G. Srinivasan

Bio: G. Srinivasan is an academic researcher from Indira Gandhi Centre for Atomic Research. The author has contributed to research in topics: Welding & Austenitic stainless steel. The author has an hindex of 9, co-authored 24 publications receiving 323 citations.

Effect of prior microstructure on microstructure and mechanical properties of modified 9Cr-1Mo steel weld joints

Abstract: Strength of modified 9Cr–lMo steel, which is used in the normalized and tempered condition, increases with increase in solutionising temperature with a corresponding reduction in percentage elongation. There is an increase in the prior-austenite grain size with increase in solutionising temperature. The heat-affected zone (HAZ) of the weld joints prepared from this material that has been subjected to solutionising at a higher temperature (1150–1200 °C for 1 h) is found to be stronger than that of the material subjected to conventional solutionising treatment (1050–1070 °C for 1 h). Tensile tests conducted on these weld joints showed that there is about 25% increase in yield strength over the weld joints made from the material subjected to normal solutionising treatment. A larger prior-austenite grain size, with correspondingly increased martensite lath size, in the base metal significantly alters the tempering behaviour of the base material and HAZ. The inter-critical HAZ (ICHAZ) microstructure of the weld joint is also modified because of the modification in the base material microstructure. Improvement in the strength of the ICHAZ by increasing the solutionising heat treatment temperature is attributed to the absence of the typical fine grained microstructure found in this material subjected to normal solutionising heat treatment.

Weldability of 17-4PH stainless steel in overaged heat treated condition

Abstract: Studies on the weldability of 17-4PH stainless steel, in the 621°C overaged condition, showed that Creq/Nieq ratio higher than 1·5 resulted in primary ferritic mode of solidification in the weld metal. Post-weld aging treatment at 482°C enhanced the strength of the weld joint with corresponding reduction in impact toughness of the weld metal while post-weld aging at 621°C caused marginal reduction in strength of the weld joint with significant increase in impact toughness of the weld metal.

Study on microstructure and mechanical characteristics of low-carbon steel and ferritic stainless steel joints

Abstract: In this work, examinations on the microstructure and mechanical properties of plain carbon steel and AISI 430 ferritic stainless steel dissimilar welds are carried out. Welding is conducted in both autogenous and using ER309L austenitic filler rod conditions through gas tungsten arc welding process. The results indicate that fully-ferritic and duplex ferritic–martensitic microstructures are formed for autogenous and filler-added welds, respectively. Carbide precipitation and formation of martensite at ferrite grain boundaries (intergranular martensite) as well as grain growth occur in the heat affected zone (HAZ) of AISI 430 steel. It is found that weld heat input can strongly affect grain growth phenomenon along with the amount and the composition of carbides and intergranular martensite. Acquired mechanical characteristics of weld in the case of using filler metal are significantly higher than those of autogenous one. Accordingly, ultimate tensile strength (UTS), hardness, and absorbed energy during tensile test of weld metal are increased from 662 MPa to 910 MPa, 140 Hv to 385 Hv, and 53.6 J m −3 to 79 J m −3 , respectively by filler metal addition. From fracture surfaces, predominantly ductile fracture is observed in the specimen welded with filler metal while mainly cleavage fracture occurs in the autogenous weld metal.