钨合金的塑性加工对组织和性能的影响研究

发布时间：2018-06-28 14:14

本文选题：钨合金 + 塑性加工　；参考：《北京科技大学》2016年博士论文

【摘要】：核聚变能是解决未来人类能源需求的重要途径。制约核聚变应用的关键问题之一是面向等离子体材料(PFMs)的发展。PFMs在服役过程中会受到辐照和热流冲击。钨(W)材料以其高熔点,高热导率,优异的高温力学性能和低氘／氚滞留等特点被认为是PFMs的最主要候选材料。但是,钨材料的严重脆性限制了其在核聚变堆中的真正应用。现已证明塑性变形和第二相掺杂可以改善钨材料的脆性。另外,抗瞬态热流载荷性能和抗粒子辐照性能也决定着PFM能否满足核聚变装置应用要求。因为钨晶粒的抗粒子辐照性能与其晶体取向有关,所以通过调节钨材料的织构特点可以改善其抗粒子辐照性能。因此本文通过塑性变形工艺制备了纯钨(PW),氧化镧弥散钨(W-1.0wt%La2O3,简称WL10)和钾泡弥散钨(W-K),研究其微观组织、织构化程度、力学性能尤其是强度、韧脆转变温度(Ductile-Brittle Transition Temperature,简称DBTT)和热导率等指标,并评价其抗瞬态热流载荷性能和织构特点。首先,通过单向轧制工艺制备了不同变形量的纯钨、镧钨材料。对于纯钨材料而言,与其他轧制变形量相比较,60%轧制变形量样品具有最高的抗弯强度(1068 MPa)、最低的DBTT(823-873 K)、最高的热导率(176.5 W/mK)和最高的夏比冲击功。对于镧钨而言,与其他轧制变形量相比较,52%轧制变形量样品具有较高的抗弯强度(1312 MPa)、最低的DBTT(723-773 K)、较高的热导率(140.1 W/mK)和最高的夏比冲击功。所以纯钨、镧钨材料的最优轧制变形量分别为60%和52%。中间变形量样品不仅具有晶粒细化效应、亚结构韧化效应而且避免了由织构化程度高和显微裂纹诱发的脆断。此外,我们选择“旋锻+轧制”新工艺制备了钾钨材料,并将其与60%轧制变形量纯钨、52%轧制变形量镧钨作比较。结果表明纤维化程度(纤维结构的长径比)、织构化程度(主要织构的体积占有率)、显微裂纹、动态再结晶和第二相是影响钨基材料强韧性的主要因素。“旋锻+轧制”钾钨具有最低的抗弯强度(856MPa)和最高的DBTT(923 K),这主要是由其样品中存在的显微裂纹导致的。52%轧制变形量镧钨具有最高的强度(1312 MPa)、最低的DBTT(723-773)和最高的夏比冲击功,这主要是由于其样品中显微裂纹较少,同时具有较多的动态再结晶晶粒以及La203颗粒对位错和晶界的钉扎作用。相比之下,60%轧制变形量纯钨具有居中的强度(1068 MPa)和DBTT(823-873 K)。另外,与60%轧制变形量纯钨相比较,“旋锻+轧制”钾钨的夏比冲击功更高,这是因为钾钨样品中存在钾泡对位错的钉扎效应和可能的湮灭效应。然后,通过EMS-60装置对60%轧制变形量纯钨,52%轧制变形量镧钨、“旋锻+轧制”钾钨的抗瞬态电子束热冲击和抗瞬态电子束热疲劳性能进行评价。结果表明,对于60%轧制变形量纯钨而言,其裂纹阈值介于0.22-0.44GW/m2之间,熔化阈值和再结晶阈值均高于1.1 GW/m2。对于52%轧制变形量镧钨而言,其裂纹阈值低于0.22 GW/m2,熔化阈值介于0.66-0.88 GW/m2之间,再结晶阈值高于1.1 GW/m2。对于“旋锻+轧制”钾钨而言,其裂纹阈值介于0.44-0.66 GW/m2之间,熔化阈值高于1.1 GW/m2,再结晶阈值介于0.44-0.66 GW/m2之间。在抗瞬态电子束热疲劳性能方面,60%轧制变形量纯钨经过1000次、0.24 GW/m2热疲劳后表面出现裂纹,52%轧制变形量镧钨经过100次、0.17 GW/m2热疲劳后表面出现裂纹,“旋锻+轧制”钾钨经过1000次、0.44 GW/m2热疲劳后表面无裂纹而仅出现表面粗糙化和再结晶现象。钾泡对位错的钉扎效应和可能的湮灭效应是“旋锻+轧制”钾钨具有最好的抗瞬态热流载荷性能的主要原因。基体的低热导率和La203颗粒的分解,熔化是52%轧制变形量镧钨具有最差的抗瞬态热流载荷性能的主要原因。最后,我们第一次系统地研究了轧制方式、轧制变形量、弥散La203和再结晶退火对钨基材料的织构特点影响。结果表明,1)与交叉轧制和周向轧制纯钨相比较,单向轧制纯钨具有较强的{100}面织构和较弱的{111}面织构。2)热轧过程中的动态回复和动态再结晶是影响钨基材料织构变化的主要因素。动态回复导致72%、80%轧制变形量纯钨和43%、57%、72%轧制变形量镧钨的{001}110织构增强；动态再结晶导致80%轧制变形量纯钨和72%轧制变形量镧钨的{001}100织构增强。3)再结晶退火导致单向轧制、周向轧制纯钨的{100}面织构体积分数升高并且导致交叉轧制、周向轧制纯钨的{111)面织构体积分数降低。
[Abstract]:Nuclear fusion can be an important way to solve the future human energy demand. One of the key problems that restricts the application of nuclear fusion is the development of plasma material (PFMs) for the development of.PFMs in the course of service, which will be subjected to radiation and heat shock. Tungsten (W) materials are characterized by high melting point, high thermal conductivity, excellent high temperature mechanical properties and low deuterium / tritium retention and so on. It is considered to be the most important candidate for PFMs. However, the serious brittleness of tungsten materials restricts its real application in the nuclear fusion reactor. It has been proved that plastic deformation and second phase doping can improve the brittleness of tungsten materials. In addition, the resistance to transient heat flux and the resistance to particle irradiation also determine whether PFM can meet the application of nuclear fusion devices. Requirements. Because the anti particle irradiation properties of tungsten grains are related to their