor deflection and critical speed calculations
Poisson's Ratio	0.28 – 0.30	–	Used in multi-axial stress analysis of rotor journals
Thermal Expansion Coefficient (20–100°C)	11.5 – 12.0	×10⁻⁶/°C	Determines hot blade tip clearance in assembly stage
Thermal Expansion Coefficient (20–400°C)	12.5 – 13.0	×10⁻⁶/°C	Thermal growth at operating temperature; affects rotor axial positioning
Thermal Conductivity (at 20°C)	33 – 36	W/(m·K)	Influences heat transfer during quenching — lower than carbon steel, requiring controlled spray quench on large rotors
Thermal Conductivity (at 400°C)	28 – 32	W/(m·K)	Reduced conductivity at operating temp — considered in transient thermal stress models
Specific Heat Capacity	460 – 480	J/(kg·K)	Affects ramp-up heating and cool-down time in heat treatment scheduling
Electrical Resistivity	0.27 – 0.30	μΩ·m	Reference for eddy-current NDT calibration during ultrasonic inspection
Hardness (after final heat treatment)	248 – 302	HB	Brinell hardness range corresponding to Rp0.2 730–830 N/mm² after Q+T

⚙️ Why Thermal Conductivity Matters in Forging Production

26NiCrMoV14-5 has approximately 15–20% lower thermal conductivity than plain carbon steel. In practical terms, this means that during spray quenching of a large rotor shaft (∅≥600 mm), the temperature gradient between the surface and core builds up more slowly than it would in a leaner steel grade. At Jiangsu Liangyi, we compensate by extending our spray quench duration and monitoring core temperature with embedded thermocouples — a step that most general forging suppliers skip, but which is essential for achieving the specified axial core FATT values on large rotors.

26NiCrMoV14-5 Mechanical Properties at Elevated Temperatures

Room-temperature data tells only half the story for turbine materials. A gas turbine rotor may operate continuously at 380–450°C for years. At these temperatures, both yield strength and elastic modulus decline — and a design based solely on room-temperature figures would produce unsafe safety margins. The table below reflects typical property retention values for 26NiCrMoV14-5 in the quenched-and-tempered condition (Rp0.2 ≥ 730 N/mm² baseline).

Table 6: 26NiCrMoV14-5 (1.6957) Elevated-Temperature Mechanical Property Retention
Test Temp.	Rp0.2 Yield Str. (N/mm²)	Rm Tensile Str. (N/mm²)	Elongation (%)	Elastic Modulus (GPa)	Retention vs. RT (%)
20°C (Room Temp.)	730 – 830	830 – 950	≥ 15	206 – 210	100%
100°C	700 – 800	800 – 920	≥ 15	200 – 205	~96%
200°C	660 – 760	770 – 890	≥ 16	193 – 198	~91%
300°C	620 – 720	730 – 850	≥ 17	183 – 190	~86%
400°C	585 – 685	690 – 810	≥ 18	172 – 180	~81%
450°C	555 – 655	660 – 780	≥ 18	166 – 175	~77%

* Typical values for Q+T condition (Rp0.2 ≥ 730 N/mm²). Actual values depend on specific heat treatment parameters and cross-section size. Consult our engineering team for design-specific data.

⚠️ The 350°C Temper Embrittlement Trap – What Engineers Must Know

NiCrMoV steels including 26NiCrMoV14-5 are susceptible to reversible temper embrittlement (RTE) if held in or cooled slowly through the 350–500°C temperature range during heat treatment. This phenomenon — driven by grain-boundary segregation of trace phosphorus and tin — can reduce impact toughness by 40–60% without any visible change in hardness or tensile strength. It is therefore invisible to standard hardness checks and only detectable by Charpy V-notch testing. At Jiangsu Liangyi, our tempering furnace protocols mandate a minimum cooling rate of 25°C/h from 600°C down through 300°C. Any deviation is logged, flagged for metallurgical review, and may trigger a re-temper cycle before the forging advances to NDT. This is a non-negotiable quality gate in our production workflow.

