Tensile, bending, room temperature and low temperature-40 ℃ impact and hardness tests were performed on Q450NQR1 high-strength weathering steel MAG welded 45°, 50°, 60° HV grooved butt joints, and the fractures of the tensile and impact specimens were scanned and the microstructure for analysis. The results showed that the tensile properties of the three different included angle joints were good, and the tensile properties of the 45° bevel joint were the best, the 45°, 50°, 60° HV included angle joints had good bending properties. The room temperature impact performance was good, but the low temperature impact performance was significantly reduced. The room temperature and low temperature impact performance of the 50° included angle joint was higher than that of the other two included angle joints. Observing the fracture surface showed that the specimens at different temperatures were all ductile fractures, the hardness distribution of the three different included angle joints was roughly the same. The hardness value near the fusion line of the 60° included angle joint was higher than that of the other two included angle joints, and the hardness values were all in line with the standard, the 60° included angle was pre-eutectoid in the joint weld due to the large included angle and slow heat dissipation. The amount of ferrite was more than the other two groove joints.
To effectively improve the exothermic welding effect of the subway copper grounding grid, it was necessary to reasonably set the exothermic welding process parameters. Therefore, the optimization method of the exothermic welding process parameters of the subway copper grounding grid was studied. Taking T2 type copper tube with a diameter of 35 mm, a wall thickness of 3 mm, a length of 1 800 mm, and w（Cu）99. 98% as an example, the exothermic welding process was selected, and the three main exothermic welding process parameters, namely preheating temperature, welding speed and welding time, were analyzed by orthogonal experiment to optimize the exothermic welding process parameters of copper tube. The experimental results showed that the order of the primary and secondary factors affecting the exothermic welding effect of the subway copper grounding grid was: welding speed, preheating temperature, compaction pressure, and the corresponding optimal process parameters were 0. 6 mm∕s, 100 ℃, 0. 43 MPa respectively. After optimizing the exothermic welding process parameters, the exothermic welded joints of the welded metro copper grounding grid were neat and beautiful, without burrs and solution splashing, and there were almost no cavities on the welding cutting surface. The surface was relatively flat and dense. The maximum impact energy at the welding point could reach 91. 6 J, and the maximum compressive strength could reach 481. 5 MPa. It had good toughness and compression resistance, and the welding effect was good.
在实际生产中,650轧机2000kW电机轴发生了突然断裂,从断裂看,断口有10％旧裂纹.电机轴材质为35CrMo钢,因没有备品,需要尽快修复.为了防止变形,采用芯轴热装对接的方法,精准对中;同时,为防止长轴产生焊接变形,采取了预热和消除应力的措施,成功进行了修复,及时恢复了生产.
为满足国家对海洋油气生产装备制造业的战略需求,同时适应集团公司"建设国际一流能源公司"的总体布局,结合公司发展战略和转型升级需要及滨海新区场地现状,本公司拟在天津港保税区临港区域建设一个海洋工程装备制造基地.利用此次契机,同时为了盘活国有闲置资产,经过考察、论证,决定重新启用原上海振华港机制造的1台900 t门式起重机,通过拆解、运输、合龙、安装、调试,达到重新启用的目的.龙门吊主体的合龙、安装主要采用手工焊接的方法,安装、调试完成后经过第三方的质检和特检所的验收,各方面均合格,一次性通过验收,完全可以重新投入使用.经过一段时间的试运营,设备各方面指标、性能都得到充分的验证,性能稳定,运行平稳,受到使用方和业主的高度评价和赞扬.
通过对不锈钢药芯焊丝E308LT1-1在使用防飞溅剂时,焊接后容易产生气孔进行分析,发现防飞溅剂污染焊接坡口后焊接时产生了大量的气体,导致不锈钢药芯焊丝E308LT1-1焊缝容易产生氢气孔.合理控制氟化物和氧化物的加入量能够提高不锈钢药芯焊丝对防飞溅剂的适应性,使焊缝不产生气孔;合理加入氧化铁和氧化铈不会对该药芯焊丝工艺性能和力学性能产生不良影响.
The integral closed impeller is more and more widely used in industry because of its superior performance,high efficiency and stability,long life and other advantages. As the structure of integral closed impeller is becoming more optimized,the wire arc additive manufacturing（ WAAM） is becoming more competitive in manufacturing the blank of integral closed impeller with high efficiency and high quality near-net forming due to its advantages of high deposition efficiency, large process flexibility and low forming cost. The large dip angle ring structure is the key component of the integral closed impeller,and its angle. The dip angle changes greatly and under different dip angles,the droplet transfer behavior is different in the process of additive manufacturing,resulting in different layer width,layer height,and weld bead overlap between layers,which poses a great challenge to the high-quality near-net forming of WAAM. In view of this,this paper had carried out the research on the process of WAAM with large dip angle ring structure,analyzed the structural characteristics and formed the additive manufacturing path strategy,that was,each layer was formed by two circular tracks overlapping,and the normal direction of the tracks was adapted to the dip angle.The influence of process parameters such as feed rate and overlap rate on the forming quality was studied. On this basis,the manufacturing process was determined,that was,the wire feed rate was 7 m/min,the feed rate was 500 mm/min,and the overlap rate was 50%. Finally,the high quality near-net forming of large dip angle annular structure blank was achieved.
