Numerical simulation technology has been widely used in the foundry industry to analyze and improve casting processes.During the casting filling process,many filling-related defects form easily at the confluences of l...Numerical simulation technology has been widely used in the foundry industry to analyze and improve casting processes.During the casting filling process,many filling-related defects form easily at the confluences of liquid metal streams.The main filling-related defects are cold shut defects.To calculate the positions of casting defects,the characteristics of liquid metal confluences were analyzed.The flow front of liquid metal was captured by the volume-of-fluid algorithm to obtain a time field,which was used to calculate the time derivatives of the liquid front position and the confluences of liquid metal streams.To distinguish small confluences from the main confluences,the concept of confluent scale was developed,which was used to filter the small confluences based on a threshold.The calculation process was demonstrated through the post-processing of numerical simulation.A "W" shaped casting and a steering wheel casting were calculated to validate the accuracy of the method developed in this study.The positions of cold shut defects were predicted by calculating the confluences of liquid metal streams.The method was proved to be practical by comparing the calculation results with the positions of cold shut defects in an end cover casting.The computation of confluences and cold shut defects can improve the analysis efficiency and provide assurance for the optimization of a casting process plan.展开更多
The microstructure, phase composition and cold shut defect of thick titanium alloy electron beam welded joint were studied. The results showed that the microstructure of weld zone was composed of α′ phase; the heat ...The microstructure, phase composition and cold shut defect of thick titanium alloy electron beam welded joint were studied. The results showed that the microstructure of weld zone was composed of α′ phase; the heat affected zone was divided into fine-grained zone and coarse-grained zone, the microstructure of fine-grained zone was primary α phase ＋ β phase ＋ equiaxed α phase, and the microstructure of coarse-grained zone was primary α phase ＋ acicular α′ phase; the microstructure of base metal zone basically consisted of primary α phase, and a small amount of residual β phase sprinkled. The forming. reason of cold shut was analyzed, and the precaution of cold shut was proposed.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2020YFB2008300 and 2020YFB2008302)the Program of Key Research and Development Program of Guangdong Province(No.2019B090921001)。
文摘Numerical simulation technology has been widely used in the foundry industry to analyze and improve casting processes.During the casting filling process,many filling-related defects form easily at the confluences of liquid metal streams.The main filling-related defects are cold shut defects.To calculate the positions of casting defects,the characteristics of liquid metal confluences were analyzed.The flow front of liquid metal was captured by the volume-of-fluid algorithm to obtain a time field,which was used to calculate the time derivatives of the liquid front position and the confluences of liquid metal streams.To distinguish small confluences from the main confluences,the concept of confluent scale was developed,which was used to filter the small confluences based on a threshold.The calculation process was demonstrated through the post-processing of numerical simulation.A "W" shaped casting and a steering wheel casting were calculated to validate the accuracy of the method developed in this study.The positions of cold shut defects were predicted by calculating the confluences of liquid metal streams.The method was proved to be practical by comparing the calculation results with the positions of cold shut defects in an end cover casting.The computation of confluences and cold shut defects can improve the analysis efficiency and provide assurance for the optimization of a casting process plan.
基金Project (2010CB731704) supported by the National Basic Research Program of China
文摘The microstructure, phase composition and cold shut defect of thick titanium alloy electron beam welded joint were studied. The results showed that the microstructure of weld zone was composed of α′ phase; the heat affected zone was divided into fine-grained zone and coarse-grained zone, the microstructure of fine-grained zone was primary α phase ＋ β phase ＋ equiaxed α phase, and the microstructure of coarse-grained zone was primary α phase ＋ acicular α′ phase; the microstructure of base metal zone basically consisted of primary α phase, and a small amount of residual β phase sprinkled. The forming. reason of cold shut was analyzed, and the precaution of cold shut was proposed.
