Interrupt Shearing Test for Evaluating Effect of Large Shear Deformation on Evolution of Microstructure into Ultrafine Grains

Abstract

A new physical simulation method for evaluating the effect of shear deformation on the evolution of a microstructure is proposed. This method utilizes a high-speed compression testing machine and is capable of simulating the formation of fine grained steels in the transformation route. The outline of the proposed method, which is based on shearing and named the 'interrupt shearing test', is presented. The result of the preliminary application of the newly proposed test at an elevated temperature is shown. It becomes clear that the large shear deformation reproduced by the proposed method is capable of producing fine grained steels with a grain size of around 2 µm surrounded by high angle grain boundaries (HAGBs), although controlled cooling immediately after plastic deformation to accelerate transformation into finer grains is not applied in the present test.

Microstructural evolution and formation mechanism of bimodal structure of 0.2% carbon steel subjected to the heavy-reduction controlled rolling process

“…Among these methods, grain refinement is suitable for producing high-strength materials without any additive elements, showing that a reduction in elongation is less significant than an increase in strength with superior cost performance. Thus, various studies concerning the grain refinement 3 of metals including by severe plastic deformation (SPD) have also been steadily carried out [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. The variation of the strength of metallic materials as a result of such grain refinement has been well established by Hall [23] and Petch [24] and many investigations still are based on the Hall-Petch equation (ߪ ௬ ൌ ߪ ݇݀ ିଵ/ଶ ) [25][26][27][28].…”

Effect of carbon content on formation of bimodal microstructure and mechanical properties of low-carbon steels subjected to heavy-reduction single-pass hot/warm deformation

“…Among the methods of microstructure control including precipitate control, dispersion strengthening, and solid-solution strengthening, grain refinement is the simplest means of controlling mechanical properties of metals by controlling the grain size, crystal morphology, and texture without any additive elements. Mainly focusing on the generation of ultrafine grains in a matrix, various studies have been conducted with the aim of achieving numerous high-strength metallic materials [1][2][3][4][5][6][7][8][9][10]. Such studies have intensified because of the strong demand for high-strength metals to realize new lightweight structural materials that can be applied to the components of vehicles.…”

Through-Thickness Microstructure and Strain Distribution in Steel Sheets Rolled in a Large-Diameter Rolling Process

“…After rolling, the sheets were cooled immediately to 500-550 °C by rapid water cooling, and then they were air-cooled to ambient temperature. The equilibrium transformation point, Ae3, of the present steel is about 820 °C [20]. However, since the transformation point from austenite (γ) to ferrite (α) depends on the cooling rate and prior γ grain size, the accurate Ar3 in the The rolling schedules are shown in Figure 3.…”