Jiangsu Liangyi is a professional ISO 9001:2015 certified manufacturer of Grade 660, AISI 660, Type 660, ASTM A453 Grade 660 Class A/B/C/D, GR 660, grade 660A, and ASTM A638 Gr 660 open die forging parts and seamless rolled steel forged rings from Jiangsu, China. With over 25 years of superalloy forging experience, we produce high-quality Grade 660 forged parts that meet strict international standards and custom customer specifications for clients in the USA, Europe, Middle East, Southeast Asia and over 50 countries worldwide.
ASTM A453 Grade 660, also known as AISI 660, Type 660 and meeting ASTM A638 and AMS 5731 standards, is a high-strength iron-based superalloy strengthened by heat treatment. It mainly consists of around 24–27% nickel, 13.5–16% chromium, 1.90–2.35% titanium, 1.00–1.50% molybdenum, 0.25–0.50% vanadium, and about 54% iron as the main part. Titanium and aluminum are the main elements that create strong internal matrix to boost the alloy’s strength.This alloy has outstanding overall performance: its tensile strength ranges from 1000 MPa to 1170 MPa based on grade, and it can work reliably at temperatures from −196°C to 700°C. It also resists oxidation and corrosion well, is non-magnetic, and is easier to weld and machine than nickel-based superalloys. So that ASTM A453 Grade 660 are used for turbine valve parts, nuclear reactor components, high-pressure oil and gas valves, compressor impellers, and aerospace fasteners.
In 25 years of producing this alloy, we have received orders listing it as UNS S66286, Alloy A286, 1.4980, HR51, or even just “the turbine bolt alloy”. All these names refer to the same material. The confusion comes from the fact that this alloy is covered by five different standards, used in three major industries, and has a 60-year engineering history. Below is how to identify it no matter which country or standard your specification uses.
| Designation | Authority | Context & Notes |
|---|---|---|
| ASTM A453 Grade 660 | ASTM International | Primary specification for high-temperature bolting with Class A/B/C/D mechanical tiers. The "Grade 660" refers to the alloy family, not a single heat treatment condition. |
| ASTM A638 Grade 660 | ASTM International | Covers bars, forgings, and forging stock -- the form used by forge shops like us. Same alloy chemistry as A453, but written specifically for wrought forging product forms rather than finished fasteners. |
| UNS S66286 | SAE / ASTM (Unified Numbering System) | The universal alloy identifier used in ERP systems, material databases, and cross-referencing. If you need to specify this alloy unambiguously across standards, use UNS S66286. |
| AISI 660 / Type 660 | AISI (American Iron and Steel Institute) | Legacy designation still widely used in the USA power generation industry, particularly for turbine OEM specifications. Identical chemistry to UNS S66286. |
| Alloy A286 / A-286 | Common trade / industry name | The most common informal name globally. If a customer asks for "A286 forgings," they want this alloy. Originally developed by Allegheny Ludlum in the 1950s; the A286 trade name has outlasted the original company by decades. |
| ASME SA453 | ASME (Boiler & Pressure Vessel Code) | The ASME equivalent of ASTM A453, adopted verbatim under ASME BPVC Section II Part A. Required when the component falls under ASME code jurisdiction (pressure vessels, nuclear construction). If your project is ASME-stamped, specify SA453, not A453. |
| EN 10269 -- 1.4980 | European Committee for Standardization (CEN) | The European equivalent. DIN material number 1.4980 (also written X6NiCrTi26-15). Used in EU-flagged projects, PED (Pressure Equipment Directive) applications, and CE-marked assemblies. Chemical limits are nearly identical to ASTM A453. |
| AMS 5731 / AMS 5734 / AMS 5737 | SAE Aerospace Material Specifications | Aerospace variants specifying bar/billet (5731), sheet/strip (5525), and welding wire (5737). Required for aerospace and defense components where SAE/AMS traceability is mandated. |
| BS HR51 | British Standards (BSI) | British equivalent designation. Encountered in legacy UK power station projects and some Middle East contracts based on British engineering standards. |
Forger's Note on Cross-Standard Ordering: If your purchase order uses a non‑ASTM name such as 1.4980 or UNS S66286, we check that the chemical composition meets both that standard and ASTM A453/A638 before forging. We also include dual‑standard certification on the Mill Test Certificate at no extra cost. This is especially important for projects where parts must meet both ASME code and EU PED requirements at the same time.