26NiCrMoV14-5 (1.6957) International Equivalent Grades

Engineers sourcing turbine rotor material from multiple regions frequently need to verify cross-standard equivalency. The table below maps 26NiCrMoV14-5 to comparable grades across major national and international standards systems. Important: these equivalents are functional approximations — chemical composition limits, testing requirements, and certification routes differ between standards bodies, and direct substitution must always be confirmed by a qualified metallurgist for each specific application.

Table 7: 26NiCrMoV14-5 International Equivalent Grades Cross-Reference
Standard System	Designation / Grade	Equivalency Level	Key Differences
DIN / EN (Germany / Europe)	26NiCrMoV14-5 / 1.6957	✅ Identical	Primary designation; all other grades referenced to this
ASTM (USA)	A470 Class 8 (rotor shafts) / A471 Class 10 (discs)	🔶 Close (functional)	A470/A471 use Ni 3.25–4.00% vs EN 3.40–3.80%; ASTM permits slightly wider Mn range; EN requires lower P/S impurity limits (≤0.010% vs ≤0.012% in ASTM)
BS (United Kingdom)	836M40 (approximate)	🔶 Approximate	836M40 has lower Ni content (3.0–3.5%); toughness requirements differ; BS grades largely superseded by EN harmonized standards post-2000
NF (France)	26NCD14 / 35NCD16 (approximate)	🔶 Approximate	NF 26NCD14 is compositionally close; AFNOR and EN now largely harmonized for pressure vessel forgings
ГОСТ (Russia / CIS)	25ХНМФ (25KhNMF, approximate)	🔶 Approximate	ГОСТ grade has comparable Cr/Ni/Mo/V content; however, ГОСТ testing standards (GOST 9454, 1497) and acceptance criteria differ from EN ISO; always request dual certification for CIS projects
JIS (Japan)	SFVA F52A (functional equivalent for turbine duty)	🔶 Functional only	JIS SFVA grades define application class rather than exact composition; Ni content and impact requirements similar; chemical limits not directly identical
VdTÜV (Germany)	VdTÜV Werkstoffblatt 397	✅ Directly applicable	This German technical association specification is the principal industrial reference for NiCrMoV turbine rotor steels; our manufacturing practice is written to comply with WB 397 in addition to EN requirements

⚠️ Substitution Caution — From Our Engineering Team: After processing over 2,000 turbine rotor forgings across 25+ years, our metallurgists have observed that the most common substitution error involves treating ASTM A470 Cl.8 and EN 1.6957 as fully interchangeable on the same drawing. While the room-temperature tensile properties converge, the impact testing location requirements differ significantly: EN specifies tangential core and axial core test specimens per defined shaft positions, whereas ASTM A470 uses a disk-end quarter-point convention. A rotor certified to ASTM methods on an EN drawing — or vice versa — may satisfy hardness numbers while missing key toughness requirements at the critical bore location. Always specify the exact standard and testing protocol in your RFQ.

Detailed Heat Treatment Parameters for 26NiCrMoV14-5 Forgings

Heat treatment is the single most consequential step in 26NiCrMoV14-5 forging production. The mechanical properties specified in the customer's drawing are not inherent to the steel — they are created by heat treatment. A deviation of ±20°C in tempering temperature, or ±5°C/h in cooling rate, can shift yield strength by 30–50 N/mm² and halve the Charpy impact energy. The following parameters reflect our actual production practice after 25+ years of process optimization on this specific grade.

Soft Annealing (Pre-Forging Blank Preparation)

Ingots and intermediate billets are annealed prior to forging to reduce hardness and improve workability.
Temperature: 630–680°C Duration: 6–10 h (based on cross-section) Cooling: Furnace cool to <250°C then air

Austenitizing (Hardening Heating)

The forged blank is heated uniformly into the austenite phase field to dissolve carbides and homogenize the structure.
Temperature: 840–870°C (target center: 855°C) Heating rate: ≤ 40°C/h above 400°C Hold time: 1 h per 100 mm cross-section (min. 4 h) Atmosphere: Controlled (neutral) to prevent decarburization

Liquid Quenching

Quenching converts the austenite to martensite throughout the cross-section. The method depends on forging geometry and size.
Method (∅ < 600 mm): Water immersion, agitated Method (∅ ≥ 600 mm): Rotating spray ring system Core temperature endpoint: ≤ 80°C before transfer Transfer time (furnace to quench): ≤ 90 seconds

Why spray quench for large rotors: Water immersion of a heavy rotor (≥10 t) causes severe thermal gradients at the surface vs. core, risking surface cracking from residual tensile stress. A rotating spray ring delivers controlled, uniform surface cooling while allowing the core to self-quench at a rate determined by the thermal diffusivity of the steel — producing a more uniform martensite structure through the cross-section.

