Difference between A517 Grade B and A517 Grade E steel plate

ASTM A517 Grade B and E are both high-strength, quenched and tempered alloy steel plates for pressure vessels, but they differ in their specified maximum thickness and some mechanical property nuances, with Grade E generally allowing for thicker plates (up to 6 in.) than Grade B (up to 1.25 in.), and Grade E having slightly varying yield strengths depending on thickness, while Grade B maintains a 100 ksi minimum yield strength across its range. Both offer excellent weldability and toughness, but specific grade selection depends on the vessel's design pressure, temperature, and thickness requirements.

Chemical Composition

Mechanical Property

Maximum Thickness:

Grade B: Limited to 1.25 inches (32 mm).

Grade E: Can be supplied in much thicker plates, up to 6 inches (150 mm).

Yield Strength:

Grade B: Minimum yield strength of 100 ksi (690 MPa).

Grade E: Minimum yield strength of 100 ksi (690 MPa) for thicknesses up to 2.5 inches, but drops to 90 ksi (620 MPa) for thicker plates (over 2.5 inches to 6 inches).

Applications: Both are for fusion-welded pressure vessels, but Grade E's higher thickness capability suits thicker-walled vessels.

Toughness: Both have excellent Charpy V-Notch impact requirements, but Grade B specifically requires a minimum lateral expansion of 0.015 inches.