Joining of dissimilar materials

Abstract:In this study, an attempt on pulsed-fiber laser welding on an austenitic-duplex stainless steel butt joint configuration was investigated. The influence of various welding parameters, such as beam diameter, peak power, pulse repetition rate, and pulse width on the weld beads geometry was studied by checking the width and depth of the welds after each round of welding parameters combination. The weld bead dimensions and microstructural progression of the weld joints were observed microscopically. Finally, the full penetration specimens were subjected to tensile tests, which were coupled with the analysis of the fracture surfaces. From the results, combination of the selected weld parameters resulted in robust weldments with similar features to those of duplex and austenitic weld metals. The weld depth and width were found to increase proportionally to the laser power. Furthermore, the weld bead geometry was found to be positively affected by the pulse width. Microstructural studies revealed the presence of dendritic and fine grain structures within the weld zone at low peak power, while ferritic microstructures were found on the sides of the weld metal near the SS 304 and austenitic-ferritic microstructure beside the duplex 2205 boundary. Regarding the micro-hardness tests, there was an improvement when compared to the hardness of duplex and austenitic stainless steels base metals. Additionally, the tensile strength of the fiber laser welded joints was found to be higher when compared to the tensile strength of the base metals (duplex and austenitic) in all of the joints.

Section: Introductionmentioning

confidence: 99%

Fiber Laser Welding of Dissimilar 2205/304 Stainless Steel Plates

Mohammed

Ishak

Ahmad

et al. 2017

“…They are applied in various fields such as thermal power station, nuclear industries, automobile, aerospace, etc. A number of dissimilar joints with aluminum, titanium, ferrous and many kinds of materials have been successfully formed by various methods from fusion welding to friction welding process [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Mechanical Properties of Friction Welding Joints with Dissimilar Titanium Alloys

Zhao

2016

Titanium alloys, which are important in aerospace application, offer different properties via changing alloys. As design complexity and service demands increase, dissimilar welding of the titanium alloys becomes a particular interest. Linear friction welding (LFW) is a relatively novel bond technique and has been successfully applied for joining titanium alloys. In this paper, dissimilar joints with Ti-6Al-4V and Ti-5Al-2Sn-2Zr-4Mo-4Cr alloys were produced by LFW process. Microstructure was studied via optical microscopy and scanning electron microscopy (SEM), while the chemical composition across the welded samples was identified by energy dispersive X-ray spectroscopy. Mechanical tests were performed on welded samples to study the joint mechanical properties and fracture characteristics. SEM was carried out on the fracture surface to reveal their fracture modes. A significant microstructural change with fine re-crystallization grains in the weld zone (WZ) and small recrystallized grains in the thermo-mechanically affected zone on the Ti-6Al-4V side was discovered in the dissimilar joint. A characteristic asymmetrical microhardness profile with a maximum in the WZ was observed. Tensile properties of the dissimilar joint were comparable to the base metals, but the impact toughness exhibited a lower value.

“…However, since Inconel alloy 617 and 12Cr steel alloy have different chemical compositions and mechanical properties, reliable welding technology needs to be developed to manufacture hybrid structures that can withstand extreme environmental conditions [4,5]. There are many suitable processes for the joining of dissimilar material as comprehensively summarized by Martinsen et al [6]. These dissimilar material welded structures often experience variable loadings, ranging from cyclic to completely random fluctuation during their practical working.…”

Section: Introductionmentioning

confidence: 99%

Welding Residual Stress Analysis and Fatigue Strength Assessment of Multi-Pass Dissimilar Material Welded Joint between Alloy 617 and 12Cr Steel

Ahmad

Hwang

Lee

et al. 2017

Abstract:The reliability of welded structure can be evaluated through welding residual stress analysis and fatigue strength assessment. In this study, welding residual stresses of multi-pass dissimilar material welded joint between alloy 617 and 12Cr steel were analyzed numerically and experimentally. Fatigue strength was then assessed in the air. Based on results of welding residual stress analysis and fatigue strength assessment, a fatigue design method considering welding residual stress was investigated. Welding residual stresses at the weld of dissimilar welded joints distributed complicatedly on longitudinal and transverse directions, showing differences but a very similar distribution tendency between numerical and experimental results. Numerical and experimental peak values of welding residual stresses at HAZ of the weld on the 12Cr steel side were predicted to be 333 MPa and 282 MPa HAZ, respectively. The fatigue limit of dissimilar material welded joint between alloy 617 and 12Cr steel was assessed to be 306.8 MPa, which was 40% of tensile strength (767 MPa) of dissimilar material welded joint. However, the stress range including welding residual stress was assessed to be 206.9 MPa, which was 14% lower than that calculated by including the effect of residual stresses.