ASTM A573 Grade 58 is a carbon-manganese steel plate designed for applications requiring improved notch toughness compared to standard structural grades like ASTM
A36. It offers a minimum yield strength of 220 MPa (32 ksi) and tensile strength ranging from 400 to 485 MPa. The steel is supplied in the killed condition with fine grain practice (ASTM grain size No. 5 or finer), ensuring reliable impact resistance at temperatures down to -20°C to -40°C depending on thickness.
Typical applications include low-temperature pressure vessel shells, storage tanks for liquefied gases, bridge components in cold climates, and offshore platform structural members.
ASTM A573 Grade 58 Steel Welding Recommendations:
ASTM A573 Grade 58 exhibits excellent weldability due to its low carbon equivalent (CEV typically 0.35–0.42%). Recommended processes include SMAW (shielded metal arc), GMAW (gas metal arc), FCAW (flux-cored arc), and SAW (submerged arc). Preheating is generally not required for plates under 25 mm thickness when ambient temperature is above 5°C. For thicker sections or cold environments, a preheat of 50–100°C is advised to prevent hydrogen-induced cracking. Low-hydrogen electrodes (E7018 or equivalent) should be used. Post-weld heat treatment (PWHT) is typically not mandatory but may be specified for heavy sections or service below -30°C.
ASTM A573 Grade 58 Heat Treatment Conditions:
ASTM A573 Grade 58 is normally supplied in the as-rolled or normalized condition. Normalizing (heating to 890–930°C followed by air cooling) refines grain structure and optimizes toughness. Stress relieving at 550–620°C for 1 hour per 25 mm thickness reduces residual stresses after heavy machining or welding, provided the temperature does not exceed the tempering temperature used during original plate production.
In summary, ASTM A573 Grade 58 combines moderate strength with enhanced low-temperature toughness, offering a cost-effective alternative to fully alloyed steels for many structural and pressure vessel applications.
