Properties Of ASTM A333 GR.8 Steel Tubes For Low Temperatures
Nov 21, 2024
ASTM A 333 GR8 This standard covers seamless and welded alloy steel tubing for cryogenic applications.
Chemical Composition:
Ni: 8.40-9.60
Heat treatment
1. Quenching + tempering. Heating evenly to 800±15℃, keeping at this temperature proportional to the wall thickness for at least 2min/mm, then quenching in circulating water, reheating the steel pipe evenly to 565~605℃; keeping at this temperature proportional to the wall thickness for at least 2min/mm but not less than 15min; then air cooling or water quenching at a cooling rate of not less than 165℃/h.
2. Secondary normalizing + tempering. Heating evenly to 900±15℃; keeping at this temperature proportional to the wall thickness for at least 2min/mm but not less than 15min; then air cooling. Reheat the steel pipe evenly to 790±15℃, keeping at this temperature proportional to the wall thickness for at least 2min/mm but not less than 15min; then air cooling. Reheat evenly to a temperature of 565~605℃, and keep it at this temperature for at least 2min/mm in proportion to the wall thickness, but not less than 15min; then air cool or water quench at a cooling rate of not less than 165℃/h.
Mechanical properties:
Tensile strength: ≥690Mpa
Yield strength: ≥515Mpa
Charpy impact test
Test temperature: -195°C.
The lateral expansion value shall be measured for each notched impact specimen, which shall be ≥0.38mm.
Hydrostatic or non-destructive testing
Each steel pipe shall be subjected to non-destructive electrical testing or hydrostatic testing. Unless otherwise specified in the purchase order, the test form to be adopted shall be determined by the steel mill.
