I. C. Kuo, C. F. Tseng, National Formosa University, Yunlin, Taiwan; C. P. Chou, National Chiao-Tung University, Hsinchu, Taiwan; I. K. Lee, Dayeh University, Changhua, Taiwan
The mechanism of thermal fatique failure of SUS 410 martensite stainless steel hardfacing weldments were investigated in this study.
Two different type of martensite stainless steel strip were deposited by Submerged-Arc welding process. Specimens in this study, were annealed after welding. Hardness and thermal fatigue testing was conducted. Their microstructures of deposited metal were evaluated by OM, SEM, and TEM. Experimental results indicate that the hardness of weld pools decreased as post-heat-treating temperature increased. However, the amount of precipitated carbides increased as post-heat-treating temperature increased, resulting in increased thermal fatigue resistance. After thermal fatique test, the M23C6 carbide was found to precipitate and cracks were occured. The primary mechanisms of thermal fatique failure were found in this study was that the separation of M23C6 out of grain boundaries. The stress of thermal fatigue produces micro voids and fissues by precipitates, and carbide grows in the inside and causes the integrated stress of bracing and stretching. The weldment cracks as a result.
Summary: Martensite stainless steel strip were deposited by Submerged-Arc welding process. Specimens were annealed after welding. Hardness and thermal fatigue testing was conducted. Their microstructures of deposited metal were evaluated by OM, SEM, and TEM. The mechanism of thermal fatique failure of martensite stainless steel hardfacing weldments were investigated.
