Numerical calculation of the main factors on cold cracking

Abstract

Prof. Dr. mont. habil. Hermann Mu È ller zu seinem 65. Geburtstag gewidmet.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.

Hydrogen-Assisted Cracking in GMA Welding of High-Strength Structural Steel—A New Look into This Issue at Narrow Groove

“…However, for a complete release of diffusible hydrogen a DHT after welding is necessary. TEKKEN samples that have been subjected to DHT at 250 The diffusible hydrogen introduced into the weld metal can diffuse into highly stressed and strained areas which are located around the root notch in the TEKKEN test [59,60]. For the determined H D from Figure 4 the HAZ of the base material as well as the weld metals show a significant degradation of the mechanical properties with related risk to HAC [37,39,61].…”

“…Figure 8a,b. At this area significantly increased stresses and strains are present which lead to high stress intensity [59]. Therefore, cracks start to form transgranular.…”

Evaluation of Cracking Susceptibility of Weldment Container for Nuclear Power Plant

“…• Occurrence of cold cracking in the weldment heat affected zone (HAZ) due to induced hydrogen through the modified "Controlled Thermal Severity" test and the TEKKEN test [5][6][7]. • Susceptibility to reheating cracking through the VINCKIER test [8].…”