Microstructure and mechanical properties of AZ91 tubes fabricated by Multi-pass Parallel Tubular Channel Angular Pressing

Parallel Tubular Channel Angular Pressing (PTCAP) process is a novel recently developed severe plastic deformation (SPD) method for producing ultrafine grained (UFG) and nanograined (NG) tubular specimens with excellent mechanical and physical properties. This process has several advantageous compared to its TCAP counterparts. In this paper, a fine grained AZ91 tube was fabricated via multi pass parallel tubular channel angular pressing (PTCAP) process. Tubes were processed up to three passes PTCAP at 300 °C. Evolution of microstructure, mechanical properties and fracture behavior of the processed tubes after different passes were evaluated. Hardness, strength, and elongation were increased for processed tubes. Mean grain size was notably reduced to 3.8 μm for the tube which processed three passes from a 150 μm for the unprocessed tube. The maximum strength was found for second passes PTCAP processed tube which increased considerably about 108 %. The strength of the first pass processed tube increased about 62.5%. Increasing in elongation at room temperature was occurred, too. Mechanical properties of the third pass processed tube were deteriorated relatively because of appearing microcracks on the surface. Also, the hardness improved and it was increased about 77%. The result showed that the achieved mechanical properties consistent with microstructure.