A novel combined severe plastic deformation method for producing thin-walled ultrafine grained cylindrical tubes

•A novel combined SPD process was developed.•An ultrafine grained thin-walled tube with the thickness of 0.75 mm was produced.•A remarkable grain refinement could achieve from ~33 µm for as-received tube to below ~3 µm after the combined process.•The Vickers microhardness was significantly increased from the 38 HV to 70 HV after the combined process.•Yield and ultimate strengths were remarkably increased.

A novel severe plastic deformation (SPD) process entitled combined parallel tubular channel angular pressing (PTCAP) and tube backward extrusion (TBE) is proposed for producing thin-walled ultrafine-grained (UFG) tubes. In this new combined SPD approach, the PTCAP and TBE processes are consequently applied to the tube material in which a severe plastic strain is applied to produce a UFG thin-walled tube. This technique was performed on an AZ31 magnesium tube, and a remarkable grain refinement was achieved. The results showed that this method could easily produce a high strength thin walled tube. The microhardness increased significantly to 70 HV after the process from an initial value of 38 HV.