金属塑性变形的表面光反射率测量方法研究

Measurement of Metal Plastic Deformation Using Method of Laser Diffraction Spectrum Intensity Ratio

本文在讨论了弹性和塑性变形对表面衍射谱的不同影响后，研究了激光衍射谱变化测量金属塑性变形的表面光反射率方法，并对不同光路布置进行了比较，提出了最佳光路布置。对45#钢、40CrNiMoA合金钢、LY12-CZ和LD10铝合金进行了实测，结果表明：用这种方法测量金属材料的塑性变形是可行的；提出用光强比-对数应变曲线的拐点作为材料是否产生塑性变形的判据；为用表面光学特征表征金属材料的塑性损伤做了测试方法的准备。

The authors' contributions will be explained in the following paragraphs. The optical system proposed by this paper is better than the method ofHirata[5] in that the elastic component can be separated from total deforma-tion, and thus the required plastic deformation can be measured. The authors experiments on four metallic materials measure plasticstrains that are much larger than those of Xu et al [1]. The authors findthat the conclusion of Xu that the escape intensity K_2 increases with increasingplastic strain is not applicable bayond the initial plastic stage of materialswith comparatively high ductility. The sensitivity of the method in this paperis better than that of Xu, the resolution of strain being ≮100με as comparedwith Xu's 200με. In this paper a new parameter, laser diffraction spectrum intensity ratioK, is proposed. This new parameter, being sensitive to plastic deformation, isvery useful in the experimental study of plastic damage. Also the authorsfind that the inflection point of K～ε curve can be considered as the beginningof plastic strain. The authors optical system does not require a strictly stable photo-source, and so it is convenient to use on the worksite. In contrast Haworth[4]requires light-source to supply coherent light.