422 Stainless Steel (UNS S42200, ASTM A565 Grade 616)
The turbine bolting stainless: 12-chrome steel alloyed with molybdenum, tungsten and vanadium for creep strength to 1200 °F, heat treated to 140 ksi.
What 422 Stainless is.
Type 422 is a martensitic stainless engineered for steam turbines. To the 12 percent chromium base it adds molybdenum, tungsten and vanadium, each of which forms fine carbides that resist coarsening at temperature, so the alloy keeps its strength and creep resistance to about 1200 °F where 410 has long since softened. It is covered by ASTM A565 as Grade 616 for bars and forgings, with stress-rupture testing available as a supplementary requirement.
We machine 422 turbine studs, bolts, nuts and blades-root hardware from certified A565 bar, heat treated to Condition HT or H, with the microstructure and non-destructive examination supplementary requirements the OEM specifications call for.
Chemical composition.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Carbon | C | 0.20 | 0.25 |
| Manganese | Mn | 0.50 | 1.00 |
| Phosphorus | P | — | 0.025 |
| Sulfur | S | — | 0.025 |
| Silicon | Si | — | 0.50 |
| Chromium | Cr | 11.00 | 12.50 |
| Nickel | Ni | 0.50 | 1.00 |
| Molybdenum | Mo | 0.90 | 1.25 |
| Vanadium | V | 0.20 | 0.30 |
| Tungsten | W | 0.90 | 1.25 |
Values per ASTM A565/A565M-10 Tables 1 and 3 (verified against the specification); 422 is covered by A565 as Grade 616, not by A276. Confirm the edition called out on your purchase order with our estimating team.
Mechanical properties.
| Condition and nominal diameter (in.) | Tensile strength, min (ksi) | Yield strength 0.2% offset, min (ksi) | Elongation, min (%) | Reduction of area, min (%) | Hardness |
|---|---|---|---|---|---|
| Condition A (annealed) — all | — | — | — | — | 248 HBW max |
| Condition T (intermediate) — all | — | — | — | — | 285 HBW max |
| Condition HT (tempered 1150 °F min) — all | 140 | 110 | 13 | 30 | 302 to 352 HBW · 8 ft·lbf |
| Condition H (tempered 1250 °F min) — all | 120 | 85 | 17 | 35 | 241 to 285 HBW |
Values per ASTM A565/A565M-10 Tables 1 and 3 (verified against the specification); 422 is covered by A565 as Grade 616, not by A276. Confirm the edition called out on your purchase order with our estimating team. Impact is Charpy V-notch at room temperature.
Specifications that apply.
How 422 Stainless ships from Houston.
- Hex and heavy hex bolts and cap screws
- Full-thread studs and threaded rod
- Socket head cap and set screws
- Hex, jam and lock nuts
- Washers and spacers
- Machined components from certified bar
422 Stainless fasteners we make.
Every item is manufactured to your drawing or standard in 422 Stainless, imperial or metric, with an EN 10204 3.1 certificate.
What is 422 stainless steel?
422 is a creep-resisting martensitic stainless developed for steam turbine blades and bolting. Molybdenum, tungsten and vanadium form fine, stable carbides that pin the structure at temperature, so the alloy retains useful strength and resists creep to about 1200 °F while keeping the corrosion resistance of a 12 percent chromium steel. ASTM A565 covers it as Grade 616, with a tempered-martensite microstructure limit and optional stress-rupture testing at 1200 °F.
422 in turbine bolting
- Studs and bolts on turbine casings, steam chests and valve bodies where A193 B16 runs out of temperature.
- Blade-root and shroud hardware to OEM drawings, with S1 non-destructive examination and S2 microstructure when specified.
- Nuts in the same material or in a compatible high-temperature grade to avoid differential expansion.
- Stress-rupture testing at 1200 °F and 26 ksi under S3 for the most critical parts.
Testing, certification and marking
- Tensile, hardness and room-temperature Charpy per lot; stress rupture on request
- Grade symbol and manufacturer's identification on every piece
- EN 10204 3.1 material test report with heat number and chemistry; 3.2 witness available
- Magnetic particle or ultrasonic examination per A565 S1 when ordered
ASTM A193 Grade B16
Vanadium-strengthened Cr-Mo bolting that holds its strength where B7 starts to relax — steam turbines, HP steam flanges and hot valve bonnets.
ASTM A453 / ASME SA-453ASTM A453 Grade 660 (A-286)
A-286 bolting for the hottest joints — 130 ksi at room temperature and rated by stress-rupture at 1200 °F, for gas and steam turbines, exhaust and high-temperature process equipment.
ASTM A193 / ASME SA-193ASTM A193 Grade B6 (410 Stainless)
Hardenable 410 stainless bolting — 110 ksi with corrosion resistance B7 lacks, for valve trim, steam and mildly corrosive service.