Walk into any steel fab shop, and you'll see both A572 Grade 50 and A36 sitting in the rack. They look alike, they weld similarly, but they're not the same animal.
The big difference? Strength. A572 Grade 50 delivers 50 ksi minimum yield, while A36 comes in at 36 ksi. That's roughly 40% stronger. What does that mean in practice? You can use thinner, lighter sections with A572 Grade 50 and still carry the same load. Less steel, less weight, sometimes less cost overall.
But A36 has its fans too. It's cheaper per pound, more forgiving in forming, and readily available everywhere. For lightly loaded members or non-critical applications, A36 does the job just fine without overspending.
Where A572 Grade 50 pulls ahead is in longer spans and heavier loads – bridges, crane runways, high-rise columns. The higher strength lets engineers design slimmer profiles, which saves material and reduces dead load on foundations.
Where A36 holds its ground is in secondary members, bracing, and thinner plates where strength isn't the driving factor. It bends and forms more easily, making it a favorite for detail work and repair jobs where fit-up matters more than muscle.
Weldability? Both are good. A36 is slightly more forgiving, but A572 Grade 50 welds just fine with standard low-hydrogen practices. No major preheat headaches for most thicknesses.
Toughness and impact – A572 Grade 50 generally offers better fatigue resistance and holds up well in cold weather, though specific Charpy requirements should be verified per project.
