A4 Conference proceedings

Experimental investigation on the fatigue strength assessment of welded joints made of S1100 ultra-high-strength steel in as-welded and post-weld treated condition


Publication Details
Authors: Ahola Antti, Skriko Tuomas, Björk Timo
Publication year: 2019
Language: English
Title of parent publication: Proceedings of the 7th International Conference on Structural Engineering, Mechanics and Computation (SEMC 2019)
Start page: 1254
End page: 1259
Number of pages: 6
ISBN: 9781138386969
eISBN: 9780429426506
JUFO-Level of this publication: 1
Open Access: Not an Open Access publication

Abstract

In this paper, a fatigue test program including 24 tested specimens made of S1100 steel was car-ried out to investigate the fatigue performance of the ultra-high-strength steel (UHSS) welded joints in the as-welded (AW) and post-weld treated (PWT) condition. The fatigue test series consisted of butt joints, load-carrying cruciform joints, and non-load-carrying T-joints. Both high frequency mechanical impact (HFMI) treatment and tungsten inert gas (TIG) dressing were considered as PWT methods in the non-load carrying joints. Fatigue strength was assessed using the conventional stress-based methods, i.e. nominal stress, struc-tural hot spot (HS) stress and effective notch stress (ENS) approaches, and using a novel multi-parametric fa-tigue design approach, named as the 4R method. The 4R method considers a mean stress level of cyclic load-ing, including material ultimate strength (Rm), weld toe quality in terms of toe radius (rtrue), residual stress (σres), and applied stress ratio (R) in the elastic-plastic analysis at the notch root. The results showed a good correspondence between the experimental results and computed fatigue lives when using the 4R method. The 4R method with the local mean stress correction adopts a single S-N curve for all welded specimens regard-less of joint or load configuration, resulting in a high accuracy of fatigue strength assessment in these tests. The conventional methods showed conservative results in R = 0.1 loading, and unconservative results in R = 0.5 loading, respectively.


Last updated on 2020-20-03 at 10:03