双金属交织结构等离子弧增材制造技术研究

发布时间：2018-03-09 06:06

本文选题：等离子　切入点：双金属　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：材料-结构-功能一体化的初级仿生双金属交织结构可以应用于到汽车、船舰、金属茶杯外壳等,具有非常广阔的应用前景。本文主要是根据贝壳等生物材料的珍珠母层结构,设计出初级仿生的双金属交织结构,采用等离子增材制造技术,对初级仿生的双金属交织结构的制备技术进行了研究。仿照贝壳等生物珍珠母层"砖-桥-泥"的微结构,设计出具有多尺度、强抗冲击等结构特征的金属初级仿生结构,选取高氮奥氏体钢作为硬质材料,Cr-Ni奥氏体不锈钢308L作为软质材料。根据目前常用的增材制造材料和结构特点选择丝材作为双金属交织结构制备的材料物理形态,采用等离子弧作为热源,根据结构设计的特点,制定了三种不同的金属沉积路径,1、沿着矩形块长度方向,即X轴方向;2、沿着长度方向往返,3、层与层之间旋转90°交织成形,即X/Y轴两个方向。研究结果表明,根据设计的结构以及尺寸要求,得到了合适的焊接参数:焊接电流为:120A,焊接速度为:20cm/min,送丝速度为:0.8m/min。当道间距为2.5mm时,增材制造构建的表面成形良好,堆敷层较为平整,可以继续增加堆敷层。对于高氮钢和不锈钢多层多道增材制造,层与层之间沿着Z轴旋转0°、90°、180°,对沿X轴所取的样的拉伸强度的影响较小,且均是韧性断裂;旋转90°增材制造所得的样件的冲击吸收功略小于不旋转和旋转180°的增材制造所得的样件的冲击吸收功。但旋转90°之后,能将Y轴方向增加增材制造构件的拉伸强度、冲击吸收功,故选取沿Z轴旋转90°作为层与层之间的堆敷路径。对于高氮钢与不锈钢双金属交织结构,由于层与层之间、道与道之间存在着两种金属或者同种金属之间的相互过渡的现象,这使得层与层之间,道与道之间的界面结合强度有所增加;并导致双金属交织结构在微观角度也存在镶嵌交织,对于整体结构设计,此种现象是有利于使设计更接近天然生物结构,在一定程度上增加双金属交织结构的强度和韧性。改变双金属交织结构样件的成分比例,依次减少不锈钢含量,增加高氮钢,拉伸强度曲线有两个峰值,分别是在纯高氮钢与高氮钢和不锈钢比例在3:1左右取得;冲击吸收功曲线也有两个峰值,分别是在纯不锈钢与高氮钢和不锈钢比例在3:1左右取得。
[Abstract]:The primary biomimetic bimetallic interlaced structure with material-structure-function integration can be used in automobile, ship, metal teacup shell and so on, and has a very broad application prospect. This paper is mainly based on the pearl mother layer structure of biological materials such as shells. The primary bionic bimetallic interleaving structure was designed. The preparation technology of the primary bionic bimetallic interleaved structure was studied by using the plasma material increasing technology. The microstructure of the biological pearl parent layer, such as shell, was modeled on the "brick-bridge-mud" structure. A metal primary bionic structure with multi-scale, strong impact resistance and other structural characteristics is designed. High nitrogen austenitic steel was chosen as hard material Cr-Ni austenitic stainless steel 308L as soft material. The plasma arc is used as the heat source. According to the characteristics of the structure design, three different metal deposition paths are developed, which are formed by rotating 90 掳interleaving between the layers along the length direction of the rectangular block, I. e., the X axis direction, the X axis direction, the length direction, and the rotation of 90 掳between the layers. That is, the X / Y axis is in two directions. The results show that according to the design structure and size requirements, the appropriate welding parameters are obtained: the welding current is 1: 120A, the welding speed is 20 cm / min, and the wire feeding speed is: 0.8 m / min. When the spacing is 2.5 mm, For high nitrogen steel and stainless steel, multilayer and multi-channel adding material, the surface is well formed and the stack layer is relatively smooth, which can continue to increase the stacking layer. The rotation of 0 掳~ 90 掳~ (180 掳) along Z axis between layers has little effect on tensile strength of samples taken along X axis, and all of them are ductile fracture. The impact absorption energy of the sample made by rotating 90 掳material is slightly lower than that of the sample made without rotation and 180 掳rotation. However, after 90 掳rotation, the tensile strength of the fabricated member can be increased in the direction of Y axis. Therefore, 90 掳rotation along Z axis is chosen as the stacking path between layers. For high nitrogen steel and stainless steel bimetallic interwoven structure, due to the interlayer between layers, There exists the phenomenon of transition between two metals or the same metal between the trace and the channel, which increases the interfacial bonding between the layers and between the trace and the trace. It also leads to the interleaving of bimetallic interleaved structures in microscopic angle. For the whole structure design, this phenomenon is beneficial to make the design more close to the natural biological structure. To a certain extent, the strength and toughness of bimetallic interwoven structure are increased. By changing the composition ratio of bimetallic interwoven structure, the content of stainless steel is reduced in turn, the content of high nitrogen steel is increased, and the tensile strength curve has two peaks. The ratio of pure high nitrogen steel to high nitrogen steel and stainless steel is about 3: 1, and the impact absorption energy curve has two peak values, respectively, when the ratio of pure stainless steel to high nitrogen steel and stainless steel is about 3: 1.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG66;TB17

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