AISI 4140 chromium-molybdenum alloy steel round bar for mechanical applications. Manufactured to ASTM A322 and AISI standards, grade 4140 offers excellent hardenability, high fatigue strength, and good toughness. Available in diameters from 10mm to 500mm, lengths from 3m to 12m. Supplied in annealed or quenched and tempered condition. Typical hardness ranges from HB 280-320. Widely used for gears, shafts, spindles, axles, bolts, connecting rods, and oil and gas components. Precision ground and polished options available.