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设计了40Cr钢的端面淬火工艺,研究了φ110 mm工件断面从表层到心部淬火后的组织,并测试了从表层到心部的硬度分布。结果表明:40Cr最佳淬火工艺为淬火3 min后250℃回火;按照此淬火工艺,φ110 mm工件断面淬火后淬硬层硬度为53~55 HRC,半马氏体深度为5~10 mm。在距表面深度超过15 mm后,马氏体消失,显微组织主要为片层状珠光体+先共析铁素体,硬度下降到表面硬度的1/2。
The quenching process of 40Cr steel was designed. The microstructure of φ110 mm workpiece after quenching from surface to heart was studied and the hardness distribution from the surface to the heart was tested. The results show that the optimum quenching process of 40Cr is tempering at 250 ℃ for 3 min after quenching. According to this quenching process, the hardened layer hardness of φ110 mm workpiece after quenching is 53-55 HRC and the depth of semi-martensite is 5-10 mm. At a depth of more than 15 mm from the surface, the martensite disappears and the microstructure is mainly lamellar pearlite + pro-eutectoid ferrite, with the hardness decreasing to 1/2 of the surface hardness.