外加纵向交流磁场对钛合金焊接接头组织和性能的影响

发布时间：2018-03-25 12:33

本文选题：TA2钛合金　切入点：TIG焊　出处：《沈阳工业大学》2016年硕士论文

【摘要】：钛及钛合金是非常好的金属材料,它具有密度小、比强度高、耐蚀性好的优点,被认为是一种“全能金属”,已经在航空航天、交通、化工、医疗等领域取得了广泛的应用。作为新兴的轻质金属材料,钛被认为会在21世纪存在非常好的发展前景。钛合金在焊接过程中极易被氧化,并且容易在接头中产生气孔、裂纹等缺陷,严重影响了焊接质量,限制了钛合金焊接技术在工业生产中的应用。近几年将磁场和焊接技术联系起来而衍生出来的磁控焊接因其能够提高焊接接头力学性能的优点而受到了重视,对磁控焊接技术也正在进行更深入的研究。本课题首先研究了TA2钛合金的焊接工艺,对不同工艺规范下获得的焊接接头进行力学性能测试和显微组织分析,确定获得最佳焊接接头性能的焊接热输入,然后通过设计正交试验在TA2钛合金焊接的过程中施加纵向交流磁场,通过改变焊接电流、磁场电流和磁场频率的大小来研究磁场对接头性能的影响,揭示电磁搅拌细化晶粒,提高焊接接头力学性能的机理。结果表明:焊接热输入是影响TA2钛合金接头力学性能和显微组织的主要因素之一,随着焊接热输入的增加,接头的力学性能呈现先增大后降低的趋势,焊接热输入为1.083kJ/mm时,焊接接头的力学性能达到最大值:σb=589.26MPa、δ=24.34%、Ψ=35.26%,焊缝的硬度为195HB,热影响区硬度为161HB。通过正交实验确定的最好接头的工艺参数为焊接电流为150A、磁场电流为2.0A、磁场频率为30Hz,此时的力学性能为:σb=612.92MPa、δ=25.78%、Ψ=39.43%,焊缝硬度为198HB,热影响区硬度168HB。外加纵向交流磁场通过与电弧、熔池的相互作用产生电磁搅拌作用,改变熔池液态金属结晶和传热过程,细化晶粒,提高焊缝的力学性能。
[Abstract]:Titanium and titanium alloys are very good metal materials. They have the advantages of low density, high specific strength and good corrosion resistance. They are considered as "all-around metals" and have been widely used in aerospace, transportation and chemical industry. As a new lightweight metal material, titanium is considered to have a very good prospect in the 21st century. Titanium alloy is easy to be oxidized in welding process, and it is easy to produce pores in joints. Cracks and other defects seriously affect the welding quality, The application of titanium alloy welding technology in industrial production is limited. In recent years, the magnetically controlled welding derived from the connection of magnetic field and welding technology has attracted much attention for its advantages of improving the mechanical properties of welded joints. Magnetic controlled welding technology is also being further studied. Firstly, the welding process of TA2 titanium alloy is studied, and the mechanical properties and microstructure of welded joints obtained under different process specifications are tested and analyzed. Determine the welding heat input to obtain the best welding joint performance, then apply longitudinal alternating magnetic field to TA2 titanium alloy welding process by designing orthogonal test, by changing welding current, The effect of magnetic field on the properties of joints is studied by the magnitude of magnetic field current and magnetic field frequency. The results show that welding heat input is one of the main factors affecting the mechanical properties and microstructure of TA2 titanium alloy joints, and with the increase of welding heat input, The mechanical properties of the joints increased first and then decreased. When the welding heat input was 1.083kJ/mm, The mechanical properties of welded joints reach the maximum value: 蟽 _ (b) 589.26 MPA, 未 _ (24.34), 蠄 ~ (35.26), the hardness of weld is 195HBb and the hardness of heat affected zone is 161HB. the best process parameters of welded joints determined by orthogonal experiment are welding current 150A, magnetic field current 2.0A, magnetic field frequency 30Hz. in this case, the optimum welding parameters are: welding current is 150A, magnetic field current is 2.0A, magnetic field frequency is 30Hz. The mechanical properties are as follows: 蟽 _ B _ (612.92) MPA, 未 _ (25) 78, 蠄 ~ (39.43), the hardness of weld seam is 198 HBB, the hardness of heat affected zone is 168 HB. The external longitudinal alternating magnetic field passes through the arc, The interaction of molten pool produces electromagnetic stirring, which changes the crystallization and heat transfer process of molten metal in the molten pool, refines the grain size and improves the mechanical properties of the weld.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG407

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