Hot Deformation Strength of Austenite during Controlled Rolling in a Plate Mill

Abstract

The effects of metallurgical factors on hot deformation strellgth of austenite have been investigated, focllsillg on the deformation strength during controlled rolling in a wide plate mill. The high speed hot compression testing equipment used made it possible to carry out intemlittent multi-stage press deformation experiments . In olle press experiment, the effects of chemistry and grain size were investigated in the temperature range 750C and 1 100C. The steels studied ranged from mild steel and high strength low alloy steels, including Nb-bearing steels, to stainless steel. In the intermittent two-or three-stage press experiments, the variolls facto rs influencing the softening ratio were studied in Si-Mn steel and b-bearing steel. The mill load and temperature during each rolling pass were measured during cOlltrolled rolling in a 180 inches wide plate mill, and were analyzed based on hot rolling theory . The e.ffective strain was introduced into the hot defon nation strellgth equation, taking into account that the residual strain deJJended on the softening ratio . The mill load during controlled rolling was estimated using this equation, and compared witlt the measured load. Excellent agreement between both values was obtained over the whole rallge of rolling temperatures.