Open-die forging
Bars, blocks, solid and hollow shafts and stepped shafts, to customer drawings.
Grade description
AISI 422 is a high-alloy martensitic stainless steel containing about 12 % chromium with additions of molybdenum, tungsten and vanadium.
Those elements form stable carbides that resist softening during tempering, which gives AISI 422 higher strength at temperature and better creep-rupture behaviour than plain 12 % chromium grades. Carbon is held at 0.20 to 0.25 %, so the grade hardens by conventional quenching and tempering and can be set to several strength levels depending on section, form and application.
Corrosion resistance is moderate. AISI 422 resists the atmosphere, fresh water, steam and the milder acids and alkalis, and it resists scaling and oxidation well, but it is not a replacement for austenitic grades in aggressive chemical service. Corrosion resistance is highest in the hardened and tempered condition.
Compared with Type 403, AISI 422 retains more strength as temperature rises, which is the usual reason for selecting it in turbine and airframe components.
Technical data on this page was last checked on 30 September 2026.
Standards and equivalents
| Standard or system | Designation |
|---|---|
| UNS | S42200 |
| AISI | AISI 422 · AISI 616 (Alloy 616) |
| AMS | AMS 5655 — bar, forging, wire |
| ASTM | ASTM A565 Grade 616 |
| DIN / EN | 1.4935 · X20CrMoWV12-1 |
| SAE | SAE 51422 · SAE J467 |
| OEM | GE B50A125E |
AISI 422 and DIN 1.4935 are treated as interchangeable for turbine blading on most projects, although 1.4935 is normally written to a narrower chromium band of 11.0 to 12.5 %. The governing standard must be named on the order, because AMS 5655 and ASTM A565 carry different test and certification requirements.
Chemical composition
| Element | Minimum | Maximum |
|---|---|---|
| Carbon, C | 0.20 | 0.25 |
| Chromium, Cr | 11.00 | 13.50 |
| Molybdenum, Mo | 0.75 | 1.25 |
| Tungsten, W | 0.75 | 1.25 |
| Nickel, Ni | 0.50 | 1.00 |
| Vanadium, V | 0.17 | 0.30 |
| Manganese, Mn | 0.20 | 0.60 |
| Silicon, Si | — | 1.00 |
| Copper, Cu | — | 0.50 |
| Phosphorus, P | — | 0.040 |
| Sulfur, S | — | 0.030 |
| Iron, Fe | Balance, about 82 % | |
Note on limits. Published limits differ slightly between standards and mills. Some specifications give manganese as 1.00 % maximum and silicon as 0.20 to 0.60 %, and the DIN 1.4935 version is usually written to chromium 11.0 to 12.5 % with molybdenum and tungsten at 0.90 to 1.25 % each. We work to the band named on the drawing and certify against it to EN 10204 3.1.
Mechanical properties
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength | 965 MPa | 140 ksi |
| Yield strength, 0.2 % offset | 793 MPa | 115 ksi |
| Elongation in 4D | 13 % | 13 % |
| Reduction of area | 25 % | 25 % |
| Hardness, Rockwell B | 95 max | 95 max |
| Hardness, Brinell | 290 max | 290 max |
| Modulus of elasticity | 190–210 GPa | 27,557–30,458 ksi |
| Poisson's ratio | 0.27–0.30 | 0.27–0.30 |
These are typical values, not guaranteed minima. Minimum values in the governing specification are lower, and what a heavy forged section will meet depends on section size and tempering route. Test coupon position and property location are agreed before production starts.
Physical properties
| Property | Value | Condition |
|---|---|---|
| Density | 7.75–7.8 g/cm³ | Room temperature |
| Thermal expansion | 11.2 × 10-6 /°C | 0–100 °C |
| Thermal conductivity | 23.9 W/m·K | 100 °C |
| Magnetic response | Magnetic | All conditions |
Heat treatment
Annealing routes
| Route | Cycle | Result |
|---|---|---|
| Martensitic structure | 1350–1430 °F (730–780 °C), soak 4 h, furnace treat, air cool | 21–25 HRC |
| Softer, for machining | 1900 °F (1040 °C), cool to 1275 °F (690 °C), hold 24–48 h, air cool | 90–95 HRB |
| Full anneal | 1600–1650 °F (871–899 °C), slow furnace cool | — |
Hardening, tempering and stress relief
-
Austenitise
Heat to about 1900 °F (1040 °C) and soak. Some specifications give the band as 1875 to 1925 °F (1025 to 1050 °C).
-
Quench
Oil quench. Complex shapes can be marquenched at 650 °F (340 °C), just above the martensite start temperature, to limit distortion and quench cracking.
-
Cool fully
Allow the part to reach room temperature before tempering.
-
Temper
The tempering temperature sets the final strength level. Higher tempering gives lower strength and greater ductility.
-
Stress relieve
1100 to 1150 °F (593 to 621 °C), followed by furnace or air cooling.
