Study On The Effect Of Heat Treatment Process On The Structure And Properties Of K110 Cold Work Die Steel

In recent years,with China’s automobile,medicine,aerospace and other industries developing rapidly,the dimensional accuracy and performance requirements of molds have been improved accordingly.And the production of precision molds has increasingly become the focus of the mold industry.Heat treatment,which is an important part of mold manufacturing,plays a key role in improving the performance and working life of the mold.However,failure caused by heat treatment have brought huge losses every year.Therefore,improving the heat treatment process of precision molds is of great significance.In view of the current problems of heat treatment of precision cold work molds,this article took K110 steel as the research object.The changes in the structure and properties of K110 steel after heat treatment by different processes were studied,the results showed:Increasing the quenching temperature could improve the uneven distribution of eutectic carbides in K110 steel,but it also led to an increase in the residual austenite content.After quenched at 1080℃,the K110 steel with cryogenic treatment + high temperature tempering in different processes had an excellent structure and hardness higher than 50 HRC,due to the low residual austenite content,the impact toughness of steel after heat treatment in different processes was poor.When the tempering temperature was low,compared with multiple tempering directly after quenching,cryogenic treatment + tempering could increase the hardness of K110 steel to above 60 HRC,and could reduce the residual austenite content in the steel.When the tempering temperature was too high,cryogenic treatment after quenching caused the hardness of the steel to decrease.After quenched at 1180℃,the microstructure was uneven in some areas and the grain coarsening was serious,after repeated high temperature tempering,granular carbides accumulated along grain boundaries and there was a tendency to form a network structure.After tempering at 540℃ for 5 times,the peak hardness reached 61.5HRC.The best heat treatment process for K110 steel was 1080℃ quenching,-130℃× 3h cryogenic treatment + 500℃ high temperature tempering for three times.The precision molds made of K110 steel by this process had excellent performance.