Very High Cycle Fatigue Behaviour of the 316L Weldment Fabricated By Laser Butt-Welding

4th International Conference on Manufacturing, Material and Metallurgical Engineering

Xiong, Z.H.^1 ; Ma, X.F.^1 ; Qi, X.Y.^2

Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-sen University, Zhuhai

519082, China^1

Wuhan Huagong Laser Engineering Co. Ltd., Wuhan

430074, China^2

关键词: Columnar dendrites;    Fatigue failures;    Fatigue strength;    Hardness distribution;    Laser butt welding;    Ultrasonic fatigue testing system;    Very high cycle fatigue;    Weld microstructures;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/538/1/012025/pdf
DOI  :  10.1088/1757-899X/538/1/012025

来源: IOP

【 摘 要 】

In nuclear industry, 316L weldments are widely used in components fabricating, which usually suffer from very-high-cycle fatigue. Therefore, the very high cycle fatigue (VHCF) behaviour of 316L weldment fabricated by laser butt-welding joint were studied using an ultrasonic fatigue testing system. The microscopic examination indicated that an evident pore is observed in the weld seam and the fine columnar-dendrite structure is formed in the central part of the weld seam. Near the weld interface in the weld seam, the weld microstructure shows larger columnar-dendrite. The hardness distribution of the weldment is to coincide with the characteristic of the microstructure. In the central part of the weld seam, the hardness is the highest, and is the lowest in the base metal. Fatigue failure still occurred in the VHCF regime. The fatigue crack initiated from the internal pores caused by laser butt-welding. Although the fatigue strength of weld seam might be decreased due to the pore, the fatigue strength of the weldment was the same as the base metal in this research. That is, the defect with a certain size in the weld seam does not affect the strength of the weldment.