The effects of boron addition on the microstructure stability and mechanical properties of a Ni-Cr based superalloy

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	The effects of boron addition on the microstructure stability and mechanical properties of a Ni-Cr based superalloy
	Yang, F; Hou, JS; Gao, S; Wang, CS; Zhou, LZ; Zhou, LZ (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang 110016, Liaoning, Peoples R China.
刊名	MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
	2018-02-07
卷号	715 页码:126-136
关键词	Service-exposed Alloy-625 Boiler Applications Room-temperature Behavior Phase Polycrystalline 650-degrees-c Precipitation Evolution Fracture
ISSN号	0921-5093
英文摘要	This study is focused on the effect of boron additions on the microstructure stability and mechanical properties of a Ni-Cr based superalloy designed for application of 700 degrees C advanced ultra-supercritical units component. The results show that boron in the content range of 25-75 ppm has no obvious influence on as-cast and heat-treated microstructure characteristics compared with that of the alloy without boron. During long-term thermal exposure, the variation of B content has no obvious effect on gamma" coarsening, delta phase precipitation and MC carbide degeneration, but inhibits the agglomeration of M23C6 carbide along grain boundary. According to the mechanical property analysis, the boron additions contribute to mainly tensile ductility especially the elongation of whether the heat treated alloy or the long-term thermal exposed alloy. The strength especially yield strength of the B doped alloy almost keeps the same level as that of the B-free alloy. Furthermore, the SEM fractography shows a change from intergranular fracture to a mixed fracture and the dimples on fracture surface obviously increase with the addition of boron. The mechanism discussion reveals that the segregation of boron at grain boundary resulted in the improvement of grain boundary cohesion and the optimization of carbides distribution at grain boundary. The strengthening mechanism of delta phase is confirmed as its obstacle effect to dislocation movement.; This study is focused on the effect of boron additions on the microstructure stability and mechanical properties of a Ni-Cr based superalloy designed for application of 700 degrees C advanced ultra-supercritical units component. The results show that boron in the content range of 25-75 ppm has no obvious influence on as-cast and heat-treated microstructure characteristics compared with that of the alloy without boron. During long-term thermal exposure, the variation of B content has no obvious effect on gamma" coarsening, delta phase precipitation and MC carbide degeneration, but inhibits the agglomeration of M23C6 carbide along grain boundary. According to the mechanical property analysis, the boron additions contribute to mainly tensile ductility especially the elongation of whether the heat treated alloy or the long-term thermal exposed alloy. The strength especially yield strength of the B doped alloy almost keeps the same level as that of the B-free alloy. Furthermore, the SEM fractography shows a change from intergranular fracture to a mixed fracture and the dimples on fracture surface obviously increase with the addition of boron. The mechanism discussion reveals that the segregation of boron at grain boundary resulted in the improvement of grain boundary cohesion and the optimization of carbides distribution at grain boundary. The strengthening mechanism of delta phase is confirmed as its obstacle effect to dislocation movement.
学科主题	Nanoscience & Nanotechnology ; Materials Science, Multidisciplinary ; Metallurgy & Metallurgical Engineering
语种	英语
资助机构	National Energy Administration Program of China [NY20150102]; National Key Research and Development Program of China [2017YFB0305204]; National Natural Science Foundation of China [51571191]
公开日期	2018-06-05
内容类型	期刊论文
源URL	[http://ir.imr.ac.cn/handle/321006/79515]
专题	金属研究所_中国科学院金属研究所
通讯作者	Hou, JS; Zhou, LZ (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang 110016, Liaoning, Peoples R China.
推荐引用方式 GB/T 7714	Yang, F,Hou, JS,Gao, S,et al. The effects of boron addition on the microstructure stability and mechanical properties of a Ni-Cr based superalloy[J]. MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING,2018,715:126-136.
APA	Yang, F,Hou, JS,Gao, S,Wang, CS,Zhou, LZ,&Zhou, LZ .(2018).The effects of boron addition on the microstructure stability and mechanical properties of a Ni-Cr based superalloy.MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING,715,126-136.
MLA	Yang, F,et al."The effects of boron addition on the microstructure stability and mechanical properties of a Ni-Cr based superalloy".MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING 715(2018):126-136.