Method for mechanical treatment of elongated amagnetic austenitic steel workpieces, especially of drill collars for oil drilling

摘要

An elongated blank (1) of non-magnetic steel, comprising by weight less than 0.08% carbon, 12-20% chromium, 17-22% manganese and 0.15-0.35% nitrogen, is given a permanent elongation of 20-30%, preferably 25-28%,by stretching at below 400 degrees C, preferably around 20 degrees C.