| German | German Beobachtung des Dehnungsverhaltens unter dem Heiztischmikroskop bei Temperaturen von 800-1350°C. Zähes Verhalten bis 1250°C, dabei Veränderungen, wie Zwillingsbildung, Entstehen von Korngrenzen, Korngrenzenwandern, Aufrauhung und Aufwölbung der Oberfläche. Bei 1350°C kaum noch Verformung, jedoch bevorzugt an den Korngrenzen Bildung fluider Filme, die den Bruch einleiten. |
| English | English Similar to experiments carried out on the Gleeble-apparatus, tensile tests were performed on Grade 45 CrMoV 6 7 steel specimens at temperatures of 800, 1000, 1200, 1250 and 1350° C, using a hot-stage-microscope equipped with a tensioning device. The tests were carried out under bright-field and interference contrast illumination and recorded cinemicrographically. The width of the image area was 200, 300 and 600 µm, respectively. It appears from the film that the material remains ductile up to temperatures of 1250° C. The processes, taking place mainly within the crystallites, cause changes on the grain surfaces such as the formation of twin crystals and grain boundaries, shifting of grain boundaries and deformation bands, and roughening and bulging of the surface. By contrast, hardly any deformation of the grains occurs at the test temperature of 1350° C. Liquid films forming preferably at the grain boundaries, initiate the macroscopically deformationless fracture of the specimens. |
