Quenching technology for lifting steel pipe
The hardness of steel tube tempering parts after quenching should reach HRC56~59, the possibility of large section is lower, but not lower than HRC48, otherwise, it means that the workpiece has not been completely quenched, there may be sostenite or even ferritic structure in the tissue, this structure through tempering, still retained in the matrix, can not achieve the purpose of tempering. After quenching, the steel pipe is tempered at high temperature, the heating temperature is usually 560~600℃, and the hardness is HRC22~34. Because the purpose of tempering is to obtain comprehensive mechanical properties, the hardness range is relatively wide. But drawings have hardness requirements, it is necessary to adjust the tempering temperature according to the requirements of the drawings, in order to ensure hardness. Such as some shaft parts require high strength, high hardness requirements; And some gear, with keyway shaft parts, because of the conditioning after milling, insert processing, hardness requirements are lower. On the tempering heat preservation time, depending on the hardness requirements and the size of the workpiece, we believe that the hardness after tempering depends on the tempering temperature, and the tempering time has little relationship, but must be back through, the general workpiece tempering heat preservation time in more than one hour.
