【作者】 范振红；

【导师】 孙永兴；

【作者基本信息】 中国石油大学 ， 材料加工工程， 2007， 硕士

【摘要】 瞬时液相扩散焊(TLP)是一种高效快速的焊接方法,其具有焊接温度低,母材不熔化,可焊接异种材料,变形小,强度接近母材,高温性能好,设备投资及焊接成本低等特点。为将TLP焊接技术应用到油田管道的焊接中,论文根据管道常用钢16MnR的特点和中间层材料选择的原则,选用Ni60自熔性合金粉末和Fe-Si-B非晶箔片作为中间层进行TLP焊接,研究了TLP焊接接头显微组织和力学性能;中间层性质和焊接工艺参数对焊接接头显微组织及力学性能的影响;焊接接头区域的元素分布情况;焊接接头拉伸断口形貌特征;TLP焊接界面形成机制;并采用有限元软件ANSYS对焊接接头区域的温度场和应力场进行模拟。研究结果表明:采用Ni60合金粉末做中间层时,焊缝区域存在大量的空洞和夹杂,焊接接头的力学性能很差(抗拉强度不足80MPa),粉末材料的致密性差是造成焊接质量差的根本原因。采用Fe-Si-B非晶箔片做中间层时,通过正交试验优化,获得最佳焊接工艺参数(焊接温度1150℃,焊接压力6MPa,保温时间10min),焊接工艺参数对焊接接头质量的影响由主到次为:焊接温度,焊接压力和保温时间。焊缝缺陷主要是空洞和未熔合缝隙,拉伸断口呈现出解理、准解理、塑性断裂的形貌特征。电子探针分析表明:硼元素在焊缝附近的母材里均匀分布;硅元素的浓度分布呈从中间层向两侧母材逐渐下降的趋势,在焊缝附近区域存在偏聚;锰元素在焊缝两侧发生局部聚集。TLP焊接界面的形成过程包括熔化的中间层在母材表面润湿及铺展;氧化膜破碎;中间层与母材发生互扩散使界面及空洞消失;接头成分均匀化四个阶段。有限元模拟分析表明:焊接接头的残余应力主要产生在冷却的初始阶段,在靠近中间层两侧的母材附近残余应力的值较大,母材上的X轴向拉应力在外周边达到最大;采用中间过渡层焊接,可以缓解焊接接头应力的集中,有利于提高焊接接头的强度。更多还原

【Abstract】 TLP is a high effective welding method whose characteristics is lowwelding temperature, infusible base material, suit to weld heterogeneitymaterial, low transformation, intension approximate to base material, goodhigh-temperature performance, low investment. Now TLP has been a preferredwelding method for welding advanced material, it also has great applicationpotential in carbon steel.In order to apply the TLP in pipeline soldering, choosing self-fluxingalloy Ni60 and Fe-Si-B amorphous foil as interlayer (according to the propertyof 16MnR). Study the microscopic structure feature and mechanics property ofthe TLP joint; the influence of the interlayer and parameters on themicroscopic structure and mechanics performance; the distribution of elementsin the joint area; the appearance of the stretch fracture; the mechanism of TLPsolder. Finally using finite element software ANSYS to simulate thetemperature field and stress field of the joint.The results indicate that when using Ni60 as interlayer, there are a lot ofcavities and foreign impurities in the joint area, the mechanics performance ofthe joint is low. The reason is the low compact of the powder Ni60. Whenusing Fe-Si-B as interlayer, the quality of the joint is good, the main defect of the joint is cavity and infusion, the welding parameters have great effect on themicrostructure, and appropriate welding parameters will reduce the weldingdefect. Through quadrature experiment, the best welding parameter istemperature 1150℃, press 6MPa, time 10min. Appearance of the stretchfracture of the joint has the character of cleavage Fracture, Dimple Ruptureand Quasi-cleavage Fracture which indicate that the joint is metallurgy joint.The main reason of the fracture is the appearance of the mechanical joint areaand microscopic gap. B distribute averagely in the joint; the concentration ofSi decline gradually from interlayer to base material; Mn convene in the joint.There are four phases in the forming of the welding interface; they are thewetting of the interlayer on the base material; the breaking of the oxide film;the diffusion between interlayer and base material and the disappearing of thecavity; the equality of the joint. The simulation of the temperature field andstress field indicate that the residual stress is generated at the cooling stage, itconcentrate in the base material near the interlayer, the tensile stress of thebase material reach the peak value at perimeter area. The using of theinterlayer can reduce the concentration of stress; improve the strength of thejoint.更多还原