Abstract
Trans-Varestraint test is basically used for hot cracking susceptibility of materials. In the Trans-Varestrain test, bending deformation is applied to the specimen during welding to produce cracking. From the shape and size of cracks, the hot cracking susceptibility indices such as Brittle temperature range (BTR) and critical strain are obtained. The nominal strain generated by the bending can be calculated from the specimen thickness and the radius of the bending block. However, it has been reported that in this test, the estimated nominal strain and the actual strain acting on the weld metal differ significantly due to localized heat. In this study, hot cracking analysis using Idealized explicit FEM, which can compute large-scale thermal elastic-plastic analysis with smaller computing time and memory, is applied to the Trans-Varestraint test. The effects of heat input and test conditions on the mechanical behavior of the welded part during the Trans-Varestraint test are investigated. The results indicate that the strain acting on the welded part during the Trans-Varestraint test is larger than the nominal strain. In addition, it is found that the welding speed has a significant effect on the amount of strain acting on the molten part. It is suggested that these were caused by local melting of the specimens, resulting in a decrease in strength. In addition, bending speeds and welding speeds affect the amount of strain produced by bending and the size of the area in which the strain occurs. In other words, they affect the size of the region and the amount of strain generated in the BTR and have a significant effect on the maximum crack length obtained in the Trans-Varestraint test.
