Difference between A283 Grade A and A283 Grade D steel plate

A283 Grade A and A283 Grade D are carbon steel plates for structural applications, conforming to the ASTM A283 standard. They are general-purpose plates used in moderate-strength components such as structural frames, tank fabrication, and machinery where welding, bending, and forming are required.

Key Differences:

The fundamental distinction is their strength level. A283 Grade A offers a minimum yield strength of 24 ksi (165 MPa) and tensile strength of 45-60 ksi (310-415 MPa). A283 Grade D provides significantly higher strength, with a minimum yield strength of 33 ksi (230 MPa) and tensile strength of 58-80 ksi (400-550 MPa).

This strength difference is achieved through varying carbon and manganese content. Grade D has a higher specified carbon range (max 0.33% vs. Grade A's max 0.23%) and manganese content (0.90% max vs. 0.90% max, but typically used at a higher level), resulting in a higher carbon equivalent (Ceq). Consequently, A283 Grade D is less ductile and has lower weldability compared to the softer, more formable Grade A. Welding Grade D requires more careful procedure controls, such as preheating in thicker sections, to prevent cracking. 

A283 Grade A steel plate Chemical composition

A283 Grade D steel plate Chemical composition

A283 Grade A steel plate Mechanical Property

A283 Grade D steel plate Mechanical Property