Influence of coil temperature after hot rolling of two-phase steel plate

For a given composition of steel, the hardenability of austenite when heated in the critical zone can be corrected by rolling the steel plate at high temperature after hot rolling. High temperature coil can make carbon, manganese and other alloying elements in the second group (pearlite or bainite) obvious enrichment. It is beneficial to improve the comprehensive properties of the two-phase steel during subsequent treatment in the critical zone. Taking the test results of 0.049%C-1.99%Mn-0.028%Al-0.0019%N steel as an example, two processes were adopted: one was the ordinary process, the final rolling temperature was 900℃; → Oil cooling to 600℃; Coil → Air cooling to room temperature → cold rolling 70%→ continuous annealing. The results of the distribution of carbon and manganese in two kinds of coil process show that the high temperature coil can enrich carbon and manganese in the second phase, while the ordinary rolling process has no enrichment trend.
The technology of using high temperature coil to correct the hardenability of steel with low alloy content in the subsequent critical area treatment, and reduce the yield strength of heat treated duplex steel and improve its ductility has been used in the relevant factory for the production of heat treated duplex steel, and the obtained heat treated duplex steel has good comprehensive performance, uniform performance of each part of the plate, and consistent longitudinal and transverse performance. For example, for 0.09%C-0.44Si-1.54%Mn-0.023%Al steel.