Hydrostatic twist extrusion (HTE) for processing relatively long ultrafine grained samples

In this study, hydrostatic twist extrusion (HTE) has been introduced for processing relatively long ultrafine grained (UFG) bulk samples. By using high-pressure fluid surrounded the sample, surface contact between die and sample was eliminated. The high-pressure fluid causes high hydrostatic pressure, which leads to improve-ment of material properties and increased the aspect ratio of the sample (length/diameter). The HTE process was applied to commercial pure aluminum samples at room temperature, and then microstructure and mechanical properties were examined. The results demonstrate that after HTE process, the grain size was reduced from 54 mu m to similar to 800 nm, and microhardness was increased from 29.2 HV to 37.7 HV. Also, yield and ultimate strength were noticeably increased from 78 MPa and 103 MPa to 166 MPa and 175 MPa, respectively. This process seems to be very promising and interesting for the future industrial application.

Automated summary

In this study, hydrostatic twist extrusion (HTE) was used to process long ultrafine grained (UFG) bulk samples. The use of high-pressure fluid eliminated surface contact between die and sample. The HTE process resulted in a reduction in grain size and an improvement in mechanical properties of the aluminum samples. The process shows promise for future industrial applications.