Effect of prior austenite grain size on the morphology and mechanical properties of martensite in medium carbon steel

In industrial application, unintentional manufacturing line troubles often consequence in heating raw materials excessively, in terms of either time or temperature. One of the effects of such occurrence is a product with a variation of prior austenite grain size, even if after the heat treatment the end result is the same, martensite. The variation of the prior austenite grain size is believed to vary the end results of the martensite. This undesirable variation includes the variation of fatigue resistance, impact strength, yield strength, hardness, etc. This research studies the effect of the prior austenite grain size on the morphology of the martensite microstructure. The results show that within the typical industrial application of temperature and holding time set up, as holding time or the temperature increases, the prior austenite average diameter increases. The block and packet sizes in the martensite also increase. The variation of mechanical property dependence on the grain size is indeed due to the different characteristics reflected in the martensite morphology. With respect to the same area, smaller grain has more blocks and packets, which agrees with higher dislocation density verified with transmission electron microscopic evaluation

Mg-based porous metals as cancellous bone analogous material: A review

Interest in cancellous bone analogous materials is driven by the development of tissue engineering and biomaterials. For the past decade, the research focus has been centered on biodegradable materials, in which the ability of the material to safely degrade in the human body while retaining sufficient qualities during service is conveniently cost-effective and less morbid. Among others, magnesium and its alloys have presented the best qualities especially as load-bearing biomaterials. In this article, the promising details of porous magnesium and its alloys as a cancellous bone analogous material developed during the past 10 years are highlighted. The manufacturing processes, mechanical performance, and biocompatibility of porous magnesium and its alloys are discussed. The Achilles' heel of current evaluation was identified. Further, a few prospective developments of porous magnesium and its alloys are put forward with advanced desirable qualities as a cancellous bone analogous material