TWI Industrial Member Report Summary 263/1985
By C S Punshon and J G Wylde
Fatigue tests have been carried out under pulsating axial tension on transverse electron beam butt welded joints in a medium carbon Ni-Cr-Mo low alloy steel to BS 970 817 M40. Specimens were manufactured from 15mm flat bar using two welding speeds - 500 and 300mm/min. The fatigue performance of specimens, produced at both welding speeds and tested in the as-welded condition, was significantly worse than previous results obtained from specimens manufactured from a lower strength C-Mn structural steel. This was due to the very poor toughness of the weld metal. Postweld heat treatment of specimens produced using the slower welding conditions resulted in an improvement in fatigue strength. The specimens made using the faster welding conditions were found to contain small solidification cracks. The orientation of these cracks was such that they did not influence the fatigue strength of the specimens.