ASTM A387/A387M Grade 21L Class 1 Introduce
ASTM A387/A387M is a standard that covers chromium-molybdenum alloy steel plates intended primarily for welded boilers and pressure vessels designed for elevated temperature service. Commonly referred to as chrome-moly steel, the composition of this alloy includes a high percentage of chromium, molybdenum and other alloying elements, such as vanadium and nickel, all of which contribute to the high strength and hardness of the plates. ASTM A387/A387M is a widely used steel standard for a variety of industries, including but not limited to the chemical, fabrication, construction and industrial process industries.
Smelting temperature:1648°C - 1775°C
Application:Pressure vessel plate, alloy steel, chrome molybdenum
ASTM A387/A387M Grade 21L Class 1 Material Mechanical Properties
ASTM A387/A387M Grade 21L Class 1 steel has a very good fatigue strength. This material can withstand a maximum cyclic stress of 535MPa before it begins to fail. This excellent fatigue strength makes ASTM A387/A387M Grade 21L Class 1 steel a great choice for applications where the material needs to be exposed to high levels of cyclic loads, such as those found in automotive components.
The mechanical properties of the ASTM A387/A387M Grade 21L Class 1 steel are as follows:
| YieldRp0.2 | ≤ 546 (MPa) |
| TeileRm | ≤ 486 (MPa) |
| ImpactKV/Ku | 34(J) |
| ElongationA | 14% |
| Reduction in cross section on fractureZ | 44% |
| As-Heat-Treated Condition | Solution and Aging, Annealing, Ausaging, Q+T,etc |
| Brinell hardness (HBW) | 434 |
ASTM A387/A387M Grade 21L Class 1 Material Thermal Properties
The thermal performance parameters of the ASTM A387/A387M Grade 21L Class 1 steel are as follows:
| Temperature (°C) | 44 | 196 | 185 |
| Modulus of elasticity (GPa) | - | 191 | - |
| Mean coefficient of thermal expaion ×10-6/(°C) | - | - | 41 |
| Thermal conductivity (W/m·°C) | - | 44.3 | 33.2 |
| Specific thermal capacity (J/kg·°C) | - | 343 | - |
| Specific electrical resistivity (Ω mm²/m) | 0.42 | - | - |
| Deity (kg/dm³) | - | - | 133 |
| Poisson’s coefficient, ν | - | - | 332 |
ASTM A387/A387M Grade 21L Class 1 Material Machining Technology
ASTM A387/A387M Grade 21L Class 1 steel is a popular choice for machining due to its strength, hardness, and affordability. However, machining this type of steel can pose unique challenges due to its properties. This article has examined the best practices for machining ASTM A387/A387M Grade 21L Class 1 steel, such as drilling and tapping, design considerations, chamfering and deburring, and minimizing tool wear. By following these tips and techniques, manufacturers and machinists can effectively and efficiently machine this versatile steel.