High temperature corrosion tests were performed on dissimilar friction weldment of low alloy steel and austenitic stainless steel. Test conditions simulated the environment of a biofuel fired boiler. The samples were exposed to synthetic salt containing 40 wt-%K2SO4, 40 wt-%Na 2SO4, 10 wt-%KCl and 10 wt-%NaCl. In the present paper, hot corrosion behaviour of friction welded AISI 4140 and AISI 304 dissimilar materials in molten salt environments at 500, 550 and 600°C was studied. Corrosion was extremely severe on the interface of the dissimilar weldment in molten salt environment. Comparative evaluation was based on the effect of burn-off length and temperature of exposure on hot corrosion behaviour of the dissimilar weldment. Even the interface was attacked through chromium rich phases in hot corrosion environment. The metals formed on the weldment were non-protective. © 2009 Institute of Materials, Minerals and Mining.

Arivazhagan N

Department of Manufacturing Engineering

School of Mechanical Engineering

Vellore Campus

Singh S

Prakash S

Reddy G.M.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Hot corrosion studies on dissimilar friction welded low alloy steel and austenitic stainless steel under chlorine containing salt deposits under cyclic conditions

Corrosion Engineering, Science and Technology

Journal of Materials Research

Effect of fillers on the microstructure, mechanical properties, and hot corrosion behavior of Nb stabilized austenitic stainless steel welds

Dissimilar joints involving Inconel 718 and the martensitic grade stainless steel AISI 416 have been employed in gas turbine applications. In the present study, an attempt has been made to compare the effect of continuous current and pulsed current gas tungsten arc welding of this dissimilar joint. These dissimilar alloys were welded using a low cost, Nb free stainless steel filler, with a view of controlling or eliminating the deleterious Laves phase. Microstructure studies performed at the fusion zones of both CCGTA and PCGTA weldments revealed the formation of martensite at the cap zones. The unmixed zone containing Nb rich phases, observed at the weld interface of Inconel 718 was found to be lower for PCGTA weldments. Tensile failures were experienced at the parent metal of AISI 416 for both the cases. Impact toughness of the weldments were lower than that of parent metals employed in the study. High temperature corrosion studies were performed on the weld coupons by exposing them to an aggressive molten salt environment containing K2SO4 − 60% NaCl at 650 °C. Owing to the recrystallization and grain refinement, the PCGTA weldments experienced better corrosion resistance compared to the CCGTA weldments. Surface analytical techniques were employed to determine the hot corroded species formed and attempts have been made to establish the corrosion kinetics. © 2017, The Indian Institute of Metals - IIM.

Transactions of the Indian Institute of Metals

Effect of Continuous and Pulsed Current GTA Welding on the Performance of Dissimilar Welds Involving Aerospace Grade Alloys

Segregation of Mo is one of the most detrimental problems associated with the welding of super-austenitic stainless steels. The present study articulates the effects of fillers on the microstructure and mechanical properties of pulsed current gas tungsten arc (PCGTA) welded joints of AISI 904L. Four different fillers namely ERNiCrMo-4, ERNiCrMo-10, ERNiCrMo-14 and ERNiCu-7 were employed for joining 5 mm thick plates of AISI 904L. Efforts had been taken to investigate the effect of filler wires on the segregation of Mo in the fusion zone. Studies attested to the retention of Mo in the dendritic regions while employing Ni-Mo rich fillers. Evidently, Mo in the fusion zones was comparatively greater than that in the parent metal. Microstructure studies revealed the formation of unmixed zones at the weld interface while employing these fillers. Migrated grain boundaries were prominent in the fusion zone of ERNiCu-7 weldments. Tensile studies demonstrated that failures occurred at the parent metal of AISI 904L irrespective of fillers employed. Charpy V-notch studies showed that the impact toughness at the cap zones of the weldments was superior to the root regions for all the cases of the weldments. Also, the welded coupons were subjected to cyclic hot corrosion studies at 650 °C in a synthetic molten salt mixture containing K2SO4 + 60% NaCl for 50 cycles. The corrosion studies attested that the fusion zone employing ERNiCrMo-14 exhibited better corrosion resistance than the other fillers and also the parent metal employed in the study. Surface analytical techniques were employed to investigate the hot corroded species. © 2016 The Society of Manufacturing Engineers

Journal of Manufacturing Processes

Effects of filler metals on the segregation, mechanical properties and hot corrosion behaviour of pulsed current gas tungsten arc welded super-austenitic stainless steel

Understanding the behavior of weldment at elevated temperatures and especially the corrosion behavior has become an object of scientific investigation recently. Investigation has been carried out on friction welded AISI 4140 and AISI 304 in molten salt of K2SO4–60% NaCl environment at 550, 600 and 650 °C under cyclic condition. The resulted oxide scales in the weldment have been characterized systematically by surface analytical techniques. From the results of the experiments, it is observed that the scale thickness on low alloy steel side was higher than that on stainless steel side. Furthermore, weld interface has been found to be more susceptible to degradation than base metals due to inter diffusion of element across the interface and the formation of intermetallic compound. The influences of welding parameters and the temperature of exposure on the hot corrosion behavior of the weldment were discussed in this paper.

Journal of Materials Science & Technology

Hot Corrosion Behavior of Friction Welded AISI 4140 and AISI 304 in K2SO–60% NaCl Mixture

Dissimilar metal welding involving AISI 304 and Monel 400 finds widespread use in marine and offshore environments for the fabrication of heat exchangers, evaporators, piping and vessels in petrochemical and power generation industries. However studies on the performance of such weldments are scantly found in the literature even though the individual metals have higher corrosion resistance and strength. This paper reports the work carried out on welding of AISI 304 and Monel 400 using Gas Tungsten Arc Welding (GTAW) technique to examine the weldability, mechanical and metallurgical properties. Investigations have been carried out on the hot corrosion behavior of these joints subjected to cyclic air oxidation and K2SO4&nbsp;+&nbsp;NaCl (60%) molten salt environment at 600&nbsp;°C. A comparative analysis was carried out on these weldments for two different filler metals such as E309L and ENiCu-7. The oxide scales formed on the various zones of the weldment have been characterized systematically using surface analytical techniques. Weld zone was found to be more susceptible to degradation than base metals used. The effect of filler materials on the hot corrosion is discussed. The studies reported in this paper would be beneficial for fabricators embracing this type of dissimilar weldments in the petrochemical and power generation industries.

Materials & Design

Effect of filler materials on the performance of gas tungsten arc welded AISI 304 and Monel 400

Spiegel der Letteren

Boekbeoordelingen

Materials Science and Engineering: B

High temperature corrosion studies on friction-welded dissimilar metals

Corrosion Science

High temperature corrosion of coatings and boiler steels below chlorine-containing salt deposits

Wear

Elevated temperature erosion–corrosion of thermal sprayed coatings in chlorine containing environments

Fuel and Energy Abstracts

00/03542 Corrosion in fluidized bed boilers burning potassium and chlorine containing fuels

Journal	Corrosion Engineering, Science and Technology
Publisher	Informa UK Limited
ISSN	1478-422X
Open Access	No