Effect of Ti Content on the Strengthening and Fracture Damage Mechanism of Mechanical Properties of Weathering Steel

Abstract

With the increasing performance demands for steel in large structures, Ti microalloying has emerged as a crucial method for enhancing steel performance. This work aims to achieve these objectives by adding trace amounts of Ti. Mechanical properties and microstructure of steels with different Ti contents (0%, 0.044%, 0.087%, and 0.140%) and precipitation behavior of precipitates, as well as strengthening mechanisms and fracture damage mechanisms of the steels were systematically investigated. The results show that the addition of trace amounts of Ti can improve the strength and plasticity of steel by refining the grain size, altering the precipitate precipitation behavior, and hindering dislocation motion. However, excessive Ti content (0.140%) leads to an abnormal growth of TiC precipitates and synergizes with the composite precipitation phases formed by elements such as N, Al, Mn, and O, causing fracture damage of the steel during the tensile process. This study provides a theoretical basis and technical guidance for the design and application of Ti microalloyed steel.

Keywords: Ti microalloyed, strengthening mechanisms, precipitate behavior, damage evolution mechanism