本文用金相显微镜、显微硬度和电子探针等试验方法研究了M_2高速钢的淬火和退火状态试样的脱碳层及碳分布。淬火脱碳层晶粒极其粗大、硬度很低、碳化物大量减少、过渡层很薄,但基体碳含量未降低太多。退火脱碳层碳化物减少,基体碳含量明显降低,过渡层较厚。脱碳愈严重,基体碳含量愈低,过渡层愈厚。一般金相法测出的脱碳层厚度未包括过渡层。脱碳使工具的性能严重下降,甚至报废,因此,应当尽量避免产生。 In this paper, the decarburization and carbon distributions of quenched and annealed M_2 high speed steels were studied by means of metallographic microscope, microhardness and electron probe. Quenched decarburization layer is extremely coarse grains, hardness is very low, a substantial reduction of carbide, the transition layer is very thin, but the substrate carbon content is not reduced too much. Annealing decarburization carbide reduction, the matrix carbon content was significantly reduced, the transitional layer thicker. The more decarburization, the lower the carbon content of the matrix, the transition layer thicker. Decarburization layer thickness measured by the general metallographic method does not include the transition layer. Decarburization of the performance of the serious decline in tools, or even scrapped, therefore, should be avoided as much as possible.