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Effect of Scrap Impurities on Microstructure and Mechanical Properties of Zr Alloys

스크랩 불순물이 Zr 합금의 미세조직 및 기계적 특성에 미치는 영향

Jeong, Gu Beom;Kim, In Won;Song, Jae Sook;Shin, Pyung Woo;Hong, Sun Ig
정구범;김인원;송재숙;신평우;홍순익

  • Received : 2015.12.08
  • Accepted : 2016.05.05
  • Published : 2016.06.30

Abstract

In this study, the effect of scrap ratio on the mechanical properties of Zr alloys was studied. Oxygen content in the ingot cake increased rapidly with increasing fraction of scrap, which can be attributed to the surface oxide of scrap including small pieces of turning, chips, etc. Iron content did not increase much with the increasing addition of scrap, suggesting scrap materials was well reserved in the iron-free container. As-cast structure of Zr alloy with the scrap:sponge ratio displayed plate/or needle ${\alpha}$ phase and no appreciable change of the cast structure was observed with change of scrap fraction. The strength increases with increasing fraction of scrap, which can be attributed to the increase of oxygen content. The ductility decreased slightly with increase of scrap fraction. Dislocation-oxygen interaction is known to increase the strength at the expense of ductility. Ingot cake with intentionally added $Fe_2O_3$ exhibited the drastic decrease of the formability, even exhibited the brittle fracture behavior during rolling. The oxidation resistance, however, increased with the increase of scrap fraction because of high oxygen content, which may prevent more penetration and diffusion of oxygen into matrix.

Keywords

Zr alloy;Strength;Ductility;Oxygen;Recycling

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Acknowledgement

Grant : BK21플러스

Supported by : 충남대학교