| 摘要 |
A tool screw and a wrench bolt for fixing, and a manufacturing method thereof are provided to improve a life span thereof by giving stronger chemical and mechanical characteristics against torsion by quenching, tempering, or austempering an inside thereof. A manufacturing method of a tool screw and a wrench bolt for fixing includes a step of selecting a material which includes 0.01~1.0% of carbon, 0.2~2% of chromium, 0.2~2% of molybdenum, 0.2~2% of nickel, and 0.1~0.8% of vanadium at a general steel including carbon, silicon, phosphorous, manganese, and sulfur; a step of cutting and rolling a coil or a round bar material to a product with a fixed size by heading and forging the coil or the round bar material; a step of performing a boronizing heat treating process to form a compound layer and a diffusion layer at a surface of the finished product by cleaning the finished product; a step of keeping the compound layer of the finished product at high temperature and performing a quenching process to increase internal strength; a step of tempering the quenched product to satisfy the internal strength, toughness, and softness simultaneously; a step of performing an austempering process by keeping the compound layer of the finished product at the high temperature; and a step of performing a sanding process to remove a foreign material of a surface. |
