Effect of Mo Microalloying on High Temperature Mechanical Properties and Microstructure of 82B Steel

Abstract

The influence of 82B steel with Mo （mass fraction） of 0. 02%，0. 04%，0. 07% and 0. 11% on microstructures and properties after high temperature stretching at different temperatures and the toughness mechanism of Mo element on 82B high carbon steel were studied. The results showed that：（1） During 200-300 ℃ high temperatures tensile， four groups of experimental steels had good mechanical properties ， at 300 ℃ to reach the peak， it was optimal experiment group with Mo content 0. 11% ， tensile strength increased from 1 139 MPa to 1 192 MPa， yield strength slightly reduced to 736 MPa， elongation and section shrinkage significantly increased to 22% and 72. 9%. Compared to the experimental steels with 0. 02% Mo content， the yield strength reduced by about 5%， but the tensile strength increased by 5%， the elongation and section shrinkage increased significantly， and the plasticity increased simultaneously with the Mo content， with the temperature continued to rise， the mechanical properties tended to decrease as the materials start to soften.（2） When the Mo content was 0. 02% and 0. 04%， the microstructures except carburite gradually increased with the increasing of tensile temperature， sorbite and pearlite did not appear obvious changes， and the same as room temperature， when the Mo content increased to 0. 07% and 0. 11%， sorbite and pearlite clusters are progressively finer and more evenly distributed. At the same time， four groups of experimental steels showed blue brittleness during high temperature tensile at 300 ℃，through the fractures observation found that there was Al， Si and other elements of inclusions， and failure mode was ductile fracture， the fracture can mainly be divided into the shear lip areas and fiber areas，the shear lip areas with the increase in temperature gradually reduced.

Keywords

• 82b steel； mo microalloying； tensile strength； high temperature tensile； refractory steel