High-Temperature Tempering

Tempering transforms brittle martensite into tempered martensite, recovering ductility and toughness while retaining strength. This is the most precision-sensitive step in the process.
Temperature range: 600–650°C Target temp (for Rp0.2 730–830 N/mm²): 615–635°C Heating rate: ≤ 40°C/h Hold time: 2 h per 100 mm (min. 8 h for rotor shafts) Cooling from 600°C to 300°C: ≥ 25°C/h (embrittlement prevention) Below 300°C: Air cool permitted

Tempering temperature directly controls the strength-toughness balance. Every 10°C increase in tempering temperature typically reduces Rp0.2 by 15–25 N/mm² while improving Charpy impact by 8–15 J. Our process engineers select the precise tempering temperature for each rotor based on the required Rp0.2 target and the actual cross-section diameter to be tested.

Stress Relief Anneal (After Rough Machining)

After rough machining removes the outer 20–50 mm of material, a stress relief cycle eliminates machining-induced residual stresses before final NDT.
Temperature: 550–580°C Hold time: 4–6 h per 100 mm of remaining wall thickness Cooling rate: ≤ 30°C/h to 300°C, then air Note: This cycle does not alter mechanical properties if below original tempering temperature

⚙️ From Our Process Records: Tempering Temperature vs. Target Strength

Based on our production data from 26NiCrMoV14-5 rotor shafts processed between ∅400 mm and ∅1,200 mm cross-sections: to consistently achieve Rp0.2 ≥ 730 N/mm² at the axial core (∅60 mm specimen), we typically target a tempering temperature of 620–630°C for medium sections (∅400–700 mm) and 610–620°C for large sections (∅700–1,200 mm), where the core transformation rate is slower. This is a refinement not found in standard material datasheets — it comes from process correlation built over hundreds of production lots.

26NiCrMoV14-5 Weldability, Machinability & Surface Treatment

Weldability of 1.6957 Steel

26NiCrMoV14-5 belongs to the high-hardenability, conditionally weldable steel category. Its Nickel, Chromium, Molybdenum, and Vanadium content collectively produce a carbon equivalent (Ceq) of approximately 0.72–0.82, which lies in the "weldable with precautions" range. This means welding is achievable — and is regularly performed for repair of minor surface defects during production — but it requires disciplined procedure controls that are stricter than those for common structural steels.

Table 8: 26NiCrMoV14-5 Welding Parameter Guidelines
Parameter	Recommended Value / Approach	Consequence of Non-Compliance
Carbon Equivalent (Ceq)	Typically 0.72 – 0.82 (IIW formula)	Reference value for preheat calculation; must be stated on MTC
Preheat Temperature	200 – 300°C (minimum 200°C before arc strike)	Cold cracking (hydrogen-induced cracking) in HAZ within 24–72 h post-weld
Interpass Temperature	Maximum 350°C	Exceeding 350°C risks grain coarsening in HAZ; below 200°C risks cold cracking
Filler Metal (SMAW)	AWS E9018-G or equivalent NiCrMo-type low-hydrogen electrode	Mismatched filler causes galvanic microstructure at fusion line; reduced fatigue life
Filler Metal (GTAW/TIG)	AWS ER100S-G or ERNiCrMo type (matching composition)	–
Hydrogen Control	Electrodes baked at 300–350°C, used within 4 h; diffusible H < 5 ml/100 g	Hydrogen trapping at inclusion sites initiates delayed cracking — detectable only by UT after 48+ h
Post-Weld Heat Treatment (PWHT)	580–620°C for 2 h minimum per 25 mm weld section; heat and cool at ≤ 40°C/h	Without PWHT: residual stresses remain; HAZ hardness >350 HV causes SCC risk in service
Post-Weld NDT Hold Time	Minimum 48 h after weld completion before UT/MT inspection	Hydrogen-induced cracks may not propagate to detectable size within 24 h

⚠️ Field Repair Welding on In-Service Rotors

Field repair welding of 26NiCrMoV14-5 turbine rotors (e.g., journal surface restoration after bearing damage) must only be carried out by certified welding engineers following an approved Welding Procedure Specification (WPS) per ISO 15614-1 or ASME IX. PWHT in-situ is often impractical for installed rotors — alternative thermal spray or plasma transferred arc (PTA) hard-facing processes are used in such cases and do not require the same preheat regime. Contact our engineering team if you need technical consultation on repair options for damaged 1.6957 components.

