Numerical simulation of low pressure die-casting aluminum wheel

The FDM numerical simulation software,ViewCast system,was employed to simulate the low pressure die casting(LPDC)of an aluminum wheel.By analyzing the mold-filling and solidification stage of the LPDC process,the distribution of liquid fraction,temperature field and solidification pattern of castings were studied.The potential shrinkage defects were predicted to be formed at the rim/spoke junctions,which is in consistence with the X-ray detection result.The distribution pattern of the defects has also been studied.A solution towards reducing such defects has been presented.The cooling capacity of the mold was improved by installing water pipes both in the side mold and the top mold.Analysis on the shrinkage defects under forced cooling mode proved that adding the cooling system in the mold is an effective method for reduction of shrinkage defects.

Process on cold crucible electromagnetic casting for titanium alloy

The parameters and factors that influence the surface quality and macrostructure of titanium alloy with reactive properties under liquid state were studied experimentally using a cold crucible electromagnetic casting method. The variations in the process parameters have great impact on the surface quality and macrostructure of cast billets. Billets with crack free and smooth surfaces as well as directional solidified primary structures were obtained after the selection of optimized process parameters. The formation mechanisms of defects such as cracks and non-directional structural morphology were interpreted briefly. Finally,the casting of billets with good outer qualities and inner column grains has been attained successfully,which in turn gives a solid foundation for further development of the technology.

Production technique of vermicular graphite iron cylinder head of vehicle diesel engine

The 25 years＇ production and application have proved that vermicular graphite iron cylinder heads with vermicularity ≥50% satisfy the machinability and performance demand of diesel engine. The method, in which using cupola-induction furnace duplex melting and pour-over process with rare earth-ferrosilicon or rare earthsilicon compound as vermJcularizing alloy plus rare earth-magnesium-ferrosilicon as stirring alloy, is an optimal vermicularizing process for obtaining satisfied vermicularity. Using top kiss risers, enlarging kissing areas and expanding covering width and making ingates to freeze earlier are the effective measures to eliminate shrinkage, blowhole and oxide inclusions in the vermicular graphite iron cylinder heads.

Derivation and application of time step model in solidification process simulation

The heat transfer during the casting solidification process includes the heat radiation of the high temperature casting and the mold,the heat convection between the casting and the mold,and the heat conduction inside the casting and from the casting to the mold. In this paper,a formula of time step in simulation of solidification is derived,considering the heat radiation,convection and conduction based on the conservation of energy. The different heat transfer conditions between the conventional sand casting and the permanent mold casting are taken into account in this formula. The characteristics of heat transfer in the interior and surface of the casting are also considered. The numerical experiments show that this formula can avoid computational dispersion,and improve the computational efficiency by about 20% in the simulation of solidification process.

钛微合金化高强汽车厢体用钢开发

河北钢铁集团承德钢铁集团有限公司依托钒钛资源优势,从钛微合金化技术生产低成本高强度钢的思路出发,通过强化铁水预脱硫及处理、严格控制钢中氮、氧气体含量,优化中间包结构,采用连铸保护浇铸技术及合理的轧制工艺,利用金相显微镜、扫描电镜、拉伸试验机、冲击试验机等检测设备,最终成功开发出化学成分最佳的600 MPa级汽车厢体用钢,生产结果表明:该钢板平均屈服强度达到566 MPa;平均抗拉强度达到655 MPa,并且组织均匀细小,具有较好冲击韧性及冷弯性能,完全满足用户的使用要求。