27NiCrMoV15-6 Forging Steel Parts | Jiangsu Liangyi Jiangyin China Factory

What is 27NiCrMoV15-6 Creep Resisting Steel?

27NiCrMoV15-6 is a low-alloy, high-strength creep resisting steel grade specifically developed by the German Steel Institute (SEW) for large forgings used in turbine and generator production. The designation follows the DIN German naming convention: "27" indicates the nominal carbon content of 0.27%; "Ni15" indicates approximately 3.75% nickel (15 ÷ 4); and "CrMoV" identifies the secondary alloying elements, with "6" representing approximately 1.5% chromium (6 ÷ 4). The combination of nickel, chromium, molybdenum, and vanadium gives this grade its characteristic high-temperature strength and creep resistance.

Through alloying with 3.40–4.00% nickel, 1.20–1.80% chromium, 0.25–0.45% molybdenum and 0.05–0.15% vanadium, this engineered steel delivers a balanced property profile that sets it apart from conventional turbine-grade steels. Main performance advantages include exceptional high-temperature tensile strength, reliable creep resistance at service temperatures up to 550°C, sound low-temperature toughness down to −20°C, and outstanding thermal fatigue resistance under repeated cyclic thermal and mechanical loading. Elevated nickel content acts as the core differentiating element. It substantially enhances deep-section hardenability for heavy forgings, enables consistent martensitic transformation across full cross-sections exceeding 1,500 mm, and optimizes ductile‑to‑brittle transition behaviour when benchmarked against low-nickel alternative turbine steel grades.

Main Advantages of 27NiCrMoV15-6 Over Conventional Turbine Steels

• 30% higher creep rupture strength than standard carbon steels at 500 °C, enabling thinner-wall designs and weight reduction in turbine rotor assemblies
• Excellent resistance to stress corrosion cracking (SCC) in wet steam and high-sulfur oil environments
• Uniform mechanical properties throughout large cross-sections up to 2,000 mm in diameter — an important advantage over lower-nickel grades where core properties degrade in thick sections
• Good hardenability and machinability after quenching and tempering (Q&T), with surface hardness typically in the 270 – 320 HB range
• Cost-effective alternative to high-nickel superalloys for mid-temperature (450 – 550 °C) applications in combined-cycle and steam turbine systems
• Better resistance to temper embrittlement than 30CrMoNiV5-11 due to the higher nickel-to-chromium ratio and strictly controlled P and Sn impurity levels

27NiCrMoV15-6 Chemical Composition (SEW 555:1984 Standard)

The chemical composition of 27NiCrMoV15-6 is tightly controlled under SEW 555:1984 to ensure consistent hardenability and high-temperature performance across all forging sizes. We make our steel ingots at Jiangsu Liangyi in our own electric arc furnace (EAF), ladle furnace refining (LF), and vacuum degassing (VOD) facility. The levels of phosphorus and sulfur are usually much lower than the standard maximums.

27NiCrMoV15-6 Mechanical Properties (Quenched & Tempered)

The mechanical property requirements below apply to the Q&T condition per SEW 555:1984. Test specimens are taken from the worst-case position (deepest point from the surface, transverse direction) to guarantee that the entire cross-section meets these minimum values.

*Typical achieved values represent our production track record on 500 – 1,500 mm diameter forgings. Actual values reported on the EN 10204 3.1 inspection certificate supplied with each delivery.

27NiCrMoV15-6 Physical & Thermal Properties vs. Temperature

The following physical and thermal properties are essential for engineering calculations including thermal stress analysis, turbine rotor dynamics simulation, and heat transfer modeling. Engineers are advised to use the temperature-dependent values from the table rather than single ambient-temperature figures in high-temperature design calculations, as properties such as elastic modulus and thermal expansion change significantly between 20 °C and 550 °C.

27NiCrMoV15-6 High-Temperature Creep Rupture Strength Data

Creep rupture strength — the stress that causes fracture after a specified time at elevated temperature — is the single most important design property for turbine rotor shafts and steam valve components. The data below represents the stress to cause rupture in 100,000 hours (approximately 11.4 years of continuous operation) for 27NiCrMoV15-6 in the Q&T condition, derived from time-temperature parametric analysis of long-duration test data.