Machinability of 26NiCrMoV14-5 (1.6957)

In the quenched-and-tempered condition at 248–302 HB, 26NiCrMoV14-5 is a moderately difficult-to-machine steel. Its high Nickel content contributes to work hardening during cutting, and the combination of toughness and hardness creates rapid tool wear if incorrect parameters are used. Our in-house CNC machining department has developed cutting parameter libraries specifically for this grade, built from direct production experience on rotor shafts and rings.

26NiCrMoV14-5 / 1.6957 (Q+T, 270 HB)~45%

30CrMoNiV5-11 (comparable turbine steel)~50%

42CrMo4 (1.7225) Q+T general reference~65%

AISI 1045 plain carbon steel (100% baseline)100%

Machinability index = relative material removal rate at equivalent tool life. Internal Jiangsu Liangyi production data.

Table 9: Recommended CNC Turning Parameters for 26NiCrMoV14-5 (270–300 HB, Q+T)
Operation	Tool Grade	Cutting Speed (Vc, m/min)	Feed (mm/rev)	Depth of Cut (mm)	Coolant
Rough Turning	CVD Coated Carbide (P25–P40)	80 – 120	0.4 – 0.8	5 – 12	High-pressure flood, 70–100 bar
Semi-Finish Turning	PVD Coated Carbide (P15–P25)	100 – 150	0.2 – 0.4	1.5 – 4	High-pressure flood
Finish Turning	PVD Coated Carbide (P10) or CBN	120 – 180	0.08 – 0.15	0.2 – 0.8	High-pressure flood or MQL
Deep Hole Boring (axial core)	TiAlN Coated Gun Drill	25 – 45	0.05 – 0.12	Single pass (gun drill)	High-pressure through-tool coolant ≥120 bar
Face / End Milling (journals)	PVD Coated Solid Carbide	70 – 110	0.10 – 0.20 fz	2 – 6 (radial: 40–60% D)	Flood coolant

⚙️ Surface Roughness Target for Journal Bearing Areas

For turbine rotor bearing journal surfaces, we typically achieve Ra 0.4–0.8 μm (N5–N6) through finish turning with CBN inserts, followed by cylindrical grinding to Ra 0.2–0.4 μm (N4–N5) where specified. The journal surface must be free of chatter marks, which act as fatigue initiation sites under high-cycle bending loads. Our CNC lathes are equipped with in-process vibration monitoring to flag any chatter conditions in real time during journal finishing.

Applicable Standards & Specifications for 26NiCrMoV14-5 Forgings

Understanding which standards govern a 26NiCrMoV14-5 forging order matters at every stage: from the RFQ (which standard defines the acceptance criteria?) to certification (which inspection body is accredited to witness testing per that standard?) to customs clearance (what documentation is required for import into the destination country?). Below is the full set of standards under which Jiangsu Liangyi regularly manufactures and certifies 1.6957 forgings, with plain-language explanations of what each standard actually covers.

EN 10222-1:2017 + EN 10222-5:1999 Steel forgings for pressure purposes — Part 1: General requirements; Part 5: Martensitic stainless steels with specified elevated temperature properties Covers the general quality, inspection, and marking requirements for pressure vessel forgings. EN 10222-5 specifically addresses Cr/Mo/V containing steels for elevated temperature service including 26NiCrMoV14-5.

EN 10269:2013 Steels and nickel alloys for fasteners with specified elevated and/or low temperature properties The primary EN reference for 1.6957 fasteners (studs, bolts, nuts) in high-temperature flange connections. Specifies chemical composition, mechanical property requirements, and test methods for 26NiCrMoV14-5 in bolt/stud form up to 160 mm nominal diameter.

