Abstract:
Thermal expansion instrument was used to study the phase transition behaviors of hydrogen sulfide corrosion resistant X80 pipeline steel during continuous cooling and continuous cooling transformation (CCT) curves were drawn. Moreover, simulation test for its rolling process was also carried out using thermal simulation test machine. And the effects of deformation temperature, cooling rate and coiling temperature on microstructure and hardness of tested steel were analyzed, and the optimized rolling process parameters were obtained. At last, for the tested steel rolled at optimized rolling process parameters, its mechanical properties and hydrogen induced cracking (HIC) resistance were tested. The results demonstrat that phase change temperature of the tested steel mainly occurred between 450 ℃ and 780 ℃. With the increase of cooling rate, the phase transformation starting temperature was overall declined. In addition, the microstructure was mainly acicular ferrite when the cooling rate was between 1.76 ℃·s-1 and 8.8 ℃·s-1. The optimum rolling process parameters was determined as phase transition temperature, cooling rate and coiling temperature of (830±15) ℃, 15 ℃·s-1 and (400±15) ℃, respectively. The tested steel rolled at the above rolling process parameters had good HIC resistance, and it can meet strength demands of API5L on X80 pipeline steel.