Chrome Molybdenum Steel – ASTM A387 Grade 22 Class 2
The A387 Grade 22 Class 2 – a grade of chromium-molybdenum alloy – is mainly intended for use in pressure vessels and welded boilers, which are designed for use in elevated temperature service.
This steel grade has excellent heat resistance and anti corrosive/oxidation qualities, and is perfect for using in the oil, gas and chemical industry.
Equivalents of ASTM A387 Grade 22 Class 2
| BS | EN | ASTM/ASME | DIN |
|---|---|---|---|
| 622-515B | 10CrMo910 | A/SA387-22-2 | 10CrMo910 |
Chromium & Molybdenum content (according to the ASTM specification):
| Designation | Nominal Chromium Content (%) | Nominal Molybdenum Content (%) |
|---|---|---|
| A387 Grade 22 | 2.25% | 1.00% |
Tensile Requirements for Class 2 Plates of ASTM A387 Grade 22 Class 2
| Designation | Requirement | Grade 22 |
|---|---|---|
| A387 Grade 22 | Tensile strength, ksi [MPA] | 75 to 100 [515 to 690] |
| Yield strength, min, ksi [MPa]/(0.2% offset) | 45 [310] | |
| Elongation in 8 in. [200 mm], min % | ||
| Elongation in 2 in. [50 mm], min, % | 18 | |
| Reduction of area, min % | 45 (measured on round specimen) 40 (measured on flat specimen) |
Chemical Requirements of ASTM A387 Grade 22 Class 2
| . | . |
|---|---|
| Carbon (C) | % |
| Heat Analysis: Product Analysis: | 0.05 - 0.15 0.04 - 0.15 |
| Manganese (Mn) | % |
| Heat Analysis: Product Analysis: | 0.30 - 0.60 0.25 - 0.66 |
| Phosphorus (P) | % |
| Heat Analysis: Product Analysis: | 0.035 0.035 |
| Sulphur (S) (Max) | % |
| Heat Analysis: Product Analysis: | 0.035 0.035 |
| Silicon (Si) | % |
| Heat Analysis: Product Analysis: | 0.50 max 0.50 max |
| Chromium (Cr) | % |
| Heat Analysis: Product Analysis: | 2.00 - 2.50 1.88 - 2.62 |
| Molybdenum (Mo) | % |
| Heat Analysis: Product Analysis: | 0.90 - 1.10 0.85 - 1.15 |
1. What is the key risk during the Post-Weld Heat Treatment (PWHT) of A387 Grade 22 Class 2 material?
This question focuses on the critical fabrication challenge of applying the mandatory PWHT to an already-tempered material, where exceeding specific time-temperature parameters can lead to over-tempering and a drop in yield strength below the minimum specification.
2. Why would a designer specify Class 2 instead of Class 1 for a Grade 22 reactor?
This question explores the primary engineering rationale, often related to the impracticality of performing a full furnace heat treatment on a massive or complex finished vessel, making the pre-tempered Class 2 plate the necessary choice.
3. How does the Charpy impact toughness of Class 2 compare after welding and local PWHT?
This question addresses a key service performance concern, investigating whether the localized heating from welding and subsequent PWHT can degrade the notch toughness in the heat-affected zone compared to the base metal.
4. What are the main cost and lead-time implications of choosing Grade 22 Class 2 over Class 1?
This question examines the project trade-offs beyond technical specs, as Class 2 plate typically commands a higher price and may have longer procurement lead times due to its additional mill heat treatment step.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.