VdTÜV Werkstoffblatt (MB) 397 NiCrMoV-Steel for Turbine Rotors and Shafts — German Technical Association Specification The de facto industrial standard for 26NiCrMoV14-5 turbine rotor shafts in Europe. More detailed than EN standards in specifying test specimen locations, acceptable NDT procedures, and documentation requirements for rotor shafts. Many European turbine OEMs (Siemens, MAN, GE) reference WB 397 in their purchase orders.

ASTM A470 / A470M Standard Specification for Vacuum-Treated Carbon and Alloy Steel Forgings for Turbine Rotors and Shafts The primary US standard for turbine rotor shaft forgings. Class 8 (Yield ≥ 725 MPa, Impact ≥ 81 J) is functionally comparable to 26NiCrMoV14-5. We regularly produce A470 Cl.8 certified forgings for US and Canadian power plants. Dual EN/ASTM certification available on request.

ASTM A471 / A471M Standard Specification for Vacuum-Treated Alloy Steel Forgings for Turbine Rotors and Shafts (Rings/Discs) Companion to A470, covering disc and ring forgings for turbine applications. Class 10 is the NiCrMoV variant closest to 1.6957. Used for high/intermediate pressure rotor disc sections.

EN 10204:2004 — Type 3.1 / 3.2 Metallic products — Types of inspection documents Defines the inspection certificate types. Type 3.1 (signed by manufacturer's authorized inspector) is our standard delivery document. Type 3.2 (countersigned by a third-party body such as TÜV, DNV-GL, ABS, LR, BV) is available for safety-critical applications. All our certificates comply with EN 10204:2004.

API 6A (21st Edition) Specification for Wellhead and Christmas Tree Equipment Governs forged valve bodies, valve stems, and pressure-retaining components for oil and gas wellheads. 26NiCrMoV14-5 is used in high-strength valve applications requiring toughness and pressure integrity. We manufacture valve forgings to the material and dimensional requirements specified in purchase orders. Note: API Monogram licensing is held by the equipment assembler/OEM, not the forging supplier. Buyers requiring API-monogrammed end products should specify their OEM's requirements; we manufacture forgings to support API-compliant assemblies.

DNV-GL Rules for Classification / ABS Rules for Materials Det Norske Veritas / American Bureau of Shipping Marine Certification Rules For marine turbine and propulsion shaft forgings, our factory fully supports and cooperates with DNV GL and ABS third-party witness inspection arranged by buyers. We have production experience manufacturing to DNV GL and ABS material requirements, and our quality management system is structured to facilitate efficient third-party audits. Relevant DNV rule sets: DNV Rules for Classification, Ships — Pt.2 Ch.2 Materials and Welding.

ISO 6892-1:2019 / ISO 148-1:2016 / EN 10160:1999 Test Method Standards: Tensile Testing / Charpy Impact / Ultrasonic Testing of Flat Products The testing method standards underpinning all mechanical property data. We have universal testing machines in our lab that are servo-hydraulic and calibrated to ISO 6892-1 and ISO 148-1.Phased-array UT probes are used for ultrasonic inspection according to EN 10228-3 (forgings) and EN 10307 (bars). These probes are better than standard pulse-echo systems.

⚙️ Which Standard Should I Specify in My RFQ?

We recommend this based on our experience processing orders from over 50 countries: For customers in Europe, please include EN 10222-5 or VdTÜV WB 397, as well as an EN 10204-3.1 certificate. Buyers can get EN 10204-3.2 certification through the third-party inspector of their choice.For clients in the US and Canada, please say ASTM A470 Class 8 for shafts or ASTM A471 Class 10 for discs.For offshore and marine uses, please include DNV GL or ABS material requirements in the purchase order. If necessary, buyers can arrange for a witness inspection.For oil and gas valve applications, please specify the required material grade, impact requirements, and NACE MR0175 traceability. Keep in mind that the equipment assembler is in charge of the API Monogram.If you're not sure, our application engineering team will suggest the best set of specifications for your project within 24 hours.

