Analysis On Couples Of Thermo-mechanical For Initial Shell In Continuous Casting Mould

After several decades of developments, CC technology has already stepped into mature phases. CC technology ispursuing the purposes of high-efficiency, highly rushed, CCDR and near net shape casting, which requires more highquality CC strands. The quality of initial shell has crucial impact on the strand surface quality; therefore, improving thequality of initial shell within the mould has important meaning in surface quality.Firstly, the solidification process of molten steel in mould is analyzed, and the latest progresses of simulation onsolidification of liquid steel in mould during CC are reviewed. Based on study of thermal-mechanical of shell, a2Dthermo-mechanical coupled model of billet in mould is established which the inherited stress behavior of shell is takeninto account. The thermo-mechanical model of billet is calculated and coupled indirectly with multiple load stepmethod by ANSYS software. Basis on the method and model, the liquid steel heat transfer in mould is analyzed withdifferent CC conditions. Secondly, the results which are respectively calculated by four methods of tradition couplemethod, initial force method, initial strain method and multiple load steps method, which the latter three methods takeaccount of inherited stress behavior, are compared. Thirdly, according to the principle of minimizing air-gap, the mouldinner wall shape is optimized, and the effects of the mould with three types inner wall of single taper, multi-taper andparabola on shell temperature and stress field are compared.The results show that, base on multiple load steps, the stress inheritance can be achieved, the simulations showthat the thickness of middle shell rises5.13%when cast temperature increases from1540℃to1550℃; the thickness ofcorner shell rises6.98%when taper adds from0.0%/m to0.7%/m; The shell thicknesses of corner and middle increase34.30%and37.84%respectively when cast speed elevates from1.5m/min to2.5m/min. The corner shell thicknessessimulated by initial force method and multiple load steps method respectively are1.02times and0.979times thickerthan by tradition couple method; and the shell thickness with initial strain method accords with tradition couple method;The corner shell’s equivalent stresses simulated by initial strain method and multiple load steps method respectively are84.6%and75.9%of stresses by tradition couple method; and the stress results by initial force method are very volatile.Compare with the mould without taper, at mould exit, using single-taper, multi-taper and parabolic mould the fluxes ofcorner increase by35.8%,50.7%and58.2%, respectively, the thicknesses of corner shell add by9.22%,14.03%and14.03%and equivalent stresses increase by1.6times,2.2times and2.3times.