Steel A387 Gr 22L Class 1-SC (Step-cooled)
Finish state
ASTM A387 Gr 22L Class 1 · UNS K21592
Use step-cooled test material to rate temper embrittlement per API 934-A with the vTr54 + 2.5ΔvTr54 criterion; controlled residuals in the low-carbon chemistry keep the transition shift small.
Values for the SC condition
Other A387 Gr 22L Class 1 tempers and conditions
A387 Gr 22L Class 1 is listed in 5 conditions; see the grade overview at A387 Gr 22L Class 1.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Order fully annealed at 135 HB when maximum machinability and cold formability are needed on forging or weldment blanks that will be re-heat-treated later; strength is at its lowest. | 270 | 450 | 28 | 135 HB | 7.9 % IACS |
N+T + simulated PWHT | Specify these values after simulated minimum and maximum PWHT cycles near 690–705 °C totalling tens of hours, used for heavy-wall reactor acceptance; strength drops slightly while toughness must still pass. | 290 | 465 | 26 | 140 HB | 7.8 % IACS |
SCThis page Step-cooled | Use step-cooled test material to rate temper embrittlement per API 934-A with the vTr54 + 2.5ΔvTr54 criterion; controlled residuals in the low-carbon chemistry keep the transition shift small. | 300 | 470 | 25 | 145 HB | 7.8 % IACS |
N+TDefault Normalized and tempered | Pick the standard Class 1 delivery condition, normalized near 900–950 °C and tempered at 680–730 °C, for heavy-wall hydroprocessing equipment needing high toughness and the best weldability. | 315 | 490 | 25 | 150 HB | — |
Quenched and tempered | Choose water quenching or accelerated cooling plus tempering on thick plate for uniform bainite and better core toughness, with strength held inside the Class 1 range at 380 MPa yield. | 380 | 530 | 24 | 165 HB | 7.6 % IACS |
What is A387 Gr 22L Class 1-SC?
A387 Gr 22L Class 1-SC is A387 Gr 22L Class 1 supplied in the SC condition — use step-cooled test material to rate temper embrittlement per API 934-A with the vTr54 + 2.5ΔvTr54 criterion; controlled residuals in the low-carbon chemistry keep the transition shift small. A387 Gr 22L Class 1-SC has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 86% of steel grades. Elongation at break is 25% and the elastic modulus is 207 GPa (30 Msi). A387 Gr 22L Class 1-SC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). N+T is the default condition FabDigit quotes; SC is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 150 MPa·√m (136.5 ksi·√in), better than 96% of steel grades
- High service temperature — 540°C (1,004 °F), better than 93% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Low strength — 300 MPa (43.5 ksi), worse than 86% of steel grades
A387 Gr 22L Class 1-SC properties
Typical room-temperature values for A387 Gr 22L Class 1-SC; 23 are specific to this condition. Other listed values are A387 Gr 22L Class 1 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A387 Gr 22L Class 1-SC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
A387 Gr 22L Class 1-SC has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 86% of steel grades. Elongation at break is 25% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A387 Gr 22L Class 1-SC is rated for continuous service to 540°C (1,004 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 12.4 µm/m·K (6.89 µin/in·°F).
Electrical3
A387 Gr 22L Class 1-SC conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of A387 Gr 22L Class 1-SC takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 20%.
Manufacturability6
A387 Gr 22L Class 1-SC's machinability is good (56/100, better than 71% of steel grades); weldability good (65/100); formability fair (54/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A387 Gr 22L Class 1-SC
Is A387 Gr 22L Class 1 easy to machine?
Cuts normally in the annealed or normalized-and-tempered condition using carbide tooling at low to moderate speed with heavier feed. Sticking on the cutting edge is moderate; run cutting speeds around 60 % of those used for 1045 steel.
Can A387 Gr 22L Class 1 be welded?
SAW/SMAW/GTAW with 2.25Cr-1Mo (low-carbon) consumables, 150–250 °C preheat with interpass temperature control. Post-weld stress relief at 690–705 °C is mandatory, and weld-metal J-factor/X-bar must be controlled.
Can A387 Gr 22L Class 1 be formed, bent or molded?
