【作者】 张璐；

【导师】 任朝晖；

【作者基本信息】 东北大学 ， 机械工程（专业学位）， 2022， 硕士

【摘要】 耗材摩擦焊作为一种新型焊接技术,在表面涂层工艺领域中的应用日益广泛。耗材摩擦焊在焊接过程中不需要额外再施加热源,仅依靠耗材与基板之间的摩擦产热以及塑性变形产热来软化材料,实现焊敷/焊接。耗材摩擦焊的能量利用率高,并且其绿色无污染的特点具有进一步成为工业级应用的巨大潜力,目前国内外正在研究开发其作为主流涂层工艺的可替代方案。随着耗材摩擦技术应用领域越来越广泛,该焊接技术所存在的一些缺点也逐渐暴露出来,传统耗材摩擦焊焊接过程中的能量来自于耗材和基板之间的旋转摩擦作用,在对高强度、高熔点、低导热性的材料进行焊接时,需要输入更大的轴向顶锻力和扭矩,以保证产生足够的热量来软化金属,实现焊接,因此传统耗材摩擦焊接设备都比较庞大,对机床的动力系统和夹持装置具有较高的要求。为了解决传统耗材摩擦焊在焊接高熔点,高强度钛合金时所需要的高转速、高轴向压力问题,本文提出一种基于激光预热的激光加热辅助耗材摩擦焊接新工艺,利用激光热源来对基板和耗材进行预热,降低材料的屈服应力和流动应力,进而达到降低焊接载荷、降低耗材转矩、提高焊接速度的效果。本文基于试验数据,采用数值建模的方法建立了传统耗材摩擦焊与激光加热辅助耗材摩擦焊的热-力耦合模型和热-流耦合模型,从焊接过程中的热过程、基板和焊敷层应力变化、残余应力分布、材料粘度分布、塑性材料流动行为等多方面、多角度来综合评价激光预热带来的效果。论文的主要研究内容如下:(1)对传统耗材摩擦焊和激光加热辅助耗材摩擦焊热-力耦合模型和热-流耦合模型的建模过程进行详细的分析,为提高计算效率,对二者的数值模型进行合理的简化与假设,介绍了所用材料热物理属性,推算了焊接过程中材料本构模型、摩擦产热和塑性变形产热的计算公式,以及辅加激光预热之后,激光热源的选择原则以及激光热源的计算公式。(2)建立了以Ti-6Al-4V材料作为耗材和基板的传统耗材摩擦焊和激光加热辅助耗材摩擦焊的完全热-力耦合模型,并进行求解计算,分析了辅加激光预热对焊接预热阶段、稳定焊接阶段以及冷却后的温度场、应力场、塑性变形场和焊后残余应力场的影响规律,通过改变激光预热功率,研究了不同的激光功率工艺参数对焊接热-力耦合模型中各个物理场的影响。(3)基于FLUENT软件建立激光加热辅助耗材摩擦焊热-流耦合模型。定量分析激光热源的导入对传统耗材摩擦焊在准稳态焊接阶段的温度分布及塑性材料流动行为的影响规律。并研究激光功率工艺参数对激光加热辅助耗材摩擦焊接热-流耦合过程的影响,综合评价激光热源的加入对传统耗材摩擦焊接工艺的影响。更多还原

【Abstract】 As a new welding technology,friction surfacing is widely used in the field of surface coating technology.Friction surfacing does not need additional heat source in the welding process.It only depends on the friction heat generation between consumables and deposit and plastic deformation heat generation to soften the material and realize welding.Friction surfacing has the characteristics of high energy utilization,green and pollution-free,and has great potential to further become an industrial application.At present,it is being studied and developed at home and abroad as an alternative to the mainstream coating process.With the more and more extensive application fields of friction surfacing technology,some shortcomings of this welding technology are gradually exposed.The energy in the traditional friction surfacing process comes from the rotary friction between consumables and deposit.When welding materials with high strength,high melting point and low thermal conductivity,it is necessary to input greater axial upsetting force and torque,In order to generate enough heat to soften the metal and realize welding,the traditional friction surfacing equipment is relatively large,which has high requirements for the power system and clamping device of the machine tool.In order to solve the problems of high speed and high axial pressure required by traditional friction surfacing in welding high melting point and high strength titanium alloy,a new laser assisted friction surfacing process based on laser preheating is proposed in this paper.The laser heat source is used to preheat the deposit and consumables in advance,so as to reduce the material yield stress and flow stress,so as to reduce the welding load and reduce the torque of consumables and improve the welding speed.Based on the test data,the thermal mechanical coupling model and thermal fluid coupling model of traditional friction surfacing and laser assisted friction surfacing are established by using the numerical modeling method.From the aspects of thermal process,deposit and cladding stress change,residual stress distribution,material viscosity distribution,plastic material flow behavior,etc.Comprehensively evaluate the effect of laser preheating from multiple angles.The main research contents of this paper are as follows:(1)The modeling process of thermal mechanical coupling model and thermal flow coupling model of traditional friction surfacing and laser assisted friction surfacing are analyzed in detail.In order to improve the calculation efficiency,the numerical models of the two are reasonably simplified and assumed.The material constitutive model,the calculation formulas of friction heat generation and plastic deformation heat generation in the welding process are calculated,and after laser preheating is added,the selection principle of laser heat source and the calculation formula of laser heat source.(2)The complete thermal mechanical coupling model of traditional friction surfacing and laser assisted friction surfacing with Ti-6Al-4V material as consumable and deposit is established,and the calculation is carried out.The influence law of auxiliary laser preheating on temperature field,stress field,plastic deformation field and post welding residual stress field in each welding stage is analyzed.By changing the laser preheating power,the effects of different laser power and process parameters on the physical fields in the welding thermal mechanical coupling model were studied.(3)The heat flow coupling model of laser assisted friction surfacing is established based on FLUENT software.The influence of laser heat source on the temperature distribution and plastic material flow behavior of traditional friction surfacing in quasi steady state welding stage is analyzed quantitatively.The influence of laser power process parameters on the heat flow coupling process of laser assisted friction surfacing is studied,and the influence of laser heat source on the traditional friction surfacing process is comprehensively evaluated.更多还原