摘要由于高硅铝合金是一种轻质材料，且具有良好的导电性、低的热膨胀系数(CTE )、化学性质稳定、易于机加工等良好性能，在电子信息行业和航空航天中得到了广泛的应用。本文主要研究CMT焊接在不同的工艺参数条件下，对Al-30Si的高硅铝合金进行堆焊后的组织及力学性能的影响。本论文主要从焊缝的气孔缺陷、焊缝的微观组织、及力学性能等几个方面进行对比分析，判断在怎样的参数范围适合该材料。86711

首先采用拉伸试验机对该高硅铝合金进行静态拉伸试验，力加载到一定程度，直接断裂，无屈服现象，表明该材料为脆性材料，得其抗拉强度和伸长率分别为193MPa、3。79%，测其硬度，得布氏硬度为141。9，表明该材料具有足够的强度，满足电子封装材料的机械支撑的要求。然后设定焊接的工艺参数，以一定的焊接速度为基础,改变送丝速度，取值在一定的范围内，进行焊接。首先拍摄超景深，发现焊缝表面有很多的孔洞缺陷，焊缝内的气孔主要沿着熔合线分布其周围，为典型的滞留型孔洞，气孔数多且大，焊缝中心的孔洞为滞留型孔洞，较小，计算其气孔分布率，发现工艺参数的送丝速度在2。5-3。0m/min左右,焊接速度在600-700mm/min时，焊缝的气孔率较小，当焊接速度为700mm/min,送丝速度为2。5m/min，气孔率最小为2。09%。选用金相显微镜分析焊缝组织形状及分布，发现热输入不同时，焊缝中心的组织也不同，当焊速为300mm/min时，送丝速度为2。5m/min时为胞状枝晶，为3。0m/min时为柱状晶，当送丝速度继续增大时，有硅晶体析出。对于HAZ来说，在相同的焊速条件下，随着送丝速度的增大，HAZ的组织变粗。对焊后材料进行断口分析，判断其断口为脆性断裂。

综上所诉：改变焊接的工艺参数，即改变热输入，可以减少焊缝的气孔率，当热输入值太大时，焊缝处会析出大量的硅晶体。

毕业论文关键字：高硅铝合金；CMT焊；气孔率；送丝速度；焊缝；

Abstract High silicon aluminum has been widely used in the electronic information industry and the aerospace application, with it is a lightweight material with good electrical conductivity, low coefficient of thermal expansion (CTE), chemically stable, easy to good performance machining, etc。 In this paper, the effect of CMT welding on the microstructure and mechanical properties of high silicon aluminum alloy Al-30Si under different process parameters was studied。 This paper mainly judgment in what range of parameters suitable for the material from the weld defects of weld microstructure, porosity and mechanical properties, and several other aspects of comparative analysis。

First, we use a tensile tester of the high silicon aluminum alloy static tensile test force loading to a certain extent, direct rupture, no yield phenomenon, indicating that the material is a brittle material, obtaining the tensile strength and elongation are 193MPa, 3。79% were measured for hardness, Brinell hardness was 141。9, indicating that the material has sufficient strength to meet the requirements for mechanical support of electronic packaging materials。 Then setting the welding process parameters, certain welding speed, based on changing wire feed speed, welding。 First, shoot over depth of field, found there are a lot of holes in the weld surface defects, pores within the weld fusion line along the main distribution around it, is a typical residence type holes, the number of stomata and more large pores weld center was stranded type holes, small pore distribution to calculate the rate of wire feed speed parameters found in the 2。5-3。0m / min or so, when the welding speed 600-700mm / min, weld porosity is small, when the welding speed is 700mm / min, wire feed speed of 2。5m / min, the minimum porosity of 2。09%。 Using metallographic microscope analysis of weld microstructure shape and distribution, found that the heat input not also, weld center organization is different, when the welding speed is 300mm / min, wire feeding speed is 2。5m / min for cellular dendrite。 3。0m/min columnar crystal, when the wire feed speed is increased, have silicon crystals。 For HAZ, under the same welding speed, with the increase of the wire feeding speed, the HAZ of the tissue becomes coarse。 Fracture analysis of materials after welding, the fracture is brittle fracture。