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用LF_6铝镁合金4毫米板材厚度制造的环形贮箱,是一种救生圈式的结构,由两个半环,以内外两条环缝焊成,焊接质量要求很高,焊缝是一级标准,长期以来难于达到设计要求的97公斤/厘米~2的爆破压力指标。我们分析了LF_6铝镁合金的焊接特点,从减少焊缝接头(特別是内环缝)内应力,减少焊接热影响区,减少结构变形及焊缝角变形,试验了自动氩弧焊(TIG),强规范快速单面一次性焊透的焊接工艺。工艺方案的选择。贮箱强规范快速单面一次焊透工艺方案(TIG)和软规范双层二次焊透工艺方案(TIG)进行工艺试验分析比较,确定使用强规范快速单面一次工艺方案更为合理。这种方案的难度在于要一次焊透并保证焊缝正反面成形良好。控制单面焊焊透及保证焊缝质量的工艺因素。确定试板的合理接头型式,对试板去包铝层的要求和装配严格要求。要想得到一条良好质量的焊缝通过大量试验过程,对焊接电流的选择应控制在钨极允许的上限,以便提高焊接速度,确定优值规范。测定焊缝机械性能,检查金相组织,说明强规范快速单面一次焊的优越性。强规范快速单面一次焊与软规范双层焊的机械性能数据进行对比,前者的抗拉强度σb34～36公斤/毫米~2,延伸率15％以上,而后者的抗拉强度较低σb 28～32公斤/毫米~2,延伸率在8％左右,塑性降低更为明显。金相组织分析情况,两者热影响区的晶粒长大并不明显,但后者焊缝晶粒度和热影响区的宽度要比前者的晶粒度大,热影响区宽,冷却慢。α相中的β相Mg_2Al_3化合物析出较多,并且成颗粒状的聚集分布,降低强度和塑性指标。前者焊接接头内应力小。另外,前者反面焊透加强高<2毫米从而减少了接头承载时应力集中。强规范快速单面一次焊的方法运用在模拟件上的试验成功,爆破压力达到设计指标。更证明焊接工艺方法正确。然后将这工艺方法用到试生产中。对试生产过程中出现贮箱破坏压力高的达100公斤/厘米~2,低的达90公斤/厘米~2之差的破坏压力不稳定情况,我们主要从工艺上找问题的症结,研究改进措施。贮箱爆破质量分析。研究爆破裂源的特征。对贮箱爆破裂源进行金相和电子扫描分析疵病和结构因素。疏松及未焊透对贮箱爆破强度值的影响,补焊的影响,局部内应力增大,β相粗大并且析出数量之多,都是降低贮箱爆破强度值的原因。改进了装焊夹具,从结构上装配预焊质量上改善应力分布状态。减少补焊提高焊接质量等因素,通过大量试验和生产的改进使贮箱的爆破压力突破了100公斤/厘米~2,满足了设计技术条件的要求。
The ring tank made of LF_6 aluminum-magnesium alloy 4 mm plate thickness is a kind of lifebuoy structure consisting of two half-rings welded to the two inner and outer rings, the welding quality is very high, the welding seam is a standard , Has long been difficult to meet the design requirements of 97 kg / cm ~ 2 burst pressure index. We analyzed the welding characteristics of LF_6 aluminum-magnesium alloy from the aspects of reducing the stress in the weld joint (especially the inner ring seam), reducing the heat affected zone (HAZ), reducing the structural deformation and the weld angle deformation, , Strong norms fast one-sided one-time penetration of the welding process. Process options. The strong single tank once-through process scheme (TIG) and the soft-standard double-layer two-pass process scheme (TIG) were compared and analyzed to determine that it is more reasonable to use the strong standard quick one-sided one-time process scheme. The difficulty of this program is to weld once and ensure that the positive and negative weld forming a good. Control of single-sided welding penetration and ensure the quality of welding process factors. Determine the type of test plate reasonable joints, to the aluminum plate to the test requirements and assembly rigorous requirements. To get a good quality weld through a large number of test process, the choice of welding current should be controlled at the upper limit of the tungsten in order to improve the welding speed, to determine merit specifications. Determine the mechanical properties of the weld, check the microstructure, indicating the strong standard one-time quick one-sided welding superiority. Strong standard fast one-sided welding and soft-specification double-layer welded mechanical properties of the data were compared, the former tensile strength σb34 ~ 36 kg / mm ~ 2, elongation of 15% or more, while the latter lower tensile strength σb 28 ~ 32 kg / mm ~ 2, the elongation at about 8%, the plasticity is more obvious. Metallographic analysis, the two heat affected zone grain growth is not obvious, but the latter weld grain size and heat affected zone width than the former grain size, heat affected zone wide, slow cooling . The β phase Mg_2Al_3 compounds in the α phase are more precipitated and aggregated in the form of granules, reducing the strength and plasticity. The former welded joints stress is small. In addition, the former reverse penetration to enhance the high <2 mm thus reducing the stress concentration joints. Strong normative rapid single-sided welding method used in the simulation of the successful test, burst pressure to meet the design specifications. More proven welding process is correct. Then this process method used in the pilot production. In the process of trial production, the pressure of sabotage is up to 100 kg / cm ~ 2, and the pressure drop of up to 90 kg / cm ~ 2 is unstable. We mainly look for the crux of the problem from the technology, and research and improvement Measures. Quality analysis of blasting tank. Research on the characteristics of blasting source. Metallographic and electronic scanning analysis of blasting cracks in storage tanks was conducted to analyze flaws and structural factors. Loose and incomplete penetration of the impact of the burst value of the tank, the impact of welding, local stress increases, β-phase coarse and precipitated as much as the number are to reduce the value of the reservoir burst value. Improve the welding fixture, from the structure of pre-welding quality improvement of stress distribution. Reduce welding repair welding quality and other factors, through a large number of tests and production improvements so that the burst pressure tank burst 100 kg / cm ~ 2, to meet the design requirements of the technical conditions.