Fatigue Crack Growth Behavior in Dissimilar Metal Weldment of Stainless Steel and Carbon Steel

Authors: K. Krishnaprasad, Raghu V. Prakash

Abstract:

Constant amplitude fatigue crack growth (FCG) tests were performed on dissimilar metal welded plates of Type 316L Stainless Steel (SS) and IS 2062 Grade A Carbon steel (CS). The plates were welded by TIG welding using SS E309 as electrode. FCG tests were carried on the Side Edge Notch Tension (SENT) specimens of 5 mm thickness, with crack initiator (notch) at base metal region (BM), weld metal region (WM) and heat affected zones (HAZ). The tests were performed at a test frequency of 10 Hz and at load ratios (R) of 0.1 & 0.6. FCG rate was found to increase with stress ratio for weld metals and base metals, where as in case of HAZ, FCG rates were almost equal at high ΔK. FCG rate of HAZ of stainless steel was found to be lowest at low and high ΔK. At intermediate ΔK, WM showed the lowest FCG rate. CS showed higher crack growth rate at all ΔK. However, the scatter band of data was found to be narrow. Fracture toughness (Kc) was found to vary in different locations of weldments. Kc was found lowest for the weldment and highest for HAZ of stainless steel. A novel method of characterizing the FCG behavior using an Infrared thermography (IRT) camera was attempted. By monitoring the temperature rise at the fast moving crack tip region, the amount of plastic deformation was estimated.

Keywords: Dissimilar metal weld, Fatigue Crack Growth, fracture toughness, Infrared thermography.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1083179

References:

[1] H. K. Lee, K. S. Kim, C. M. Kim, "Fracture Resistance of a Steel Weld Joint Under Fatigue Loading, Engineering Fracture mechanics", 2000.
[2] B. K. Choudhary, M. Roedig and S. L. Mannan, "Fatigue Crack Growth Behavior of Base Metal, Weld Metal and Heat Affected Zone of Alloy 800 at 823 K", 2004.
[3] S. J. Maddox, "Assessing the Significance of Flaws in Welds Subject to Fatigue", Welding J., 1974.
[4] Laurent Cretegny, Ashok Saxena, "Fracture Toughness Behavior of Weldments with Mis-Matched Properties at Elevated Temperature"., Int. J. Fracture, Vol 92, No. 2, 1998.
[5] B. Bruzek, E. Leidich, "Evaluation of Crack Growth at Weld Interface between Bronze and Steel", International Journal of Fatigue, 2007.
[6] Zehnder AT, Rosakis Ares J., "Temperature Rise at the Tip of Dynamically Propagating Cracks: Measurements Using High-speed Infrared Detectors", Experimental Techniques in Fracture, 1993.
[7] Shockey DA, Kalthoff JF, Klemm W, Winkler S., "Simultaneous Measurement of Stress Intensity and Toughness for Fast Running Cracks in Steel", Exp Mech 1983.
[8] Montgomery DG, "The Temperature Wave Method of Determinating Fracture Toughness Values Due to Crack Propagation", J Material Science 1975.
[9] "T. Yamauchi, H. Hirano, Examination of Onset of Stable Crack Growth Under Fracture Toughness Testing of Paper", Journal of Wood Science, 2000.
[10] B.Yang, P.K. Liaw, M. Morrison, C.T. Liub, R.A. Buchanana, J.Y. Huangc,R.C. Kuo, J.G. Huang, and D.E. Fielden (2005), "Temperature evolution during fatigue damage", Intermetallics ,13, 419-428.
[11] Jordan Eric, H., "Notch-root plastic response by temperature measurement", Exp. Mech, 1985.