Influence of Processing Conditions on Microstructure and Mechanical Properties of Large Thin-Wall Centrifugal Ti–6Al–4V Casting
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2016年第4期
论文作者：Xin Feng Jianke Qiu Yingjie Ma Jiafeng Lei Yuyou Cui Xinhua Wu Rui Yang
文章页码：362 - 371
摘 要：In this work,the effects of mould pre-heating temperatures and hot isostatic pressing（HIPping）process on the microstructural characteristics and mechanical properties,including static tensile and damagetolerance properties of large thin-wall cylindrical Ti–6Al–4V casting,have been studied.The experimental results show that with the increasing mould pre-heating temperature from 673 to 873 K,the casting microstructures change from a mixture of Widmanst?tten and colony microstructure to a primary colony.The centre of the thick wall section has relatively coarse microstructure than the edge and thin section.Lower mould pre-heating temperature brings about more porosities.HIPping process,which not only reduces the casting pores effectively but also increases the priorβgrain boundary cohesion and coarsens the microstructure,is essential to improving the ductility of the casting.Due to the oxygen contamination and finer microstructure on the surface,micro-hardness profiles on the cross section present a decreasing tendency from the surface to inner.The thickness of the reaction layers for the different mould pre-heating temperatures is nearly the same（450μm）.On the whole,the tensile strength and microhardness decrease with increasing mould pre-heating temperature from 673 to 873 K.However,the fracture toughness and fatigue crack growth resistance of the castings increase with increasing mould preheating temperature.
Xin Feng1，Jianke Qiu1，Yingjie Ma1，Jiafeng Lei1，Yuyou Cui1，Xinhua Wu2，Rui Yang1
1. Institute of Metal Research, Chinese Academy of Sciences2. Department of Materials Engineering, Monash University
摘 要：In this work,the effects of mould pre-heating temperatures and hot isostatic pressing（HIPping）process on the microstructural characteristics and mechanical properties,including static tensile and damagetolerance properties of large thin-wall cylindrical Ti–6Al–4V casting,have been studied.The experimental results show that with the increasing mould pre-heating temperature from 673 to 873 K,the casting microstructures change from a mixture of Widmanst?tten and colony microstructure to a primary colony.The centre of the thick wall section has relatively coarse microstructure than the edge and thin section.Lower mould pre-heating temperature brings about more porosities.HIPping process,which not only reduces the casting pores effectively but also increases the priorβgrain boundary cohesion and coarsens the microstructure,is essential to improving the ductility of the casting.Due to the oxygen contamination and finer microstructure on the surface,micro-hardness profiles on the cross section present a decreasing tendency from the surface to inner.The thickness of the reaction layers for the different mould pre-heating temperatures is nearly the same（450μm）.On the whole,the tensile strength and microhardness decrease with increasing mould pre-heating temperature from 673 to 873 K.However,the fracture toughness and fatigue crack growth resistance of the castings increase with increasing mould preheating temperature.
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