深冷预处理对2024-T351铝合金组织性能及激光喷丸强化效果的影响
发布时间：2018-10-25 09:06
【摘要】：激光喷丸技术通过激光诱导等离子体产生高幅冲击波压力,向材料表层植入高幅残余压应力,同时增加表层位错密度、细化晶粒以提高材料的机械力学性能。针对强化性能在高温和循环载荷条件下的稳定性问题,温度辅助的激光喷丸强化技术已日益受到国内外学者的关注。本文以典型航空铝合金2024-T351为研究对象,探索深冷预处理对2024-T531铝合金组织性能及激光喷丸强化效果的影响,主要工作包括:(1)理论上探索了深冷预处理对激光喷丸2024-T351铝合金残余应力及疲劳性能的影响,分析了激光喷丸诱导残余应力场、残余应力对金属疲劳性能的影响及高温、振动和交变载荷条件下残余应力稳定性等关键问题,研究了深冷预处理对2024-T351铝合金材料屈服强度、硬度以及弹性模量等力学性能影响的相关理论,为深冷预处理和激光喷丸改性工艺研究提供理论基础。(2)实验研究了深冷预处理对2024-T351铝合金微观组织、静态力学性能及表面残余应力的影响。以液氮(-196℃)为介质对铝合金材料进行2h~12h等不同时长的深冷预处理,随后进行常温拉伸和纳米压痕等性能测试;对深冷前后材料金相组织、第二相状态和表面残余应力进行检测分析。结果表明,深冷预处理后材料的微观组织得到改善,其抗拉极限、屈服强度、纳米硬度及弹性模量等明显提高,拉伸断口形貌的局部解理特征向塑性断裂特征转化,说明深冷预处理亦可提高2024-T351铝合金塑性。残余应力测试表明深冷预处理可消除2024-T351铝合金表面残余拉应力,并引入小幅残余压应力。(3)开展了激光喷丸处理2024-T351铝合金系列实验及其相关性能测试,研究了经深冷预处理和未处理材料的激光喷丸强化效果。结果表明深冷预处理后进行激光喷丸处理,材料的晶粒更加圆整且晶界更为清晰,表面残余应力幅值和激光喷丸影响层硬度明显增加;“梯度交变载荷”作用下的残余应力稳定性和疲劳性能测试分析表明,深冷预处理和激光喷丸均能提升2024-T351铝合金的疲劳寿命,同时深冷预处理能显著提高激光喷丸2024-T351铝合金残余应力场的稳定性,因而深冷后进行激光喷丸处理的材料疲劳增益更明显。
[Abstract]:Laser shot peening technique produces high amplitude shock wave pressure by laser-induced plasma, implants high amplitude residual compressive stress into the surface layer of the material, increases the dislocation density of the surface layer, and refines the grain size to improve the mechanical and mechanical properties of the material. Aiming at the stability of strengthening performance under high temperature and cyclic load, the temperature-assisted laser shot peening technique has been paid more and more attention by scholars at home and abroad. In this paper, the effect of cryogenic pretreatment on the microstructure and properties of 2024-T531 aluminum alloy and the effect of laser shot peening on the microstructure of typical aviation aluminum alloy 2024-T351 were studied. The main works are as follows: (1) the effects of cryogenic pretreatment on residual stress and fatigue properties of laser shot peening 2024-T351 aluminum alloy are studied theoretically. The residual stress field induced by laser shot peening, the effect of residual stress on metal fatigue performance and high temperature are analyzed. The influence of cryogenic pretreatment on the yield strength, hardness and elastic modulus of 2024-T351 aluminum alloy was studied. It provides a theoretical basis for the study of cryogenic pretreatment and laser shot peening. (2) the effects of cryogenic pretreatment on microstructure, static mechanical properties and surface residual stress of 2024-T351 aluminum alloy were studied experimentally. Aluminum alloy materials were pretreated with liquid nitrogen (-196 鈩，
本文编号：2293247
[Abstract]:Laser shot peening technique produces high amplitude shock wave pressure by laser-induced plasma, implants high amplitude residual compressive stress into the surface layer of the material, increases the dislocation density of the surface layer, and refines the grain size to improve the mechanical and mechanical properties of the material. Aiming at the stability of strengthening performance under high temperature and cyclic load, the temperature-assisted laser shot peening technique has been paid more and more attention by scholars at home and abroad. In this paper, the effect of cryogenic pretreatment on the microstructure and properties of 2024-T531 aluminum alloy and the effect of laser shot peening on the microstructure of typical aviation aluminum alloy 2024-T351 were studied. The main works are as follows: (1) the effects of cryogenic pretreatment on residual stress and fatigue properties of laser shot peening 2024-T351 aluminum alloy are studied theoretically. The residual stress field induced by laser shot peening, the effect of residual stress on metal fatigue performance and high temperature are analyzed. The influence of cryogenic pretreatment on the yield strength, hardness and elastic modulus of 2024-T351 aluminum alloy was studied. It provides a theoretical basis for the study of cryogenic pretreatment and laser shot peening. (2) the effects of cryogenic pretreatment on microstructure, static mechanical properties and surface residual stress of 2024-T351 aluminum alloy were studied experimentally. Aluminum alloy materials were pretreated with liquid nitrogen (-196 鈩，
本文编号：2293247
本文链接：https://www.wllwen.com/kejilunwen/jiagonggongyi/2293247.html
