Title: Stress analysis and fatigue life estimation for four types of super-alloy-welded joints

Authors: Gang Luo, Wei Chen, Yinhe Fan

Addresses: College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing, 210016, PR China. ' College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing, 210016, PR China. ' College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing, 210016, PR China

Abstract: By means of the finite element analysis software ANSYS, the stress concentration coefficient of four kinds of super-alloy welded joints, namely, normal butt welding, dislocation butt welding, non-isopachous butt welding and new material butt welding, were calculated. With the method of group comparison, the relationship between these calculated results and real fatigue life was analysed. It is estimated that the fatigue life of the non-isopachous butt-welded joint had an increase of 1.22–2.09 times that of normal butt-welded joint at the stress load of 520 MPa, and that of the normal butt-welded joint of a new material, GH4033, increased 2.16–3.54 times at the same stress level. The SEM fracture analysis revealed that slag, micro-cracks on the surface of weld seams or at the weld toes, and the brittle secondary particles were the dominant factors in cutting down fatigue life.

Keywords: superalloys; butt welding; welded joints; finite element analysis; FEA; stress-concentrate coefficient; stress analysis; fatigue life estimation; scanning electronic microscopy; SEM; microstructure; fracture analysis; welding defects.

DOI: 10.1504/IJMMP.2007.015314

International Journal of Microstructure and Materials Properties, 2007 Vol.2 No.3/4, pp.361 - 372

Published online: 07 Oct 2007 *

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