Research on influence of grain boundaries on the mechanical properties of 460 MPa refractory steel used for high-strength building structures

Abstract

In this paper, the microstructure of Mo-type seismic refractory steel for building g, as well as different boundary densities and boundary ratios, are combined with elevated-temperature mechanical properties analysis to explore the laws of boundary for high-temperature performance. The results show that salt water cooling (SWC) and water cooling (WC) can obtain lath bainite with a higher content, and oil cooling (OC) with a lower cooling rate can obtain the microstructure of multiphase bainite + bulk ferrite. The boundary characterization results show that when the sample contains more high angle grain boundaries (Block and High-Packet boundaries), and the dislocation density is high, it can make it have better mechanical properties at room temperature. When the content of low angle boundary and low interfacial energy twin boundary (Σ3 boundary, which is mainly composed of V1/V2 variant pair) is high, it will have better microstructure stability after high temperature tempering, and the boundary density and dislocation density will decrease slightly, ensuring that it has better refractory performance.

Keywords

• cooling rate
• boundary
• Σ3 grain boundary
• variant
• refractory properties