Effect of Austenitization Temperature on Hot Ductility of C-Mn-Al HSLA Steel

Abstract

The article aims to investigate the effect of different austenitization temperatures on the hot ductility of C-Mn-Al High-Strength Low-Alloy (HSLA) steel. The thermo-mechanical simulator of physical processes Gleeble 1500D was used for steel hot ductility study. Hot ductility was estimated by measuring the reduction of area after static tensile testing carried out at temperatures in the range 600 °C to 1200 °C with the step of 50 °C. Evaluation of fracture surfaces after austenitization at 1250 °C and 1350 °C with a holding time of the 30 s showed significant differences in the character of the fracture as well as in the ductility. The fracture surfaces and the microstructure near the fracture surfaces of samples at a test temperature of 1000 °C for both austenitization temperatures were analyzed by Scanning Electron Microscopy (SEM), Light Optical Microscopy (LOM), and AZtec Feature analysis (particle analysis of SEM). AlN and AlN-MnS precipitates at grain boundaries detected by the detailed metallographic analysis were identified as the main causes of plasticity trough in the evaluated steel. Moreover, using Thermo-Calc software, it was found that AlN particles precipitate from solid solution below the temperature of 1425 °C.

Analysis and Control of the Slab Hot Ductility Behaviors Based on Nozzle Arrangement during Continuous Casting

“…For example, the precipitation behavior of carbonitride largely influences the surface quality of the microalloying steel. [25,26] The cooling rate affects the austenite-ferrite transition temperature of steel during solidification, [27] and the differences in the hot ductility of steel at different austenitization temperature. [28] Nevertheless, to obtain the optimized parameters of nozzle arrangement, most of the studies have used methods based on the control of the water flux or the temperature distribution on the blank surface, [10,[13][14][15][16][17][18][19][20][21][22][23][24] ignoring the effect of blanks characteristics on the cooling process.…”

“…[25,26] The cooling rate affects the austenite-ferrite transition temperature of steel during solidification, [27] and the differences in the hot ductility of steel at different austenitization temperature. [28] Nevertheless, to obtain the optimized parameters of nozzle arrangement, most of the studies have used methods based on the control of the water flux or the temperature distribution on the blank surface, [10,[13][14][15][16][17][18][19][20][21][22][23][24] ignoring the effect of blanks characteristics on the cooling process. Therefore, it is necessary to develop a new strategy for nozzle arrangement matching the characteristics of the blank to reduce the surface cracks.…”

“…[29][30][31][32][33]39] There are differences in the hot ductility of steel at different austenitizing temperatures. [28] In this study, the range of austenite transition temperature during solidification of SPHC slab was obtained from 1,409.3 to 1446.8 °C by the Thermo-Calc software. To simulate the actual continuous casting solidification process, the initial holding temperature of SPHC slab specimens was taken as 1,450 °C during high-temperature tensile test.…”

An Insight into the Defects-Driven Plasticity in Ductile Cast Irons

“…In the continuous casting production of steels, for instance, the metallurgical discontinuities, such as cracks forming during solidification at the slab surface, influence appreciably the material quality resulting from the subsequent slab straightening [ 8 , 9 ]. In this case, hot tensile strength and ductility investigations have been reported to be effective tools to investigate the transformations from liquid to solid state that can foster the crack formation during solidification [ 10 , 11 ].…”