文中针对TIG焊工艺发展,综合考虑TIG焊在实际生产应用中焊接效率低等问题,在充分调研近年来新型TIG焊技术进展情况,从电弧集中、能量分布、熔深控制、提升效率等方面,对活性焊剂TIG(A-TIG)焊、热丝TIG焊、TOP-TIG焊、窄间隙TIG焊,双电极TIG(T-TIG)焊、超声波-TIG混合电弧(U-TIG)焊、TIG-MIG焊、小孔TIG(K-TIG)焊、高频脉冲TIG(H-TIG)焊、磁场控制TIG焊(M-TIG)和空心钨极负压电弧焊等方法进行了综合阐述及评价.
镍基合金-陶瓷复合涂层是近些年的研究热点,WC,Al2O3,Cr3C2等硬质相的加入可以显著提高合金涂层的耐磨性和显微硬度.在涂层的制备或后期的重熔处理过程中,受热作用的影响,粒子易于弥散分布在涂层内,被包覆于网状的组织中,涂层性能得到大幅提高.文中对国内外等离子弧喷涂、喷焊、堆焊及重熔处理NiCrBSi及其复合涂层的研究加以总结,并对未来的发展趋势进行预测.
Coarse-grained microstructure often occurs in the heat affected zone（HAZ） during welding of X10CrAlSi18 heat-resistant stainless steel, resulting in the deterioration of mechanical properties of welded joints. In this paper, the Gleeble 3800 thermal simulator was used to simulate the microstructure change of welding heat affected zone in the range of 0. 04～2. 5 k J∕mm heat input. On the basis of thermal simulation, X10CrAlSi18 steel was welded by MIG welding technology. At the same time, tensile test and fracture scanning were carried out on the welded joint at room temperature. It was found that the coarsegrain size of the joint grew from 73 μm to 110 μm when the heat input increased from 0. 31 k J∕mm to 0. 52 k J∕mm. The elongation of the joint decreased from 21. 60% to 19. 27%, and the failure mode of the joint change from ductile fracture to brittle fracture. Therefore, the use of lower heat input was one of the effective means to shorten the residence time of welding at high temperature and avoid the embrittlement of coarse crystal under the condition of ensuring the quality of welding parts.
高拉应力状态下的全焊接桥梁结构安装及成桥运营风险极大,焊接接头的防裂抗裂水平直接决定桥梁安装施工及成桥后的运营安全.文中通过对三官堂大桥这一大跨度全焊接连续钢桁梁的受力状态及焊接质量进行风险分析,针对性地提出应对措施,经工程验证行之有效,对全焊接钢结构桥梁的焊接施工有很大的借鉴价值.
The 6005A-T6 aluminum alloy profile was welded by double shoulder friction stir welding. The staggered joints with different sizes were prepared through process test,and the tensile,bending,hardness,fatigue and fracture scanning tests were carried out. The mechanical properties of 6005A-T6 aluminum alloy welded joints were studied.The test results showed that the misalignment had an effect on the tensile properties of aluminum alloy joints. With the increase of the amount of misalignment,the tensile strength of the joints decreased,while the misalignment had little effect on the bending properties and hardness of the joints. The misalignment of specimen assembly had a great influence on the fatigue performance of 5 mm thick 6005A-T6 aluminum alloy double shoulder friction stir welded joint. With the increase of misalignment,the fatigue limit value would decrease and the fatigue performance would decrease on the forward side or backward side.
在304不锈钢板的边缘用脉冲光纤激光进行单点穿孔,用高速摄像机从侧面观察小孔形成的宏观过程,并采用正交试验法设计试验,研究了激光功率、激光打开时间及关闭时间对小孔深度的影响,同时以不同的速度在钢板边缘进行连续穿孔,进一步验证小孔深度与时间(脉冲数)的关系.结果表明:对于不同的激光参数,小孔深度与激光脉冲数均呈近似对数关系,即前几个脉冲的小孔深度增大较快,随后增幅大幅减慢;激光功率越大,打开时间越长,关闭时间越短,所获得的小孔深度和直径越大,其中激光功率影响最大,激光打开时间次之,激光关闭时间影响较小.
为了降低超高强装甲钢车体焊接接头残余应力,文中通过对超高强装甲钢焊接接头频谱振动时效和超声波冲击振动时效,验证焊缝残余应力消除效果,并评价时效处理前后尺寸精度变化,最后通过焊接工艺评定试验来分析焊态、整体振动时效和超声波冲击振动时效不同状态下的力学性能、硬度和金相组织差异.通过分析研究可知:经频谱时效振动后的焊缝残余应力可降低29.52％;经超声波冲击振动后的焊缝残余应力可降低50％左右;超声波双面双侧冲击的试板尺寸变化量最小,尺寸变化量在±0.05 mm内;频谱时效振动的试板尺寸变化量最大,尺寸变化量在±0.2mm内.同时超声波冲击时效后的焊缝显著提高了接头的连接强度及抗弯能力;但不同状态下对应的焊接接头各区域硬度变化无显著差异,焊接接头各区域的组织基本一致,无差异.
