Fatigue strength of repaired welded connections made of very high strength steels

Abstract

Modern steel manufacturing techniques make it possible to produce steel with the nominal yield strength up to 1300 MPa for structural purposes. However, the application of very high strength steels is still limited in the civil engineering structures due to lack of knowledge about the effects of the manufacturing process and experimental results regarding the structural behaviour of the material. Moreover, in a fatigue loaded very high strength steel structure absolute and relative stress variations will be higher compared to stresses in structures made of lower steel grades. Accordingly, the fatigue issue will be one of the most important design criteria for very high strength steel structures. In this current study, V-shape welded specimens were manufactured from S690 and S890 rolled steels and cast steels with similar yield strengths. Fatigue cracks were created in the weld toe of the specimen under a fluctuated loading and subsequently the fatigue damaged specimens were repaired by the removal of the cracks with subsequent welding. The fatigue strength curves of repaired specimens are compared with the detail categories of EN 1993-1-9 (2006) and the fatigue strength curves of the test results in the aswelded condition from literature. The fatigue strength of the fatigue damaged connections was completely recovered by the established repair procedure.

Influence of competing notches on the fatigue strength of cut plate edges

“…He concluded that the repair weld has a limited negative influence on the fatigue strength of the material. Another study of Akyel et al [18] examined the fatigue strength of repaired welded connections made of very high strength steels. He showed that the fatigue strength of the fatigue damaged connection can be completely recovered by the established repair procedure.…”

The Assessment of Selected Properties of Welded Joints in High-Strength Steels

“…In terms of steels, new favourable properties are usually obtained either through the modification of the chemical composition or by changing methods of thermo-mechanical treatment. The controlled processing of steels enables the obtainment of various mechanical properties [1][2][3][4][5][6]. The aforesaid situation is observed in, e.g.…”

“…high-strength toughened unalloyed steels, particularly useful as regards the necessary reduction of product weight and the energy consumption of manufacturing processes [1][2][3][4]. The replacement of classical structural steels with high yield point steel significantly reduces the weight of a structure and/or may increase its load carrying capacity without increasing the weight (wall thickness) [2,5]. In turn, the use of heat treatment processes during the production of steel entails risks including irreversible changes in the structure and mechanical properties of the steel.…”

“…The aforesaid area may be affected by changes in the structure and mechanical properties. It should also be noted that changes in mechanical properties may also be triggered by temperature lower than Ac1 [1][2][3][4][5][6][7][8][9][10].…”

Effect of Preheating on the Structure and Mechanical Properties of Steel S1300QL

“…Because of the necessity of decreasing the weight of products and reducing the energy consumption of manufacturing processes, high-strength steels will enjoy increasing popularity in the years to come [1][2][3][4]. The replacement of classical structural steels with steels having a yield point of more than 500 MPa makes it possible to reduce the weight of a structure two or even three times, or looking at the issue otherwise, makes it possible to increase the load capacity of a structure without increasing its weight (wall thickness) [2,5]. To make the foregoing possible, it is necessary to develop appropriate welding technologies.…”