Dissimilar friction stir welding of AISI 430 ferritic and AISI 304L austenitic stainless steels
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(2020) 20:131
ORIGINAL ARTICLE
Dissimilar friction stir welding of AISI 430 ferritic and AISI 304L austenitic stainless steels S. Emami1 · S. Sadeghi‑Kanani1 · T. Saeid1 · F. Khan2 Received: 19 May 2020 / Revised: 21 September 2020 / Accepted: 5 October 2020 © Wroclaw University of Science and Technology 2020
Abstract Dissimilar joints of AISI 430 ferritic and AISI 304L austenitic stainless steels were produced by friction stir welding process. A sound and defect-free joint was obtained at 1 mm tool offset towards the ferritic sample located in the advancing side, and at rotational and welding speeds of 560 rpm and 50 mm/min, respectively. The XRD measurements revealed the presence of approximately equal volume fractions of ferrite (51%) and austenite (49%) phases in the stir zone (SZ). The formation of low-angle grain boundaries through the occurrence of dynamic recovery along with the presence of shear texture components in both constituent phases of ferrite and austenite in the SZ approved the occurrence of continuous dynamic recrystallization throughout the evolved microstructure. Moreover, microstructural observations showed the formation of necklace structure through the microstructure of ferrite in the SZ. Taylor map approved the strain localization in the ferrite phase. Micro-hardness measurement indicated that the hardness value is increased in the SZ. The result of tensile test showed that fracture occurred from less ductile ferritic base metal. Keywords Dissimilar friction stir welding · Stainless steels · Tool offset · Microstructure · Dynamic recrystallization
1 Introduction Welding of dissimilar materials is conducted frequently in different fields of industry such as power plants [1], chemical and petrochemical industries [2], as well as for nuclear and marine applications [3] to meet the accrued demand from the design and service conditions. This kind of joining is beneficial due to both technical and economic reasons which effectively utilizes the special properties including physical and mechanical of each individual materials [4]. In this regard, some industrial applications need the joining of austenitic stainless steels (ASSs) to ferritic stainless steels (FSSs) [5]. For example, such combination of dissimilar materials is commonly found at high-temperature applications such as energy conversion systems. For example, central power S. Emami and S. Sadeghi-Kanani contributed equally to this work. * T. Saeid [email protected] 1
Faculty of Materials Engineering, Sahand University of Technology, Tabriz, Iran
School of Mechanical Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu 632014, India
2
stations include boiler sections made from ferritic stainless steels operating at low temperature. The section is usually connected with another section made from austenitic stainless steel which operates at higher temperature. Therefore, the transition occurs through a dissimilar weld between these two materials [6]. Another typical example of such joints is commonly found in T
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