4140 alloy steel round bar is a high-strength, medium-carbon chromium-molybdenum alloy steel with excellent hardenability, toughness and wear resistance. It is widely used in machinery manufacturing, automobiles, aerospace and petroleum industries. Its chemical composition contains carbon (0.38%-0.43%), chromium (0.80%-1.10%) and molybdenum (0.15%-0.25%). After heat treatment, the tensile strength can reach 1080 MPa, the yield strength exceeds 930 MPa, and the hardness reaches 217HBW. It is suitable for high-load parts such as crankshafts, gears, transmission shafts and oil drill pipes.

Steel Square Bars are versatile structural components with square cross-sections, widely used in construction, machinery, automotive, and engineering sectors. Manufactured via hot rolling, cold drawing, or forging processes, these bars offer high strength, durability, and machinability. Common grades include AISI 1020 (mild steel), S45C/C45 (medium carbon), and 304/316 stainless steel, catering to diverse applications like framework supports, bolts, shafts, and decorative elements. Their uniform geometry enables precise welding, cutting, and bending, making them ideal for load-bearing structures in buildings, bridges, and industrial equipment.

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