【作者】 吴庆美；

【导师】 王德庆；

【作者基本信息】 大连交通大学 ， 材料加工工程， 2013， 博士

【摘要】 以双铜带压接法生产的铜包钢线为研究对象,制备不同拉拔变形量的铜包钢线试样,通过改变其热处理制度,测定导线横、纵截面的α-Fe相晶粒尺寸、扩散层厚度、界面结合强度、扩散层硬度、铜-钢基体硬度以及导线的抗拉强度、延伸率和电阻率,研究铜包钢线的界面结合及性能,最终得到铜包钢线拉拔变形量和退火处理对其组织及性能的影响规律。研究结果表明,铜包钢线钢芯横截面的α-Fe相晶粒尺寸随着其变形量的增加不断减小,纵截面的晶粒延拉拔方向的长径比增加。铜包钢线横截面的α-Fe相晶粒尺寸随着其退火温度的升高和保温时间的延长而增大,其纵截面的α-Fe相长径比减小。当退火温度升高至750℃,退火时间延长至2h时,经拉拔变形后的铜包钢线纵截面的α-Fe相晶粒趋于等轴状,即完成了回复再结晶过程。继续升高温度,其横截面和纵截面的α-Fe相晶粒尺寸和长径比变化较小。通过实验数据分析,得到了铜包钢线的退火温度和保温时间分别与其钢芯横截面的α-Fe相晶粒尺寸和纵截面晶粒长径比关系的回归方程。根据原始纯铜和钢丝的抗拉强度值,应用复合材料强度的混合法则,计算了不同拉拔变形的铜包钢线抗拉强度。经实验验证,与实测结果接近。铜包钢线的抗拉强度随其变形量的增加而升高,延伸率则降低。随着铜包钢线退火温度的升高和保温时间的延长,其抗拉强度降低,延伸率升高。当达到铜包钢线的再结晶温度后,其抗拉强度和延伸率变化较小。根据Hollomon关系式,通过实验计算得出铜包钢线的应变硬化指数n=0.4。铜包钢线的电阻率随其形变量的增加而升高。根据纯铜和钢丝原材料的电阻率,计算了经过不同拉拔变形的导线电阻率。随着铜包钢线退火温度的升高和退火时间的延长,其电阻率降低。通过实验数据分析,得到了铜包钢线的退火温度和保温时间分别与其电阻率关系的回归方程。随着退火温度的升高和时间的延长,距离界面同一位置处的铜侧、扩散层和钢侧的硬度均降低。与铜侧相比,钢侧的硬度降低较明显。在传统的测试方法基础之上,结合日本的复合钢测试标准,提出了一种新的铜-钢复合导线的界面结合强度测试方法。经过实验验证,该方法科学可靠。结果表明,随着铜包钢线退火温度的升高和时间的延长,扩散层厚度增加,结合强度提高。与保温时间相比,退火温度对其影响较大。当达到铜包钢线的再结晶温度后,继续升高温度和延长时间,扩散层厚度和界面结合强度变化较小。利用扩散方程计算Fe和Cu原子的扩散激活能和扩散的常数,确定了扩散常数与退火温度的关系。综合考虑铜包钢线扩散层厚度与结合强度的关系及生产实际要求,得到铜包钢线的最佳退火工艺为750℃保温2h。更多还原

【Abstract】 The method adopted to manufacture copper clad steel (short for CCS) wire in this study is double copper strip pressure welding and then drawing and annealing it. The grain size of a-Fe phase in cross and longitudinal section, the thickness of diffusion layer, interface bonding strength, interface hardness and its tensile strength, elongation, resistivity were test. The interface bonding and its performance were studied. The effects of drawing deformation and annealing treatment on its microscopic structure and performance were obtained.Experimental results show that the grain size in cross section of a-Fe phase is decreased with the increase of the drawing deformation. Its length diameter ratio in longitudinal section is enhanced toward the drawing direction. The grain size in cross-section of α-Fe phase is enhanced with the increase of the annealing time and annealing temperature, its length diameter ratio in longitudinal section is decreased oppositely.The grain in longitudinal section of a-Fe phase after deformation tends to be equiaxial, the recrystallization processes is thus finished at750℃for2h. The grain size in cross section and length diameter ratio in longitudinal section are almost invariant when continuing to raise the temperature. Through the experimental data analysis, the regression equation about the relation of annealing temperature and annealing time of CCS wire with the grain size in cross section and length diameter ratio in longitudinal section are obtained.According to the tensile strength of primitive pure copper and steel wire, applying the mixed rules of composite material strength, the tensile strength of the copper clad steel wire with different drawing the deformation can be calculated. Through the experimental results, they are closed to measured ones. The tensile strength of CCS wire is decreased with the increase of the drawing deformation, the elongation is increased oppositely. The tensile strength of CCS wire is decreased with the increase of the annealing temperature and time, the elongation is increased oppositely. When the annealing temperature is850℃, annealing time is2h, its tensile strength and elongation are invariable. According to the relationship of Hollomon, through the certification of experiment, the copper clad steel wire’s strain hardening exponent of drawing deformation of50%(n) is0.4.The resistivity of CCS wire is increased with the increase of the drawing deformation. According to the resistivity of primitive pure copper and steel wire, the resistivity of the copper clad steel wire with different drawing the deformation can be calculated. The resistivity of CCS wire is decreased with the increase of the annealing temperature and time. Through the experimental data analysis, the regression equation about the relation of annealing temperature and annealing time of CCS wire with the resistivity are obtained. The hardness of copper matrix, diffusion layer and steel matrix with the same deformation are decreased when continuing to increase the temperature and extend the time. Compared with the hardness in copper side, it is reduced obviously in steel side.In the foundation of traditional test methods, combined with the steel composite testing standards in Japan, this paper presents a new test method of steel composite copper wire-interface bonding strength. After the verification of test, the method in this paper is scientific and reliability. The results show that the diffusion thickness and bonding strength are increased with the increase of annealing temperature and time. Compared with annealing time, annealing temperature has more effect on it. After recrystallization temperature is reached, the interface diffusion layer thickness and bonding strength are invariable when continuing to increase the temperature and extend the time. Calculate the diffusion activation energy of Fe and Cu atoms and diffusion constant by diffusion equation, the relationship of diffusion constant and annealing temperature is conformed. According to the relation of diffusion layer thickness and bonding strength and the requirement of actual producing, the best annealing process is750℃for2h.更多还原