Stress crack after the roll cooling - 1.2550
Treatment : spheroidised
Magnification : 100 : 1
Etching medium : 3 % alcoholic nitric acid
Sampling / Specification : transverse
Testing result :
stress crack arisen at the cooling of the rod wire,
before
the annealing ; defect depth 0,22 mm ; complete
decarburization
and grain boundary oxidation 0,01 mm deep
Treatment : spheroidised
Magnification : 200 : 1
Etching medium : 3 % alcoholic nitric acid
Sampling / Specification : transverse
Testing result :
stress crack with complete decarburization and grain
boundary oxidation up to 0,01 mm deep at the crack
flanks