镍基合金激光喷丸诱导的残余压应力的高温松弛规律研究.doc
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镍基合金激光喷丸诱导的残余压应力的高温松弛规律研究,21600字47页摘 要激光喷丸 (laserpeening,lp)，是一种利用激光与材料相互作用产生的高幅冲击波压力实施材料表面改性的技术，其通过改变材料表面的残余应力分布及微观组织结构，大幅提升金属结构件的机械性能和疲劳寿命。镍基合金作为航天航空领域使用的重要材料，...
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镍基合金激光喷丸诱导的残余压应力的高温松弛规律研究
21600字 47页
摘 要
激光喷丸 (Laser Peening, LP)，是一种利用激光与材料相互作用产生的高幅冲击波压力实施材料表面改性的技术，其通过改变材料表面的残余应力分布及微观组织结构，大幅提升金属结构件的机械性能和疲劳寿命。镍基合金作为航天航空领域使用的重要材料，其关键零部件通常服役于高温条件下，此时激光喷丸诱导的有益残余压应力将产生松弛现象，进而影响激光喷丸强化的力学性能增益。因此掌握激光喷丸残余应力在高温条件下的松弛特性，进而实现残余应力松弛量和松弛速率的有效控制，是保证材料改性后性能增益和质量可靠性的关键。本文采用理论分析与试验研究相结合的方法，系统研究IN718镍基合金激光喷丸诱导的残余应力的高温松弛特性，主要工作如下：
（1）以高能短脉冲激光与材料相互作用诱导高幅冲击波的物理机制为基础，探讨金属材料激光喷丸残余压应力的产生机理，分析残余压应力的影响因素及其评价指标，引入残余压应力估算模型，在此基础上，宏微观相结合分析残余压应力在高温条件下的松弛规律和松弛机理。
（2）实验研究激光喷丸残余压应力在高温条件下的松弛特性。选用GAIA Nd:YAG高功率激光器对典型IN718镍基合金试样进行激光喷丸试验，SX2-4-10箱式电阻炉进行保温试验，通过X-350A型X射线衍射仪测量试样表面的残余应力，LEICA DFC420光学显微镜分析试样微观组织结构。通过不同温度和不同保温时间下残余应力值和显微硬度的测试，分析残余压应力在高温下的松弛规律，通过激光喷丸和保温试验后镍基合金表层的显微组织形态观察，探讨激光喷丸对材料高温稳定性的影响机制。
关键词：激光喷丸强化，残余应力，高温松弛，镍基合金
Abstract
Laser peening is a surface modification technology, using high-amplitude shock wave pressure induced by the laser-material interaction. The mechanical properties and fatigue life of metal structures are significantly enhanced by changing its residual stress distribution and microstructure of the material surface.Nickel-based alloy is an important material used in aerospace field.The key components are usually served at high temperatures, and at this time the beneficial residual stress induced by laser peening will produce release phenomenon,thereby the gain of materials’ mechanical properties by laser peening are also affected. Therefore the key point to ensure the performance improvement and the quality reliability of the material modified is to grasp the release characteristics of residual stress induced by laser peening at high temperatures and effectively control the release rate of residual stress.In this study, the distribution of the residual stress induced by laser peening and its release characteristics under high temperatures of IN718 nickel-based alloy was researched with a combination of theoretical analysis and experimental methods, and the main works are as follows:
（1）Based on the physical mechanism of high amplitude shock wave induced by high-energy short-pulse laser-material interaction, the mechanism of the residual compressive stress of metal material induced by laser peening was explored, and the influence factor and eva luation was analyzed, and the estimation model of residual compressive stress was introduced. Then the rule and mechanism of the release of residual compressive stress under high temperature conditions were analyzed macroscopically and microscopically on this basis.
（2）The release characteristics under high temperature conditions of the residual compressive stress induced by laser peening was researched. The laser peening test of typical IN718 nickel-based alloy specimens was conducted by using a high power Nd: YAG GAIA laser. The thermal insulation test was conducted with the SX2-4-10 box-type resistance furnace. The residual stress distribution on the surface of specimen was measured with X-350A X-ray diffraction. The microstructure of the specimen was analyzed with LEICA DFC420 optical microscopy. The release patterns under high temperature conditions of the residual compressive stress was analyzed by testing the residual stress and surface hardness at different temperatures and holding time. And the impact mechanism of the laser peening to the high temperature stability of materials was explored by the observation of the microstructure morphology of nickel surface after the laser peening and thermal insulation test.
Key: laser peening, residual stress, thermal release, nickel-based alloy
目 录
第一章 绪论 1
1.1 引言 1
1.2 激光喷丸强化技术 1
1.2.1 激光喷丸的基本原理及特点 1
1.2.2 激光喷丸强化工艺中的能量吸收层和约束层的选择 3
1.2.3 激光喷丸强化的发展历程及应用现状 3
1.3 高温下残余应力松弛的研究现状与进展 5
1.4 本课题选题研究意义及主要内容 7
1.4.1 研究意义 7
1.4.2 研究内容 7
第二章 激光喷丸诱导残余应力松弛特性分析 9
2.1 激光喷丸残余应力场理论 9
2.1.1 激光喷丸材料表层的塑性变形过程 9
2.1.2 激光喷丸诱导残余应力场的产生与估算 11
2.1.3 残余应力的测量 13
2.1.4 激光喷丸诱导残余应力场的影响因素及其评价指标 14
2.2 残余应力高温松弛理论 15
2.2.1 残余应力高温松弛宏观理论 15
2.2.2 残余应力高温松弛过程中晶粒尺寸与位错密度的演变 16
2...