Jiangsu Liangyi's Competitive Advantages as Your 26NiCrMoV14-5 Supplier

As a leading 1.6957 forging manufacturer in Jiangsu China, we offer several unique advantages that set us apart from our competitors:

🏭 Integrated Production Facility

Our 80,000㎡ factory in Jiangyin provides a full range of services from steel melting (30t EAF + LF + VOD), forging, heat treatment, machining, to final inspection, which guarantees complete quality control and faster lead times.

⚙️ Advanced Forging Equipment

We operate 2000T, 4000T, and 6300T hydraulic forging presses, 1–5T electro-hydraulic hammers, and 5M seamless ring rolling machines. And we can produce 26NiCrMoV14-5 forgings up to 30 tonnes in weight and 6 metres in diameter.

🔬 Comprehensive Quality Control

We have advanced NDT equipment (UT, MT, PT), chemical analyzers, mechanical testing machines, and metallography microscopes. We perform 100% inspection on all important parts.

👨‍🔬 Experienced Engineering Team

Our team of metallurgical engineers and forging specialists has over 25 years of experience in manufacturing turbine parts. We provide technical support from material choice to final product delivery.

🌍 Global Export Experience

We have been exporting 26NiCrMoV14-5 forgings to more than 50 countries for over 20 years. We know international standards well and can deal with all export documentation and logistics.

💰 Competitive Pricing

Located in Jiangyin – China's largest forging industry cluster, we benefit from economies of scale and a complete supply chain. So that we can offer high-quality 1.6957 forgings at competitive prices.

26NiCrMoV14-5 (1.6957) Industrial Applications & Project Case Studies

Power Generation Industry (60% of Our 26NiCrMoV14-5 Production)

Case Study 1: 600MW Thermal Power Plant Turbine Rotors – Southeast Asia

Client: Leading power generation company in Thailand
Product: 26NiCrMoV14-5 high-pressure and intermediate-pressure turbine rotors
Challenge: The client needed replacement rotors for their existing 600MW thermal power plant with strict delivery deadlines to minimize downtime.
Solution: We manufactured 4 sets of turbine rotors within 6 months, including complete heat treatment, precision CNC machining, and full NDT inspection.
Result: The rotors have been in continuous operation for over 5 years with zero performance issues, exceeding the client's expectations for reliability.

Case Study 2: Combined-Cycle Power Plant Gas Turbines – Middle East

Client: Major oil and gas company in Saudi Arabia
Product: 1.6957 gas turbine rotor shafts and steam turbine rotors
Challenge: The parts needed to withstand extreme temperatures up to 420°C and high cyclic loading in desert conditions.
Solution: We used premium ESR steel and optimized the heat treatment process to improve high-temperature strength and fatigue resistance.
Result: The turbines have been working well for many years, which has helped the client significantly reduce maintenance costs.

Oil & Gas Industry

Case Study 3: Natural Gas Compressor Turbines – North America

Client: Pipeline operator in the United States
Product: 26NiCrMoV14-5 turbine blades, vanes, and rotor parts
Challenge: The parts needed to resist corrosion from natural gas contaminants and operate continuously for 5 years between overhauls.
Solution: We manufactured the parts with strict control over chemical composition and applied specialized surface treatments for corrosion resistance.
Result: The parts have exceeded their design life, and they have been working well without any corrosion or fatigue for 6 years.

Marine & Heavy Industry

Case Study 4: Marine Gas Turbine Propulsion – Europe

Client: Naval shipbuilder in Germany
Product: 1.6957 turbine parts for marine propulsion systems
Challenge: The parts needed to meet strict DNV-GL marine standards and bear shock and vibration in marine environments.
Solution: We manufactured the parts according to DNV GL material and testing requirements specified in the purchase order, and performed additional shock and vibration simulation testing per the buyer's technical specification.
Result: The propulsion systems have been successfully commissioned across multiple naval vessels and have been working reliably across varied sea conditions.

Frequently Asked Questions (FAQ) About 26NiCrMoV14-5 Forgings

What is 26NiCrMoV14-5 (1.6957) steel?

According to DIN and EN standards, 26NiCrMoV14-5 (EN material number 1.6957) is a high-strength low-alloy (HSLA) Nickel-Chromium-Molybdenum-Vanadium steel.It was made for gas and steam turbine rotor shafts that work at temperatures up to 450°C.The name tells you how much alloy it has: ~3.4–3.8% Nickel, 1.4–1.8% Chromium, 0.30–0.45% Molybdenum, and ≤0.15% Vanadium give it a yield strength of at least 730 N/mm² and better impact toughness.