Caution. Any thermal cycle above the last tempering temperature will change the mechanical properties, so the stress-relief temperature must be chosen with the temper in mind.
Forging
AISI 422 air hardens, so it must be charged warm, worked hot and cooled slowly.
| Stage | Temperature or action |
|---|---|
| Preheat | 1200–1400 °F (650–760 °C) |
| Forging range | 1900–2150 °F (1040–1175 °C) |
| After forging | Slow cool to room temperature, then anneal and temper |
Caution. A finished forging must not be left to air cool unprotected straight from the finishing heat. Untempered martensite forms and the piece can crack.
In-house capability
Ring rolling
Seamless rolled rings, sleeves, flanges and casings with circumferential grain flow.
Heat treatment
Annealing, quenching, tempering and stress relief with recorded furnace charts.
Testing
Chemical analysis, tensile, impact and hardness testing, ultrasonic and magnetic particle inspection.
Machining and welding
Keep tools sharply ground to avoid galling, hold the speed down, and keep speed and feed steady. Cobalt high-speed tools work well; carbide is preferred on hardened material. The figures below are working guidelines for cobalt high-speed tooling.
| Operation | Tool geometry | Speed, sfpm |
|---|---|---|
| Turning | 8–14° side rake | 90–120 |
| Drilling | 140° point | 40–75 |
| Milling | — | 70–120 |
| Reaming | — | 20–60 |
| Threading | 10–15° back rake | — |
Welding
A controlled procedure is required. Preheating is mandatory to prevent cracking, and the weld needs a post-weld stress relief at 1100 to 1400 °F (590 to 760 °C) for four hours. Filler wire matching AMS 5655 gives the best result. Cold working is limited, so forming should be done hot.
Products supplied
| Form | Items |
|---|---|
| Bars | Forged round bars, square bars, flat and rectangular bars, turbine blade stock |
| Hollow sections | Hollow bars, sleeves, bushings, pipes and tubes, barrels, casings, shells, cylinders, hubs, housings |
| Rings | Forged rings, seamless rolled rings |
| Discs and blocks | Forged blocks, discs, plates |
| Turbine parts | Steam and gas turbine valve spindles, stems and rods |
| Fasteners | Double-ended studs, bolts, high-temperature bolting |
Every shipment carries a mill test certificate to EN 10204 3.1. Third party inspection by SGS, BV, TUV or the customer's own inspector is welcome at our works.
Common questions
What is the maximum service temperature of AISI 422?
AISI 422 is designed for use at temperatures up to 1200 °F (649 °C), and it keeps good creep-rupture properties and resistance to scaling and oxidation at that temperature. The safe limit for a particular part depends on the atmosphere, the loading and the operating cycle, so it should be checked against the design code.
Is AISI 422 the same as 1.4935 or AISI 616?
They describe the same 12 % chromium creep-resistant martensitic stainless steel. AISI 422 is the American name, UNS S42200 the unified number, AISI 616 or Alloy 616 the name used in ASTM A565 Grade 616, and DIN 1.4935 X20CrMoWV12-1 the European equivalent. Composition bands differ slightly between these standards, so the order must name the one that governs.
How does AISI 422 compare with Type 403?
AISI 422 contains molybdenum, tungsten and vanadium that Type 403 does not. These form carbides that resist tempering, so AISI 422 keeps more of its strength as temperature rises and has better creep-rupture properties. It is the normal choice when a 403 blade or bolt cannot hold strength at temperature.
Can AISI 422 be welded?
Yes, but it is difficult and needs procedure control. Preheating is mandatory to prevent cracking, and a post-weld stress relief at 1100 to 1400 °F (590 to 760 °C) for four hours is required. Filler matching AMS 5655 gives the best results. Welding on already hardened and tempered parts changes the properties locally.
How corrosion resistant is AISI 422?
Moderately. It suits applications where maximum corrosion resistance is not the requirement, resisting the atmosphere, fresh water, steam and the milder acids and alkalis, with resistance highest in the hardened and tempered condition. For strongly corrosive or marine service, use an austenitic or duplex grade instead.
What is AISI 422 used for?
Mostly steam turbine blades and buckets. It is also used for gas turbine components, rotors, turbine valve spindles and valve trim, high-temperature bolting, jet engine and other aircraft parts, and high-heat components in power generation, refineries and chemical plant.
Can you supply one-off or small quantity AISI 422 forgings?
Yes. Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory, so we make single pieces, prototypes and production batches of AISI 422 forgings to drawing. Send the drawing or the dimensions, quantity, governing standard and required tests to sales@steelforgepieces.com.
What is needed for a quotation?
Grade, dimensions, quantity, governing standard and any inspection requirement. A quotation normally follows within one working day.
About the supplier
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin City, Jiangsu Province, China. We make forged bars, seamless rolled rings, forged flanges, discs, shafts and custom forged components in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys.
The data on this page is drawn from published grade standards and from our own production experience with AISI 422. Figures are guidelines; the values for a given order are those stated on the mill test certificate.