Hot corrosion of unwelded and welded 2.25 Cr-1Mo steel coated with a potassium sulphate and sodium chloride mixture is discussed. The coating composition is a eutectic mixture with 40 wt% K2SO4 and 60 wt% NaCl. Weight gain studies were done for welded specimens containing only weld metal and composite specimens containing both weld metal and heat-affected zone. The results indicated that the coated specimens were more corroded than uncoated specimens. Also welded samples showed less attack than unwelded samples. © 1993.

S. Ahila

Srinivasa Ramakrishna K Iyer

Vellore Margabandhu Radhakrishnan

corrosion

Eutectics

Heat affected zone

High temperature effects

Protective coatings

Sodium chloride

Welding

Welds

Hot corrosion

POTASSIUM SULFATE

Steel

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

A comparative study of hot corrosion of welded and unwelded 2.25 Cr-1Mo steel

Materials Letters

The oxidation behaviour of manual metal arc welded (MMA) 2.25Cr-1Mo steel was studied in a potassium sulphate-sodium chloride salt mixture. The presence of this salt mixture accelerated the attack. The variation of weight gain with time indicated a parabolic growth of oxides. The outer layers consisted of oxides whereas inner layers showed the presence of sulphides. This is an example of hot corrosion attack wherein the degradation resulted in internal oxidation and sulphidation of the material. © 1993.

Acceleration of high-temperature oxidation of manual metal arc welded 2.25Cr-1Mo steel by sulphate-chloride mixture

Alloy C-276 is widely used in the power plant environment due to high strength and corrosion in highly aggressive environment. The investigation on high- temperature corrosion resistance of the alloy C-276 PCGTA weldment is necessary for prolonged service lifetime of the components used in corrosive environments. Investigation has been carried out on Pulsed Current Gas Tungsten Arc Welding by autogenous and different filler wires (ERNiCrMo-3 and ERNiCrMo-4) under molten state of K2SO4-60% NaCl environment at 675oC under cyclic condition. Thermogravimetric technique was used to establish the kinetics of corrosion. Weight gained in the molten salt reveals a steady-state parabolic rate law while the kinetics with salt deposits displays multi-stage growth rates. PCGTA ERNiCrMo-3 shows the higher parabolic constant compared to others. The scale formed on the weldment samples upon hot corrosion was characterized by using X-ray diffraction, SEM and EDAX analysis to understand the degradation mechanisms. From the results of the experiment the major phases are identified as Cr2O3, Fe2O3, and NiCr2O4. The result showed that weld fabricated by ERNiCrMo-3 found to be more prone to degradation than base metal and ERNiCrMo-4 filler wire due to higher segregation of alloying element of Mo and W in the weldment. © Published under licence by IOP Publishing Ltd.

Fulltext

IOP Conference Series: Materials Science and Engineering

High Temperature Corrosion studies on Pulsed Current Gas Tungsten Arc Welded Alloy C-276 in Molten Salt Environment

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

Hot corrosion of Gas Tungsten Arc Welded (GTAW) AISI 304 and AISI 4140 dissimilar weldment exposed in air as well as molten salt environment of Na2SO4-60%V2O5 and K2SO4-60% NaCl are discussed. Weight gain studies were done for composite specimens containing both weld metal and heat-affected zone. The results indicated that the specimens were more corroded in molten salt environment as compared to air oxidation. Also weld interface of the samples showed more attack than base metals.

Communications in Computer and Information Science Trends in Intelligent Robotics, Automation, and Manufacturing

Hot Corrosion Studies on Gas Tungsten Arc Welded AISI 304 and AISI 4140 Dissimilar Joints

Journal of Materials Science Letters

Melting point determination of the K2SO4-NaCl system

Oxidation of Metals

Behavior of oxide scales on 2.25Cr-1Mo steel during thermal cycling. II. Scales grown in water vapor

Materials Science and Engineering

NaCl-induced hot corrosion of stainless steels

Metals Technology

Creep deformation and local strain distributions in dissimilar metal vvelds betvveen AISI type 316 and 2–25Cr–1 Mo steels made vvith 17Cr–8Ni–2Mo weld metal

Corrosion Science

The salt-induced corrosion behaviour of FeCr alloys at elevated temperatures—I. Alloys dilute in chromium

Journal	Materials Letters
ISSN	0167577X
Open Access	No