STICKING PHENOMENON OCCURRING DURING HOT ROLLING OF FERRITIC STAINLESS STEELS

Abstract

Sticking phenomenon occurring during hot rolling of two ferritic stainless steels, STS 430J1L and STS 436L, was investigated in this study. A hot rolling simulation test was carried out using a high-temperature wear tester capable of controlling rolling speed, load, and temperature. The simulation test results at 900 degrees C and 1000 degrees C revealed that the sticking process proceeded with three stages, i.e., nucleation, growth, and saturation, for the both stainless steels, and that STS 4,30J1L had a smaller number of sticking nucleation sites than the STS 436L because of higher high-temperature hardness, thereby leading to a smaller amount of the sticking. When the test temperature was 1070 degrees C, the sticking hardly occurred in both stainless steels as Fe-Cr oxide layers were formed on the surface of the rolled materials. These findings suggested that the improvement of high-temperature properties of stainless steels and the appropriate rolling conditions for readily forming oxide layers on the rolled material surface were required in order to prevent or minimize the sticking.