TY - JOUR
T1 - Microstructural factors governing hardness in friction-stir welds of solid-solution-hardened Al alloys
AU - Sato, Yutaka S.
AU - Park, Seung Hwan C.
AU - Kokawa, Hiroyuki
N1 - Funding Information:
The authors are grateful to Messrs. Yoshihiro Ohsawa and Akira Honda for technical assistance and acknowledge Professor Keisuke Ikeda and Dr. Zhan Jie Wang for their helpful discussions. They thank Dr. Masatoshi Enomoto, Mr. Shigetoshi Jogan, Dr. Takenori Hashimoto, Dr. Tomiyoshi Kanai, and Mr. Shoichi Sato for useful advice. They are also grateful to Professor Kiyohito Ishida and Dr. Ikuo Ohnuma for the thermochemical calculation. They also thank Professors Shuji Hanada and Naoya Masahashi for TEM observations. Financial support from the Japanese Ministry of Education, Culture, Sports, Science and Technology with a Grant-in-Aid for Exploratory Research is grateful acknowledged.
PY - 2001/12
Y1 - 2001/12
N2 - Microstructural factors governing hardness in friction-stir welds of the solid-solution-hardened Al alloys 1080 and 5083 were examined by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The effect of grain boundary on the hardness was examined in an Al alloy 1080 which did not contain any second-phase particles. The weld of Al alloy 1080 had a slightly greater hardness in the stir zone than the base material. The maximum hardness was located in the thermomechanically affected zone (TMAZ). The stir zone considered of recrystallized fine grains, while the TMAZ had a recovered grain structure. The increase in hardness in the stir zone can be explained by the Hall-Petch relationship. On the other hand, the hardness profiles in the weld of Al alloy 5083 were roughly homogeneous. Friction-stir welding created the fine recrystallized grains in the stir zone and recovered grains in the TMAZ in the weld of this alloy. The stir zone and the TMAZ had slightly higher dislocation densities than the base material. Many small Al6(Mn,Fe) particles were detected in all the grains of the weld. The hardness profiles could not be explained by the Hall-Petch relationship, but rather by Orowan hardening. The results of the present study suggest that the hardness profile is mainly affected by the distribution of small particles in friction-stir welds of Al alloys containing many such particles.
AB - Microstructural factors governing hardness in friction-stir welds of the solid-solution-hardened Al alloys 1080 and 5083 were examined by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The effect of grain boundary on the hardness was examined in an Al alloy 1080 which did not contain any second-phase particles. The weld of Al alloy 1080 had a slightly greater hardness in the stir zone than the base material. The maximum hardness was located in the thermomechanically affected zone (TMAZ). The stir zone considered of recrystallized fine grains, while the TMAZ had a recovered grain structure. The increase in hardness in the stir zone can be explained by the Hall-Petch relationship. On the other hand, the hardness profiles in the weld of Al alloy 5083 were roughly homogeneous. Friction-stir welding created the fine recrystallized grains in the stir zone and recovered grains in the TMAZ in the weld of this alloy. The stir zone and the TMAZ had slightly higher dislocation densities than the base material. Many small Al6(Mn,Fe) particles were detected in all the grains of the weld. The hardness profiles could not be explained by the Hall-Petch relationship, but rather by Orowan hardening. The results of the present study suggest that the hardness profile is mainly affected by the distribution of small particles in friction-stir welds of Al alloys containing many such particles.
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U2 - 10.1007/s11661-001-0178-7
DO - 10.1007/s11661-001-0178-7
M3 - Article
AN - SCOPUS:0035715387
SN - 1073-5623
VL - 32
SP - 3033
EP - 3042
JO - Metallurgical Transactions A (Physical Metallurgy and Materials Science)
JF - Metallurgical Transactions A (Physical Metallurgy and Materials Science)
IS - 12
ER -