Established in 1997, our modern factory covers 80,000㎡ and has 2000–6300 ton hydraulic presses and 5-meter seamless rolling machines. We produce ASTM A453 Grade 660 forgings ranging from 30 kg to 30,000 kg with an annual production capacity of 120,000 tons. We provide a full range of service from steel melting and forging,heat treatment to CNC machining.
We make a full range of ASTM A453 Grade 660 forging parts in all kinds of shapes and custom dimensions to meet the most important industrial requirements. Our production capabilities include:
We specialize in making custom AISI 660 forgings based on customer drawings and technical requirements. Our engineers can help you make parts that work better, cost less, and are more efficient.We can handle both small sample orders and large-scale mass production, and we can change the lead times to meet the needs of your project.
Custom Design Support: Our experienced engineering team provides DFMA (Design for Manufacturing and Assembly) analysis to optimize your part design for forging, ensuring cost-effectiveness and superior performance.
Grade 660 (AISI 660) is a heat-treatable iron-based superalloy with outstanding high strength, strong corrosion resistance and good oxidation resistance up to 700°C. It also keeps excellent non-magnetic properties and strength at low temperatures down to -196°C. This special mix of properties makes it perfect for important uses in the most extreme industries.
Our Type 660 forging parts are made based on the following international standards:
| Class | Tensile Strength (min) | Yield Strength (min) | Elongation (min) | Typical Application |
|---|---|---|---|---|
| Class A | 1000 MPa (145,000 psi) | 690 MPa (100,000 psi) | 20% | General purpose high-temperature applications |
| Class B | 1035 MPa (150,100 psi) | 759 MPa (110,000 psi) | 25% | High-strength bolting and fasteners |
| Class C | 1100 MPa (160,000 psi) | 827 MPa (120,000 psi) | 22% | High-stress structural components |
| Class D | 1170 MPa (170,000 psi) | 896 MPa (130,000 psi) | 20% | Ultra-high-stress critical components |
The chemical composition of our ASTM A453 Grade 660 forged material is tested according to ASTM E354, ASTM E1473, ASTM E2465 and ARP1313 standards for trace elements (lead, bismuth and selenium). Final product analysis conforms to ASTM B880 specifications.
| Element | Content (%) | Element | Content (%) |
|---|---|---|---|
| Iron (Fe) | Balance (~54) | Vanadium (V) | 0.25-0.50 |
| Nickel (Ni) | 24.0-27.0 | Aluminum (Al) | 0.10-0.35 |
| Chromium (Cr) | 13.5-16.0 | Carbon (C) | ≤0.08 |
| Titanium (Ti) | 1.90-2.35 | Phosphorus (P) | ≤0.030 |
| Molybdenum (Mo) | 1.00-1.50 | Sulfur (S) | ≤0.020 |
| Manganese (Mn) | ≤2.00 | Boron (B) | 0.003-0.010 |
| Silicon (Si) | ≤1.00 |
Our AISI 660 forgings are given solution treatment and precipitation hardening to get the following mechanical properties:
| Property | Metric | Imperial |
|---|---|---|
| Tensile Strength (min) | 1035 MPa | 150,100 psi |
| Yield Strength (0.2% offset, min) | 759 MPa | 110,000 psi |
| Elongation at Break (min) | 25% | 25% |
| Reduction of Area (min) | 40% | 40% |
| Hardness (Rockwell C) | 30-36 HRC | 30-36 HRC |
| Hardness (Brinell) | 302-331 BHN | 302-331 BHN |
The physical properties listed below are important for engineers designing joints. Thermal expansion is especially why this alloy was developed: it was first created in the 1950s so Grade 660 bolts and studs would not loosen or over‑stress austenitic stainless steel flanges during temperature changes — both materials expand and shrink at the same rate.