These figures are representative of forgings in the 300 – 800 mm effective diameter range. Engineers should apply a safety factor appropriate to their design code (typically 1.5× per EN 13480 or ASME B31.1) and note that creep strength is sensitive to section size: larger forgings with slower through-thickness cooling may exhibit 5 – 10% lower creep strength at the core compared to the values shown here.

Interpreting Creep Data: Guidance for Turbine Engineers

The 100,000-hour rupture stress of 220 MPa at 500 °C is the benchmark value cited most frequently in turbine procurement specifications. When comparing 27NiCrMoV15-6 against alternative grades, this number captures long-term structural reliability. Practically:

• At 450 – 500 °C: 27NiCrMoV15-6 is the preferred choice for HP and IP turbine rotor shafts in subcritical and supercritical steam plants, offering an excellent balance of creep strength, toughness, and deep hardenability
• At 500 – 520 °C: The grade remains serviceable but approaches its practical limit; thermal cycling duty cycles and the number of cold starts must be carefully evaluated in fatigue-creep interaction assessments
• Above 550 °C: 9 – 12% chromium martensitic steels (e.g., X12CrMoWVNbN10-1-1 or X10CrMoVNb9-1) are required; 27NiCrMoV15-6 should not be specified for primary structural duty above this temperature in new designs

27NiCrMoV15-6 International Equivalent Grades

Because 27NiCrMoV15-6 was developed specifically under the German SEW 555 standard for large turbine forgings, no other national standard has an identical equivalent. The grade’s combination of high nickel content (3.5 – 4.0%), controlled vanadium addition, and the ultra-low P/S requirements places it in a unique category. When procurement documents or engineering drawings reference this grade across different national standards, the following closest approximate equivalents are used in practice. Engineers must always verify actual composition and property requirements before substituting.

Multi-Grade Choice Matrix: 27NiCrMoV15-6 vs Competing Turbine Steel Grades

Choosing the right turbine forging steel needs balancing creep strength, low-temperature toughness, hardenability (important in large cross-sections), machinability, weldability, and cost. The matrix below compares 27NiCrMoV15-6 against the four most commonly considered alternatives across the full range from general-purpose grades to advanced high-chromium steels. The highlighted column is 27NiCrMoV15-6.

When to Choose 27NiCrMoV15-6: A Practical Decision Guide

• Choose 27NiCrMoV15-6 when your component operates continuously in the 450 – 550 °C range, requires uniform properties throughout a cross-section exceeding 500 mm, or demands excellent low-temperature toughness (e.g., cold-climate installation or frequent startup-shutdown cycling)
• Choose 26NiCrMoV14-5 when the maximum section size exceeds 1,800 mm and the slightly lower creep strength at core positions is acceptable per your finite element analysis
• Choose 30CrMoNiV5-11 when operating temperature exceeds 540 °C but budget constraints rule out 9 – 12%Cr steels, and the smaller cross-section (≤ 1,200 mm) allows adequate through-hardening
• Choose 34CrNiMo6 for general-purpose mechanical applications below 480 °C where creep is not the primary design driver and cost is a priority
• Choose X12CrMoWVNbN10-1-1 when your design steam temperature exceeds 565 °C (ultra-supercritical plant) and the premium price is justified by the thermodynamic efficiency gain

27NiCrMoV15-6 Welding Guidelines & Parameters

Welding 27NiCrMoV15-6 demands rigorous procedure qualification and strict parameter control due to the steel’s high hardenability and susceptibility to hydrogen-induced cold cracking (HICC) in the heat-affected zone (HAZ). The parameters below are based on our production experience welding this grade for turbine component repair, shaft coupling attachment, and end-cap welding on hollow forgings. All procedures must be qualified per ISO 15614-1 (or ASME Section IX) before production welding commences.

