Microstructure, texture and mechanical properties in a low carbon steel after ultrafast heating

Abstract

Microstructure, texture and mechanical properties in a low carbon steel after ultrafast heating. AbstractHeating experiments in a wide range of heating rates from 10 to 1200 °C/s and subsequent quenching without isothermal soaking have been carried out on a low carbon steel. The thermal cycles were run on two different cold rolled microstructures, namely ferrite + pearlite and ferrite + martensite. It is shown that the average ferritic grain size, the ferrite grain size distribution, the phase volume fractions and the corresponding mechanical properties (ultimate tensile strength and ductility) after quenching are strongly influenced by the heating rates and the initial microstructure. The ferrite grain size distribution is significantly modified by the heating rate, showing a markedly bimodal distribution after fast annealing. The rise of the heating rate has produced a change in the relative intensities of texture components, favouring those of the cold-deformed structure (RD fibre) over the recrystallization components (ND fibre).

Study of Carbide Dissolution and Austenite Formation during Ultra–Fast Heating in Medium Carbon Chromium Molybdenum Steel

“…Liu and Argen et al [6,7] observed the precipitation of austenite as Widmanstätten plates in Fe-Cr-C steels due to Cr enrichment of the cementite outer layer. More recently, austenite growth was studied by Cerda et al [18][19][20] under ultrafast heating rates, indicating that local C concentration is responsible for changes in the mechanism of austenite formation. In addition, De Knijf et al [21], and Cerda et al, [22] studied the effect of ultrafast heating on recrystallization, showing that nucleation of recrystallized ferrite grains is enhanced by increasing the heating rate and results in refined microstructures.…”

The Effect of Ultrafast Heating on Cold-Rolled Low Carbon Steel: Formation and Decomposition of Austenite

“…Although very fast heating rates have been applied in the case hardening of the structural steels, ultrafast heating (UFH) of flat steel products is now considered to be among the new processing routes [1][2][3][4][5]. A recent study on cold-rolled low carbon steel [5] shows that both strength and ductility can be enhanced at the same time after the application of ultrafast heating rates.…”

“…A recent study on cold-rolled low carbon steel [5] shows that both strength and ductility can be enhanced at the same time after the application of ultrafast heating rates. The improvement in mechanical properties stems from the variety of microstructures resulting from the application of UFH.…”

“Flash” Annealing in a Cold‐Rolled Low Carbon Steel Alloyed with Cr, Mn, Mo, and Nb: Part II—Anisothermal Recrystallization and Transformation Textures

“…In the case of austenite formation, the analogy holds as very fast heating rates shift the onset of austenite formation to high temperatures. The martensitic structure‐refining effect observed in samples heated at UFH rates reported elsewhere is a consequence of the enhanced nucleation of austenite on heating. In Figure d–f, different nucleation sites are shown for austenite (martensite).…”

“…Samples were cut from each heat‐treated specimen. As in previous studies, the zone of homogeneous microstructure in each specimen was determined by plotting the Vickers hardness (HV3) measured in the TD plane (i.e., the plane perpendicular to TD of the cold rolled sheet) as a function of the distance along the RD direction. Subsequent characterization and data collection were performed within the limits of the homogeneous zone.…”