Microstructure and mechanical properties analyses of Ti(C, N)–Fe/low-carbon steel composite material

Abstract

In this paper, mixed powders containing Ti(C, N), Fe, Mo, and Cr were combined with a low carbon steel (LCS) plate by heating to 1723 K in an argon-protected furnace and holding for 30 min to form a metallurgical bonding layer at the interface. By SEM and EPMA, it was observed that there were neither pores nor other defects at the interface. In Ti(C, N)–Fe/LCS (TFS), the Ti(C, N)–Fe (TF) side consists mainly of Ti(C, N), and the main particle morphology was round; however, there were some cyclic and semicyclic Ti(C, N) particles produced by dissolution, and the reprecipitation of fine particles along the austenite grain boundaries was observed during the sintering process. Moreover, Mo was polarized at the interface between Ti(C, N) particles and the steel matrix, forming a Mo-containing interfacial compound layer and improving the wettability of the interface between Ti(C, N) and the matrix. At the interfacial bonding surface of the TF and LCS, the direction and speed characteristics of the growth of the grains were different, leading to the present square and triangular diagrams of Ti(C, N). The diffusion distances of Cr and Ni in the LCS were approximately 35∼45 μm and 40–50 μm, respectively. The shear strength of the composite interface measured by a universal testing machine and a homemade mold was 245 MPa, which was better than the brazing strength. Compared with TF, the tensile strength of TFS was 50.2 % higher, and the bending strength was 63.5 % higher.