Thu, 26 Jul 2018 08:07:29 +0000
Factors of deformation and cracking of high speed steel tool
1. Effect of tissue stress: various structural changes occur in the process of tool heating and cooling. As the specific capacity of each tissue in steel is different, volume changes occur during phase change. In order to reduce tissue stress, the relative quantities of martensite, austenite and bainite are adjusted during heat treatment.
2. Influence of thermal stress: thermal stress is caused by internal and external temperature difference caused by tool heating and cooling. Due to the existence of various temperature differences in the workpiece surface, resulting in thermal expansion and cold shrinkage inconsistent. The thermal conductivity of high speed steel is poor, which aggravates the thermal stress.
3. High quenching temperature: the steel strength is greatly reduced, so deformation and cracking are easy to occur during heating and cooling.
4. Too fast heating can also cause deformation and cracking.
5. Deformation and cracking caused by improper tempering.
6. The quality of tool material steel affects the deformation and cracking of heat treatment.
7. Quenching medium influences deformation and cracking.
According to the above main factors that influence the effect of tool heat treatment, the whole process from material selection to heat treatment can be strictly controlled to reduce or even avoid deformation and cracking.