Study On Casting Process And Metallurgical Interface Characteristics Of Copper Water Jacket Embedded By Monel Alloy Pipe

Strengthening metallurgy is an important way for energy saving and emission reduction in metallurgical industry,which is the development direction of metallurgical technology.However,strengthening metallurgy usually cause serious damage to the refractory brick lining of metallurgical furnace.Therefore,how to protect furnace lining is critical for strengthening metallurgy.At present,the most effective way is to insert copper water jacket between the bricks in metallurgical furnace.The production of copper water jacket by embedded tube has become a hot spot because of its prominent advantages,such as low cost,free design of cooling water pipe and high reliability in use.The key question to improve the cooling effect of copper water jacket is how to eliminate the gap the porosity between the embedded cooling pipe and the cast copper body.Compared with the pre-embedded pure copper pipe water jacket,the pre-embedded Monel alloy pipe copper water jacket has drawn much attention in recent years because of its higher reliability.Based on the requirement of cast copper water jacket in metallurgical flash furnace,a typical copper water jacket was selected in this paper.Firstly,the influence of casting temperature and mold temperature on flow field and temperature field of the jacket were studied.Then,the test pieces and finished castings of the jacket were prepared by shower gating casting method.The effect of casting temperature and pipe surface morphology on metallurgical bonding properties was discussed.The effects of casting temperature and pipe embedding mode on microstructure and metallurgical bonding properties were analyzed.The main results are as follows:(1)The numerical simulation of melt filling and solidification process at different casting temperatures indicates that the optimum pouring temperature is 1250 ? and the suitable mold temperature is 100 ?~200 ?.(2)The surface morphology of the pipe(plain pipe and screw pipe)have an affect on the interfacial bonding characteristics of the jacket by pre-embedded Monel alloy pipe.With the casting temperature increase from 1150 ? to 1250 ?,the average thickness of the interfacialreaction layer of plain tube castings increased from 16.03 ?m to 29.22 ?m and that of screw tube castings increased from 15.99 ?m to 19.51 ?m.At the same casting temperature,the average thickness of diffusion layer of plain tube casting is larger than those of screw tube casting,and the microhardness is lower than those of screw tube casting,but the interfacial shear strength of plain tube casting is equivalent to those of screw tube casting.When pouring temperature is 1150 ?,the microhardness and shear strength of the interfacial layer of the castings are obviously lower than those of the castings whose casting temperature is higher than 1200 ?.The hardness of the interfacial layer of the screw tube castings reaches a maximum of 109 HV at 1200 ?,and the interfacial shear strength of the plain tube castings reaches a maximum of 170 MPa at 1250 ?.(3)The way of pipe protection affects the interface microstructure and metallurgical bonding characteristics of the jacket embedded by Monel alloy pipe.When casting temperature is 1180 ?,the average interfacial thickness of silicon sand-filled castings and nitrogen-filled castings is 18.07 ?m and 18.35 ?m,respectively,and the average Vickers microhardness and shear strength are 92 HV and 96 HV,respectively,136 MPa and 167 MPa,respectively.When casting temperature is 1240 ?,the average thickness of the interface layer is 28.31 ?m and 29.48 ?m,and the average Vickers microhardness and shear strength are 112 HV and 120 HV,172 MPa and 198 MPa,respectively.The metallurgical bonding property of nitrogen-filled casting is higher than those of silicon sand-filled casting.(4)Combined with numerical simulation and experimental results,the suitable casting parameters of the jactet embedded by Monel alloy pipe are as follows: casting temperature is1240 ?,die temperature is 180 ?,filling time is 30 s,the appearance of the outer pipe wall is plain,and the pipe is protected by nitrogen gas.Based on the optimum casting process,the metallurgical bonding ratio,tensile strength,elongation and conductivity of the prepared jacket casting reach to 99.1 %,190 MPa,42 % and 88 %(IACS),respectively,which can meet the demand of copper water jacket for metallurgical furnace.