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本文研究快速小平台循环退火对高速钢硬度和显微组织的影响,循环退火在温度为850—700℃的两盐浴中进行,每一盐浴保温时间为10分钟或30分钟。研究表明:快速循环退火的时间不应超过1～7小时,根据预先热处理温度和钢的化学成份不同而在该范围内变化。直径30毫米以下的整体毛坯及焊接毛坯建议采用885～875℃温度区间的无平台循环退火;较大尺寸的毛坯建议采用小平台循环退火。圆柱形毛坯循环退火时间可按公式:τ退火=aD+C计算,式中:a—系数分/毫米;D—毛坯直径毫米;C—完成相变所必须的补充时间。研究表明:循环退火后碳化物相的组织、分布及化学成份与等温退火后的差异很小。
In this paper, the effect of rapid small stage cyclic annealing on hardness and microstructure of HSS was studied. Cyclic annealing was carried out in a two-salt bath at a temperature of 850-700 ℃. The holding time of each salt bath was 10 minutes or 30 minutes. Studies have shown that rapid cycle annealing time should not exceed 1 to 7 hours, according to the pre-heat treatment temperature and the chemical composition of the steel in the range of change. It is recommended to adopt the platformless annealing at the temperature range of 885 ~ 875 ℃ for the whole blank and welding blank with the diameter less than 30mm. The larger size blank is recommended to be cycled by the small platform. Cylindrical blank annealing cycle time can be calculated according to the formula: τ annealing = aD + C, where: a-coefficient of points / mm; D-blank diameter mm; C- completion phase change necessary supplemental time. The results show that the microstructure, distribution and chemical composition of the carbide phase after cyclic annealing are very similar to those after the isothermal annealing.