Microstructure and Mechanical Properties of Brass L63 after Friction Mixing Treatment

Abstract

The processing of materials by the friction mixing method is one of the advanced technologies for hardening and modifying the surface of metals and alloys in modern mechanical engineering. This technology has been widely used in the processing of aluminum, titanium and, in particular, copper alloys. Recent studies in the field of frictional mixing processing (FMA) of zinc-based copper alloys show that, depending on the technological parameters (speed of rotation and movement of the tool, load) and processing modes, a change in the microstructure and mechanical properties of the material is observed. However, the effect of a multipass FPO on the L63 brass alloy has not actually been studied. Therefore, in this work, we studied the effect of a four-pass FPO on the structure and mechanical properties of the L63 copper alloy. According to the analysis, it was revealed that the microstructure in the mixing zone is a region of equiaxed recrystallized grains with an average grain size of about 1.5-2 μm. Due to severe plastic deformations, a fine-grained structure is formed in the material, which causes the increase of microhardness in the mixing zone. The tensile strength of the material after one pass by the tool increases from 314 to 487 MPa, and after the fourth pass up to 497 MPa, no softening of the metal occurs. No visible defects were found in the cross-section of the material due to the optimally selected processing modes.