Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Strength Change due to Plastic Deformation in Al 2024 Ultrafine Grained ECAP Metal

ECAP 성형가공한 Al 2024 초미세결정립 재료의 소성변형량에 따른 강도 변화

  • Published : 2005.10.01
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Abstract

Strength change of an over-aged A12024 material was studied after being subjected to stages of severe plastic deformation by ECAP (Equal Channel Angular Pressing). Various kinds of strength value were measured using the conventional tensile test, Rockwell and Vickers hardness and the SP (small punch) test Due to limitation of the specimen size, tension test in transverse direction could not be conducted. Hence, SP test was employed for assessing the strength in transverse direction. Based on TEM observation the measured strength characteristics were explained based on the relation between microstructure, dislocation and strength. As the number of ECAP pass increases, the strength of A12024 was also increased. However, considerable change of strength, which is generally predicted, was not observed in this study. For the strength in transverse direction even decrease of the strength was observed after 6 passes of ECAP. It was argued that this decrease was due to dynamic recovery of dislocation density during or after ECAP processes at $150^{\circ}C$. The strength assessment equation proposed by the authors in the previous paper was shown to be very accurate. This argument was supported by comparing the results of conventional tensile test with those of SP test. It was also pointed that the Rockwell har(3ness value seemed to be able to represent the strength in the transverse direction.

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References

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