Strukturotvorné procesy při teplotně řízeném válcování a ochlazování bezešvých trubek z mikrolegované oceli

Abstract

In the laboratory conditions, the structuring processes of HSLA steel with a composition of 0.17 C - 1.1 Mn - 0.2 Si - 0.028 Al - 0.011 N - 0.025 Nb (in wt. %) were investigated. The effects of finish rolling temperatures on the resulting structure were also evaluated and the non-recrystallization temperature of the steel was determined just above 850 ° C. The DCCT diagram after deformation at 900 ° C was assembled. Decreasing of the finish rolling temperature in the range 990 - 850 ° C resulted in grain refinement and homogenization of the resulting microstructure. The apparent decrease in grain size below 890 ° C was most likely due to precipitation, which slowed recrystallization. Laboratory rolling has achieved a smallest grain size of 17 μm. It was found that the rolling force at 850 °C was about 60% higher than the rolling at 990 ° C.