Influence of vibration on mechanical properties of electroslag welded joint

Electroslag welding (ESW), has great superiority in thick plate structure, composite structure and thick wall vessel etc. However, large heat input in welding process results in a wide coarse grained region and high residual stress. Furthermore, examination of weld metal toughness reveals very low Charpy V-Notch (CVN) impact toughness values. Vibratory weld conditioning (VWC) technology is the procedure that the workpieces are vibrated while welding to improve the properties of welded joint. In this paper, VWC process was carried out in ESW of the blast furnace steel 14MnNbTi. The mechanical properties of the welded joint were investigated. The test results show that VWC reduces the residual stress of the welded joint. And long time vibratory stress relief (VSR) is very important to relieve the residual stress after welding. The metallographs show that the sizes of the grains at the weld and at the heat-affected zone (HAZ) are reduced after vibration conditioning. The test results also show that the tensile strength of the joints remains constant while the side bend property improves significantly with vibratory conditioning. Especially, in the 6m/s(2) vibratory condition, the side bend performance is up to 100 percent of pass The influence of vibration on impact value is complex. The impact value increases by 70% at HAZ, whereas decreases by 30% at weld. But both are in qualified scale. The impact values in two vibratory acceleration conditions (3 m/s(2) and 6 m/s(2)) are compared and the changing mechanism is discussed in the paper. The internal friction test indicates that the Snoek-Ke-Koster (SKK) peak of the weld metal has good correlation with the impact value of the weld.