液相烧结90W-7Ni-3Fe高密度钨合金组织性能研究
发布时间：2018-11-21 12:04
【摘要】：高密度钨合金是一种典型的两相合金,具有高密度、高强度和良好的塑性等优异性能,是制作动能穿甲弹弹芯的主要材料。穿甲弹从发射、飞行到穿甲侵彻的过程中处在温度场和应力-应变场耦合环境下,所以综合研究钨合金在温度场和应力-应变场下的变形和失效行为是非常必要的。本课题选用液相烧结90W-7Ni-3Fe高密度钨合金作为实验材料,重点研究了钨合金在室温、高温不同应变速率下的拉伸和压缩力学性能,并对钨合金在室温下的动态力学性能和微观组织也进行了实验分析,同时建立了基于不同模型的本构方程。本文对烧结态90W合金的基本物理及力学参数进行了测定和表征,对90W在室温下的力学性能和微观组织进行实验分析。发现90W合金在室温拉伸时随着应变速率增加,强度增加、塑性降低、W颗粒的解理断裂增加、粘结相的韧性撕裂减少;在室温压缩时,塑性变形是钨相与粘结相变形相互协调的过程,在应变速率10-3s-1塑性最高;90W合金在动态压缩时相对于准静态压缩屈服强度明显升高。90W合金在473-1473K高温拉伸实验结果表明应变速率对高温力学性能影响并不显著。研究发现90W合金在673K和1273K时强度和塑性出现明显变化,强度在473-673K时明显降低,随后升高并出现平稳台阶直到1273K时再次出现明显下降;塑性在673K最高,随温度升高缓慢降低在1273K时已经基本没有塑性并趋于稳定。通过对断口的扫描发现,在673K时,90W的断裂方式以粘结相的韧性撕裂为主,极少看到W-W沿晶断裂。对90W合金在1073至1473K、应变速率10-3s-1至10-1s-1下压缩实验表明,90W合金力学行为受温度和应变速率耦合影响,在1473K、应变速率10-3s-1时力学性能明显恶化,试样中心部位出现钨颗粒异常长大现象;在1073K压缩时,试样边角部位出现于压缩方向成45°的剪切带,温度上升到1473K,边角部位相界面则由于变形不一致导致相界面产生大量缺陷。为了描述90W合金在高温下的塑性变形行为,本文建立了基于JC模型、修正后JC的模型、Arrhenius模型和修正后的ZA模型等四个模型共六个本构方程,其中针对JC和修正后的JC分别以293K和1073K为基准建立了本构方程。对每个方程的准确性和预测性利用相关系数和平均相对误差来进行定量计算。通过对比可以得出,以Arrhenius模型和修正后的ZA为基础所构建的本构方程有较高的准确度和拟合度,以JC和修正后的JC模型建立的本构方程误差较大,这是因为Arrhenius模型和ZA模型比较全面的考虑了温度、应变和应变速率对应力的耦合效应。
[Abstract]:High density tungsten alloy is a typical two-phase alloy with excellent properties such as high density, high strength and good plasticity. The armor-piercing projectile is in the coupled environment of temperature field and stress-strain field during the process of launching, flying and penetrating through the armour. Therefore, it is necessary to study the deformation and failure behavior of tungsten alloy under the temperature field and stress-strain field. In this paper, 90W-7Ni-3Fe high density tungsten alloy sintered in liquid phase was selected as the experimental material. The tensile and compression mechanical properties of tungsten alloy at different strain rates at room temperature and high temperature were studied. The dynamic mechanical properties and microstructure of tungsten alloy at room temperature were also analyzed experimentally, and constitutive equations based on different models were established. The basic physical and mechanical parameters of sintered 90W alloy were measured and characterized. The mechanical properties and microstructure of 90W alloy at room temperature were analyzed experimentally. It is found that the tensile strength of 90W alloy decreases with the increase of strain rate at room temperature, the cleavage fracture of W particles increases and the ductile tear of bonding phase decreases. At room temperature compression, plastic deformation is the process of coordination between tungsten phase and bonding phase deformation, and the plasticity is the highest at strain rate 10-3s-1. Under dynamic compression, the yield strength of 90W alloy is obviously higher than that of quasi-static compression. The tensile test results at 473-1473K show that the strain rate has no significant effect on the mechanical properties at high temperature. It was found that the strength and plasticity of 90W alloy changed obviously at 673K and 1273K, the strength decreased obviously at 473-673K, and then increased and stable steps appeared until 1273K. The plasticity is the highest at 673K, and decreases slowly at 1273K with the increase of temperature. By scanning the fracture surface, it is found that at 673K, the fracture mode of 90W is mainly the ductile tear of the bonding phase, and the W-W intergranular fracture is rarely seen. The compression tests of 90W alloy at 1073 ~ 1473K, strain rate 10-3s-1 to 10-1s-1 show that the mechanical behavior of 90W alloy is affected by the coupling of temperature and strain rate. At 1473K, the mechanical properties of 90W alloy deteriorate obviously at the strain rate 10-3s-1. The abnormal growth of tungsten particles appears in the center of the sample. When compressed at 1073K, the edge corner of the specimen appears in a 45 掳shear band in the compression direction, and the temperature rises to 1473K, and the phase interface at the edge corner produces a large number of defects due to the inconsistency of deformation. In order to describe the plastic deformation behavior of 90W alloy at high temperature, six constitutive equations were established based on JC model, modified JC model, Arrhenius model and modified ZA model. The constitutive equations of JC and modified JC are established based on 293K and 1073K, respectively. The accuracy and predictability of each equation are calculated quantitatively by using correlation coefficient and average relative error. By comparison, it can be concluded that the constitutive equation based on Arrhenius model and modified ZA model has higher accuracy and fitting degree, and the error of constitutive equation established by JC model and modified JC model is large. This is because the Arrhenius model and the ZA model take into account the coupling effect of temperature, strain and strain rate on the stress.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.411
