The Effects of Alloying Elements on Thermal Fatigue and Thermal Shock Resistance of the HSLA Cast Steels

摘要

The effects of alloying dements on thermal properties of the HSLA(High Strength Low Alloy) cast steels have been investigated by thermal fatigue, thermal shock, and tensile tests. The thermal fatigue resistance of the HSLA cast steels was superior to those of SC42 cast steels. Excellent thermal resistance of the HSLA cast steels was mainly caused by high thermal conductivity, elastic modulus, and tensile strength. In case of the HSLA cast steels, the steels with both Nb and V showed higher thermal fatigue life than those with Nb or V. Increasing of C contents decreased thermal fatigue resistance. In case of Mn contents, HSLA cast steels with 1.2% Mn content showed the higher thermal fatigue life than 0.6% Mn and 1.5% Mn steels. Therefore, the optimum composition of HSLA cast steels to obtain the highest thermal fatigue resistance was 0.1%C- 1.2%Mn-0.05%Nb-0.05%V, resulting in polygonal ferrite plus small amounts of bainitie mierostructure. Thermal shock resistance of HSLA cast steels was also superior to that of SC42 cast steels. However, the difference between the HSLA cast steels with both Nb and V, and those with Nb or V individually has not been found.