Effect of welding process parameters and diffusible hydrogen content on residual deformation and mechanical behaviour of p92 steel w elds

Abstract

ABSTRACT newlineThe weldability P92 steel depends upon suitable heat treatment and welding procedures. With newlinerespect to varying heat treatment temperature regimes the nature of precipitation strengthening newlineand mechanical properties of P92 steel vary. The present research work deals with the effect of newlineheat treatment procedures on the mechanical properties and microstructural behaviour of P92 newlinesteel base metal and welded joints. Effects of weld groove geometries on the weldability of the newlineaforementioned steel were also studied. An optimum combination of heat treatment procedure newlinefor normalizing and tempering of P92 steel was determined during the current investigation. newlineSince the P92 steel is used for high temperature applications, it s high-temperature Charpy newlineimpact strength with respect to different tempering conditions was also determined. The newlineoptimum combination of weld properties in terms of Charpy impact strength, short-term creep newlinestrength, hardness and homogeneity of microstructure were determined for varying heat newlinetreatment conditions. The effect of varying post welding heat treatment (PWHTs) on type IV newlinecracking behaviourwere also studied. It is known that, delayed cracking in high strength steels newlinesuch as P92 occurs as a consequence of combined effect of high residual stress, high diffusible newlinehydrogen content and propensity of microstructure to crack. In practical welding situation, in newlinespite of all the precautions, hydrogen pick-up may occur which can adversely affect the newlineweldability of P92 steel. In the present research work, the effects of diffusible hydrogen content newlineon the flexural strength, lower critical stress and tensile strength of P92 steel welds were also newlinedetermined with respect to different electrode conditions. The consequence of the welding such newlineas shrinkage of the P92 welds, shrinkage stress and residual stresses were also studied in details. newline