What is the difference between 26NiCrMoV14-5 and 1.6957?

26NiCrMoV14-5 and 1.6957 refer to the same high-strength low-alloy steel grade. 26NiCrMoV14-5 is the steel designation per DIN standard (chemical symbol notation), while 1.6957 is the material number per EN standard. They have identical chemical composition and mechanical properties.

What is the maximum size of 26NiCrMoV14-5 forgings you can produce?

We can manufacture 26NiCrMoV14-5 forgings up to 30,000 kg in single-piece weight. For round bars, the maximum diameter is 2,000 mm. For seamless rolled rings, the maximum diameter is 6,000 mm. For turbine rotor shafts, the maximum length is 15 meters.

What are the mechanical properties of 26NiCrMoV14-5 steel?

26NiCrMoV14-5 (1.6957) minimum room-temperature properties: 0.2% Yield Strength ≥ 730 N/mm² (typical 780), Tensile Strength ≥ 830 N/mm² (typical 920), Elongation ≥ 15%, Reduction of Area ≥ 50%, Charpy V Impact ≥ 100 J (typical 135 J). For axial cores (exciter end): FATT ≤ −10°C. For barrel radial: FATT ≤ +10°C, Impact ≥ 70 J.

What certifications do you provide for 1.6957 forgings?

Jiangsu Liangyi provides EN 10204-3.1 mill test certificates as standard with every order. EN 10204-3.2 certificates — which require countersignature by an independent third-party inspector — are available when buyers arrange witness inspection by bodies such as TÜV Rheinland, DNV GL, ABS, LR, or BV. Our factory fully cooperates with and welcomes third-party witness inspection. Our facility holds ISO 9001:2015 certification.

What is the typical lead time for 26NiCrMoV14-5 forgings?

The typical lead time for standard 26NiCrMoV14-5 bars and rings is 4–6 weeks. For custom turbine rotor shafts and complex parts, the lead time is 12–20 weeks, depending on size and drawings. We can speed up production for urgent orders.

Can you provide machining services for 1.6957 forgings?

Yes, we provide complete CNC machining services in-house. We can supply 26NiCrMoV14-5 forgings in rough machined, semi-finished, or fully finished condition according to your drawings. We also provide heat treatment and surface treatment services.

What industries use 26NiCrMoV14-5 (1.6957) forgings?

26NiCrMoV14-5 forgings are used in: power generation (gas turbines, steam turbines, generator rotors – 60% of our production), oil and gas (compressor turbines, high-pressure valves, pump shafts), marine propulsion (naval vessel turbines, marine gas turbines), and heavy industrial machinery. We have supplied many clients in Southeast Asia, Middle East, Europe, North America, South America, and Africa.

What are the physical properties of 26NiCrMoV14-5 (density, elastic modulus, thermal expansion)?

26NiCrMoV14-5 (1.6957) key physical properties: Density 7.84–7.86 g/cm³ · Young's Modulus 206–210 GPa · Poisson's Ratio 0.28–0.30 · Thermal Expansion (20–100°C) 11.5–12.0 ×10⁻⁶/°C · Thermal Expansion (20–400°C) 12.5–13.0 ×10⁻⁶/°C · Thermal Conductivity (20°C) 33–36 W/(m·K) · Specific Heat 460–480 J/(kg·K) · Hardness after Q+T: 248–302 HB.

What is the yield strength of 26NiCrMoV14-5 at 400°C or 450°C?

For 26NiCrMoV14-5 (1.6957) in the Q+T condition (Rp0.2 ≥ 730 N/mm² at room temperature): at 400°C, yield strength is typically 585–685 N/mm² (~81% of room temperature value); at 450°C, approximately 555–655 N/mm² (~77% retention). Elastic modulus also decreases to approximately 166–175 GPa at 450°C. Always use the high-temperature values for turbine design calculations, not the room-temperature figures.

Is 26NiCrMoV14-5 equivalent to ASTM A470 Class 8?

