1. What Is A656 Grade 60?
ASTM A656 covers hot-rolled high-strength low-alloy structural plates with improved formability, in grades 50, 60, 70 and 80. Grade 60 guarantees a minimum yield strength of 415 MPa (60 ksi), about 20% higher than Grade 50, and it is designed for structural applications where superior strength, toughness and weldability are required. The plate is micro-alloyed and is typically supplied in the normalized or controlled-rolled condition, which ensures a fine grain size, consistent properties and reliable behavior at moderate low temperatures.
2. Mechanical Properties
The guaranteed minimum yield strength of A656 Grade 60 is 415 MPa (60 ksi). Tensile strength and elongation follow the thickness-related tables of the standard, with supplier tables commonly quoting a tensile range around 485–655 MPa and elongation of 18% or more; the values for the specific thickness must be verified against the current edition of ASTM A656 and the mill certificate. Impact testing is not automatic and should be specified when the service requires it.
3. Chemical Composition
Typical composition maxima quoted for A656 Grade 60 include carbon up to about 0.23%, manganese up to 1.35%, silicon up to 0.40%, phosphorus and sulfur each up to 0.035%, with optional copper, nickel, chromium and molybdenum in small amounts. The exact limits are defined by grade and thickness in ASTM A656, and because the standard applies one family of micro-alloyed compositions, the heat analysis should always be confirmed on the mill certificate.
4. Grade 60 vs Grade 50
The practical difference between Grade 60 and Grade 50 is strength: at 415 MPa the yield of Grade 60 is about 20% higher, which allows lighter structures or higher load capacity in the same section. Grade 60 also carries a higher ultimate tensile strength, which improves resistance to heavy loads and stress. The grade is preferred for heavier loads, thicker sections and more demanding structural applications, while Grade 50 remains the economical choice for ordinary structural work. Grade 60 may cost slightly more because of the higher mechanical requirements, and the higher yield must be considered in fabrication, especially for bending and springback.
5. Where A656 Grade 60 Is Used
The grade is used for bridge girders, beams and trusses; columns, beams and frames of high-rise and industrial buildings; heavy machinery such as cranes, loaders and equipment frames; and industrial structures such as platforms, piping racks and supports. In these applications the key requirements are high load-bearing capacity, resistance to dynamic loads and impact, and good weldability of thick sections. As with any general structural grade, pressure-boundary service must be checked separately against the applicable code rather than assumed from the structural properties.
Frequently Asked Questions
What does Grade 60 mean in A656? It refers to a minimum yield strength of 60 ksi, about 415 MPa, which is about 20% higher than A656 Grade 50.
What is the difference between A656 Grade 50 and Grade 60? Grade 60 guarantees 415 MPa yield versus 345 MPa for Grade 50, with higher tensile strength; it is chosen for heavier loads and more demanding applications.
Is A656 Grade 60 weldable? Yes, with standard arc processes; its micro-alloyed composition and controlled carbon support weldability with normal HSLA practice.
Does A656 Grade 60 require impact testing? Not automatically; where low-temperature or dynamic service requires toughness, a Charpy requirement must be added to the specification.
What thickness range is available? The available range depends on the mill; confirm the required thickness and the corresponding property values with the supplier, since properties vary with thickness.
Can A656 Grade 60 be used for pressure vessels? Not on the strength of A656 alone; pressure-boundary service must be verified against the applicable code and a suitable certified grade selected.