| Physical Property | Value | Engineering Significance |
|---|---|---|
| Density | 7.94 g/cm³ (0.287 lb/in³) | Close to 316 SS (8.0 g/cm³); use for weight estimation in rotating machinery |
| Elastic Modulus (20°C) | 200 GPa (29,000 ksi) | Bolt preload and flange deflection calculations |
| Elastic Modulus (540°C) | 172 GPa (25,000 ksi) | Use this value for high-temperature joint analysis, not room-temperature modulus |
| Thermal Expansion Coefficient (20–600°C) | 16.6 µm/m·°C | Virtually identical to 316L SS (16.5 µm/m·°C) -- this is the alloy's design purpose |
| Thermal Conductivity (100°C) | 14.2 W/m·K | Lower than carbon steel; relevant for heat exchanger tubesheet design |
| Specific Heat Capacity | 502 J/kg·K | Thermal mass calculations in transient heating applications |
| Electrical Resistivity | 0.91 µΩ·m | Relevant for electromagnetic stirring roll and non-magnetic retaining ring applications |
| Magnetic Permeability | ≤1.02 (fully austenitic) | Genuinely non-magnetic in solution-treated and aged condition -- critical for nuclear and measurement applications |
The four classes of ASTM A453 Grade 660 are not just random strength levels. They are four different heat treatment processes that create different material structures, resulting in different levels of strength, toughness, and testing requirements. With 25 years of experience working with this alloy, we explain each class from a material science perspective.
| Class | Solution Treatment | Aging Treatment | Mechanism | Stress Rupture Test Required? | Charpy Impact Requirement |
|---|---|---|---|---|---|
| Class A | 980°C (1800°F) min, air cool | 720°C (1325°F) / 16 h, air cool | Standard solution + single age. γ' precipitates form uniformly. Good balance of strength and ductility. | Yes -- 100 h at 650°C under specified stress | Not specifically required by ASTM A453 |
| Class B | 980°C (1800°F) min, air cool | 720°C (1325°F) / 16 h, air cool | Same cycle as Class A but with tighter tensile and rupture requirements. Higher Ni/Ti ratio ingot selection. Meets NACE MR0175 if hardness ≤35 HRC. | Yes -- 100 h at 650°C under specified stress | ≥40 J at −100°C (Charpy V-notch) |
| Class C | 1010°C (1850°F), air cool | 720°C (1325°F) / 16 h, air cool | Higher solution temperature dissolves more carbides, producing finer γ' on aging. Results in higher tensile strength at slight cost to elongation. | Yes -- 100 h at 650°C under specified stress | Not specifically required by ASTM A453 |
| Class D | None (single-stage direct aging) | 720°C (1325°F) / 16 h, air cool | No prior solution treatment -- the as-forged microstructure is aged directly. This produces the highest strength but relies on controlled forging practice to ensure homogeneity. No stress rupture test required -- the trade-off buyers often don't realize until they read the fine print. | No -- stress rupture test waived for Class D | ≥70 J at −196°C (cryogenic impact, Charpy V-notch) |
Why Class D Has No Stress Rupture Requirement -- and Why It Matters to You: Class D has the highest tensile strength of at least 1170 MPa by using direct aging without solution treatment. As a trade-off, ASTM A453 does not need the 100-hour stress rupture test for Class D, since the single-stage process is less consistent for long-term creep performance. If your parts work at continuous high temperatures above 500°C under constant load, Classes A, B, or C with stress rupture certification are more reliable. If your application needs maximum strength for structural use instead of long-term creep resistance, Class D is the more cost-effective option. We help customers understand this difference during the quotation stage, not after production.
Compared to more expensive nickel-based superalloys like Inconel® 718 (a registered trademark of Special Metals Corporation), Grade 660 works very well at a lower cost for applications up to 700°C. It is easier to shape, weld and machine, while still keeping high strength and corrosion resistance—making it the best choice material for many industrial uses. For applications that need to work at higher temperatures, we also make a variety of nickel-based superalloy forgings.
This is the question our engineering team answers most often. The spec sheet tells you the numbers -- we'll tell you how to read between the lines based on what we've seen go wrong (and right) across 25 years of production.
