| Title |
Evaluation of Microstructure and Ductile-Brittle Transition Behavior in Weld Heat-Affected Zone of Intercritically Heat-Treated Mn-Mo-Ni Low Alloy Steels |
| Authors |
김종식(Jong Sik Kim); 김민철(Min Chul Kim); 이봉상(Bong Sang Lee); 홍준화(Jun Hwa Hong) |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Intercritical heat treatment; IHT; Low alloy steel; Heat-affected zone; HAZ; Impact toughness; Ductile-brittle transition |
| Abstract |
The effects of intercritical heat treatment(IHT) on microstructures and mechanical properties of weld heat-affected zone(HAZ) in Mn-Mo-Ni low alloy steels were investigated using the simulated HAZ specimens prepared by a gleeble thermal simulator system. The microstructures and mechanical properties of coarse-grained HAZ(CGHAZ) and fine-grained HAZ(FGHAZ) were not influenced by the heat treatment condition before welding, whereas they showed a significant increase in impact toughness after post-weld heat treatment(PWHT). In case of tempered HAZ(THAZ), carbide sizes were slightly increased after welding and PWHT process. However the microstructural improvements by IHT, such as precipitate refinement and spherodization were maintained during the welding and PWHT process, and consequently THAZ with IHT showed better ductile-brittle transition behavior than those with conventional heat treatment(CHT). In conclusion, the application of IHT shows beneficial effects on mechanical properties of both base metal and THAZ. |