International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 02 | Feb -2017
p-ISSN: 2395-0072
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Evaluation of Hardness of Bimetallic Weld joint between SA-508Gr3 and SS-304L Mudit Sharma1, Rahul2, Arshad Mehmood3 1Department
of Mechanical Engineering, JIMS Engineering Management Technical Campus, Greater Noida, India 2M.Tech Scholar, NGF College of Engineering and Technology, Palwal, India 3Department of Mechanical Engineering, College of Engineering/ University of Buraimi, Oman
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Abstract - Bimetallic Welds has its importance in the
employed in the dissimilar weld joint is useful in reducing the residual stresses in the HAZ of the ferritic steel and thus the buttering will be beneficial to avoid/minimize residual stress related failures of dissimilar weld joints [2]. The study of structural changes in laboratory welds of 6Cr-Mo-V 8-3-2 (T25) and X12Cr-Mo-V-Nb 10-1 (P91) steels annealed at temperatures from 600° to 900°C(1112° to 1652°F). Carbon redistribution measurements by the EPMA method were complemented with detailed structural analyses aimed at the phase and chemical compositions of coexisting carbides and carbonitrides. The results of experimental work were compared with thermodynamic and kinetic calculations using the Thermo-Calc and DICTRA software. A very good agreement between the calculations and the experiments was obtained, in particular for the phase composition of individual areas of the weld joints [3]. Power station pipelines and other structural fabrications operating at high temperature are predominantly made of creep-resistant steels. These steels may become martensitic even if the cooling medium was air due to their relatively high Cr, Mo, and V content, which can retard the Bai nitic transformations. These steels must, therefore, be preheated, and filler materials must be carefully selected. In heterogeneous joints, substantial diffusion takes place during high-temperature service conditions. This paper describes the layered formation in the heterogeneous welded joint and reports on the investigation of the consequences of such diffusion. The principal goal of this investigation was to reduce the probability of cracking during service [4]. The welding of 11–12%chromium steels is subject to the traditional concern with ferritic grain growth in the heataffected zone of ferritic stainless steels. The grain growth could be inhibited if austenite on the ferrite grain boundaries could be stabilized at high temperatures. This article discusses the possibility that diffusion from the weld metal can increase the carbon or nitrogen content of the heataffected zone, and consequently stabilize grain boundary austenite [5]. Dissimilar metal joints between austenitic stainless steels and carbon steels containing low amounts of carbon are being extensively utilized in many high-temperature applications in energy conversion systems. In steam generating power stations, the parts of boilers that are subjected to lower temperatures as in the primary boiler tubes and heat exchangers are made of ferritic steel for
Pressurized Vessels used in Nuclear Power Plants which consists of pressurized water reactors (PWR) and steam generators in Boilers, where metals have to bear high temperature. The main focus of this work is to improve the mechanical properties of weld formed by joining the two dissimilar metals because failure of such metals at weld is very common in power plants and boilers where high temperature start-ups and shut- down are taken very frequently. In this work, dissimilar materials carbon steel SA 508 Gr3 and stainless steel type SS304 L was used. Buttering is considered for improving the properties, which is done with stainless steel (Grade-SS309L) and stainless steel (Grade-SS308L) as a filler material. Hardness and impact test were conducted to measure the micro hardness and toughness. The maximum hardness 37.5 and 27.5 were found in the weld joint for buttering and without buttering respectively. Key Words: Bimetallic Welding, SA-508Gr3, SS-304L, Toughness, Hardness.
1. INTRODUCTION Dissimilar metal welds composed of low alloy steel, Inconel 82/182weld, and stainless steel were prepared by gas tungsten arc welding and shielded metal arc welding techniques. Microstructures were observed using optical and electron microscopes. Typical dendrite structures were observed in Inconel 82/182 welds. Tensile tests using standard and mini-sized specimens and micro-hardness tests were conducted to measure the variation in strength along the thickness of the weld as well as across the weld. In addition, fracture toughness specimens were taken at the bottom, middle, and top of the welds and tested to evaluate the spatial variation along the thickness. It was found that while the strength is about 50–70MPa greater at the bottom of the weld than at the top of the weld, fracture toughness values at the top of the weld are about 70% greater than those at the bottom of the weld [1]. Residual stresses present in the weld joint are one of the main factors, which cause failures in dissimilar weld joints. A typical dissimilar pipe weld joint, representing a joint used in an Indian Fast Breeder Test Reactor (FBTR) was fabricated between 2.25Cr–1Mo ferritic steel and AISI type316 stainless steel with and without Inconel-82 buttering on the ferritic steel side. Residual stress profiles across these weld joints were determined using the X-ray diffraction (XRD) technique. The Inconel-82 buttering layer
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