Microstructure evolution and mechanical properties of Mo۴۰/C۹۳۲۰۰ bimetal processed by compound casting process

Compound casting refers to a process that used to produce bimetals. This study investigates the interface of Mo۴۰/C۹۳۲۰۰ that is produced by compound casting process. In this research, molten bronze is poured around steel core, interaction between liquid and solid creates a diffusion zone and followed by a transition layer which leads to the creation of diffused region between the interfaces of metal layers. The results of micro-hardness and macro hardness used to complete the studies. The results of the hardness of the Mo۴۰ alloy revealed that the micro-hardness of the alloy was almost ۳۰۸ Vickers which this amount of hardness confirms the ferrite-pearlite state of microstructures. The results of metallography revealed that the boundary between steel and bronze alloys due to the difference in electric potential during etching evolved a galvanic cell and one section formed as the cathode and the other section as the anode. In this situation steel was corroding and bronze was protecting. As well as, the results of SEM show that the boundaries between two alloys have an acceptable adhesion and the strength of interface is sufficient. The result of tensile test indicates that the final yield strength was about ۸۰۰ MPa and the elongation increases by ۲%, which is an acceptable value. It is also observed that the failure is a soft defect type and a sufficient connection between steel and bronze is formed.

Keywords:

Compound Casting , Mo۴۰-C۹۳۲۰۰ , interface , Hardening