Riktning och dess påverkan på de mekaniska egenskaperna vid leveranstillstånd av kallbearbetat rostfritt stål

The main purpose with this investigation was to clarify when or if specific grades will soften or harden during the straightening process in a seven roll cross roll straightening machine. The aim was solely made to include tubes which had been cold worked to achieve high yield strength levels. The straightening process will induce lengthwise tensile and compressive stress and strain. According to theory straightening could therefore also induce considerable Bauschinger effect. Physical tests, with material from pilgered tubes, in a laboratory environment were performed to give a well-defined set up of the strain levels and sign of the same. Real in process trials were also performed. Parallel to the physical laboratory tests and the real process tests a FEM-simulation and a FEM-model to calculate strain levels was developed. Two material types were investigated, but the results are only unambiguous for material A. Further investigations need to be done on material B to give a clear picture