Deformation behavior of an ultrahigh carbon steel (UHCS-3.0Si) at elevated temperature

Rate-controlling mechanisms of hot deformation in a medium carbon vanadium microalloy steel

“…Hence the high activation volumes estimated by using both models for the test steel suggests that cross slip should be the rate-controlling mechanism in the high strain rate region. This result is consistent with Luo's finding [12] concerning the strain rate effect on an ultrahigh carbon steel (Fe-1.28C-3.0Si, wt%) hot deformation behavior, which indicates that at high deformation strain rates (5-30 s À 1 ), cross slip is the main deformation mechanism, while at low deformation strain rates (0.1-1 s À 1 ), climb-controlled dislocation creep is the main deformation mechanism.…”

“…Moreover, the stress exponent obtained is 3.37, very close to n ¼3 as predicted by deformation theories involving dislocation climb as the ratecontrolling process irrespective of the detail of the models [25]. Therefore all the parameters indicate that the rate-controlling mechanism at the low strain rates is dislocation climb, which has also been demonstrated by other researchers [12,15,23,25].…”

“…It is important to notice that Q values can only be obtained from the linear ranges of data in lne À ln[sinh(as)] and 1/TÀ n [sinh(as)] curves [8,10,11,12]. Therefore the lneÀln[sinh(as)] and 1/TÀ ln[sinh(as)] plots at strain¼ 0.2 and 0.7 are shown respectively in Fig.…”

“…Extensive investigations [1,5,6] have been conducted on the hot deformation behavior of medium carbon vanadium microalloy steels, however the strain rates in these researches are usually lower than 10 s À 1 and there is no detailed research on the rate-controlling mechanisms of hot deformation. Concerning the rate-controlling mechanism, many comprehensive investigations have been done in the field of magnesium alloy [7,8], g-TiAl alloy [9], electrolytic copper [10,11], and some researches on this topic for steels have been reported [12][13][14][15]. But these researches for steels have no direct and comprehensive results like those for other types of metals mentioned above.…”

Microstructure and mechanical properties of the Al-added ultrahigh carbon steel

“…However, the prerequisite for achieving the abovementioned properties is that the steel must have a fine grain-sized microstructure on both carbides and ferrites. Although many methods, such as thermomechanical processing [2,5], powder metallurgy [6][7][8][9], complete heat-treatment route [10] and spray forming process [11,12], were used to produce the fine microstructure in the steel, complicate preparing procedure was obligatory in each method.…”