Martensitic stainless steel · UNS S42200
ASTM A565 Grade 616 Forgings Also AISI 422, AISI 616, SAE 51422, AMS 5655, EN 1.4935, X20CrMoWV12-1 and JIS SUH 616
Grade 616 is a hardenable 12 % chromium stainless steel with molybdenum, tungsten and vanadium added for creep strength. ASTM A565 limits it to 1200 °F [650 °C] where strength at temperature governs, and calls it useful to 1450 °F [790 °C] for scaling resistance at low stress. Quenched and tempered to Condition HT it holds 140 ksi [965 MPa] tensile and 110 ksi [760 MPa] yield as minimums.
We melt this grade in our own furnaces and forge it in the same works: bars, seamless rolled rings, discs, hollow sections, turbine blade blanks, valve spindles and high-temperature bolting, from 10 kg up to a 30 t single piece.
- Specification
- ASTM A565 Gr 616
- UNS
- S42200
- Type
- Hardenable martensitic Cr-Mo-W-V stainless
- Conditions
- A, T, HT, H
- Service limit
- 1200 °F [650 °C] on strength; 1450 °F [790 °C] on scaling
- Hardness HT
- 302 to 352 HBW
- Delta ferrite
- 5 % max after full heat treatment
- Forms
- Bars, rings, discs, hollows, shafts, blades, studs
- Max piece
- 30,000 kg
- Min order
- 10 kg, no minimum piece count
- Lead time
- 20 to 60 days
Chemical requirements
The A565 window is narrower than the AMS 5655 window on manganese, silicon and chromium, so the two are not freely interchangeable. Name the specification on the order.
| Element | ASTM A565 Grade 616 | AMS 5655 |
|---|---|---|
| Carbon | 0.20 to 0.25 | 0.20 to 0.25 |
| Manganese | 0.50 to 1.00 | 0.20 to 0.60 |
| Silicon | 0.50 max | 1.00 max |
| Phosphorus | 0.025 max | 0.040 max |
| Sulfur | 0.025 max | 0.030 max |
| Chromium | 11.00 to 12.50 | 11.00 to 13.50 |
| Nickel | 0.50 to 1.00 | 0.50 to 1.00 |
| Molybdenum | 0.90 to 1.25 | 0.75 to 1.25 |
| Tungsten | 0.90 to 1.25 | 0.75 to 1.25 |
| Vanadium | 0.20 to 0.30 | 0.17 to 0.30 |
| Copper | not specified | 0.50 max |
| Iron | balance | balance |
Turbine buyers often restrict residuals below the standard, for example P 0.020 % and S 0.010 % as published for X20CrMoWV12-1 bar. Our ladle furnace and vacuum decarburisation route can hold those limits. State them at enquiry.
Mechanical property requirements
A565 recognises four conditions: A annealed, T heat treated for machining, HT heat treated for high-temperature service, and H heat treated. Material supplied in Condition A or T must still be capable of reaching the Condition HT room-temperature properties after the Table 2 heat treatment.
| Condition | Tensile | Yield 0.2 % offset | Elongation 2 in. / 4D | Reduction of area | Charpy V-notch, room temp. | Brinell |
|---|---|---|---|---|---|---|
| A · annealed | — | — | — | — | — | 248 max |
| T · for machining | — | — | — | — | — | 285 max |
| HT · high-temp. service | 140 ksi [965 MPa] | 110 ksi [760 MPa] | 13 % | 30 % | 8 ft-lbf [11 J] | 302 to 352 |
| H · heat treated | 120 ksi [825 MPa] | 85 ksi [585 MPa] | 17 % | 35 % | — | 241 to 285 |
Yield is determined by the offset method of A370. Impact is tested at 70 to 80 °F [21 to 27 °C] on a Type A Charpy V-notch specimen. Hardness is taken at the surface for control only; tensile properties govern acceptance. For cross-sections above 30 in.² [193 cm²] A565 suggests that properties be agreed between purchaser and vendor, which covers most heavy open-die work, so send us the finished section size.
