Study on the Life of High Speed Steel Taps with Cryogenic Treatment

The influences of various processes of cryogenic treatment, optimization of parameters and prolongation the life of the high speed steel taps have been studied in the paper. Taking W9Mo3Cr4V for an example, the influences of temperature raising and decreasing rate, cryogenic treatment temperature and holding time, times for treatment, temper process and sequence of cryogenic treatment are discussed. Two kinds of cryogenic treatment process that one is before temper and the other is after it are put forward. Process flow is designed according to the process suitability and economy, the reported research results and existent problem. The results show that the life is prolonged after cryogenic treatment and the life is longer if the cryogenic treatment is carried out before tempering. To different material, the quantity of prolonging is different. To 30CrMnTi, 1.43 times of life of the tap is prolonged if the cryogenic treatment is arranged before tempering and only 61% is prolonged after tempering. To 1Cr18Ni9Ti, 1.08 times is prolonged before tempering and only 46% is prolonged after tempering. To 5CrMnMo, 1.65 times is prolonged before tempering and only 89% is prolonged after tempering. Research indicates that after cryogenic treatment, the harder the material is, the better the cutting is.