26NiCrMoV14-5 (1.6957) and ASTM A470 Class 8 are functional equivalents for most turbine rotor applications, but they are not identical. Key differences: EN 1.6957 specifies Ni 3.40–3.80% while A470 permits 3.25–4.00%; EN requires P and S ≤ 0.010% vs ASTM ≤ 0.012%; impact test specimen locations and acceptance criteria differ significantly between the two standards. We can provide dual EN + ASTM A470 certification on request — contact our engineering team to discuss your specific drawing requirements.

What is the recommended tempering temperature for 26NiCrMoV14-5?

The standard tempering temperature range for 26NiCrMoV14-5 to achieve Rp0.2 ≥ 730 N/mm² is 600–650°C. In practice, the optimal target depends on cross-section size: 620–630°C for medium sections (∅400–700 mm) and 610–620°C for large sections (∅700–1,200 mm). The cooling rate through 300–600°C must be ≥ 25°C/h to prevent temper embrittlement — an important but frequently overlooked requirement for NiCrMoV steels.

Can 26NiCrMoV14-5 (1.6957) be welded?

Yes, 26NiCrMoV14-5 is conditionally weldable. Its carbon equivalent (Ceq ≈ 0.72–0.82) requires: preheat 200–300°C minimum before welding; interpass temperature maintained 200–350°C; low-hydrogen filler (AWS E9018-G or ER100S-G equivalent); and post-weld heat treatment at 580–620°C for minimum 2 h per 25 mm section thickness. Without proper preheat and PWHT, cold cracking and/or residual stress cracking will occur. A minimum 48-hour NDT hold after welding is required before UT inspection.

Which standards cover 26NiCrMoV14-5 forgings?

Main standards for 26NiCrMoV14-5 (1.6957) forgings: EN 10222-5 (pressure vessel forgings), EN 10269 (high-temperature fasteners), VdTÜV Werkstoffblatt 397 (turbine rotor shafts — the primary European industry reference), ASTM A470/A471 (US turbine rotors/discs), API 6A (oil and gas wellhead components), and DNV GL/ABS rules for marine applications. EN 10204-3.1 mill test certificates are issued as standard. EN 10204-3.2 certificates are available when buyers commission third-party witness inspection.

Global Delivery & Logistics from Jiangsu China

As a leading Chinese 26NiCrMoV14-5 forging exporter, we have extensive experience of shipping our products to customers worldwide. Our strategic location in Jiangyin, Jiangsu Province, provides excellent access to main ports in Shanghai, Ningbo, and Qingdao, guaranteeing fast and reliable delivery.

Shipping Options: Sea freight (FCL/LCL), air freight, and express delivery for small urgent orders
Packaging: Standard export packaging with wooden crates and anti-rust treatment to protect products during transit
Documentation: We provide all necessary export documentation including commercial invoice, packing list, bill of lading, certificate of origin, and inspection certificates
Customs Clearance: We can assist with customs clearance procedures in most countries
Lead Time: 2–4 weeks sea freight to most Asian countries, 4–6 weeks to Europe and North America, 6–8 weeks to South America and Africa

Quality Assurance & Certification

Quality is the foundation of our business. At Jiangsu Liangyi, we implement a strict quality management system throughout the entire production process, from raw material inspection to final product testing.

ISO 9001:2015 certified quality management system
100% ultrasonic testing (UT) on all critical components
Magnetic particle testing (MT) and liquid penetrant testing (PT) available
Complete chemical analysis and mechanical property testing for every heat
EN 10204-3.1 mill test certificate provided as standard with every order
EN 10204-3.2 certificates available when buyers arrange third-party witness inspection (TÜV Rheinland, DNV GL, ABS, LR, BV and others welcomed)
Full traceability from raw material to finished product

Contact Us for Your 26NiCrMoV14-5 (1.6957) Forging Needs

Jiangsu Liangyi is your trusted 26NiCrMoV14-5 China manufacturer and 1.6957 Jiangsu supplier. We welcome your inquiries for custom forged steel products according to your drawings and technical specifications. Our engineering team will provide you with a detailed quotation within 24 hours. Contact us today to get started!

Inquiry Email: sales@jnmtforgedparts.com

Phone/WhatsApp: +86-13585067993

Website: www.jnmtforgedparts.com

Address: Chengchang Industry Park, Jiangyin City, Jiangsu Province, China 214400

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