Physical data
| Property | Value |
|---|---|
| Density | 7.8 g/cm³ [0.2817 lb/in³] |
| Elastic modulus | 190 to 210 GPa [27,557 to 30,458 ksi] |
| Poisson's ratio | 0.27 to 0.30 |
| Thermal conductivity at 100 °C | 23.9 W/m·K |
| Pitting resistance equivalent | PREN approx. 17 |
| Stress rupture, 1200 °F, 25 h min | 26 ksi min, per GE B50A951 practice |
The stress rupture line is the GE turbine requirement published for Grade 422 bar, not an A565 requirement. A565 mandates rupture testing only for UNS S42226.
Heat treatment and processing
| Condition | Austenitize | Quench | Temper |
|---|---|---|---|
| HT | 1875 to 1925 °F [1020 to 1050 °C] | Air or oil | 1150 °F [620 °C] min, 2 h min |
| H | 1875 to 1925 °F [1020 to 1050 °C] | Air or oil | 1250 °F [675 °C] min, 2 h min |
Quench medium follows section size. Sections of roughly 3 in. [76.2 mm] and heavier should be oil quenched, and suitable synthetic quenchants may replace oil. If a bar or forging is straightened, a stress-relieving treatment is necessary, about 50 °F [28 °C] below the final tempering temperature.
Forging
Preheat to 1200 to 1400 °F [650 to 760 °C], then forge from 1900 to 2150 °F [1040 to 1175 °C]. Cool slowly to room temperature, then anneal and temper before further work. Our 6,300 t, 4,000 t and 2,000 t presses and five hammers cover the full size range.
Machining
Workable but prone to galling. Sharp tooling, a lower constant cutting speed and a steady feed give the best result, with cobalt high-speed tooling preferred. We rough or finish machine in-house on vertical lathes to 5,000 mm swing and lathes to 14,000 mm between centres.
Welding
Hard to weld, welding group 7.2 under ISO/TR 20172. Preheat to prevent cracking, use matching AMS 5655 filler, then stress relieve at 1100 to 1400 °F [590 to 760 °C] for about 4 hours. We supply one-piece forgings so that welded joints can be avoided entirely.
Corrosion behaviour
Good scaling and oxidation resistance, with resistance to steam, fresh water, atmospheric exposure and mild acids and alkalis. Best corrosion performance comes in the quenched and tempered condition.
Microstructure control
Not more than 5 % delta ferrite after full heat treatment. We report the volume fraction by visual estimation over representative areas, and fall back to E 562 point counting where the estimate is close to the limit.
Examination
Supplementary requirement S1 of A565 allows eddy current, wet or dry magnetic particle, liquid penetrant or ultrasonic examination. Linear indications longer than 1/16 in. [1.5 mm] and over three times their width are not acceptable under LPI or MPI.
Equivalents and cross-reference
| System | Designation |
|---|---|
| UNS | S42200 |
| AISI / SAE | AISI 616, AISI 422, SAE 51422 |
| ASTM | A565 Grade 616, A437 Grade B4B |
| SAE aerospace | AMS 5655, bars, wire and forgings, hardened and tempered |
| EN / DIN | 1.4935, X20CrMoWV12-1 |
| JIS | SUH 616 |
| BS | BS 970 442S19, EN61 |
| General Electric | B50A125, B50A951, B50A951A1 |
| Defence | DOD-F-24669/7, MIL-S-861 |
These names describe the same steel, but acceptance testing and composition windows differ between documents. Order to the specification printed on your own drawing.
Applications and forms we supply
Grade 616 earns its place where a part must hold strength and creep resistance in steam or hot gas near 650 °C while resisting scale. It is stronger at temperature than the plain 12 % chromium grade 403, and the vanadium addition is what carries the creep strength.
Usual work: steam turbine blades and buckets, compressor and turbine rotors, high-temperature fasteners and bolting, inlet valves and valve trim, aero engine parts, and hardware for refineries, thermal power, chemical plant and nuclear service.
Bars and blocks
Forged round, square and flat bars, turbine blade blanks and die blocks, hot rolled, rough turned or machined.
