Experimental characterization and fatigue behavior of thermally and mechanically treated 316L stainless steel MIG-welded
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RESEARCH PAPER
Experimental characterization and fatigue behavior of thermally and mechanically treated 316L stainless steel MIG-welded joints Hichem Guizani 1,2
&
Brahim Tlili 2 & Moez Chafra 3
Received: 3 April 2020 / Accepted: 15 September 2020 # International Institute of Welding 2020
Abstract The improvement and optimization of post-weld treatments in the case of austenitic 316L stainless steels are, to a large extent, a condition of the service life of the associated structures. In this regard, mechanical brushing and heat treatment are post-weld techniques dedicated to the assembly of mechanically welded structures applicable in the aeronautics, food, and transport sectors. In this study, two techniques are applied to welded joints: mechanical brushing and heat treatment at high temperature. The base material is austenitic stainless steel with molybdenum (AISI316L) in sheet of 5-mm thick. The adopted welding process is Arc Welding under Metal Inert Gas (MIG). Monotonic Tensile test, micro-hardness measurement, low cycle fatigue, micro-hardness measurement, and MES (scanning electron microscopy) observation were conducted in order to qualify the welded, brushed, and heat-treated weldment. Compared with the welded and brushed samples, the treatment with heat annealing specimen maintains the longest lifetime and the lowest consolidation stress ± 0.4% imposed strain rate and 10−3/s as displacement speed. The annealing heat treatment has a softening effect on the welded structure during the test of the cycle fatigue; this is consistent with the micro-hardness levels measured in the weldment. Keywords Cyclic behavior . Stainless steel . Mechanical brushing . Annealing . Micro-structure
1 Introduction Several studies have dealt with various technics for posttreatment of welded joints. They have revealed that such techniques improve the fatigue strength of the welded steel structures. These techniques can be classified in weld geometry improvement methods and residual stress methods [1, 2]. Mechanical and thermal post-welding treatment techniques are applied in order to overcome the effects related to fatigue failure of welded joints [3]. The post-treatment techniques
Recommended for publication by Commission XIII - Fatigue of Welded Components and Structures * Hichem Guizani [email protected] 1
Laboratory of Applied Mechanics and Engineering (LR-MAI): National School of Engineers of Tunis, University of Tunis El Manar, Tunis, Tunisia
2
ISET, University Campus of Boulifa, Kef, Tunisia
3
Applied Mechanics and Systems Research Laboratory, Tunisia Polytechnic School, University of Carthage, Tunis, Tunisia
such as re-melting, shoot peening, grinding, ultrasonic peening, and special welding techniques allow a smooth transition between the different zones of the weldment, reducing the stress concentration. Mainly, this results in an extended crack initiation phase in the fatigue life. As reported by Kim et al. [3], these methods are usually applied to improve the fatigue strength of steel structures afte
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