Improvement of corrosion fatigue behaviour of high-strength steel welds by means of optimized post weld treatments

: Müller, F.; Sonsino, C.M.; Muesgen, B.

Abstract
In this research work the fatigue behaviour of welded V-shaped specimens made of the steels FeE 355 KT and Fe E 690 V with two types of post weld treatment (TIG-dressing of the weld toe, shot peening of the weld toe) were examined. The specimens were submitted to random bending loading (variable amplitudes, spectrum loading with linear distribution of the amplitudes) under presence of a corrosive environment (artificial sea-water) until final fracture occurred. When compared to the aswelded state, shot-peening led to an increase of fatigue life by a factor of 3 to 10, depending on the material of the weld. TIG-dressing led to a factor of 13. The combination of both, TIG-dressing and subsequent shot-peening, led to an increase of fatigue life by a factor of 50 in the case of the Fe E 355 KT. On the other hand, if the influence of the corrosive environment on the TIG-dressed welds of Fe E 690 V was reduced by means of a cathodic protection, fatigue life could be improved by a factor of 1 00. The results of this research work show, that fatigue performance can be improved significantly, if the above mentioned post weld treatments are applied. It is now possible to apply the two steels with a higher efficiency, which will subsequently lead to a remarkable reduction of costs.