Experimental research on the magnetic and acoustic properties of 15CrMoR welding cold cracking

Welding cold crack is the most serious defects in welding structure, which has a direct impact on product quality and may even cause major accidents. In this paper, the inclined y-shaped groove butt welding experiments have been conducted. The present work explored the acoustic and magnetic properties by means of acoustic emission and MMM testing during the cooling process after welding. The change rule for the acoustic emission and magnetic memory signals was found. Meanwhile, the experiment indicates that the thickness of specimen and the length of restraint weld have a great influence on the acoustic emission and magnetic memory signals. And, with the increase of thickness and length, stress concentration becomes obvious and the cold cracks appear more easily and earlier. The results of the present work validate the feasibility and effectiveness of applying acoustic emission and MMM detection technique in the early forecasting of cold crack.