Precision Heat Treatment Parameters for 27NiCrMoV15-6

To achieve optimal mechanical properties, all 27NiCrMoV15-6 forgings at Jiangsu Liangyi undergo a strictly computer-controlled quenching and tempering (Q&T) process. Each furnace zone is independently controlled with calibrated type K or type N thermocouples, and complete real-time temperature records are retained as part of the EN 10204 3.1 inspection documentation package. Our heat treatment capability covers single pieces up to 30 tons and 6,000 mm in length in our car-bottom furnaces.

1. Stress Relief Anneal (after rough forging, if required): Heat to 550 – 600 °C and hold for 1 – 3 hours per 100 mm to relieve residual stresses and improve machinability before finish machining or initial inspection
2. Preheating: Slowly heat to 600 – 650 °C at ≤ 60 °C/hour and hold for 1 – 2 hours per 100 mm of maximum cross-section thickness to eliminate temperature differentials in large sections that could cause thermal cracking
3. Austenitizing: Heat to 860 – 900 °C at ≤ 80 °C/hour and hold for 1.5 – 3 hours per 100 mm of thickness to ensure complete, uniform austenite formation throughout the entire forging cross-section
4. Quenching: Transfer to quench tank within 30 seconds of furnace exit; quench in oil (preferred) or polymer quenchant (PAG concentration adjusted for section size) to achieve a fully martensitic microstructure; minimum quench rate to 300 °C must exceed 10 °C/minute at the core
5. Intermediate Temper (heavy sections > 800 mm dia.): Apply an intermediate temper at 550 – 580 °C for 2h per 100 mm before final tempering to reduce hydrogen content and relieve quench stresses, improving final toughness
6. Final Tempering: Heat to 580 – 650 °C and hold for 2 – 4 hours per 100 mm of thickness, followed by controlled air cooling at ≤ 50 °C/hour to 300 °C, then free air cooling to ambient — getting the target balance of strength, toughness, and creep resistance

Complete Range of 27NiCrMoV15-6 Forged Products & Size Specifications

At Jiangsu Liangyi, we manufacture a full spectrum of custom 27NiCrMoV15-6 forged parts to your detailed drawings and technical specifications. Our advanced forging and inspection equipment enables us to produce components across the full size range below. Components outside these ranges may be feasible — contact our engineering team for a feasibility review.

Forged Bars — Size Specifications

Seamless Rolled Rings — Size Specifications

Turbine Rotor Shafts — Size Specifications

Discs, Blocks & Other Forging Shapes

27NiCrMoV15-6 Industrial Applications & Proven Global Success Cases

Ready to discuss your 27NiCrMoV15-6 forging project? Contact our sales team for a customized solution!

Advanced Manufacturing Process for 27NiCrMoV15-6 Forgings

Our state-of-the-art manufacturing facilities enable us to produce 27NiCrMoV15-6 forgings with consistent, high-quality results. Our complete in-house process includes:

1. In-House Steel Melting: Our own electric arc furnace (EAF) + ladle refining furnace (LF) + vacuum degassing (VOD) process, achieving ultra-low impurity levels (P ≤ 0.007%, S ≤ 0.004%) and full melt traceability from heat number to finished forging
2. Controlled Ingot Casting: Solidification in protective atmosphere to minimize macro-segregation, porosity, and inclusions
3. Multi-Stage Open Die Forging: 2,000 – 6,300-ton hydraulic presses with a minimum 3:1 forging ratio to refine grain structure and close internal voids
4. Precision Heat Treatment: Computer-controlled Q&T with independently regulated furnace zones, calibrated thermocouples, and full temperature traceability records
5. CNC Machining: High-precision 5-axis CNC machining to dimensional tolerances as tight as ±0.02 mm
6. Rigorous Quality Inspection: Ultrasonic testing, magnetic particle testing, hardness survey, chemical analysis, and mechanical testing carried out by our in-house qualified NDT and QC team before every dispatch

Industry Standards & Compliance

All our 27NiCrMoV15-6 forgings are manufactured and tested in accordance with the following international standards and customer-specified requirements:

• SEW 555:1984 — Steels for larger forgings for turbine and generator components (material specification)
• EN 10228-3 — Non-destructive testing of steel forgings: ultrasonic testing (UT inspection standard)
• ASTM A388 — Standard practice for ultrasonic examination of steel forgings
• ASTM E709 — Standard guide for magnetic particle testing
• ISO 9001:2015 — Quality management systems (Jiangsu Liangyi is ISO 9001:2015 certified)
• EN 10204 — Metallic products: types of inspection documents. EN 10204 Type 3.1 inspection certificate issued as standard with every delivery. EN 10204 Type 3.2 (countersigned by buyer-nominated independent TPI body) available upon arrangement.

