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图1所示的游标卡尺,要求主尺尺身硬度HRC40～53,内外量爪硬度大于HRC59,前端面区硬度大于HRC59,深度测量面硬度大于HRC40。测量面金相组织要求不超过4级的马氏体。平面热处理变形量不超过0.3mm,侧面不超过0.2mm。此外,要求热处理后残余内应力尽量小些,以便保持良好的尺寸稳定性。按传统工艺,主尺整体淬火——清洗——中温回火,外卡爪淬火——清洗,内卡
The vernier caliper as shown in Fig. 1 requires that the main ruler shall have a hardness of HRC 40-53 and that of the inner and outer claws should be greater than HRC59. The hardness of the frontal area should be greater than HRC59 and the hardness of the depth measuring surface should be greater than HRC40. Measurement of the microstructure requires not more than 4 levels of martensite. Planar heat treatment deformation does not exceed 0.3mm, the side does not exceed 0.2mm. In addition, the residual stress after heat treatment is required to be as small as possible in order to maintain good dimensional stability. According to the traditional process, the main ruler overall quenching - cleaning - tempering at the temperature, the outer jaw quenching - cleaning, internal card