Gear rack steel plate having a maximum thickness of 177.8 mm manufactured by continuous casting steel piece and its manufacturing method

摘要

A method for producing a gear rack steel having a maximum thickness of 177.8 mm produced by using a continuously cast billet, wherein the chemical components are C: 0.11 to 0.15% by mass percentage, Si: 0.15 to 0.1% by mass. 0.35%, Mn: 0.95 to 1.25%, P: ≦ 0.010%, S: ≦ 0.002%, Cr: 0.45 to 0.75%, Mo: 0.4 to 0 0.6%, Ni: 1.3 to 2.6%, Cu: 0.2 to 0.4%, Al: 0.06 to 0.09%, V: 0.03 to 0.06%, Nb: ≦ 0.04%, N: ≦ 0.006%, B: 0.001 to 0.002%, the balance being iron and unavoidable impurity elements, after continuous casting, rolling and tempering. The steel sheet has features of high strength, good toughness, and excellent low-temperature toughness.