，
本文编号：2346915
[Abstract]:High density tungsten alloy is a typical two-phase alloy with excellent properties such as high density, high strength and good plasticity. The armor-piercing projectile is in the coupled environment of temperature field and stress-strain field during the process of launching, flying and penetrating through the armour. Therefore, it is necessary to study the deformation and failure behavior of tungsten alloy under the temperature field and stress-strain field. In this paper, 90W-7Ni-3Fe high density tungsten alloy sintered in liquid phase was selected as the experimental material. The tensile and compression mechanical properties of tungsten alloy at different strain rates at room temperature and high temperature were studied. The dynamic mechanical properties and microstructure of tungsten alloy at room temperature were also analyzed experimentally, and constitutive equations based on different models were established. The basic physical and mechanical parameters of sintered 90W alloy were measured and characterized. The mechanical properties and microstructure of 90W alloy at room temperature were analyzed experimentally. It is found that the tensile strength of 90W alloy decreases with the increase of strain rate at room temperature, the cleavage fracture of W particles increases and the ductile tear of bonding phase decreases. At room temperature compression, plastic deformation is the process of coordination between tungsten phase and bonding phase deformation, and the plasticity is the highest at strain rate 10-3s-1. Under dynamic compression, the yield strength of 90W alloy is obviously higher than that of quasi-static compression. The tensile test results at 473-1473K show that the strain rate has no significant effect on the mechanical properties at high temperature. It was found that the strength and plasticity of 90W alloy changed obviously at 673K and 1273K, the strength decreased obviously at 473-673K, and then increased and stable steps appeared until 1273K. The plasticity is the highest at 673K, and decreases slowly at 1273K with the increase of temperature. By scanning the fracture surface, it is found that at 673K, the fracture mode of 90W is mainly the ductile tear of the bonding phase, and the W-W intergranular fracture is rarely seen. The compression tests of 90W alloy at 1073 ~ 1473K, strain rate 10-3s-1 to 10-1s-1 show that the mechanical behavior of 90W alloy is affected by the coupling of temperature and strain rate. At 1473K, the mechanical properties of 90W alloy deteriorate obviously at the strain rate 10-3s-1. The abnormal growth of tungsten particles appears in the center of the sample. When compressed at 1073K, the edge corner of the specimen appears in a 45 掳shear band in the compression direction, and the temperature rises to 1473K, and the phase interface at the edge corner produces a large number of defects due to the inconsistency of deformation. In order to describe the plastic deformation behavior of 90W alloy at high temperature, six constitutive equations were established based on JC model, modified JC model, Arrhenius model and modified ZA model. The constitutive equations of JC and modified JC are established based on 293K and 1073K, respectively. The accuracy and predictability of each equation are calculated quantitatively by using correlation coefficient and average relative error. By comparison, it can be concluded that the constitutive equation based on Arrhenius model and modified ZA model has higher accuracy and fitting degree, and the error of constitutive equation established by JC model and modified JC model is large. This is because the Arrhenius model and the ZA model take into account the coupling effect of temperature, strain and strain rate on the stress.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.411
，
本文编号：2346915
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