Abstract
Objectives: The present experimental work investigates the effect of post weld heat treatments on the pitting, impact toughness and metallurgical properties of gas tungsten arc welded martensitic stainless steel joints. Methods/Statistical analysis: Martensitic stainless steel (AISI410 SS) cold rolled plates used as a base materials and welded using GTAW process with two filler materials (ER 304LSS and ER 410 SS for root pass and cover passes respectively). Three heat treatments namely annealing, quenching and plasma nitriding were given to the specimens. After the heat treatments the specimens were subjected to pitting corrosion test, impact toughness test, microhardness testing and microstructural examination. Findings: Pitting corrosion results under different heat treatments of the welds showed that the post weld heat treatment induces the significant variations in the pitting resistance. The maximum pitting resistance (minimum mass loss of 0.5108mg) was possessed by the weld with plasma nitriding treatment. The maximum energy absorption capacity of the welds of 62 Joules was obtained in the annealing treatment. The average microhardness values of 474VHN, 372 VHN, 492VHN and 559VHN was obtained in as welded condition, under annealing treatment, under quenching treatment and under plasma nitriding treatment respectively of the welded joints. Based on the micro-structural studies of the welded joint in as received and post weld heat treated conditions, the significant microstructural changes were observed in weld metal zones. Novelty/Applications: The present experimental study can beneficially be adopted for welding of martensitic stainless steel (AISI 410 SS) as it suggests the processing conditions to forecast the adequate pitting resistance, impact toughness and microhardness behaviour in similar service conditions. Keywords Pitting corrosion, impact toughness, post weld heat treatments, microhardness, microstructure, GTAW
Highlights
Martensitic (AISI 410) stainless steels are heat treatable type of steel and contain 11.5% to 13% chromium
A plasma nitriding treatment helps to improve the pitting corrosion resistance of the martensitic stainless steel welds [14], very small sized pits were observed in PT3 treated specimens
Pitting resistance of the welded joint is significantly affected by the post weld heat treatments
Summary
Martensitic (AISI 410) stainless steels are heat treatable type of steel and contain 11.5% to 13% chromium. The metallurgical performance and mechanical performance of the martensitic stainless steels can be modified by heat treatments. Different post weld heat treatments (annealing, tempering, quenching etc) effect the metallurgical behaviour and mechanical properties of the welded joints[1]. The pre heating temperature and heat treatment parameters (temperature, soaking period and cooling rate) are affecting the properties of the joints [2,3,4,5]. Tempering treatments helps to improve the impact toughness of the welds, and this improvement in the toughness of welds due to the coarsening of lath martensite[6]. The surface properties like hardness, wear resistance and corrosion resistance of the martensistic stainless steel can be modified by using plasma nitriding and nitrocarburising treatments
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