Our products for sour service oil and gas applications meet NACE MR0175 / ISO 15156 standards. ASTM A453 Grade 660 Class B can meet NACE requirements as long as the final part hardness is tested and confirmed to be no more than35 HRC (≤331 BHN). This hardness level is within the alloy’s normal Class B range, but it must be specifically checked and not just assumed. Our quality control includes hardness testing for every heat-treated batch, and we can provide NACE compliance documents together with the standard EN 10204 3.1 material test certificate when needed.
Critical point on NACE compliance: Even though class D has higher hardness potential, it is still not used for H₂S service because hardness may exceed the NACE limit. If your application needs both maximum strength and sour-service compliance, specify Class B with NACE MR0175 supplemental documentation at the time of order.
Grade 660 (UNS S66286) can be welded, but it does not tolerate bad welding practices well. This alloy hardens through precipitation, so the heat-affected zone (HAZ) may partially age or over-age based on how much heat is applied during welding, which can change local mechanical properties. Below is the guidance we give to customers who machine weld preparations on our forgings before assembly:
Forger's note on weld repair: We can supply forgings that are only solution-treated (pre-aged) if customers weld the assembly before performing final aging. This lets the whole welded assembly go through aging at the same time, creating a consistent microstructure across all parts. Contact our engineering team to talk about this option for your specific use.
Grade 660 has high strength and narrow forging temperature range, so it is difficult to forge. At Jiangsu Liangyi, we have developed special manufacturing processes just forASTM A453 Grade 660 forgings to make sure they all have the best material properties and part quality.
Heat Treatment Expertise: Our heat treatment process is strictly controlled to get the improved balance of strength, ductility and toughness. We use computer-controlled furnaces with consistent temperature distribution to make sure results are consistent across all parts.
Quality is our top priority. We have implemented a full quality management system per ISO 9001:2015 standards to make sure that every GR 660 forging meets or exceeds customer requirements.
Certification & Documentation: All of our Grade 660 forgings come with full Mill Test Certificates (MTC) meeting EN 10204 3.1, which is verified by our own inspection team. EN 10204 3.2 certification set by a third-party agency such as SGS, Bureau Veritas, TÜV or others are available per request. All chemical analysis is performed based on ASTM E354, ASTM E1473, and ASTM E2465 standards.
Specialized experience of forging Grade 660, A286 and high-temperature superalloys since 1997. we have deep process knowledge that others cannot match.
Have 2,000–6,300 ton hydraulic presses and a 5-meter ring rolling machine. Single pieces up to 30,000 kg, rings to 6 m diameter.
Melting, forging, heat treatment (Class A–D), CNC machining and NDT testing under one roof. One purchase order, one point of contact.
Every piece ships with EN 10204 3.1 MTC. Third-party 3.2 witness inspection (SGS, BV, TUV) arranged on request.
Sea, air and express freight to USA, Europe, Middle East, Southeast Asia and beyond. We handle customs documentation end-to-end.
Price directly from the manufacturer, with no markup from the trading company.20–35% cheaper than Western equivalents with similar specs.
DFMA review, class selection guidance, NACE compliance advice and pre-aged forging supply for weld-then-age assembly sequences.
Prototype singles to full-production runs. 4–6 week lead time for raw forgings; 6–8 weeks for machined parts
We have extensive experience in international shipping and can offer door-to-door delivery to customers around the world. We will handle all the steps of shipping, such as packing, filling out paperwork, getting through customs, and moving the goods.We work with the best international freight forwarders to make sure your ASTM A453 Grade 660 forgings get to you safely and on time.We can send your package by sea, air, or express courier.
Jiangsu Liangyi is your trusted partner for high-quality Grade 660, AISI 660, Type 660, ASTM A453 Grade 660 Class A/B/C/D and ASTM A638 Gr 660 forged steel parts. We welcome your inquiries and can provide custom solutions based on your drawings, material specifications and quantity requirements.
To get a detailed quotation, please send us your drawing, material grade, quantity and any special requirements to our email below. Our experienced sales team will respond with a competitive quotation within 24-48 hours.
📧 Inquiry Email: sales@jnmtforgedparts.com
📞 Phone/WhatsApp: +86-13585067993
🌐 Website: https://www.jnmtforgedparts.com
📍 Address: Chengchang Industry Park, Jiangyin City, Jiangsu Province, China