摘要本文综述了Q690D高强度钢的国内外研究现状，以及MAG焊的基本工作原理和特点，使用MAG焊的方式对船用高强钢Q690D进行了焊接工艺的试验，并且对焊接后的接头进行了一系列的显微组织观察和分析，主要是接头各个区域的金相组织观察。同时，也对焊接接头进行了拉伸、冲击、弯曲和硬度的一系列力学性能的测试，通过这些测试来检测预先设计好的焊接工艺参数和规范对于Q690D高强钢板的焊接的稳定性。试验的结果表明：在本文研究的焊接参数（200~250A的焊接电流，23~28V的焊接电压，预热温度180℃，焊后加热至250℃后缓冷等）下，均得到了良好、美观、整洁的焊接接头。使用同一焊接工艺参数焊接多块试板，将焊接好的试板进行力学性能试验和金相观察，试验结果和组织观察相互比对后得到，当采用本试验的焊接工艺焊出来的Q690D钢板焊接接头，通过焊丝的等强匹配，得到较高的拉伸强度、低温冲击韧性和较大的硬度，室温抗拉强度最高可达到824Mpa；在硬度方面，其焊缝区的硬度有较大的提高，最高可达320HV；焊接接头的焊缝中心低温冲击值为55J，热影响区、热影响区+1mm、热影响区+3mm和热影响区+5mm处的冲击功分别为70J、103J、131J和153J，都达到了要求；此焊接工艺稳定，良好，很适合Q690D高强钢的焊接。82245

毕业论文关键词：低合金高强钢；Q690D；熔化极氩弧焊；微观组织；力学性能

Abstract In this paper, the present research status of Q690D high strength steel at home and abroad is reviewed。The basic working principle and characteristics of the melting electrode argon arc welding, using MAG welding of ship for Q690D steel welding process test and of welded joints were a series of microstructure observation and analysis, mainly joint in various regions of the metallographic observation。 And of the welded joints were tensile strength, impact strength, bending strength and hardness of a series of mechanical properties test, through these tests to detect in advance design good welding process parameters and specifications for Q690D steel plate welding stability。 Test results show that: in the welding parameters (200~250A welding current, welding voltage of 23~28V, preheating temperature of 180℃, after welding, heating temperature of 250℃ and slow cooling), were obtained the good, beautiful, clean the welding joint。 Matching Q690D, would use the same welding parameters such as welding a plurality of test plate welding test plate mechanical properties test and metallographic observation。 The experiment results and microstructure observation were compared with each other after, when the test of welding process welding steel plate welded joint, through the wire and other strong, high tensile strength and low temperature impact toughness and high hardness, tensile strength is the highest attainable 808MPa ; The hardness of the weld zone hardness larger increase, up to a maximum of 285HV ; The low temperature impact value of weld center is 55J, the heat affected zone, the heat affected zone +1mm, the heat affected zone +3mm and the heat affected zone +5mm are 70J, 103J, 131J and 153J, which all meet the requirements。 The welding process stability, good, it’s very suitable for Q690D steel welding。

Keywords: Low alloy high strength steel; Q690D; melting electrode argon arc welding; microstructure; mechanical properties

目  录

第1章 绪论 1

1。1本文研究的目的及意义 1

1。2高强度钢的概念 2

1。3高强钢的国内外研究现状及发展 2

1。4高强钢的焊接性、焊接工艺措施与焊接技术难点 4