Study On The Forming Process Of High Strength Oxygen Free Copper Alloy Microfilament

With the rapid development of information and weapon equipment technology at home and abroad,the timely detection and control of aircraft and rocket engine running state has become an important symbol to measure the level of equipment technology.It can improve the operation reliability of the equipment to monitor the stress distribution and heating state of the engine core parts under the working conditions.At the same time,the information acquisition or conversion depends on the sensor components composed of strain resistance,thermistor and copper alloy wires.Due to the particularity of the engine working environment,the designers put forward the requirements for the sensor lead,which includes the strength,conductivity,heat resistance,oxidation resistance,thermoelectric coefficient and size refinement.Currently,copper alloy filaments used in domestic aviation and aerospace industries are all imported,the diameter of which are under 30 ?m.Although the strength and other indexes of domestic filaments meet the design conditions,the surface quality and conductivity stability of the filaments are poor,so it is not suitable for use in high-end technical products.After in-depth study on the quality of domestic copper alloy fine wire products,it is found that there are a small amount of ring or burr on the surface of the wire material,the thickness of which is below 2?m.Moreover,there are discontinuous linear defects along the axis in the wire material,most of which come from the "genetic effect" of the alloy billet.Therefore,three kinds of casting processes and plastic processing technologies for CuAg3Zr0.5 alloy are studied to explore the best forming method and process parameters of the micro wires in this paper.At first,this paper designs and optimizes the process of directional solidification,vacuum induction furnace smelting and electroslag remelting for CuAg3Zr0.5 alloy,and three kinds of ingot samples are obtained.In terms of structure,it is found that directional solidification ingot is in single crystal structure while vacuum induction furnace melting ingot and electroslag remelting ingot are in polycrystalline structure.In terms of properties,the cross-section hardness of directionally solidified ingot is 74.79 HV and the longitudinal-section hardness is 81.4 HV,while its conductivity is 59.39 %IACS.In according to the ingot melted by vacuum medium frequency induction furnace,its cross-section hardness is 83.49 HV and longitudinal-section hardness is 80.41 HV,while the conductivity is 64.21 %IACS.With regard to electroslag remelting ingot,its cross-section hardness is 98.35 HV and the longitudinal-section hardness is 94.33 HV,while its conductivity is 63.72% IACS.From the perspective of casting structure and further plastic processing,the directional solidification process and electroslag remelting process are more suitable for the production of micro wires than the vacuum medium frequency induction furnace smelting process.In order to prepare micro wires from directionally solidified and electroslag remelting alloys,the corresponding plastic processes are designed and optimized,which includes single-mode drawing,water tank multi-mode drawing and dust-free multi-mode drawing processes.It is found that the hardness of the both CuAg3Zr0.5 alloy increases with the deformation degree.At the same time,the conductivity of directionally solidified alloy is not sensitive,but the conductivity of ESR alloy decreases obviously.In the aspect of tensile strength,the strength of both alloys increases,but the growth rate of electroslag remelting alloy strength is faster than that of single crystal alloy.Based on the comprehensive analysis of the finished micro wires,it can be concluded that the tensile strength and conductivity of directionally solidified alloy micro wires are 1131 MPa and 61.21% IACS respectively,while that of electroslag remelting are 1098 MPa and 57.68% IACS respectively.Therefore,the alloy micro wires have excellent comprehensive properties,which are produced by directional solidification,single-mode drawing,water tank multi-mode drawing and dust-free multi-mode drawing.