21600字 47页
摘 要
激光喷丸 (Laser Peening, LP)，是一种利用激光与材料相互作用产生的高幅冲击波压力实施材料表面改性的技术，其通过改变材料表面的残余应力分布及微观组织结构，大幅提升金属结构件的机械性能和疲劳寿命。镍基合金作为航天航空领域使用的重要材料，其关键零部件通常服役于高温条件下，此时激光喷丸诱导的有益残余压应力将产生松弛现象，进而影响激光喷丸强化的力学性能增益。因此掌握激光喷丸残余应力在高温条件下的松弛特性，进而实现残余应力松弛量和松弛速率的有效控制，是保证材料改性后性能增益和质量可靠性的关键。本文采用理论分析与试验研究相结合的方法，系统研究IN718镍基合金激光喷丸诱导的残余应力的高温松弛特性，主要工作如下：
（1）以高能短脉冲激光与材料相互作用诱导高幅冲击波的物理机制为基础，探讨金属材料激光喷丸残余压应力的产生机理，分析残余压应力的影响因素及其评价指标，引入残余压应力估算模型，在此基础上，宏微观相结合分析残余压应力在高温条件下的松弛规律和松弛机理。
（2）实验研究激光喷丸残余压应力在高温条件下的松弛特性。选用GAIA Nd:YAG高功率激光器对典型IN718镍基合金试样进行激光喷丸试验，SX2-4-10箱式电阻炉进行保温试验，通过X-350A型X射线衍射仪测量试样表面的残余应力，LEICA DFC420光学显微镜分析试样微观组织结构。通过不同温度和不同保温时间下残余应力值和显微硬度的测试，分析残余压应力在高温下的松弛规律，通过激光喷丸和保温试验后镍基合金表层的显微组织形态观察，探讨激光喷丸对材料高温稳定性的影响机制。
关键词：激光喷丸强化，残余应力，高温松弛，镍基合金
Abstract
Laser peening is a surface modification technology, using high-amplitude shock wave pressure induced by the laser-material interaction. The mechanical properties and fatigue life of metal structures are significantly enhanced by changing its residual stress distribution and microstructure of the material surface.Nickel-based alloy is an important material used in aerospace field.The key components are usually served at high temperatures, and at this time the beneficial residual stress induced by laser peening will produce release phenomenon,thereby the gain of materials’ mechanical properties by laser peening are also affected. Therefore the key point to ensure the performance improvement and the quality reliability of the material modified is to grasp the release characteristics of residual stress induced by laser peening at high temperatures and effectively control the release rate of residual stress.In this study, the distribution of the residual stress induced by laser peening and its release characteristics under high temperatures of IN718 nickel-based alloy was researched with a combination of theoretical analysis and experimental methods, and the main works are as follows:
（1）Based on the physical mechanism of high amplitude shock wave induced by high-energy short-pulse laser-material interaction, the mechanism of the residual compressive stress of metal material induced by laser peening was explored, and the influence factor and eva luation was analyzed, and the estimation model of residual compressive stress was introduced. Then the rule and mechanism of the release of residual compressive stress under high temperature conditions were analyzed macroscopically and microscopically on this basis.
（2）The release characteristics under high temperature conditions of the residual compressive stress induced by laser peening was researched. The laser peening test of typical IN718 nickel-based alloy specimens was conducted by using a high power Nd: YAG GAIA laser. The thermal insulation test was conducted with the SX2-4-10 box-type resistance furnace. The residual stress distribution on the surface of specimen was measured with X-350A X-ray diffraction. The microstructure of the specimen was analyzed with LEICA DFC420 optical microscopy. The release patterns under high temperature conditions of the residual compressive stress was analyzed by testing the residual stress and surface hardness at different temperatures and holding time. And the impact mechanism of the laser peening to the high temperature stability of materials was explored by the observation of the microstructure morphology of nickel surface after the laser peening and thermal insulation test.
Key: laser peening, residual stress, thermal release, nickel-based alloy
目 录
第一章 绪论 1
1.1 引言 1
1.2 激光喷丸强化技术 1
1.2.1 激光喷丸的基本原理及特点 1
1.2.2 激光喷丸强化工艺中的能量吸收层和约束层的选择 3
1.2.3 激光喷丸强化的发展历程及应用现状 3
1.3 高温下残余应力松弛的研究现状与进展 5
1.4 本课题选题研究意义及主要内容 7
1.4.1 研究意义 7
1.4.2 研究内容 7
第二章 激光喷丸诱导残余应力松弛特性分析 9
2.1 激光喷丸残余应力场理论 9
2.1.1 激光喷丸材料表层的塑性变形过程 9
2.1.2 激光喷丸诱导残余应力场的产生与估算 11
2.1.3 残余应力的测量 13
2.1.4 激光喷丸诱导残余应力场的影响因素及其评价指标 14
2.2 残余应力高温松弛理论 15
2.2.1 残余应力高温松弛宏观理论 15
2.2.2 残余应力高温松弛过程中晶粒尺寸与位错密度的演变 16
2...
