对３０ＣｒＮｉ３ＭｏＶ低合金钢切削速度为４．９７５ｍ／ｓ的正交切削试验所得切屑上大应变区进行Ｘ射线衍射分析．结果表明，在高速切削变形中少量索氏体转变成奥氏体；衍射线明显宽化．通过测量衍射线的宽化度（ｍ），利用谢乐公式Ｄ＝Ｋλ／ｍｃｏｓθ，可得位错胞直径，位错密度和微观应力，从而确定变形区的应变． X-ray diffraction analysis was performed on the large strain area of ​​the chip obtained from the orthogonal cutting test with the cutting speed of 4.975 m / s for 30CrNi3MoV low-alloy steel. The results show that a small amount of sorbite transformed into austenite during high-speed cutting deformation; the diffraction line is obviously widened. By measuring the width (m) of the diffraction line, the dislocation cell diameter, dislocation density and micro-stress can be obtained by using the Schrödinger’s formula D = Kλ / mcosθ to determine the strain in the deformation zone.