Microstructure and Mechanical Properties of ZK60 Magnesium Alloy Prepared by Multi-Pass Friction Stir Processing

Abstract

Friction stir processing (FSP) is a novel severe plastic deformation technique developed in recent years to produce fine-grained structural materials. In this paper, the microstructure and mechanical properties of ZK60 magnesium alloy prepared by the single-pass and two-pass FSP were studied. The first-pass was subjected with 800r/min-100mm/min and the second-pass was subjected with 600r/min-100mm/min. The results show that the coarse second phase was dissolved into magnesium matrix and the α-Mg grains were remarkably refined in stir zone after FSP. The average grain sizes of the single-pass and two-pass FSP alloys were 6.8μm and 6.0μm respectively. The microhardnesses of the specimens were 70HV and 65HV, the ultimate tensile strengths were 276MPa and 272MPa, and the elongations were 31.6% and 42.5%, respectively. Through increasing the processing pass, the microstructure became finer and the second phase is dissolved more thoroughly. The combined effect of grain refinement and second phase dissolved was responsible for the change of mechanical properties.

Excellent High‐Strain‐Rate Superplasticity of Fine‐Grained ZK60 Magnesium Alloy Produced by Submerged Friction Stir Processing

“…It is reported that FSP/FSW can result in obvious dissolution of particles in ZK60 alloy. [ 38,39 ] However in this work, the dissolution of the particles is not so obvious because the decline of the particle fraction is small. This may be attributed to the lower processing temperature.…”

Friction Stir Processing of Magnesium Alloys: A Review

“…Because of the obvious shortening of diffusion distance and the increasing of diffusion rate, the secondary phases in Mg alloys are completely dissolved instantly during FSP. Usually, this phenomenon exists in the FSP of precipitationstrengthened Mg alloys, including AZ series [11,14,15], ZK series [16], and rare-earth Mg alloys [17][18][19][20][21].…”

Impact of speed of traverse during joining of CDA101 plates by FSW process

“…2e). Thus, it can be understood that the joints fabricated at smaller speeds of tool traverse are found to possess fine sized, completely refined smaller sized uniaxial grains when compared with that of the joints fabricated at greater speeds of tool traverse [41,42]. In better words, the size of the grains seems to increase with the increase in the speed of tool traverse.…”