What difference between A517 Grade B and A517 Grade E?

ASTM A517 Grade B and Grade E are both high-strength, quenched and tempered alloy steel plates for fusion-welded pressure vessels, but they differ in their specific alloying elements and sometimes thickness ranges, with both offering excellent strength (e.g., 100 ksi min yield for thinner sections) and impact toughness, making them ideal for demanding applications like unfired vessels, with Grade E often containing Molybdenum and Chromium for enhanced properties.

Chemical Composition

Mechanical Property

Key Similarities

Standard: Both fall under ASTM A517, a specification for high-strength, quenched, and tempered alloy steel plates.

Application: Primarily used for fusion-welded boilers and pressure vessels where high strength is needed.

Heat Treatment: Both undergo quenching and tempering for superior mechanical properties.

Mechanical Strength: Both can achieve high yield strengths (e.g., 100 ksi for thicknesses up to 2.5 inches).

Toughness: Both require Charpy V-notch impact testing for toughness.

Key Differences 

Alloy Composition: Different grades within A517 have varying alloy additions (like Molybdenum, Chromium, Vanadium, Nickel) to tailor properties, with Grade E often having more specific alloy requirements for higher performance.

Thickness: Grade B might be specified for thinner plates (e.g., up to 1.25 inches in some cases), while Grade E is available in thicker sections (up to 6 inches or more) with consistent strength levels, notes SSAB, SSAB, and SSAB.

Specific Properties: Grade E often targets higher strength and toughness for extreme conditions, with required lateral expansion values, whereas Grade B is a strong performer for general pressure vessel use.