Welding in The World 

About: Welding in The World is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Welding & Materials science. It has an ISSN identifier of 0043-2288. Over the lifetime, 2183 publications have been published receiving 21982 citations. The journal is also known as: Welding in the world (Print).

A Consideration of Allowable Equivalent Stresses for Fatigue Design of Welded Joints According to the Notch Stress Concept with the Reference Radii r ref = 1.00 and 0.05 mm

Abstract: In the literature, allowable stresses (FAT-values) for the fatigue design of welded joints are established according to the notch stress concept with the reference radii rref = 1.00 mm for thick connections (t ≥ 5 mm) and 0.05 mm for thin connections (t < 5 mm). However, it is not clear for which strength hypothesis they are valid. As local equivalent stresses may be calculated by the principal stress or von Mises hypotheses, it is necessary to distinguish between the applied hypotheses. The FAT-values according to the principal stress and von Mises hypotheses are compiled for steel, aluminium and magnesium for the reference radii rref = 1.00 and 0.05 mm. The allowable stresses are derived from normal as well as from shear stresses. However, the values derived from pure normal loading (axial or bending) and from pure torsion are not compatible when the principle stress or the von Mises hypotheses are applied. Therefore, in case of biaxial loading, the stated incompatibility between the values obtained from different loading modes should be overcome by the Gough-Pollard relationship.

Friction Stir Welding Tools and Developments

Abstract: The basic principle of Friction Stir welding (FSW) is described. Certain applications (butt and lap welding) are reviewed, with particular emphasis on probe types currently under development (Flared-Triflute™ probe and an A-Skew™ probe). Both give lap welds of 190% of the plate thickness, an improvement in weld integrity, a reduction in upper plate thinning and an increased welding speed over current practice. Butt welds produced with Whorl™ and MX-Triflute™ frustum-shaped probes that gave acceptable weld quality are also described.

Fatigue strength improvement of steel structures by high-frequency mechanical impact: proposed fatigue assessment guidelines

Abstract: In the past decade, high-frequency mechanical impact (HFMI) has significantly developed as a reliable, effective, and user-friendly method for post-weld fatigue strength improvement technique for welded structures. During this time, period 46 documents on HFMI technology or fatigue improvements have been presented within Commission XIII of the International Institute of Welding. This paper presents one possible approach to fatigue assessment for HFMI-improved joints. Stress analysis methods based on nominal stress, structural hot spot stress, and effective notch stress are all discussed. The document considered the observed extra benefit that has been experimentally observed for HFMI-treated high-strength steels. Some observations and proposals on the effect of loading conditions like high mean stress fatigue cycles, variable amplitude loading, and large amplitude/low cycle fatigue cycles are given. Special considerations for low stress concentration details are also given. Several fatigue assessment examples are provided in an appendix. A companion paper has also been prepared concerning HFMI equipment, proper procedures, safety, training, quality control measures, and documentation has also been prepared. It is hoped that these guidelines will provide stimulus to researchers working in the field to test and constructively criticize the proposals made with the goal of developing international guidelines relevant to a variety of HFMI technologies and applicable to many industrial sectors. The proposal can also be used as a means of verifying the effectiveness of new equipment as it comes to the market.

S-N Lines for Welded Thin Joints — Suggested Slopes and FAT Values for Applying the Notch Stress Concept with Various Reference Radii

Abstract: An assessment of thin welded structures with actual IIW design lines results in an overestimation of fatigue lives (strengths) at high load levels and a conservative estimation at low load levels, in many cases, independently of the applied fatigue assessment approach (nominal, structural or notch stress). This is mainly due to the slopes of the design S-N line k = 3.0 for normal and k = 5.0 for shear stresses, which are valid for thick and stiff structures. To overcome this inconsistency for welded thin and flexible structures, the slopes k = 5.0 for normal and k = 7.0 for shear stresses are suggested, keeping the already known FAT values derived for the notch stress concept variants with rref = 1.0, 0.3 or 0.05 mm, respectively. However, the slope is not only determined by plate thickness; it is the result of an interaction between thickness, local geometry (stress concentration), structural stiffness, loading mode and last but not least residual stresses. This complexity makes it difficult to identify the driving parameters and to predict the slope of the S-N line in many cases.

IIW guideline for the assessment of weld root fatigue

Abstract: At welded joints, fatigue cracks usually initiate either at the weld toe or the weld root. The latter may be influenced by small defects or other irregularities or even by non-fused root faces forming a slit which acts like a crack. Weld root failure has therefore to be checked for several weld types. Different approaches exist for fatigue assessment, including the rather simple nominal stress approach, local stress approaches and the crack propagation approach which are partly well suited for the assessment of weld root fatigue. However, it is not easy to keep the overview and to decide which approach should be applied in the case in question. For this purpose, the guideline has been established giving an overview of the different approaches with special emphasis on weld roots and discussing their suitability and the limitations. Six typical examples are described where different approaches are applied and in some cases compared with fatigue tests, thus giving insight into the practical application and allowing own judgement.