The Applied Research Of Cryogenic Treatment On HSS Tools

The paper discusses the sequence of several factors of influencing cryogenic treatment and the optimal process conditions, through the study on the W6Mo5Cr4V2 high speed steel process of the cryogenic treatment, which offering values change of the hardness、red hardness and impact toughness among without cryogenic treatment and after cryogenic treatment by orthogonal test. The results found that the hardness of W6Mo5Cr4V2 high speed steel increases by 0.2-1.2HRC and red hardness by 0-3.7HRC, besides, the impact toughness increases up to 70%. In addition, the number of cryogenic treatment is the most important factor of influencing the comprehensive performance indicators of hardness、red hardness and impact toughness of W6Mo5Cr4V2 high speed steel, and the second most important factors are the way of cryogenic treatment and the number of tempering by analyzing the process factors extreme values. It is considered that the optimal process conditions of cryogenic treatment on W6Mo5Cr4V2 high speed steel is twice cryogenic treatment times、cooling slowly and heating up slowly、200 ℃ tempering times at a time and immersion time of 4 hour by combining with the average size of each factors. This optimal process conditions provides the late experimental data base for cryogenic treatment process on W6Mo5Cr4V HSS finished products twist drill tools.The results found that cryogenic treatment improves the wear resistance of after cryogenic treatment on high speed steel by means of friction-wear test, which investigates the wear resistance of cryogenic treatment on high speed steel at the pressure of 2.5kg、speed of 350r/min、one hour and room temperature. Furthermore, it found that white blocky retained austenite reduced to a certain degree, the tiny distribution、more uniform acicular martensite are increased. White fine carbide particles increased obviously around the martensitic, and its dispersion and distribution is more uniform. Besides, it is also found that primary carbide from order ribbon into more uniform distribution appearance. Cryogenic treatment can effectively improve the high speed steel of improper heat treatment through deal with the overheating high speed steel by cryogenic treatment. According to production practice test, after cryogenic treatment of HSS twist drill is widely improved service life. It can be considered that the liquid method of cryogenic treatment can effectively reduce the cost of processing.