针对标准动车组转向架构架侧梁焊接过程中存在的变形,基于Simufact数值仿真平台,研究焊接顺序对焊接变形产生的影响.通过对热弹塑性有限元法计算数据的充分分析,得出最优的焊接顺序方案,为确定有效的焊接变形控制方法提供理论和数据支撑,为构架侧梁结构优化设计、焊接工艺设计提供有力支持.
为了适应当前新工科教育的需要,提高材料成型及控制工程专业实践教学质量,培养学生创新能力,以含缺陷焊接结构可靠性评价实训课程为研究对象,进行了材料成型及控制工程专业实践教学改革的探索.将当前教育领域的探究式教学理念、虚实融合方法及数字孪生技术方法融入材料成型及控制工程新工科实践教学改革,构建了基于"虚拟+数字孪生"环境的焊接结构裂纹扩展混合实践教学平台,将理论学习、虚拟仿真试验和实际"实验操作"结合一体;同时针对实际工程案例,学生独立自主设计试验方案,完成数据分析及应用,实现理论与实践的统一.利用此混合实践教学模式,解决了新工科项目式教学设计难题,有利于促进学生的自主学习,激发学生工程实践的探究兴趣,增强学生的实践动手能力和创新能力,从而有效提高实践教学效果.
阀门唇边密封焊缝完成对阀门的二次密封,确保了阀门长期运行时的密封效果,但是密封唇焊的手工切割及焊接工艺却并不完善,因此探索阀门密封唇焊手工切割及焊接工艺对提高密封焊缝质量和增加阀门服役寿命具有重要意义.
建设桥梁拼接焊接是目前最常用的连接方式,但是这种方式容易导致焊接接头因热处理出现裂纹,经长时间腐蚀加重裂纹,导致桥梁出现塌方等事故.其中残余应力是判定桥梁焊接区稳定性的重要指标,提出桥梁钢厚板焊缝区残余应力数值模拟研究方法.分析桥梁钢厚板焊缝区温度传导,得出钢厚板温度场边界条件以及温度场热传导的总控制结果、应力场的热塑应力,获得焊缝区应变与位移的关系,并通过高斯函数描述加热斑点中的热流密度,构建应力学数学模型,计算出焊接过程的温度场,明确残余应力与应变间关联,最终划分应力场网格,在有限元模型上模拟出焊缝区的残余应力数值.试验结果表明:所提方法的残余应力数值模拟精度高.
The slag removal of E309lT1-1 titanium stainless steel flux cored wire in mass production was unstable. The chemical composition of deposited metal was analyzed, and the composition and structure of slag were analyzed by fluorescence spectrometer and scanning electron microscope. The results showed that the non-uniformity of trace components of flux powder of stainless steel flux cored wire led to great differences in the internal surface microstructure of slag, resulting in unstable slag removal performance of stainless steel flux cored wire in mass production. Due to the fluctuation of trace components, the rod bundle structure with strong adhesion couldn′t be formed on the inner surface of the slag, which reduced the internal adhesion of the slag, and the slag shell itself was broken first after welding, even slag sticking. The main reason for the non-uniformity of trace components in powder was the great difference of shunting mobility among each group. After the improvement of the production process of strictly selected raw materials, the slag removal ability of stainless steel flux cored wire had been significantly improved and its performance was stable.
文中针对一种铝合金锁底结构的电子束焊,当锁底宽度尺寸小到一定程度时,易产生背部焊瘤、背面飞溅等缺陷,通过研究锁底宽度尺寸对电子束焊焊缝成形的影响,提出了合理的焊接工艺参数和结构参数,满足锁底结构电子束焊要求.
With the development of radar technology, microwave modules are developing in the direction of miniaturization,lightweight and high reliability. In the actual production process,T/R module sealing cover and the shell are prone to defects such as cracks and pores,which make the air tightness of the product not up to the standard.In this paper,an experimental study on the laser welding process of silicon aluminum alloy commonly used in TR modules was carried out,and the influence of peak power,pulse width,pulse frequency and defocusing amount on the welding appearance and air tightness of the T/R module was analyzed to obtain the optimal process parameter. The test results showed that when the peak power was 4. 5 k W,the pulse width was 3. 5 ms,the welding speed was 2 mm/s,the laser frequency was 15 Hz,and the defocus was-1 mm,the sealing welding quality could be obtained,and the helium leakage rate below 5 × 10 -6 Pa·m~3/s. Finally,it was concluded that the sealing welding quality was needed to be observed in time to fine tune the laser sealing welding process parameters in the production process,and replaced the new laser protective lens if necessary. The test results had certain significance for laser sealing welding to guide production and process research.
