Grain refinement and superplasticity of pipes processed by high-pressure sliding

ABSTRACT

The high-pressure sliding (HPS) process was applied for grain refinement of a pipe form of an Al-3wt%Mg-0.2wt%Sc alloy by developing two types of straining techniques (called in this study anvil sliding and mandrel sliding). To achieve a homogeneous microstructure throughout the cross-section of the pipe, the sample is rotated around the longitudinal axis every after sliding operation by introducing multi-pass technique, named multi-pass HPS (MP-HPS) as developed earlier for rods. The MP-HPS-processed sample shows ultrafine-grained structures with an average grain size of ∼260 and ∼300 nm after the HPS processing using anvil sliding and mandrel sliding. The samples also exhibit superplasticity with total elongations well more than 400%, respectively. A finite-element method is used to simulate the evolution of strain in the HPS processing and demonstrates that the simulation well represents the experimental results.

KEYWORDS:

• Multi-pass high-pressure sliding
• pipe
• grain refinement
• superplasticity
• Al alloy

Acknowledgments

This work was conducted under a project subsidized by the New Energy and Industrial Technology Development Organization (NEDO)/The Strategic Core Technology Advancement Program. In addition, this work was supported in part by the Light Metals Educational Foundation of Japan and in part by Grant-in-Aids for Scientific Research (S) and (A) from the MEXT, Japan (No. 26220909 and 19H00830). The HPS process was carried out in the International Research Center on Giant Straining for Advanced Materials (IRC-GSAM) at Kyushu University and Nagano Forging Co., Ltd.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported in part by the Light Metals Educational Foundation of Japan and in part by Grant-in-Aids for Scientific Research (S) and (A) from the MEXT, Japan [grant number 26220909 and 19H00830].