| Title |
Microstructural Change of Hardfacing Fe-Cr-Ni-C Stainless Steels during Thermal Cycling Fatigue |
| Authors |
정재영(Jae Young Jung) ; 백응율(Eung Ryul Baek) ; 안상호(Sang Ho Ahn) |
| Abstract |
The thermal cycling fatigue behavior on the microstructure of hardfacing Fe-Cr-Ni-C stainless steels has been investigated using optical microscopy, scanning and transmission electron microscopy. x-ray diffractometry, differential scanning calorimeter, and high temperature tensile testing. The as-welded microstructures of Fe-Cr-Ni-C stainless steels exhibit a fully martensitic structure except for Fe-14%Cr-1Ni-0.11C alloy consisting of the small amount of δ-ferrite and the martensite. The thermal cycling fatigued microstructure varied as the distance of penetration increased from the top-surface to the inner region. A recrystallized ferrite structure of equiaxed grains followed by a lath-shaped ferrite structure and a tempered martensite structure were observed depending on C and Ni contents. The increase in the high thermal expansion coefficient due to low C and high Ni contents accelerated plastic deformation during thermal fatigue in hardfacing Fe-Cr-Ni-C stainless steel. In the case of alloys containing relatively high C and low Ni, the recrystallized ferrite region was not observed in thermally damaged region. This can be explained by low thermal expansion coefficient combined with the pinning effect of carbides. |