Chromium-molybdenum steels for elevated temperature — see the grade table below for full datasheets and equivalents within this family.
See All Grades ↓Alloy steel tube sheets add chromium and molybdenum to a carbon steel base, improving high-temperature strength retention and creep resistance beyond what carbon steel can provide, at a lower cost than moving to a full stainless or nickel alloy. This makes the family the standard choice for elevated-temperature, moderate-pressure service that doesn't involve significant corrosion risk.
The most common grades are the Cr-Mo series under ASTM A387 — Grade 11 (1.25Cr-0.5Mo) and Grade 22 (2.25Cr-1Mo) are widely specified, with the chromium content chosen based on the design temperature and hydrogen service requirements of the application.
| Grade | Designation | Best For |
|---|---|---|
| A387 Grade 11 (datasheet in development) | 1.25Cr-0.5Mo | Moderate elevated-temperature service |
| A387 Grade 22 (datasheet in development) | 2.25Cr-1Mo | Higher-temperature and hydrogen service |
When the design temperature is high enough that carbon steel's allowable stress drops significantly — alloy steel's chromium-molybdenum content retains strength at temperatures where carbon steel would require excessive thickness.
Yes, in most applications — PWHT relieves welding residual stress and restores the material's designed mechanical properties, and is standard practice for Cr-Mo alloy steel welds.
Grade 22's higher chromium and molybdenum content gives better high-temperature and hydrogen-service performance; Grade 11 is adequate for moderately elevated temperatures at lower cost. The choice depends on your specific design temperature and hydrogen partial pressure.
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