Abstract
In this investigation, Austenitized AISI 4340 and A2 tool steel were ausformed using ECAE as a sole deformation mechanism. In addition, AISI 1552 steel was deformed by ECAE. The effect of deformation on hardness, tensile properties, and microstructure was determined. Significant improvements in these properties were realized with some sacrifice of ductility. The ausformed (at 950' C) and tempered (at 700' C) A2 tool steel produced 275%, 233%, and 61% higher hardness, YS, and UTS values than that of as received, respectively. The percent elongation of ausformed (at 950' C) A2 tool steel was 120% higher and 163% lower than conventional and as received tool steels, respectively. In addition, ausformed (at 750' C) A2 tool steel had four times better percent elongation as compared to conventional steel. The YS and UTS of ausformed (at 850' C) and tempered (at 700' C) 4340 steel was 12% and 12% higher as compared to that of as received, respectively. Strikingly, this ausformed and tempered steel also produced the highest percent elongation, which was about 25%. The tensile properties of as deformed 1552 steel were also enhanced by ECAE. IA and 4B produced the highest YS and UTS, respectively. The YS and UTS were 96% and 71% higher than that of as received steel. 2B had the highest percent elongation among all routes (IA, 2A, 2B, 2C, etc.) of ECAE extrusions. This percent elongation was about 63% higher than that of one pass extrusion. The as deformed and as ausformed hardness were higher than that of as received steel. The hardness of 4340 and A2 tool steel decreased with increasing tempering temperature. Optical and electron micrographs of the deformed steel indicated a refinement of the microstructure. This refinement and the effects of cold work that was imparted by ECAE may be associated with the increase in mechanical properties of 1552, 4340, and A2 tool steels.
Shadat, Mohammed Anower (1998). The effect of equal channel angular extrusion on the microstructure and mechanical properties of AISI 1552, AISI 4340, and A2 tool steels. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1998 -THESIS -S53.