crystal orientation, so by adjusting the texture characteristics of tungsten materials, the properties of their anti particle irradiation can be improved. So in this paper, pure tungsten (PW), W-1.0wt%La2O3 (WL10) and potassium diffusion tungsten (W-K) are prepared by plastic deformation process, and the microstructure of the tungsten particles is studied. Construction degree, mechanical properties especially strength, toughened and brittle transition temperature (Ductile-Brittle Transition Temperature, DBTT) and thermal conductivity, and evaluation of its transient thermal current load performance and texture characteristics. First, pure tungsten, lanthanum tungsten materials with different deformation quantities were prepared by unidirectional rolling process. For pure tungsten materials, and others Compared with the rolling deformation, the 60% rolling deformation samples have the highest bending strength (1068 MPa), the lowest DBTT (823-873 K), the highest thermal conductivity (176.5 W/mK) and the highest Charpy impact power. For lanthanum tungsten, compared with other rolling deformation, the 52% rolling deformation samples have higher bending strength (1312 MPa) and the lowest DBTT ( 723-773 K), higher thermal conductivity (140.1 W/mK) and the highest Charpy impact power. Therefore, the optimum rolling deformation of pure tungsten and lanthanum tungsten materials is 60% and 52%. intermediate deformation samples not only have grain refinement effect, substructure toughening effect but also avoid the brittle fracture induced by high texturing degree and microcrack. In addition, we choose " The new process of rotary forging + rolling is used to prepare potassium and tungsten materials and compare them with the 60% rolling deformation quantity pure tungsten and 52% rolling deformation amount of lanthanum tungsten. The results show that the degree of fibrosis (the length to diameter ratio of fiber structure), the degree of texturing (the volume occupancy of the main texture), the microcrack, the dynamic recrystallization and the second phase are the main factors affecting the strength and toughness of the tungsten based materials. Factors. "Spin forging + rolling" potassium tungsten has the lowest bending strength (856MPa) and the highest DBTT (923 K), which is mainly caused by the microcracks in the samples of its samples, the.52% rolling deformation of lanthanum tungsten has the highest strength (1312 MPa), the lowest DBTT (723-773) and the highest Charpy impact work, mainly due to the microcracks in the samples. Fewer, more dynamic recrystallized grains and La203 particle pinning effect on dislocation and grain boundary. In comparison, the 60% rolling deformation of pure tungsten has a medium strength (1068 MPa) and DBTT (823-873 K). In addition, the Charpy impact work of "rotary + rolling" of potassium tungsten is higher than that of pure tungsten with 60% rolling deformation, which is due to potassium tungsten. The pinning effect and possible annihilation effect of potassium vesicles on dislocations exist in the samples. Then, the anti transient electron beam thermal shock resistance and