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国家标准GB228-76关于测量屈服现象不明显材料的σ_(0.2)规定有两种方法:图解法和引伸计法。引伸计法又分为卸荷法和直接加荷法。但这些方法操作麻烦、花费时间多。按照国家标准规定:“如掌握试验材料屈服强度所对应总伸长的大致范围,则可使第一次加荷的总伸长接近预计值,以便迅速求得P_(0.2)”。由此而想到是否可以用总伸长一定来测定求出σ_(0.2)值。其方法是先确定某一钢种、某一形状尺寸的试样屈服强度所
National Standard GB228-76 There are two methods for the σ_ (0.2) regulation of materials with insignificant yield phenomena: graphic method and extensometer method. Extensometer is divided into unloading method and direct loading method. However, these methods are troublesome and time consuming. According to national standards: “If you grasp the test material yield strength corresponding to the general range of total elongation, you can make the first load of the total elongation close to the expected value in order to quickly find P_ (0.2)”. From this it is possible to determine whether the σ_ (0.2) value can be determined by measuring the total elongation. The method is to determine a certain type of steel, a shape and size of the specimen yield strength