摘要：静止轴肩搅拌摩擦焊(StationaryShoulderFrictionStirWelding,SSFSW)是英国焊接研究所在传统搅拌摩擦焊技术的基础上开发的一种新型固相连接技术，具有焊接载荷低、焊缝表面光滑，基本无飞边与减薄、摩擦热沿板厚较均匀及适应性强等优点，在钛合金、铝合金的搅拌摩擦焊接等方面具有广阔的应用前景。6061-T6铝合金一直是工业各领域应用最广泛的轻型结构材料之一。标记材料示踪法是一种常用的研究材料流动的可视化研究方法，选择铜箔作为标记材料能够直观而有效的观察接头塑性金属的迁移方式。

本论文对6061-T6铝合金进行了对接形式的静止轴肩搅拌摩擦焊接，焊后对焊接接头取样观察分析。分析发现，焊核区中部和下部金属主要来自于前进侧母材，而后退侧母材主要进入焊核区上部。前进侧金属进入焊核区时间较早，并发生剧烈的机械搅拌摩擦变形，后退侧金属进入焊核时间较晚，受到的机械作用相对较弱。在水平方向上，前进侧金属既向焊接方向迁移，也向焊接相反方向迁移，而后退侧金属只向焊接相反方向迁移。

搅拌针旋转速度升高，会增加焊缝金属的流动性。塑性材料的流动性随着焊接速度的增加而逐渐降低，但焊接速度对塑性材料流动性的影响不如旋转速度的影响明显。

关键词：静止轴肩搅拌摩擦焊；6061-T6铝合金；塑性金属；流动性

Abstract：Stationary Shoulder Friction Stir Welding(SSFSW), proposed by The Welding Institute, is a novel adaptable technology based on conventional friction stir welding. It produces smooth welds with little flash and thickness reduction using low welding load and creates homogenous heat input through the thickness direction, leading to small distortion and low residual stress, it has a promising potential in the welding of Titanium alloy and Aluminum alloy. 6061-T6 aluminum alloy has always been one of the most widely used light structural materials in various fields of industry. It is an effective and intuitive method to choose copper foil being the marking material for observing the plastic formation in SSFSW joint.

In this paper, 6061-T6 aluminum alloy are selected as the experiment objects to create butt joints. After welding experiment, the writer analyzed the welded joints. The middle and lower metals of WNZ are mainly from the base material in advantage  side, and the base material in retreating side mainly enter the upper part of WNZ. Firstly, base  material in advantage side transfer into the WNZ; they have suffered severe plastic distortion. Material in retreating side transfer later into WNZ; they have just suffered slight plastic distortion. In the horizontal direction, the metals in advantage side not only migrate to welding direction, but also migrate to the opposite direction of the welding direction, and the metals in retreating side only migrate to the opposite direction of the welding direction.

Raising the rotation speed of the pin will lead to the increase of weld metal flow. The plastic metal flow decreases as the welding speed increases, but the impact of welding speed on the fplastic metal flow is not as obvious as the rotation speed.

Keywords: Stationary shoulder friction stir welding; 6061-T6 aluminum alloy; Plastic metal; Flow

目录

第一章 绪论 1

1.1课题研究的背景及意义 1

1.2SSFSW技术简介 2

1.3SSFSW技术的工业应用前景 4

1.4材料流动性介绍 5

1.5搅拌摩擦焊缝流场可视化研究 5

1.5.1标识材料示踪法