<p>Breakdowns of welded structures are usually a consequence of fatigue loading. Fatigue fractures are commonly initiated in the region close to the weld toe but can also initiate from the weld root and from discontinuities inside the weld. The purpose of this investigation was to examine the weld quality of welded joints produced at Volvo Wheel Loaders factory in Arvika. The goal of the investigation is to give a clearer insight regarding factors influencing the fatigue strength of the welded joints and thereby give a better foundation for fatigue strength calculations.</p><p>The investigation is including examination of the weld geometry, weld discontinuities and the effects of shot peening. Mainly three different methods for collecting test data have been used: Plastic replicas cast on the weld profile, weld specimens from a rear frame belonging to a wheel loader of model L110E/120E and Almen testing of the shot peening.</p><p>The results showed that it is not possible to control even transition between the weld material and the base material without after treatment. The most frequent reason why the welded joints did not fulfill the demands in the Volvo Corporate Standard was leg deviation outside the acceptable limit. The most frequent weld defect was lack of fusion inside the weld. The occurrence of this defect was overrepresented in butt welds. The results also showed that the fatigue enhancing effects of shot peening are with today’s process just being used to a minor degree.</p>

Breakdowns of welded structures are usually a consequence of fatigue loading. Fatigue fractures are commonly initiated in the region close to the weld toe but can also initiate from the weld root and from discontinuities inside the weld. The purpose of this investigation was to examine the weld quality of welded joints produced at Volvo Wheel Loaders factory in Arvika. The goal of the investigation is to give a clearer insight regarding factors influencing the fatigue strength of the welded joints and thereby give a better foundation for fatigue strength calculations. The investigation is including examination of the weld geometry, weld discontinuities and the effects of shot peening. Mainly three different methods for collecting test data have been used: Plastic replicas cast on the weld profile, weld specimens from a rear frame belonging to a wheel loader of model L110E/120E and Almen testing of the shot peening. The results showed that it is not possible to control even transition between the weld material and the base material without after treatment. The most frequent reason why the welded joints did not fulfill the demands in the Volvo Corporate Standard was leg deviation outside the acceptable limit. The most frequent weld defect was lack of fusion inside the weld. The occurrence of this defect was overrepresented in butt welds. The results also showed that the fatigue enhancing effects of shot peening are with today’s process just being used to a minor degree.

Svetsning är idag den mest använda sammanfogningsmetoden för metaller, och pågrund av metodens relativt enkla utförande och höga produktivitet är MIG/MAG-svetsning idag den mest använda svetsmetoden industriellt i hela världen. En viktig del av svetsutrustningen till MIG/MAG är svetspistolen. Strömöverföringen från pistol till tillsatsmaterial sker genom en komponent som kallas kontaktrör. Kontaktröret är traditionellt tillverkat av koppar. Målet med detta examensarbete är att fastställa huruvida det nya materialet i ett kontaktrör påverkar grundmaterialet och svetsgodset negativt vid svetsning. Slutsatsen som drogs var att det nya materialet i kontaktröret inte har en negativ påverkan på grundmaterialet eller svetsgodset vid svetsning. Produkten kaneventuellt leda till stora ekonomiska och ekologiska vinster för svetsindustrin i framtiden.