Effect of Flame Straightening on Material Properties of Q+T High Strength Steels

Abstract

In designing, dimensioning of welded structures, also selecting the welding technology we strive to minimize the deformations of structures during manufacturing. Even with the maximum observance of technological discipline, in many cases, the deformation of our products beyond the margin of tolerance is often unavoidable. Therefore, we need to straighten our structures with a mechanical or thermal source of heat. Nowadays, steel construction and machine manufacturing companies prefer to use flame, (or other hot) levelling technologies to recover and ensure the shape and dimensional stability of parts, welded structures. There was a need for exact specification of the technology parameters before, but due to the introduction of the EN 1090 standard series, it is becoming more and more important to follow and document the steps of flame straightening. The warm straightening is an important part of the production life cycle of the structure, therefore, the operation of the physical phenomena of the technology must be known must be experienced in the process, as well as the mechanical and microstructure changes of the materials which used. Regarding to the new developed advanced materials (e. g. Q+T and TM high strength steels) in many cases there is not enough experience of the possible behaviour of the material. At the moment there is very little scale of literature on flame straightening of steels, especially for high strength steels. For this reason, it is advisable to prove the applicability of flame straightening with preliminary technological tests. The following summary shows how different materials are affected in different ways by flame straightening technology through a series of experiments on several material qualities.