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of the patient during the acetabular time. Conclusion: We have encoded all the steps of thisapproach that we have called the Anterior Lateral Decubitus Intermuscolar (ALDI) approach.Thursday, October 7, 2010, 8:00-8:50Session A1: Alternate Bearings in THA 1Ultrafine Grain Refinement of Biomedical Co-29Cr-6Mo Alloy UsingConventional Hot-Compression*Akihiko Chiba - Tohoku University - Sendai, JapanYungping Lee - Tohoku University - Sendai, JapanShingo Kurosu - Tohoku University - Sendai, JapanHiroaki Matsumoto - Institute for Materials Research, Tohoku University - Sendai, Japan*Email: a.chiba@imr.tohoku.ac.jpCo-Cr-Mo alloys are widely used for biomedical implant materials such as artificial hip andknee joints owing to their excellent corrosion and wear resistance as well as higherstrengthening properties. However, the alloys exhibits sever brittle nature under an as-castcondition. It is generally recognized that refinement of the grain size of the metallic materials bymeans of hot-forging processes is an effective methodology to strengthen the alloy. Dynamicrecrystallization (DRX) is an effective metallurgical process for grain refinement during hotdeformation. However, there are few studies on the hot deformation behavior of Co-Cr-Moalloy, especially grain refinement through DRX. In the present study, DRX and grain refinementduring hot deformation of Co-29Cr-6Mo alloy has been investigated under various conditionssuch as deformation temperature and strain rate.Although at strain of 5% hot deformed microstructure maintains the original grains, the grainsize decreases with increasing the strain and exhibits the average grain size of approximately2μm at strain of 60%. Ultra fine grained microstructure with the grain size of approximately0.5 μm was obtained under deformation at a 1323 K at a strain rate of 0.1s -1 . The originalgrains are broken up into different grains due to the new boundary formation not only near theinitial boundaries but also in the interior of the grains at large strain. This grain fragmentationwithout bulging in the course of hot deformation is associated with considerably low stackingfault energy (SFE) of the Co-29Cr-6Mo alloy even at the deformation temperatures.file:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]