Single-pass hot compression tests are performed to study the hot deformation behavior of a low carbon microalloyed steel at temperatures in the range of 950-1050 C and strain rate from 0.01 to 0.5 s-1. Based on true stressstrain data, the effect of strain rate and temperature on the flow behavior of this steel is analyzed and peak stress is determined as well. The partial derivative of the strain hardening rate to stress is used to determine the critical stress. The value of activation energy and the ratio of critical stress (strain) to peak stress (strain) are estimated. The relationship between characteristic points and Zener-Hollomon parameter is established. The kinetic model for the calculation of volume fraction of dynamic recrystallization is also established. The strain dependence of material constants are determined from fifth-order polynomials and the flow stresses under different deformation conditions are predicted, consistent with the experimental results. Figure 7. Comparisons between measured and predicted flow stress at different strains. www.advancedsciencenews.com www.steel-research.de steel research int. 2018, 89, 1700395

Based on the new generation TMCP technology, The State Key Laboratory of rolling and automation, Northeastern University(RAL) developed an advanced cooling system(ADCOS-PM). The system was combination of ultra-fast cooling (UFC) equipment with the advantage of high cooling intensity and homogeneous cooling and traditional accelerated cooling equipment(ACC). The UFC equipment was composed of jet impingement cooling device with high-pressure water and the ACC equipment was composed of laminar cooling device with good controllability. The control object of ADCOS-PM control system including finish cooling temperature and cooling-rate of every stage was controlled by adjusting the parameters such as the run-out table speed, state of active and inactive jet, flow rate of active jet. The temperature profile of plate was completed on the run-out table so that the product with fine microstructure and good mechanical properties was produced. The ADCOS-PM was built in 4300mm plate mill of Anshan Iron and Steel Co., Ltd. in 2010 and the recycling products with high-performance were produced.

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This study aims to investigate the influences of rare earth element cerium (Ce) on microstructure and mechanical properties of low alloy ultra-high strength steel. The strength, plasticity, and impact toughness of steels with 0.0367% Ce and without Ce were tested. The influence mechanism of Ce on the microstructure and mechanical properties were investigated by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and electron back scattered diffraction (EBSD). The results showed that the addition of Ce improved the comprehensive mechanical properties of low alloy ultra-high strength steel. In particular, the plasticity and toughness were improved obviously. The addition of Ce increased the elongation from 9.47% to 10.49%, and the low-temperature impact energy from 50J to 58J. The elongation and impact energy increased by 10.77% and 16%, respectively. And the yield strength of all samples remained above 1400 MPa. The rare earth element Ce did not change the matrix composition phase which were martensite. However, the addition of Ce increased the proportion of high-angle grain boundary from 33.2% to 40.2%. In addition, the Ce make the inclusions denatured and hence spherical inclusion with small size can be obtained. The EDS results showed that rare earth and harmful elements P and O formed inclusions, which as a purifier for the molten steel and hindered the formation of the large-size composite inclusions.

A vertical type twin roll caster with two side dams was used to cast aluminium alloy strip with a thickness of about 5mm at speed higher than 10m/min. The characteristics of the twin roll caster with two side dams are as follows: The diameter of the copper roll is 500mm, the width of the copper roll is 110mm and the thickness of the copper roll sleeve is 25mm.The maximum casting speed is up to 60m/min. Using the vertical type twin roll caster, a 4.5mm thickness of 6111 strip could be cast at a speed of 30m/min. The microstructure of the as-cast strip was equiaxed and spherical, not columnar. The mechanical properties of the strip casted from the vertical type twin roll caster were almost as same as that of the strip made from the conventional cast ingot.