Comprehensive Quality Assurance System

Quality is the foundation of our business at Jiangsu Liangyi. Every 27NiCrMoV15-6 forged part undergoes strict quality control at every stage of the production process. We provide an EN 10204 Type 3.1 inspection certificate as standard with every delivery, which includes:

• Complete identification and order information
• Material designation and heat number
• Full chemical analysis including trace elements (As, Sn, Sb, Cu, N)
• Ingot weight, L/D ratio, and forging reduction data
• Detailed heat treatment records (temperature, time, cooling rate, and all reheat treatments)
• Mechanical test results with specimen locations
• Residual stress measurement results (if required by order)
• Ultrasonic and magnetic particle inspection reports
• Final dimensional inspection data sheet

EN 10204 Type 3.2 certification (countersigned by an independent inspection body such as SGS, BV, TÜV Rheinland, DNV, or ABS) is available upon request — please specify at time of order.

27NiCrMoV15-6 Fatigue & Fracture Properties

Startup-shutdown sequences, speed transients, and rotating bending loads put cyclic stress on the turbine rotor shafts and compressor discs. It is just as important to know how 27NiCrMoV15-6 behaves when it is tired and broken as it is to know how it behaves when it is still. The data below covers fatigue endurance, fracture toughness, and crack propagation parameters — all of which must be considered in fail-safe damage-tolerant design per API 579-1 / ASME FFS-1 or EN 13445-8.

Practical Fatigue Design Guidance for 27NiCrMoV15-6 Components

The high-nickel content of 27NiCrMoV15-6 confers two specific advantages in fatigue-critical applications compared with lower-nickel turbine steels. First, it substantially reduces the ductile-to-brittle transition temperature (DBTT), shifting the fracture mode transition to below −40 °C in well-heat-treated material — this means the steel maintains high fracture toughness even during cold startup conditions where thermal shock could cause brittle fracture in less tough grades. Second, the high KIC values (100 – 135 MPa·m½) result in a generous critical crack size (typically 5 – 9 mm for surface semi-elliptical cracks at working stress), providing substantial margin for in-service inspection programs to detect defects before they reach critical size.

Temper Embrittlement Assessment: J-Factor, X-Factor & Step Cooling Testing

Temper embrittlement is the most critical metallurgical degradation mechanism in Ni-Cr-Mo-V turbine steels in long-term service at 350 – 550 °C. It occurs when tramp elements (primarily phosphorus, antimony, tin, and arsenic) segregate to prior austenite grain boundaries during slow cooling or extended service at these temperatures, raising the ductile-to-brittle transition temperature (DBTT) without any detectable change in room-temperature strength. Because turbine rotor shafts remain in service for 20 – 40 years, temper embrittlement resistance is a mandatory qualification criterion for this grade. Two quantitative indices are used globally:

The Bruscato X-Factor (Temper Embrittlement Susceptibility Index)

The Bruscato X-factor quantifies the combined effect of the four most potent embrittling tramp elements on grain-boundary segregation kinetics:

The Watanabe-Iwasaki J-Factor (Grain-Boundary Segregation Risk)

The J-factor also accounts for silicon and manganese, which act as co-segregants that enhance the grain-boundary accumulation of phosphorus and tin. It is defined as:

Step Cooling Test Capability

For clients requiring quantitative evidence of temper embrittlement resistance beyond the chemical index approach, Jiangsu Liangyi offers step cooling simulation testing on production or separately forged test blocks from the same heat. The step cooling cycle (per SEP 1923 or equivalent buyer specification) thermally simulates 20 – 40 years of service at 480 °C in approximately 10 days of controlled furnace cycling. Pre- and post-step-cooling Charpy transition curves are generated and the DBTT shift (ΔDBTT) is reported in the EN 10204 3.1 inspection document. Our consistently low X-Factor (6 – 10) and J-Factor (25 – 45) translate into step-cooling DBTT shifts well below 25 °C — meeting the most demanding premium turbine forging specifications.