Seamless rolled rings
Ring-rolled on radial-axial mills to 6,000 mm outside diameter, rectangular or contoured section. Smaller rings from 50 mm OD by the upset-and-punch route.
Discs and tube sheets
Solid forged discs, covers and tube sheets up to 5,000 mm machined diameter, supplied proof-machined for volumetric inspection.
Hollows and sleeves
Hollow bars, sleeves, bushings, cylinders and heavy-wall sections bored from solid, to 1,600 mm diameter by 10,000 mm on the deep-hole drilling machine.
Shafts and spindles
Turbine and compressor shafts, rotors, valve spindles and stems, turned to 14,000 mm length with vertical quenching in a 15 m pit furnace.
Bolting
Double-end and double-headed studs, bolts and other high-temperature turbine bolting, heat treated to Condition HT or H as ordered.
Questions
What is ASTM A565 Grade 616?
A hardenable martensitic chromium stainless steel bar and forging grade for high-temperature service, designated UNS S42200 and commonly called AISI 422. It carries 0.20 to 0.25 % carbon and 11.00 to 12.50 % chromium with molybdenum, tungsten and vanadium, and reaches its properties by quenching and tempering rather than by cold work.
How hot can Grade 616 run?
A565 limits these steels to 1200 °F [650 °C] where strength at temperature is a factor. For oxidation and scaling resistance at low stresses they remain useful to 1450 °F [790 °C].
What strength does it reach?
In Condition HT, 140 ksi [965 MPa] tensile and 110 ksi [760 MPa] yield as minimums, with 13 % elongation, 30 % reduction of area and 302 to 352 HBW. In Condition H, with the higher 1250 °F [675 °C] temper, 120 ksi [825 MPa] tensile and 85 ksi [585 MPa] yield, with 17 % elongation and 241 to 285 HBW.
Is AISI 422 the same steel as Grade 616?
Yes. Both names cover UNS S42200. Grade 616 is the A565 designation, 422 is the AISI name used by AMS 5655 and matched by EN 1.4935 or X20CrMoWV12-1, and JIS calls it SUH 616.
Can you melt to a tighter chemistry than the standard?
Yes. The works melts its own steel through an electric arc furnace, ladle furnace and vacuum oxygen decarburisation, with electroslag and vacuum arc remelting available for the cleanest material. Residual limits below the A565 window can be agreed before the heat is made rather than selected from stock afterwards.
What is the smallest order you take?
10 kg, with no minimum piece count. Single prototype forgings are normal work on an open-die press. Lead time usually runs 20 to 60 days depending on size, heat treatment and machining.
Ordering
- Send a drawing, or rough dimensions and quantity, to sales@steelforgepieces.com.
- Name the specification, ASTM A565 Grade 616, AMS 5655 or EN 1.4935, and the delivery condition: A, T, HT or H.
- Confirm testing: analysis, tensile, Charpy, hardness, delta ferrite, any non-destructive examination, and the certificate level.
- We melt, forge, heat treat, machine, inspect and ship from Jiangyin. Approvals held: CCS, BV, DNV, LR and NK.
Data sources
- ASTM A565/A565M-05a (Reapproved 2009), Tables 1, 2, 3 and 4, Sections 1.2, 5.1, 7.1, 8.1 to 8.5 and Supplementary Requirement S1.
- SAE AMS 5655 composition and hardened and tempered property data as published by alloy distributors.
- BGH Edelstahlwerke GmbH data sheet, Grade 422 / X20CrMoWV12-1, for the GE B50A951 stress rupture and hardness practice.
- Published UNS S42200 physical property and fabrication data for density, modulus, conductivity, forging, welding and machining practice.
Figures above are for enquiry and design reference. The specification named on the purchase order, together with the mill certificate issued with the goods, governs acceptance.
Jiangyin Jiangnan Metal Co., Ltd. · No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China · Page reviewed 2 October 2026 · Plain-text version
Need Grade 616 forged to drawing? Quotations normally within one working day.