Welding is a key manufacturing technology in the production of heavy steel structures, but it is likewise a weak link in the production chain since fatigue fractures in welds is a common cause of failures. This paper proposes several changes in the process to make the manufacturing more efficient and to improve the fatigue properties. The idea is to adopt the weld quality demands for the purpose of the weld and to connect them to the welding procedures. This approach ensures that the primary focus during welding is at the critical characteristics which add value to the welded structure through an enhanced fatigue life. These fatigue life-critical properties have been found to be related to the local weld geometry in the weld toe and at the weld root. Traditional demands related to the good workmanship of welding can often be neglected, due to its limited effect to the fatigue life. The research presented in this paper has contributed to the development of welding procedures for improved fatigue life properties at the critical points of the weld. Results indicate a considerable potential for enhanced fatigue life of fillet welds. The idea is to replace the standard fillet welds with a new toolbox containing three different welds: (i) welds with optimized penetration, (ii) welds with optimized weld toe, and (iii) welds with a low cost. Right usage of these weld types contributes to an efficient production that offer a long fatigue life. This paper describes a holistic view of the subject and highlights issues with the traditional way of working. The challenge and the novelty in the paper are the connection between the welding process, weld demands, and fatigue life properties. This connection is necessary for the development of welding procedures that can contribute to the fabrication of weight optimized welded structures with a predictable life. © 2015 Springer-Verlag London

This paper presents the results of an experimental study of gas metal arc welded, GMAW, cruciform joints made of common construction steel S355. The hypothesis is that smooth undercuts in as welded conditions can give enhanced fatigue properties similarly as post treated welds. Undercuts are generally seen as a defect or imperfection. Welders try to avoid these and repair them when they occur, which result in increased production lead time. Post weld improvement methods i.e. grinding or high-frequency-impact treatment (HFMI) as fatigue-enhancing post-treatment methods enforce amongst other effects a certain smooth undercut-shaped groove in the treated weld toe region. The obtained shallower weld toe transition reduces the geometrical notch effect and increases fatigue strength. This paper presents a study whereas welded specimens with a weld toe geometry similar to what is obtained by weld toe grinding or HFMI-treatment, has been produced, fatigue tested and analyzed. The improvement of the fatigue strength is comparable to post-weld treated specimens. It has proven to be an efficient way to achieve high-quality welds without introducing any additional operations in production, thus enabling weight reduction using cost-effective methods.

In this study, the fatigue life improvement by adopting the toe weaving technique on nonload carrying cruciform welded joints has been investigated. Fatigue testing was conducted on two batches of specimens welded using double-pass manual welding. One batch had a straight second pass and the other was weaved. The influence of different weaving shape parameters was analyzed by performing crack growth analyses. The fatigue testing shows a slightly improved fatigue life for the two different batches compared to as-welded joints; the improvement is similar for both batches. The crack growth analysis concludes that the batch with the straight second pass should provide slightly higher fatigue life compared to the toe weaved batch. Measurements show a presence of undercuts in the vicinity of the crack initiation site. Nonetheless, an increased fatigue life is obtained, due to the low flank angle created during welding of the second pass, which reduces the stress concentration in the weld toe, prolonging the fatigue life.

The purpose of the research conducted is to describe the consequences of variation in the welding industry and the effect it has on manufacturing productivity. The potential has shown to be hidden in unnecessarily stringent requirements and over-processing. This has been studied in steps: customer requirements, design and analysis, preparation, welding, and assessment. The effect of variation in each step has been analyzed including estimations of its productivity improvement potential. Theoretically, in a perfect situation, with customized requirements and eliminated variation, more than half of all welding could be removed. Such a reduction is certainly neither practical nor possible. However, a sensible, controlled reduction could still have a very high impact. The financial implications are therefore substantial. The improved productivity of the manufacturing resources could be used for business development and increased production. To be able to realize the potential, interdisciplinary efforts are necessary. Management across different functions need to agree on the intended product life and make decisions thereafter.