Difference SA662 Grade A and SA662 Grade B steel plate

SA662 Grade A and Grade B are ASME-specified carbon-manganese-silicon steel plates designed for moderate to low-temperature pressure vessels, with Grade B generally offering slightly higher strength/toughness than A, though both feature good weldability and low-temp performance; the key differences lie in their specific mechanical properties (tensile, yield, elongation) and acceptable thickness ranges, with Grade B often having tighter controls on chemistry (like Carbon content) and impact testing requirements.

Key Characteristics & Differences:

Standard: Both fall under ASME SA-662/SA-662M for pressure vessel plates.

Application: Used for fabricating pressure vessels operating in moderate to lower temperature environments.

Composition: C-Mn-Si steels, with specific limits on Carbon, Silicon, Manganese, etc..

Mechanical Properties (General Trends):

Grade B typically has higher yield/tensile strength and elongation than Grade A, requiring specific Charpy V-notch impact tests for toughness.

Grade A also offers good toughness and weldability, but with generally lower minimum strength values compared to B.

Processing: Grade A plates often require normalization heat treatment

Chemical Composition

Carbon Equivalent: Ceq = 【C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15】%

Carbon Equivalent: Ceq = 【C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15】%

Mechanical Property

Choose Grade B for slightly higher performance needs in low-temp service or when stricter impact/strength requirements are mandated, while Grade A serves general moderate/low-temp pressure vessel needs with good weldability.