Carbon Equivalent & Weldability Assessment for 27NiCrMoV15-6

The carbon equivalent (CE) quantifies the combined hardenability effect of all alloying elements and is the primary index used to assess cold cracking risk during welding. Because 27NiCrMoV15-6 contains high nickel (3.7%), significant chromium (1.5%), and molybdenum (0.35%) in addition to 0.27% carbon, its CE values are substantially higher than those of structural steels — explaining why this grade demands the strict preheat and PWHT requirements described in our welding section.

Three commonly used CE formulae are shown below, calculated for a representative heat analysis (C=0.27%, Mn=0.30%, Si=0.10%, P=0.007%, Cr=1.50%, Ni=3.70%, Mo=0.35%, V=0.10%, Cu=0%):

Graville Diagram Position

Plotting 27NiCrMoV15-6 on the Graville weldability diagram (CE vs. carbon content) places this grade firmly in Zone III — the "difficult to weld" region where both the carbon content and the hardenability are high, making hydrogen-induced cracking (HIC) a serious risk without proper preheat, low-hydrogen consumables, and mandatory PWHT. This is consistent with the welding parameters specified earlier (preheat 150 – 200 °C, PWHT 580 – 630 °C) and highlights why all welding procedures must be rigorously qualified before production welding. Zone III steels are not inherently impossible to weld — they simply require metallurgically sound procedures, and 27NiCrMoV15-6 has an excellent field service record when these procedures are followed.

27NiCrMoV15-6 Machinability & CNC Cutting Parameters

With a hardness of 280 – 310 HB in the Q&T condition, 27NiCrMoV15-6 is a moderately challenging material to machine. Its high nickel content increases work-hardening tendency compared to lower-alloy turbine steels, and the stable carbide precipitates (principally Mo₂C, V₄C₃, and Cr₃C₂) are significantly harder than the ferritic matrix. However, the material is not unusually difficult by the standards of industrial alloy steels: with the correct cutting parameters and tooling, 27NiCrMoV15-6 can be machined to tight tolerances (±0.02 mm) and fine surface finishes (Ra ≤ 1.6 μm) routinely. The table below provides our in-house production machining parameters as a guide to customers performing their own final machining:

Key Machinability Tips for 27NiCrMoV15-6

• Avoid work-hardening: Never make zero-feed dry "rubbing" passes; always maintain positive feed to ensure the cutting edge engages fresh material below the work-hardened layer from the previous pass
• Coolant strategy: Use water-soluble coolant (5 – 8% concentration) for all wet turning and milling operations. Dry machining is possible with coated carbide for roughing but significantly shortens tool life. For grinding, use ample flood coolant (≥ 100 L/min) to prevent surface burning and the formation of untempered martensite which would cause premature bearing failure
• Thermal damage detection: After bearing journal grinding, nital etch inspection (per ASTM B487) should be performed to verify the absence of grinding burn or rehardening zones. We recommend specifying nital etch as part of the acceptance criteria for all finish-ground bearing surfaces.
• Pre-machining stress relief: For tight-tolerance finish machining (±0.02 mm or finer), always perform a low-temperature stress relief (550 – 580 °C for 2 h) between rough and finish machining operations to relax residual stresses introduced by rough turning. Skip this step and dimensional drift during finish machining will exceed tolerances

NDT Acceptance Criteria & Inspection Details for 27NiCrMoV15-6 Forgings

Non-destructive testing (NDT) is performed on every 27NiCrMoV15-6 forging we produce as part of our standard quality assurance, not as an optional add-on. Our NDT capability includes ultrasonic testing (UT), magnetic particle testing (MT), liquid penetrant testing (PT), hardness testing, and visual inspection (VT). The acceptance criteria below represent our standard production requirements; buyers may specify more stringent levels by reference to a specific acceptance class in the standards listed.

