What Is SA633 Steel?
ASME SA633, corresponding to ASTM A633, covers normalized high-strength low-alloy structural steel plates for welded, bolted, or riveted structures. The specification includes Grades A, C, D, and E, which provide different combinations of strength and toughness. All grades are supplied in the normalized condition, which gives a uniform grain structure and reliable mechanical properties.
SA633 Grade D Properties
Grade D is a normalized HSLA plate designed for general structural applications with moderate strength needs. The minimum yield strength is 345 MPa for plate up to 63 mm and 315 MPa for plate from 63 mm to 100 mm, with a tensile range of 485-620 MPa and elongation of 18-23% depending on thickness. It performs well in moderately low-temperature environments, with impact toughness suitable for service around -45 °C after normalizing.
SA633 Grade E Properties
Grade E provides higher yield strength and better low-temperature toughness than Grades A, C, and D. The minimum yield strength is 415 MPa (about 60 ksi) for plate up to about 100 mm and 380 MPa (about 55 ksi) for thicker plate, with a tensile range of 550-690 MPa and elongation of 18-21%. The composition uses a vanadium addition of 0.04-0.11% for strengthening, and the grade is suitable for low-temperature service around -45 °C when required.
Chemical Composition Comparison
Grade D has a maximum carbon of 0.20%, manganese of 0.70-1.35% (up to about 1.60% for thicker plates), silicon of 0.15-0.50%, and low phosphorus and sulfur. Grade E allows carbon up to 0.22%, uses a higher manganese range of 1.15-1.50%, and adds vanadium 0.04-0.11% as a micro-alloying element. The higher alloying of Grade E is what gives it greater strength and improved notch toughness.
Mechanical and Application Differences
Grade E is significantly stronger than Grade D, with a yield of about 415 MPa versus 345 MPa and a tensile range of 550-690 MPa versus 485-620 MPa, at the cost of slightly lower ductility. Grade E is preferred for heavy structural loads, high-strength demanding applications, and colder environments, while Grade D is very suitable for general structural work and moderate strength needs, where Grade E would be over-specified.
Frequently Asked Questions
What is the difference between SA633 Grade D and Grade E? Grade E provides higher yield strength (415 MPa versus 345 MPa), higher tensile strength, and better low-temperature toughness than Grade D.
What is the yield strength of Grade D? The minimum yield strength is 345 MPa for plate up to 63 mm and 315 MPa for 63-100 mm plate.
What is the yield strength of Grade E? The minimum yield strength is 415 MPa for plate up to about 100 mm and 380 MPa for thicker plate.
Are SA633 grades supplied in the normalized condition? Yes, SA633 covers normalized plates, which provide a uniform grain structure and consistent properties.
Which grade is better for cold environments? Grade E, with its improved notch toughness and low-temperature performance around -45 °C.
What are SA633 plates used for? Welded, bolted, or riveted structures such as bridges, storage tanks, and heavy structural components.