Heavy plate is best hot formed at 900–1000 °C followed by re-normalizing and tempering. Cold rolling or bending requires large bend radii and subsequent stress relief.
What surface finishes work on A387 Gr 22L Class 1?
External surfaces are blast cleaned and given high-temperature weather-resistant coating or insulation. Internal walls are usually weld overlaid with 309L/347 stainless against wet H2S and corrosion, with overall PWHT after overlay.
A387 Gr 22L Class 1 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Clow-carbon variant, tighter than Gr 22 (0.05–0.15) | ≤ 0.1 | 0.08 |
| Mn | 0.3 – 0.6 | 0.45 |
| Siheavy-wall H2 service often limits Si≤0.10 vs temper embrittlement | ≤ 0.5 | 0.2 |
| Phydroprocessing orders often limit P≤0.010 and control J factor | ≤ 0.03 | 0.01 |
| Soften additionally limited to S≤0.010 | ≤ 0.03 | 0 |
| Cr | 2 – 2.5 | 2.25 |
| Mo | 0.9 – 1.1 | 1 |
| Febalance; Cu/Ni/Sn/As/Sb residuals per API 934-A J and X factors | balance | — |
A387 Gr 22L Class 1-SC — frequently asked
What is A387 Gr 22L Class 1-SC used for?
A387 Gr 22L Class 1-SC is typically used for heavy-wall hydrocracker reactors, hydrogen service vessels and welded pressure equipment. In short: standard reactor plate steel; low-carbon 2.25Cr-1Mo; improved temper-embrittlement resistance.
What is the yield strength of A387 Gr 22L Class 1-SC?
A387 Gr 22L Class 1-SC has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 86% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A387 Gr 22L Class 1-SC easy to machine?
Reasonably — machinability is rated good (56/100, better than 71% of steel grades). Cuts normally in the annealed or normalized-and-tempered condition using carbide tooling at low to moderate speed with heavier feed. Sticking on the cutting edge is moderate; run cutting speeds around 60 % of those used for 1045 steel.
Can A387 Gr 22L Class 1-SC be welded?
Yes — weldability is rated good (65/100). SAW/SMAW/GTAW with 2.25Cr-1Mo (low-carbon) consumables, 150–250 °C preheat with interpass temperature control. Post-weld stress relief at 690–705 °C is mandatory, and weld-metal J-factor/X-bar must be controlled.
What surface finishes work on A387 Gr 22L Class 1-SC?
External surfaces are blast cleaned and given high-temperature weather-resistant coating or insulation. Internal walls are usually weld overlaid with 309L/347 stainless against wet H2S and corrosion, with overall PWHT after overlay.
Can A387 Gr 22L Class 1-SC be formed, bent or molded?
Heavy plate is best hot formed at 900–1000 °C followed by re-normalizing and tempering. Cold rolling or bending requires large bend radii and subsequent stress relief.
What is the maximum service temperature of A387 Gr 22L Class 1-SC?
A387 Gr 22L Class 1-SC is rated for continuous use to about 540°C (1,004 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A387 Gr 22L Class 1 N+T and A387 Gr 22L Class 1-A?
N+T is the default condition — pick the standard Class 1 delivery condition, normalized near 900–950 °C and tempered at 680–730 °C, for heavy-wall hydroprocessing equipment needing high toughness and the best weldability. A: order fully annealed at 135 HB when maximum machinability and cold formability are needed on forging or weldment blanks that will be re-heat-treated later; strength is at its lowest. Yield strength is 315 MPa in N+T versus 270 MPa in A.
Sources
- ASTM A387/A387M Standard Specification for Pressure Vessel Plates, Alloy Steel, Chromium-Molybdenum — ASTM International (2021)
- ASME BPVC Section II Part D — Properties (Metric) — ASME (2023)
- API RP 934-A Materials and Fabrication of 2.25Cr-1Mo, 2.25Cr-1Mo-0.25V, 3Cr-1Mo Heavy Wall Pressure Vessels — API (2019)
- API RP 941 Steels for Hydrogen Service at Elevated Temperatures — API (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- GB/T 713 (12Cr2Mo1R) — SAC (2014)
- (Mysteel / SMM / 1688) — market survey (2026)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.