七丝旋转电弧自动气电立焊及接头性能调控机理研究

Automatic seven wire rotating arc electrogas welding (EGW) only needs an arc welding power source, a wire feeding machine and a welding torch, generating an independent rotating arc in the welding process, melting 7 (single) welding wire at the same time, which is a new hull erection welding method with the advantages of high efficiency and quality. The preliminary research shows that automatic seven wire rotating arc EGW has features of simple welding equipment, good accessibility of welding torch, high welding deposition rate and small heat input. In the welding process, a rotating arc is generated and the property of welded joint can be improved by the adjustment of (single) wire alloy components. The applicant intends to make the welding equipment consist of a constant-current external characteristic arc welding power and a variable speed wire feeding machine. In addition, welding voltage(arc length) negative feedback control mode is also be researched to realize the stable arc length in welding process and automatic creeping mechanism of welding tractor as well .Besides, we conduct studies of seven wire rotating arc reciprocating spiral movement and welding metallurgy behavior by changing diameter, types and alloy components of seven (single) wire. At last, the study reveals the influence rule of welding arc heat and force, welding wire melting and metal transfer, flow of molten pool liquid metal, temperature variation and distribution, the microstructure of welded joint, the alloy composition distribution, penetration and toughness. As a result, we establish dependence relation of “welding criterion parameters—welding arc movement behavior+welding metallurgy behavior—welded joint penetration and toughness”.

七丝旋转电弧自动气电立焊是一种只需1台弧焊电源、1台送丝机、1把焊枪，焊接时产生1个自主旋转电弧，同时熔化7根（分）焊丝的高效优质船体大合拢焊接新方法。前期研究表明，七丝旋转电弧自动气电立焊设备简单、焊枪可达性好；焊接熔敷速度高、焊接热输入量少；焊接时电弧自主旋转；可通过调整（分）焊丝合金成分改善接头性能。申请者拟采用垂降外特性弧焊电源配合变速送丝机组成焊接设备，研究焊接电压（弧长）负反馈控制模式以实现气电立焊过程弧长稳定及焊接小车自动爬行机制；研究七丝旋转电弧气电立焊往复式螺旋线运动，以及改变7根（分）焊丝的直径、类别及合金成分形成的焊接冶金行为，对焊接电弧产热产力、焊丝熔化与熔滴过渡、熔池液态金属流动、温度变化及分布、焊接接头微观组织、合金成分分布、熔深和韧性的影响规律；建立“焊接规范参数--焊接电弧运动行为+焊接冶金行为--接头熔深及韧性”的相关性关系。

船体分段大合拢立缝焊接是船舶建造过程中的瓶颈环节，气电立焊因焊接效率高、成本低、焊缝成形美观等优点已成为船体分段大合拢立缝的主要焊接方法，但其存在着侧壁未熔合、焊缝组织粗大、焊缝韧性差等问题。. 本项目采用了试验研究与理论分析的方法，通过垂降外特性弧焊电源配合变速送丝机组成焊接设备，研究了焊接电压（弧长）负反馈控制模式以实现气电立焊过程弧长稳定及焊接小车自动爬行机制；通过建立高速摄像系统和电信号同步采集系统，研究了七丝旋转电弧气电立焊电弧旋转耦合行为和熔滴过渡行为。研究了焊接电流、焊枪偏移量及坡口间隙对电弧形态的影响；分析了电弧旋转耦合运动机制，并将其运动过程解耦为轴向运动过程、耦合运动过程及周向旋转过程；根据焊枪的摆动与否，建立了电弧旋转运动数学模型和空间模型。. 基于七丝分焊丝可灵活组配和自主旋转电弧可均匀搅拌熔融金属的特点，以现有增韧（含Ni、Cr元素）焊丝与普通焊丝进行组合设计了增韧七丝，焊缝冲击韧性试验结果表明富Cr七丝无法满足中国船级社标准要求，而富Ni七丝均可满足中国船级社标准要求；采用1根富Ni分焊丝和6根普通分焊丝组成的增韧七丝，焊缝平均冲击功最高，焊缝中诱导针状铁素体形核和长大的夹杂物中心主要组成为Al基氧化物、Ti基氧化物、Si基氧化物、Mn基氧化物，夹杂物的边缘主要组成为Mn、Cu的硫化物（MnS、CuS）；焊缝中更多的针状铁素体、有效夹杂物及更大的大角度晶界比例是其平均冲击功更高的主要原因，延伸率和断面收缩率最高，焊缝塑性最佳。. 本项目建立了七丝旋转电弧自动气电立焊“焊接规范参数--焊接电弧运动行为+焊接冶金行为--接头熔深及韧性”的相关性关系，研究成果有助于全面深入的了解七丝旋转电弧自动气电立焊焊接接头性能调控机理和相关焊接工艺理论，对促进我国大厚度、高强度等级的船用钢的高效优质焊接快速发展具有重要。