Toughness Improvement of the HAZ for Machine Structural Carbon and Low Alloy Steels (Report 4) : Effect of PWHT on the Absorbed Energy of HAZ for Medium, High Carbon Machine Structural Steels(Materials, Metallugy & Weldability)

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In the previous papers, the authors have investigated the ductility of simulated HAZ using "Gleeble 1500" in continuous cooling methods and isothermal heating treatment methods during weld heat cycle in medium, high carbon steels with or without alloying element. The improvement of toughness for higher carbon steels than 0.25%C was generally poor in continuous cooling methods, but the ductility of these steels could be fairly improved in isothermal heating treatment methods in comparison with the results of the continuous cooling methods, although the degree of improvement is depending on carbon level of steel. Therefore, this paper has been investigated on the improvement of toughness by means of PWHT (Post Weld Heat Treatment) after the continuous cooling for medium and high carbon steels. Main conclusions obtained are as follow: (1) For rapid cooled HAZ to room teperature as Δt_<8/3>: 12sec increasing heating temperature up to 923K in PWHT is increased the absorbed energy for each steels. (2) For HAZ having slow continuous cooling time PWHT treatment for lower temperature decreased inversely the absorbed energy in comparison with that of non PWHT
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