Investigation of microstructure and mechanical properties of newly developed advanced high strength TRIP steel

In this research, the heat treatment and production of high-strength advanced TRIP 1150 steel were investigated and then the mechanical properties of the welds of this steel were evaluated by spot welding. For this purpose, the effect of rolling process and heat treatment of alloy steel sheets to achieve the ultra-high strength TRIP 1150 steel microstructure was discussed. Microstructural examinations by Scanning Electron Microscopy (SEM) identified ferrite with bainite phases and martensite in matrix. The microstructural characteristics were examined using SEM microscopy with EBSD analysis. The EBSD results showed that the type and orientation of the grains changed and the fraction of high-angle to low-angle boundaries in the present steel varied due to the presence of different phases. The EBSD results showed the acceptable rate of primary austenite in the structure according to the phaseology of this method. Having desirable mechanical properties was one of the most important results of this study, which at the same time maintained impact resistance and mechanical strength.