Identification and Prevention of Quench Crack of Hot-rolled Seamless Steel Tube

Briefed in the essay are the morphology and characteristics of quench cracks of the hot-rolled seamless steel tube，and described are the methods to identify and distinguish the quench crack from the rolling crack.Furthermore，case analyses concerning the two different cracks are conducted，including how to identify the mixed type cracks. Preventative actions against the steel pipe quench crack are proposed，involving such issues as control of C and Mn contents，control of the heating temperature，and control of cooling velocity，etc. The analysis result reveals that for steel types subjected to water quenching treatment，their mass fractions of C and Mn must be strictly controlled，and in case of w（C）＋w（Mn）/3≥0.9%，using the water-quenching process means a pipe cracking risk，and therefore oil quenching process is preferred. And for hi-C & Mn steel types，reducing quench temperature and cooling velocity will be good for preventing occurrence of the said pipe quench crack.