A leading producer of castings, ingots and forgings, Pilsen Steel, Pilsen, Czech Republic, recently experienced difficulties with ingots cracking in a forging operation. The company contracted with COMTES FHT to investigate and determine the root cause of the formation of longitudinal cracks on a diverse load of 34CrNiMo6 steel ingots in a forging operation. Previously the ingots were cooled after casting in water to between 500oC and 600oC. The ingots were then placed in the forging furnace which was at a temperature of 1100oC to 1200oC. It was unclear whether the root cause of the cracks was heating the ingots or the forging operation.
COMTES used MSC Software’s Marc nonlinear FEA software to analyze the process of heating the ingots in the furnace, which was suspected as the root cause of the cracks. The results of the software showed that raising the ingot temperature to 700oC completely eliminated the cracking problem. COMTES FHT researchers worked with Pilsen Steel engineers to modify the soaking process used to cool the ingots after casting to provide assurance that ingots would be at least this temperature when they were placed in the furnace. As predicted by the analysis, when Pilsen Steel implemented this changes they eliminated the cracking problem.