Cost savings using different post-welding treatments on an I-beam subject to fatigue load

Abstract

In the framework of this work research has been carried out to obtain current data on the potential of post weld treatment (PWT) since new PWT technologies appeared in the last years, and the older technologies have been improved. The economy of post-welding treatments is illustrated by means of a numerical example of a simply supported welded I-beam loaded in bending by a pair of pulsating forces. The vertical stiffeners are welded to the I-beam upper flange by double fillet welds, which cause a significant decrease of fatigue stress range. This low fatigue stress range is improved by various post-welding treatments. Based on the published experimental data, it is possible to determine the measure of the increase of the fatigue stress range as well as the required treatment time for grinding, TIG dressing, hammer peening and ultrasonic impact treatment. This article provides an overview of current PWT methods and the possible improvement in fatigue strength. Furthermore, optimization of a welded I-beam has been conducted to reduce the fabrication cost. The data from the research in the form of increase in fatigue strength and application speed were included in this optimization. The treatment time is included into the cost function, and the improved fatigue stress range is considered in the fatigue constraint. The comparison of costs for optimum structural versions with and without treatments shows the economy of different treatment methods. This comparison helps designers to consider the applicability of PWT and the select the best available.

Fatigue strength assessment of ground fillet-welded joints using 4R method

“…Peening methods are notably more effective for high-and ultra-high-strength steel joints than for mild steels [7,8], while the beneficial effect of the HFMI treatment is lost at high mean stress levels [1] and overload peaks [9]. Consequently, grinding is a recommended PWT method to enhance the fatigue strength of welded joints although it is not the most cost-effective one [10][11][12]. The grinding procedure, nevertheless, usually provides at least a moderate improvement in fatigue strength compared to joints in the AW condition, regardless of the environmental [13] or load conditions [14], and material strength [15].…”

Effect of high frequency mechanical impact treatment on fatigue strength of welded 1300 MPa yield strength steel

“…Different degrees of improvement in fatigue strength of welds after HFMI treatment have been reported. In a review paper by Jármai et al [45], up to 110% increase in fatigue strength has been reported for steels with yield strength higher than 900 MPa. It has also been discussed that the degree of improvement produced by HFMI treatment increases with steel yield strength [28,29,45].…”

“…In a review paper by Jármai et al [45], up to 110% increase in fatigue strength has been reported for steels with yield strength higher than 900 MPa. It has also been discussed that the degree of improvement produced by HFMI treatment increases with steel yield strength [28,29,45]. For instance, Yildirim and Marquis [28], after assessing about 228 fatigue data points, proposed FAT 500 for welded steels with yield strength higher than 960…”

Usage of Ti-surface-modified filler material to increase the joint strength of High-Strength Low Alloyed (HSLA) steels under different load types

“…An effective way to reduce the effect of welds on fatigue strength is to soften the notch at the weld toe between weld metal and base metal [8].…”