Abstract
While the solidification macrostructure of continuous cast billets is an important factor influencing the final performance and rolling yield of oil casing steel, the continuous casting process parameters have a direct influence on the solidification structure. This study simulated the solidification process of the continuous casting round billets of oil casing steel using a cellular automaton–finite element (CAFE) model. According to the simulation results, at a superheat degree of 20–35 K, a casting speed of 1.9–2.1 m/min, and a secondary cooling specific water flow of 0.34–0.45 L/Kg, the solidification structure had a relatively high equiaxed crystal ratio and small average grain radius. Guided by the simulation results, this paper establishes optimal process schemes for producing 26CrMoVTiB steel round billets, comparatively analyzes the equiaxed crystal ratio and central shrinkage of round billets produced according to these schemes, and defines the optimal continuous casting process conditions, which are: superheat degree = 25 K, casting speed = 2.1 m/min, and specific water flow = 0.35 L/Kg. When adopting these process parameters, the 26CrMoVTiB steel round billets demonstrate a tiny central shrinkage and an equiaxed crystal ratio of 45.2%.
Highlights
Oil casing steel is an important metallic material used in the mining of petroleum and natural gas, mainly to support shaft walls and sustain shaft operations [1]
The production process, casting speed, superheat degree, secondary cooling intensity, and other process conditions directly influence the solidification structure of continuous casting round billets and further affect the mechanical properties and corrosion resistance of oil casing steel. In this sense, seeking a continuous casting process characterized by higher equiaxed crystal ratio, less composition segregation, and less internal shrinkage constitutes an important prerequisite for producing high-quality oil casting steel and providing a safe production environment in petroleum and natural gas mining
The microstructure simulations were performed under the following conditions: casting speed = 2.0 m/min; secondary cooling of specific water flow = 0.51 L/Kg; superheat degree = 15, 25, 35, and 45 K
Summary
Oil casing steel is an important metallic material used in the mining of petroleum and natural gas, mainly to support shaft walls and sustain shaft operations [1]. In most cases, continuous casting round billets are adopted for the production of oil casing steel. The production process, casting speed, superheat degree, secondary cooling intensity, and other process conditions directly influence the solidification structure of continuous casting round billets and further affect the mechanical properties and corrosion resistance of oil casing steel. In this sense, seeking a continuous casting process characterized by higher equiaxed crystal ratio, less composition segregation, and less internal shrinkage constitutes an important prerequisite for producing high-quality oil casting steel and providing a safe production environment in petroleum and natural gas mining. The cellular automaton–finite element (CAFE) model, by virtue of its explicit physical mechanism, Metals 2019, 9, 993; doi:10.3390/met9090993 www.mdpi.com/journal/metals
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