Numerical calculation of the main factors on cold cracking

Abstract

Low alloy high-strength steels are nowadays very common in industrial application offering a number of favourable characteristics. However, cold cracking is an increasing problem concerning the weldability of these materials. For the prediction of cold cracking susceptibility many different tests exist. The most important ones are the Tekken-(Y-groove restraint test), the controlled-thermal-severity test (CTS) and the implant test. But in spite of the same or similar welding conditions, one gets different minimum preheat temperatures dependent on the used test procedure. Therefore, a better evaluation of these tests seems to be necessary. Based on the commercial FEA-tool SYSWELD three main factors influencing cold cracking were investigated for MAG-welded Tekken specimens: the distribution of microstructure, the stress-strain state and the hydrogen concentration. The analysis was performed for S690 low alloy high-strength steel. Also, welding experiments were carried out to determine temperature field and microstructure.