Effect of compression overload on fatigue strength improved by ICR treatment

ICR (Impact Crack-closure Retrofit) treatment was developed for extending fatigue life of cracked steel structures by closing the fatigue crack opening. By applying the ICR treatment to as-welded condition, compressive stress remains at weld toe. Therefore, ICR treatment can be used for the improvement of fatigue strength of welded joint at the same level of the other fatigue strength improved techniques. If a compression overload is subjected after ICR treatment, however, the residual compressive stress at weld toe will shift the tensile stress region. Accordingly, improved fatigue strength of welded joints by ICR treatment will be reduced after the compression overloaded. In order to investigate the effect of the compression overload on fatigue strength improved by ICR treatment, fatigue tests of out-of-plane gusset specimens were carried out. As the results, fatigue strength improved by ICR treatment was hardly reduced under the compression overload condition of nominal stress of −190 MPa.