ASTM A537 is a specification that covers heat-treated carbon-manganese-silicon steel plates intended for fusion-welded pressure vessels. The steel plates specified under ASTM A537 are commonly used in applications where improved notch toughness is required, such as in the construction of boilers and pressure vessels.

The ASTM A537 specification includes several grades of steel plates, each denoted by a numerical designation. The most common grades are A537 Class 1, A537 Class 2, and A537 Class 3.