一、前言 伸长率是金属材料的主要塑性指标之一。这一参数与强度指标(诸如δ_s,δ_b等)及另一塑性指标(ψ)相比,有一显著的特点,那就是在非定标距的伸长率中,人为的引进了一个参数——K值。只有K值为某一定值时,所测得之伸长率才可作为材料参数,以供比较。在材料的试验条件完全相同的情况下,K值不同,所测得之伸长率也是不同的。 First, the preface Elongation is one of the main plastic indicators of metal materials. This parameter has a notable characteristic compared with the strength index (such as δ_s, δ_b, etc.) and another plastic index (ψ), that is, artificially introduces a parameter in the non-gauge elongation, K value. Only when the K value is a certain value, the measured elongation can be used as a material parameter for comparison. In the case of the same test conditions of the material, K value is different, the elongation measured is also different.