Copper-caused Surface Cracking of Steel During Hot Working.
U S Pat 3 875 777 1975 Apr; :
The cracking of steel containing approximately 1 pct cu during hot- rolling is believed to be related to the presence of undissolved cu at the interstices between the scale formed on the ingots in the soaking pits and the metal. Such cu was not detected on steel coated, between some scaling and rolling, with glass containing borax. The coating is done most effectively by dipping in molten glass at 1,100 deg-1,300 deg c, but more conveniently by dusting powdered glass on the steel at the above temperature. Best results were obtained with borax-glass mixed with up to 50 pct feldspar containing 30-5 (ed.: No doubt should be 50) pct sio2 to increase the viscosity. Steel containing sn with cu may require this treatment for crack-free hot-rolling when the cu content is at least 0.25 pct; if ni is also present, hot-rolling without cracks may be possible with up to 1.25 pct cu.
U.S. Pat. 3,875,777; Apr. 8, 1975; Chem. Abstr. 81:P94,962n