【作者】 彭昌永；

【导师】 李伟； 郭鹏；

【作者基本信息】 四川大学 ， 机械工程， 2003， 硕士

【摘要】 本论文根据壳体研制需求立项。壳体在工作过程中要经历很大的冲击载荷，并且不能发生严重变形，要求壳体必须具有很高的强度和塑性。总体设计采用超高强度钢D6A材料和大长径比的结构设计，分段加工后进行焊接成型。因此如何解决超高强钢分段焊接后的焊缝开裂问题，获得强度高、塑性、韧性好的优质D6A钢焊接接头，就成为壳体研制生产过程中决定总体设计成败、必须解决的关键技术问题。 本论文通过对D6A钢的焊接裂纹敏感性计算、D6A钢裂纹敏感机理分析、D6A钢的工艺焊接性分析、多种焊接方法的分析与选择比较，结合本项目的使用要求，确定了研究目标，以电子束焊接方法(EBW)和手工钨极氩弧焊(TIG)方法作为重点研究内容。对焊缝作了X射线探伤，微型剪切试验，机械性能试验，金相分析，对拉伸试样进行了扫描电镜断口分析。通过以上两种方法的研究比较，优选出最终的产品焊接生产工艺方法。产品生产后，最后通过壳体的冲击效果验证优选确定的焊接工艺方法、工艺措施、工艺参数、焊缝质量的可行性、可靠性。研究结果表明： 1．D6A钢的裂纹敏感性计算、工艺焊接性分析、裂纹敏感机理分析、焊接工艺试验都表明其焊接的冷、热裂纹敏感性极高，若焊接工艺方法、工艺措施、工艺参数选择不当，焊缝极易开裂。 2．采用手工钨极氩弧焊(TIG焊)方法，选用H18CrMoA焊丝作填充材料，采取切实有效的工艺措施，焊缝内部质量达一级，焊接接头呈较低强度高塑性匹配，焊缝强度约为1030MPa，塑、韧性显著优于母材。 3．TIG焊采用H1Cr18Ni9Ti焊丝打底，H18CrMoA焊丝填充，控制层间温度270℃以上，焊后进行300℃保温1小时的后热对防止裂纹是有效的。 4.采用电子束焊接方法，通过优化参数等措施，焊缝内部质量达GB 3 3 23二级焊缝水平，成功地解决了D6A钢电子束焊缝易开裂、超标气孔等问题。电子束焊接接头机械性能与母材基本相等，接头各区无剧烈性能变化，焊接接头综合性能良好，实现了D6A超高强钢的等强度焊接。 5.电子束焊接工艺采用oo字偏转函数，表层下4二处聚焦，优化各参数匹配，对改善焊缝成型，防止裂纹、超标气孔的产生是有效的。 6.通过优选，本项工艺研究为壳体的试验研制及批量生产提供了合理、可靠、高效的电子束焊接工艺方法。 7.经冲击验证，壳体头部的电子束焊接结构可行，试验后壳体的焊缝部位即使在壳体发生严重变形的情况下皆完好无损，解决了整体加工在工艺上困难的问题，消除了在结构设计上对焊缝性能下降的担心。更多还原

【Abstract】 This paper sets a project required by the development of Shell. The body of Shell not only has to endure great impact load in the process of penetrating the tamped earth, concrete and pebble bed, but also should not be deformed severely, so it requires very high intensity and plasticity. The design that super-strength steel of "D6A " and large length-diameter ratio and welding fabrication after being machined in segments are adopted in the overall design of the bomb shape. Therefore, to solve the problem of welding crack and to acquire high quality welding joint with high Strength, plasticity and flexibility are critical technology issue which determine the success of the overall design in developing and producing of Shell and it must be settled.For "D6A" super-strength steel, we calculated its the welding crack susceptibility, analysed its crack mechanism and compared manifold welding method. Aiming at the demands of this item, we establish the target, blue print and content of our research, and we made Electron Beam Welding technology research and Tungsten-arc Inert-Gas Welding technology research as emphases. We optimized the dependable and effective welding technology and after manufacturing Shell, we validated the dependability of welding technology, welding parameters and weld quality by concussion of Shell at last. Results are showed as follow:1. Calculating of welding crack susceptibility, Analysis of weldability and crack mechanism and welding technology experiment indicated that the weld joint of "D6A" super-strength steel is easy to break welding crack if the welding technology and welding parameters are not appropriate.2. In Tungsten-arc Inert-Gas welding technology research, we chose "H18CrMoA" welding rod to fill in and adopted reasonable technical measures. In result, the welding quality is up to "I" welding line, the strength is up to 1030 MPa and the toughness excels that of "D6A" base metal.3. In Tungsten-arc Inert-Gas welding technology, it is efficacious to prevent welding crack that "HlCrl8Ni9Ti" welding rod was adopted to lay the foundations, we adopted "HISCrMoA" welding rod to fill in, we cortrolled the temperature at 270^1, made matching post-weld heat treatment at 360t for one hour.4. In Electron Beam Welding technology research, we solved the problem that "D6A" steel is easy to accrue welding crack and gas porosity by optimizing welding parameters and adopting effective measures. In result, the welding quality is up to "IT welding line, the mechanical properties of the welded joint are equal to those of "D6A" base metal.5. In Electron Beam Welding technology, it is efficacious to prevent welding crack, gas porosity and ameliorate molding of welded joint to adopt "? deflexion function, optimiz welding parameters and lay the Electron Beam Focus 4mm underlying the surface of workpiece.6. By comparing and choosing, we found out the dependable and effective welding technology for developing and mass-produce of Shell.7. According to concussion, the structure made by Electron Beam Welding on the warhead works is feasible in the penetrating test, and the warhead kept in very good condition even the body of the bomb seriously deformed. This research solved the problem of the designer’s worry about the vulnerable spot in the structure of the welding line. The satisfactory welding quality get a good opinion from the overall design organization.更多还原