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Duplex stainless steel/martensitic steel dissimilar resistance spot welding: Microstructure-properties relationships
, Article Welding Journal ; Volume 98, Issue 9 , 2019 , Pages 263S-272S ; 00432296 (ISSN) ; Pouranvari, M ; Sharif University of Technology
American Welding Society
2019
Abstract
This paper addresses the phase transformations and mechanical performance of dissimilar resistance spot welds between 2304 duplex stainless steel (DSS) and 1.2-GPa martensitic (MS) advanced high-strength steel (AHSS). The solidification mode and transformation path of the fusion zone (FZ) were analyzed. The key metallurgical feature of the FZ was the formation of a duplex microstructure consisting of delta ferrite and martensite. The FZ size at the sheet/sheet interface was the critical factor controlling the fraction of pullout failure during the partial thickness-partial pullout mode, the load-bearing capacity, and the energy absorption capability of the DSS/MS dissimilar resistance spot...
Upset Resistance Welding of Duplex Stainless Steel to Martensitic Stainless Steel
, M.Sc. Thesis Sharif University of Technology ; Movahedi, Mojtaba (Supervisor)
Abstract
Upset Resistance Welding (URW) is a solid-state joining process which can be used to join a variety of parts and profiles including railways, wheel rims and pipes used in oil and petrochemical industries. This process has three primary parameters, welding current, current passage time and mechanical pressure. Martensitic Stainless Steels (MSSs) due to high strength and wear resistance, good atmospheric corrosion resistance and relatively low price and Duplex Stainless Steels (DSSs) because of higher strength and better corrosion resistance in chlorine environments, are widely used in different industries. Dissimilar MSS/DSS joints are of great importance for piping, specially in oil and...
Welding Metallurgy and Weldability of Martensitic Advanced High Strength Steel and Duplex Stainless Steels during Resistance Spot Welding
, M.Sc. Thesis Sharif University of Technology ; Pouranvari, Majid (Supervisor)
Abstract
Duplex stainless steels and advanced high strength steels are both known as new materials in automobile industry applications. Process of resistance spot welding is the main process in welding of auto-body structures. Hence investigating the welding metallurgy and weldability of similar and dissimilar joints of duplex stainless steels and advanced high strength steel are crucial. The purpose of this study is to analyse the relationship between welding process and geometric characteristic of weld nugget, phase transformations of Weld nugget and heat affected zone, mechanical properties (i.e force bearing capacity and energy absorption capability) and failure mode (interfatial or pullout). in...
Microstructure-mechanical Properties Relation of Duplex Steel Friction Stir Welds
, M.Sc. Thesis Sharif University of Technology ; Movahedi, Mojtaba (Supervisor) ; Pooranvari, Majid (Supervisor)
Abstract
Fusion welding of Duplex Stainless Steel (DSS) and dissimilar welding of This alloy and other steels have a lot of problems such as losing phase balance and formation of secondary phases i.e. Sigma Phase. Therefore, Friction Stir Welding (FSW) was used as a substitute for traditional fusion welding techniques of DSS. The present study investigates the relationship between the process variables and microstructural and the mechanical properties of frictional welding of similar and dissimiliar FSW of DSS to carbon steel in order to obtain the joint with the highest mechanical strength. In this study, similar welding of S2304 DSSs and dissimilar welding of S2304 and St12 using FSW were...
Effect of Process Parameters on Microstructure and Mechanical Properties of Duplex Stainless Steel Produced by Wire-Arc Additive Manufacturing
, M.Sc. Thesis Sharif University of Technology ; Ashouri, Hossein (Supervisor) ; Movahedi, Mojtaba (Supervisor)
Abstract
Wire-arc additive manufacturing is one of the types of additive manufacturing methods that creates the desired part through layer-by-layer deposition. Heat input and interlayer temperature have an important role in this process. Duplex stainless steels have a wide range of applications due to their high corrosion resistance in chloride environments and higher strength than austenitic stainless steels. In this study, the effect of heat input (0.3 kJ/mm and 0.8 kJ/mm) and interlayer temperature (250 ºC and 40 ºC) was investigated on the macrostructure, microstructure and mechanical properties of 2209 duplex stainless steel walls that produced by gas metal arc welding based wire-arc additive...
Study on the Phase Transformation and Mechanical Behavior of Duplex Stainless Steel Resistance Spot Welds
, M.Sc. Thesis Sharif University of Technology ; Pouranvari, Majid (Supervisor) ; Movahedi, Mojtaba (Supervisor)
Abstract
Use of materials with both high strength and good formability in car structure is a serious approach in the automotive industry to reduce weight as well as maintain the security of occupants. Stainless steels such as duplex steels are one of the most attractive candidates. Thus, metallurgical and mechanical behavior during resistance spot is important. The aim of this work is to study the microstructure-property relationships in resistance spot welding of duplex stainless steel. Austenite-ferrite phase balance and weld nugget size are two key factors determining the mechanical properties of these steels. High cooling rate of resistance spot welding can have a significant impact on the...
Welding metallurgy of duplex stainless steel during resistance spot welding
, Article Welding Journal ; Volume 96, Issue 9 , 2017 , Pages 307s-318s ; 00432296 (ISSN) ; Pouranvari, M ; Movahedi, M ; Sharif University of Technology
Abstract
This paper investigates the metallurgical and mechanical response of 2304 duplex stainless steel-as an interesting candidate for automotive body-in-white applications-to resistance spot welding. The results showed the high cooling rate associated with the resistance spot welding process suppressed the postsolidification ferrite-austenite transformation leading to improper ferrite-austenite phase balance with a reduced volume fraction of austenite and consequent precipitation of chromium-rich nitrides. The effects of welding current, as the key parameter determining the weld heat input, on the austenite volume fraction and precipitation are discussed. The minimum fusion zone hardness...
Effect of welding heat-input on tensile strength and fracture location in upset resistance weld of martensitic stainless steel to duplex stainless steel rods
, Article Journal of Manufacturing Processes ; Volume 35 , 2018 , Pages 517-525 ; 15266125 (ISSN) ; Movahedi, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Effect of welding current (2–4 kA) was investigated on the microstructure evolution and mechanical properties of the upset resistance dissimilar welds of Martensitic Stainless Steel (MSS) to Duplex Stainless Steel (DSS) rods. While in MSS side of the welds, no martensite was formed at lower welding currents (2–3 kA), small values of martensite was formed at the higher welding currents (3.5–4 kA). In DSS side of the welds, hotspot formation and change in the phase balance between ferrite and austenite phase were the most important phenomena. Strength of welds first increased and then decreased with welding current. Increase of strength was related to superior plastic deformation and stronger...
Pathways to improve the austenite–ferrite phase balance during resistance spot welding of duplex stainless steels
, Article Science and Technology of Welding and Joining ; Volume 24, Issue 1 , 2019 , Pages 8-15 ; 13621718 (ISSN) ; Pouranvari, M ; Movahedi, M ; Sharif University of Technology
Taylor and Francis Ltd
2019