Mechanical properties and creep behavior of Q460E continuous casting slab were studied by means of uniaxial tensile tests on a Gleeble-3800 thermomechanical simulator from 1000 to 1100 ℃.The high-temperature creep constitutional equation was derived based on experimental data.The parameters in the equation were calculated by using the regression analysis inverse-estimation method.The experimental curves in the primary and secondary creep stages are fitted well.A three-dimensional elastic-plastic and creep finite element model was proposed in order to investigate the bulging deformation of slab and the bulging deformation at the beginning position of bending segment on the slab continuous casting machine was computed accurately.The results indicate that the maximum bulging deformation appears at the geometric center of the slab.The maximum value of the bulging deformation obtained by the elastic-plastic analysis is 1.301 ram.Consideririg the creep effect,the deformation increases to 1.827 mm which is about 1.4 times the value obtained by the elastic-plastic analysis.The calculation of buleing deformation usin2 the elastic-plastic creed model is more reliable and/iccurate.
To improve the slab quality, a kind of non-sinusoidal oscillation technique of mold driven by elliptic gears was developed. The waveform functions of non-sinusoidal oscillation were determined, and the calculation method and curves of technological parameters for non-sinusoidal oscillation were given. At the case of waveform deviation factor a equal to 0.31 and oscillation amplitude h equal to ±2.7 mm, the relationship between oscillation frequency and casting speed is determined, and the technological parameters for non-sinusoidal oscillation are calculated. The testing results of industrial application indicated that this technique could not only improve the Slab surface quality, but also reduce the steel breakout.
A new continuous bending and straightening casting curve with the aim of full using of high-temperature creep deformation was proposed. The curvature of bending and straightening segment varies as sine law with arc length. The basic arc segment is shortened significantly so that the length of bending and straightening area can be extended and the time of creep behavior can be increased. The distance from so lidifying front in the slab was calculated at 1200 ℃ by finite element method. The maximum strain rate of new casting curve at different locations inside the slab is 6.39 × 10 ^-5 s ^-1 during the bending segment and it tends to be 3.70 × 10 ^-5 s ^-1 in the straightening segment. The minimum creep strain rate is 7.45× 10 ^-5 s ^-1 when the stress is 14 MPa at 1 200 ℃. The strain rate of new casting machine can be less than the mini mum creep strain rate. Thus, there is only creep deformation and no plastic deformation in the bending and straightening process of steel continuous casting. Deformation of slabs depending on creep behavior only comes true. It is helpful for the design of the new casting machine and improvement of old casting machine depending on high temperature creep property.
To clarify the correlation between alloy elements and growth pattern of the rust layers, the rusting evolution of the carbon and weathering steels was investigated by using the gold markers method. The corrosion experiments were carried out in a simulated environment containing chloride ions. The results indicate that Ni, Cu, Cr and Mo elements in the weathering steel suppress the rust crystallization and impede the rust layer growth to an internal development, and the suppression function benefits the formation of a protective rust layer. Moreover, c-FeOOH is mainly located in the outer rust layer, while b-FeOOH is mainly located in the inner rust layer, and the distribution of the rust compounds in the rust layer is closely related to the growth pattern of the rust layer.
