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工作键(见附图)是百吨锻压机床重要零件之一,材料为40CrNi,硬度要求HRC52～57,热处理允许变形量——直线度0.8mm。试验和生产表明:该零件采用常规工艺840℃、20号机油淬火,变形量可以在规定值内,但表面硬度则大大低于要求指标;若采用840℃、水油双液淬火,表面硬度虽能达到要求,但变形量又会超差。作者分析认为,矛盾点主要由以下两因素造成:1.截面尺寸较大,采用常规温度加热,油中淬火,表面硬度无法达到要求(一般截面尺寸≤25
Work keys (see photo) is one of the important parts of 100T forging machine tools, the material is 40CrNi, hardness requirements HRC52 ~ 57, the heat treatment allows deformation - straightness 0.8mm. The test and the production show that the part adopts the conventional process of 840 ℃ and the No. 20 oil is quenched, the deformation can be within the specified value, but the surface hardness is much lower than the required index. If 840 ℃ is used, Can meet the requirements, but the amount of deformation will be ultra-poor. The author believes that the contradiction point is mainly caused by the following two factors: 1. Cross-section size larger, the use of conventional temperature heating, oil quenching, surface hardness can not meet the requirements (general cross-sectional size ≤ 25