Solidification modes and delta-ferrite of two types of 316L stainless steels:a combination of as-cast microstructure and HT-CLSM research  

作　　者：Yang Wang Chao Chen Xiao-yu Yang Zheng-rui Zhang Jian Wang Zhou Li Lei Chen Wang-zhong Mu 

机构地区：[1]College of Materials Science and Engineering,Taiyuan University of Technology,Taiyuan,030024,Shanxi,China [2]Department of Materials Science and Engineering,KTH Royal Institute of Technology,Stockholm,10044,Sweden [3]College of Artificial Intelligence and Big Data for Medical Sciences,Shandong First Medical University and Shandong Academy of Medical Sciences,Jinan,250117,Shandong,China [4]College of Mechanical Engineering,Taiyuan University of Technology,Taiyuan,030024,Shanxi,China [5]Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education),Northeastern University,Shenyang,110819,Liaoning,China

出　　处：《Journal of Iron and Steel Research International》2025年第2期426-436,共11页钢铁研究学报(英文版)

基　　金：support of the Research Project Supported by Shanxi Scholarship Council of China(2022-040);"Chunhui Plan"Collaborative Research Project by the Ministry of Education of China(HZKY20220507);National Natural Science Foundation of China(52104338);Applied Fundamental Research Programs of Shanxi Province(202303021221036);Shandong Postdoctoral Science Foundation(SDCX-ZG-202303027,SDBX2023054).

摘　　要：In 316L austenitic stainless steel,the presence of ferrite phase severely affects the non-magnetic properties.316L austenitic stainless steel with low-alloy type(L-316L)and high-alloy type(H-316L)has been studied.The microstructure and solidification kinetics of the two as-cast grades were in situ observed by high temperature confocal laser scanning microscopy(HT-CLSM).There are significant differences in the as-cast microstructures of the two 316L stainless steel compositions.In L-316L steel,ferrite morphology appears as the short rods with a ferrite content of 6.98%,forming a dual-phase microstructure consisting of austenite and ferrite.Conversely,in H-316L steel,the ferrite appears as discontinuous network structures with a content of 4.41%,forming a microstructure composed of austenite and sigma(σ)phase.The alloying elements in H-316L steel exhibit a complex distribution,with Ni and Mo enriching at the austenite grain boundaries.HT-CLSM experiments provide the real-time observation of the solidification processes of both 316L specimens and reveal distinct solidification modes:L-316L steel solidifies in an FA mode,whereas H-316L steel solidifies in an AF mode.These differences result in ferrite and austenite predominantly serving as the nucleation and growth phases,respectively.The solidification mode observed by experiments is similar to the thermodynamic calculation results.The L-316L steel solidified in the FA mode and showed minimal element segregation,which lead to a direct transformation of ferrite to austenite phase(δ→γ)during phase transformation after solidification.Besides,the H-316L steel solidified in the AF mode and showed severe element segregation,which lead to Mo enrichment at grain boundaries and transformation of ferrite into sigma and austenite phases through the eutectoid reaction(δ→σ+γ).

关 键 词：316L austenitic stainless steel As-cast microstructure High-temperature confocal laser scanning microscopy Solidification mode FERRITE Characterization 

分 类 号：TG1[金属学及工艺—金属学]