Thermomechanical analysis and optimisation for beam blank continuous casting

Abstract

The present work aims to simulate the solidification process during beam blank continuous casting, to determine the causes of defects, and to optimise the process parameters. A transient finite element model has been developed to compute the temperature and stress profile in beam blank continuous casting. It has been found that the surface temperature fluctuated greatly and that the equivalent stress and strain have their highest values at the flange tip and the web. By comparing the calculated values with metallurgical constraints, the key factor causing surface cracks on the web was determined and an optimum cooling regime was proposed. Online verification of this optimisation project has led to a reduction in the incidence of web surface cracks. List of symbolsc(T) specific heat , J kg 21 uC 21 f s solid fraction h heat transfer coefficient, W m 22 K 21 H(T) enthalpy, J m 23 k(T) thermal conductivity, W m 21 uC 21 L latent heat of fusion, J kg 21 q heat flow density, kW m 22 q latent heat source, W m 23 t casting time, s T temperature, uC T 0 pouring temperature, uC T a air temperature, uC T s surface temperature of blank, uC T w cooling water temperature, uC x,y,z rectangular coordinates, m e strain e' emission ratio, e'50?8 r(T) density, kg m 23 r(T) s density of solid, kg m 23 s stress, MPa s' Boltzman constant, s'55?765610 28 , W m 22 uC 24

Initiation of Surface Cracks on Beam Blank in the Mold during Continuous Casting

“…The simulation results in this study are basically the same as that of Chen et al [5]; thus, the simulation results are credible and the model is reasonable.…”

“…During the Chen et al [4] established a FEM coupled thermo-elastic-plastic model to compute the temperature and stress contours in the continuous casting of a steel beam blank and found that cracks were easily generated in the web and the flange tips. Chen et al [5] developed a 2D transient state model to simulate the stress and temperature distribution on the beam blank surface, discovering that high heat flow was the critical factor in surface crack formation on the web. They proposed an optimum water-spraying intensity, according to metallurgical criteria, to suppress surface cracking.…”

“…The heat transfer between the blank shell and mold wall is expressed as equivalent heat transfer coefficient; the convective heat transfer coefficient in the mushy zones and liquid pool can be considered as three times and six times the thermal conductivity of the solid shell respectively [5].…”

“…where q is the heat flux (kW/m 2 ), α employs the empirical constant 2688 kW/m 2 [4,5,15,16], and β is obtained by the formula:…”

Enhanced Thermochromic Properties of Vanadium Dioxide (VO2)/Glass Heterostructure by Inserting a Zr-Based Thin Film Metallic Glasses (Cu50Zr50) Buffer Layer

“…In response to a large energy-consuming and environmentally deteriorating condition, developing energy-saving materials and sustainable energy has aroused wide attention. Vanadium dioxide (VO 2 ) thin film is a first-order phase-changed material with superfast reaction speed that is near the critical temperature, 340 K [1,2]. This phase transformation is called a metal-insulator transition (MIT), and involves significant changes in electrical and optical characteristics.…”