Effect of Ti content on the strengthening and fracture damage mechanism of mechanical properties of weathering steel

Abstract

In this paper, the relationship between mechanical properties and microstructure of steels with different Ti contents (0 wt%, 0.044 wt%, 0.087 wt% and 0.140 wt%) is systematically investigated. The results show that the addition of trace amounts of Ti can improve the strength and plasticity of steel by grain refinement, change in precipitation behavior, and obstruction of dislocation motion. The observation of the interaction behavior of TiC with different sizes and dislocations shows that dislocations can shear the small precipitates, but form dislocation pile-up at the boundary of the large precipitates. The difference between the predicted and tested values of yield strength gradually increases with increasing Ti content. The synergistic effect of the formation of precipitates (TiN and its composites) and the coarsening of TiC under a high content of Ti can make the steel more susceptible to cracking and fracture during the tensile process. This study provides a theoretical basis and technical guidance for the design and application of Ti-microalloyed steels by investigating the strengthening and fracture mechanisms of different Ti content.

Keywords

• Ti-microalloyed
• Strengthening mechanisms
• Precipitate behavior
• Damage evolution mechanism