ASTM A965 (USA) and GB/T 3078 (China) govern stainless round bars for mechanical applications with these tolerance differences:
Cold-finished bars: ASTM A965 offers h9 tolerance (±0.03mm for 10mm diameter), while GB/T 3078 provides tighter ±0.01mm for precision grades.
Hot-rolled bars: ASTM allows ±0.76mm for 50mm diameter, slightly wider than GB/T 3078's ±0.5mm.
Straightness: ASTM specifies ≤1.6mm/m, while GB/T 3078 requires ≤0.5mm/m for cold-drawn bars, reflecting higher precision demands in Chinese manufacturing.
Both standards meet their respective market needs, with dimensional compatibility achievable through grade selection.