UT Reference Block Configuration (ASTM A388 / EN 10228-3 Comparison)

For shafts and round bars, our UT is performed using both longitudinal (compression) and shear wave probes, with reference calibration on a block machined from the same or equivalent 27NiCrMoV15-6 material at similar hardness. The calibration reflectors are:

• Flat-bottom holes (FBH): 2 mm and 3 mm diameter at depths of T/4, T/2, and 3T/4 (where T = component thickness or radius), per EN 10228-3 QL3/QL4
• Side-drilled holes (SDH): 1.5 mm diameter at T/4 and T/2 depth, per ASTM A388 Method 1 — used for longitudinal defect scanning on long shafts
• Back-wall echo technique: Used for attenuation characterization; forgings with back-wall signal loss > 6 dB compared to reference block are rejected or subjected to supplementary angle-probe scanning to locate the absorbing zone

27NiCrMoV15-6 Procurement Checklist & RFQ Guide

To ensure our quotation exactly matches your technical and commercial requirements, please include the following parameters in your request for quotation (RFQ). Incomplete RFQs are the most common cause of delivery delays — not manufacturing time. The table below serves as a procurement checklist for engineering teams issuing purchase orders for 27NiCrMoV15-6 forgings. Items marked ★ are mandatory; items marked ○ are recommended for quality-critical applications.

Typical Lead Times by Product Type

The following standard lead times assume prompt receipt of a complete RFQ, drawing approval, and advance payment confirmation. Rush options (at additional cost) are available for most product types:

• Forged Bars (all cross-sections, as-forged or rough-machined): 4 – 6 weeks standard; 2 – 3 weeks rush if material is in stock
• Seamless Rolled Rings (OD up to 2,000 mm): 6 – 8 weeks standard; 4 – 5 weeks rush
• Seamless Rolled Rings (OD 2,000 – 6,000 mm): 10 – 14 weeks standard (large ring rolling requires dedicated scheduling)
• Custom Turbine Rotor Shafts (rough-forged + rough-machined): 8 – 12 weeks standard; 6 – 8 weeks rush
• Custom Turbine Rotor Shafts (finish-machined per drawing): 12 – 16 weeks; includes finish machining, NDT inspection, and final dimensional report
• Prototype / Single-piece Feasibility Forgings: Engineering review required first; typically 6 – 10 weeks from drawing approval

GEO Advantages: Why Choose Our Jiangyin Forging Factory in China

We are one of the best manufacturers of 27NiCrMoV15-6 in China. Our factory is in Jiangyin, which is a well-known center for the heavy forging industry. Following are our main advantages:

• Complete Industrial Chain: Access to high-quality raw materials, advanced forging equipment, and skilled labor within a 50 km radius
• Cost-Effective Solutions: 20 – 30% lower manufacturing costs compared to European and North American forging factories without compromising quality
• Fast Delivery: Standard lead time of 4 – 6 weeks for forged bars and 8 – 12 weeks for custom-shaped forgings
• Global Logistics Support: Proximity to Shanghai Port (only 120 km away) ensures efficient sea freight to all major ports worldwide
• Multilingual Technical Support: English-speaking engineers available for on-site inspection and technical consultation
• Customization Capability: Ability to produce non-standard sizes and shapes according to your detailed drawings and technical specifications

Shipping & Packaging Options for Global Clients

We offer flexible shipping and packaging options to ensure your 27NiCrMoV15-6 forgings arrive at your facility safely and on time:

• Packaging: Standard seaworthy packaging, including wooden crates, pallets, and waterproof wrapping; custom packaging available upon request
• Shipping Methods: Sea freight (FCL/LCL), air freight, and express courier (DHL, FedEx, UPS) for urgent small orders
• Shipping Terms: FOB Shanghai, CIF, CFR, EXW, and other Incoterms 2020 available
• Documentation: Complete shipping documentation, including commercial invoice, packing list, bill of lading, and EN 10204 3.1/3.2 inspection certificate

Frequently Asked Questions (FAQs) About 27NiCrMoV15-6 Forgings