Laser Beam Direct Energy Deposition of graded austenitic-to-martensitic steel junctions compared to dissimilar Electron Beam welding

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:824

Article

Villaret, Flore^1,5  Boulnat, Xavier²  Aubry, Pascal⁴  Yano, Yasuhide³  Ohtsuka, Satoshi³  Fabregue, Damien²  de Carlan, Yann¹ 

[1] Univ Paris Saclay, CEA, Serv Rech Met Appl, F-91191 Gif Sur Yvette, France

[2] Univ Lyon, INSA Lyon, CNRS, MATEIS,UMR 5510, F-69621 Villeurbanne, France

[3] Japan Atom Energy Agcy, 4002 Narita Cho, Oarai, Ibaraki 3111393, Japan

[4] Univ Paris Saclay, CEA, Serv Etude Analyt & React Surfaces SEARS, F-91191 Gif Sur Yvette, France

[5] EDF R&D, Dept Mat & Mecan Composants MMC, F-77250 Les Renardieres, Moret Sur Loing, France

关键词: Gradient material;    316L;    Fe-9Cr-1Mo;    Additive manufacturing;    Mechanical properties;    Electron beam welding;   

DOI  :  10.1016/j.msea.2021.141794

来源: Elsevier

【 摘 要 】

This article presents the Laser Beam Direct Energy Deposition (DED-LB) process as a method to build a graded austenitic-to-martensitic steel junction. Builds were obtained by varying the ratio of the two powders during DED-LB processing. Samples with gradual transitions were successfully obtained using a high dilution rate from one layer to the next. Long austenitic grains are observed on the 316 L side while martensitic grains are observed on the Fe-9Cr-1Mo side. In the transition zone the microstructure is mainly martensitic. Characterisations performed after building and after a tempering heat treatment at 630 degrees C for 8 h were compared to dissimilar Electron Beam (EB) welds. Before heat treatment the DED-LB graded area has high hardness (values of around 430 HV) due to fresh martensite formed during building. Tempering heat treatment reduces this hardness to 300 HV. EDS measurements indicate that the chemical gradient between 316 L and Fe-9Cr-1Mo obtained by DED-LB is smoother than the chemical change obtained in EB welds. Microstructures in DED-LB are quite different from those obtained by EB welding. Hardness values in DED-LB samples and in welds are similar; the weld metal and the Fe-9Cr-1Mo heat-affected zone are relatively hard after welding because of fresh martensite, as found in the DED-LB transition zone; both are softened by tempering heat treatment. Tensile tests show that DED-LB samples and EB welds have similar behaviour with failure in 316 L base metal at 20 degrees C and 400 degrees C and failure in Fe-9Cr-1Mo base metal at 550 degrees C. DED-LB samples have comparable mechanical properties to EB welds.

【 授权许可】

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