Effect of Alloying and Coiling Temperature on the Microstructure and Bending Performance of Ultra-High-Strength Strip Steel

Abstract

Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.

Effect of coiling temperature on impact toughness of hot rolled ultra-high-strength multiphase steel strips

“…4e. Microstructural constituents are identified considering their morphological characteristic as reported in the literature [46] and also shown in our recent study [11]. The intricate microstructural details can be identified from the TEM images in Fig.…”

“…These coarse and brittle precipitates could be the potential sites for cleavage crack initiation [61]. Detailed discussion on the evolution of microstructure and precipitation during the casting, rolling and final coiling treatment of the investigated strip samples are available in our earlier study [11].…”

“…The highest uniform elongation and total elongation were observed in Ti-460 followed by Al-450, whilst, Ti-380 showed the lowest ductility. More details regarding the tensile properties of the investigated samples have discussed in our previous study [11]. The variation in the strain-hardening exponent (n) as the function of true strain is plotted in Fig.…”

“…Regarding thermomechanically processed and controlled cooled high-strength strip steels, the role of processing parameters such as soaking temperature, start-and finish-rolling temperatures, rolling reduction ratio, cooling start-and end temperatures and cooling rate on the microstructure and mechanical properties have been studied extensively [4][5][6]. It is noteworthy that UHSS strips (< 10 mm thickness) are usually coiled after finish rolling, and use accelerated cooling to a lower temperature range (typically, 350 -460 C) to achieve high strength by the formation of bainite-martensite mixed microstructures [7][8][9][10][11][12][13]. An increase in strength, however, is often accompanied by a decrease in ductility and impact toughness [14].…”

“…That is the objective of our paper. In a recent article [11], we have reported the effect of coiling temperatures on the microstructural evolution and the bending performance of two different B-containing structural grades of steels (one treated with Ti and the other treated with Al). The present study correlates the microstructural parameters with the tensile and Charpy impact properties of those multiphase UHSS strips.…”