transient electron beam thermal fatigue resistance of 60% rolled pure tungsten, 52% rolling deformation amount of lanthanum tungsten, "rotary forging + rolled" potassium tungsten are evaluated by the EMS-60 device. The results show that the 60% rolling deformation is pure tungsten. The threshold of the crack is between 0.22-0.44GW/m2, the melting threshold and the recrystallization threshold are higher than 1.1 GW/m2.. The threshold of the crack is lower than 0.22 GW/m2 for the 52% rolling deformation of lanthanum and tungsten, the melting threshold is between 0.66-0.88 GW/m2 and the recrystallization threshold is higher than 1.1 GW/m2. for "rotary + rolled" potassium tungsten. The crack threshold is between 0.44- and 0.44-. Between 0.66 GW/m2, the melting threshold is higher than 1.1 GW/m2, and the recrystallization threshold is between 0.44-0.66 GW/m2. In the anti transient electron beam thermal fatigue property, the 60% rolling deformation amount of pure tungsten is 1000 times, the surface cracks after 0.24 GW/m2 thermal fatigue, 52% rolling deformation amount of lanthanum tungsten through 100, 0.17 GW/m2 thermal fatigue surface cracks, "spin forging +" The surface roughness and recrystallization of the rolled potassium tungsten after 1000 times and 0.44 GW/m2 thermal fatigue are only surface roughness and recrystallization. The pinning effect and possible annihilation effect of potassium vesicles on dislocation are the main reasons for the best resistance to transient heat flux of "rotary forging + rolling" of potassium tungsten. The low thermal conductivity of matrix and the decomposition of La203 particles are the main reasons. Melting is the main reason for the worst resistance to transient heat flux of the 52% rolling deformation of lanthanum. Finally, we first systematically studied the rolling mode, the rolling deformation, the dispersion La203 and the recrystallization annealing on the texture characteristics of tungsten based materials. The results showed that 1) compared with the cross rolling and the circumferential rolling of pure tungsten, unidirectional rolling. The dynamic recovery and dynamic recrystallization in the hot rolling process of pure tungsten have strong {100} texture and weak {111} texture.2. The dynamic recovery and dynamic recrystallization are the main factors affecting the texture changes of tungsten based materials. The dynamic recovery leads to 72%, 80% rolling deformation of pure tungsten and 43%, 57%, 72% of the {001}110 texture of the tungsten in the rolling deformation of lanthanum; dynamic recrystallization leads to 80% rolling. The {001}100 texture enhanced.3 by the deformation of pure tungsten and 72% rolling deformation of lanthanum tungsten, the recrystallization annealing leads to unidirectional rolling. The volume fraction of the {100} surface texture of the circumferential Rolled Pure Tungsten increases and leads to the cross rolling, and the texture volume fraction of the {111 surface of the circumferential tungsten is reduced.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TL627;TG339

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