铝合金型材搅拌摩擦焊无减薄接头组织和性能

传统铝合金型材通常采用接头局部加厚的凸台设计，用于抵消搅拌摩擦焊中轴肩下压力造成的接头减薄量.然而，此类铝型材表面焊后需要耗费大量工时进行人工打磨.为了减少焊缝的打磨量，文中设计了一种无凸台结构的铝型材，通过改变搅拌头轴肩的结构形式，实现了无减薄工艺的焊接.从焊缝的成形质量、力学性能和组织结构角度开展深入研究，确定了焊接下压量等关键工艺参数.最后，结合实际生产中型材存在挤压公差和拼接公差的特点，研究了接头错边量对焊接质量的影响，并确定合理的接头公差范围.     

Al-10Sr合金焊接接头组织和性能分析

分别采用TIG焊和火焰钎焊焊接了铝锶合金,并比较了焊接接头的显微组织和力学性能.结果表明,在铝锶合金的TIG焊焊缝中,均匀分布着Al4Sr、Al2Sr两相混合物针状组织;而在火焰钎焊的焊缝中,未出现典型的针状组织.由于TIG焊焊缝中针状相的弥散析出,引起Sr元素再分配,并强化焊缝基体,使得TIG焊焊缝的硬度远高于母材;TIG焊接接头的抗拉强度为78.44 MPa,拉伸断口显示母材中心有局部未焊透现象.采用火焰钎焊焊接铝锶合金时,能获得焊缝表面成形良好、无焊接缺陷的焊接接头,接头抗拉强度为72.07 MPa,达到TIG焊的抗拉强度水平.     

客车水箱焊接工艺性能研究

采用钨极氩弧焊(TIG焊)对客车水箱用304不锈钢薄板进行焊接,获得4种焊接接头:全焊透板对接接头、T型接头、单面角焊缝接头和搭接接头,对其力学性能、组织结构、残余应力分布、氯离子敏感度等进行测试和分析。结果表明:4种焊接接头形式中,全焊透板对接接头在力学性能、焊接残余应力分布、耐腐蚀性等方面最优,而单面角焊缝接头在力学性能、焊接残余应力分布、耐腐蚀性等方面最差。     

铝蜂窝板与5A05铝合金的搅拌摩擦焊工艺

文中主要研究铝蜂窝版与5A05铝合金的搅拌摩擦焊工艺,解决了铝蜂窝板搅拌摩擦焊时受搅拌针轴肩压力易塌陷的难题,优化铝蜂窝板焊接接头形式,设计镶嵌式对接接头,进行搅拌摩擦焊工艺试验,分析焊缝力学性能、X射线探伤并观察金相组织,优化搅拌摩擦焊焊接工艺参数,得到了无缺陷、力学性能较好的焊缝.试验结果表明,铝蜂窝板和5A05铝...     

保护气体对铝母线MIG焊产生气孔的影响

MIG焊在电力行业铝母线安装过程中由于功效高而成为普遍采用的焊接方法,其缺点是较容易产生气孔.气孔的存在削弱了焊缝的有效截面积、接头强度、塑性下降和电导率下降,严重影响焊接接头使用性能和寿命.通过对铝母线MIG焊进行工艺试验,利用三种保护气体分别对四个焊位进行焊接试验,确定出铝母线MIG焊气体保护的最佳方法.     

铝钢复合箱形搅拌摩擦焊焊接结构柱的研究

基于第三届全国大学生焊接创新大赛固定题目焊接结构设计要求,设计一个铝钢复合材料的抗压箱形柱结构,经过有关软件对设计结构进行模拟计算和焊接工艺方法分析,确定了采用搅拌摩擦焊的技术方案。在对实验室近40年的老旧台钻床改造手动搅拌摩擦焊机的基础上进行铝钢丁字接头的搅拌摩擦焊试验。通过实际对铝钢复合结构承受压力测试以及铝钢搅拌摩擦焊焊接接头的界面抗剪强度测试表明,该焊接技术方案满足焊接创新大赛比赛要求,取得很好的比赛成绩。     

CO_2保护焊焊接车身骨架常见缺陷及其预防

二氧化碳气体保护焊是一种先进的电弧焊工艺,现已在我国大客车生产中得到了普遍的应用。我厂在客车生产中也大量采用CO2保护焊焊接车身骨架。在骨架构件中,异形钢管的连接形式主要为T形接头(如图1)和对接接头(如图2),焊缝形式为角焊缝和I形焊缝,一般采用!0.8～!1.0mm焊丝进行焊接,能获得良好的焊接接头,达到客车所要求的焊缝强度。但由于受各种因素的影响,在骨架焊接中常会出现诸如变形、未焊透、气孔、焊缝加厚高过大等焊接缺陷。针对这些缺陷,本文逐一进行了分析,探讨了其改进措施,以进一步提高客车生产水平。1车身骨架的焊接变形焊接变…     

铝锂合金FSW焊接接头的组织与性能

对2 mm的Al-Li-S-4铝锂合金薄板进行了FSW焊焊接试验,利用光学显微镜和扫描电镜观分析了焊接接头的显微组织和断口形貌特征,并对其室温拉伸性能和显微硬度进行了测试。结果表明:Al-Li-S-4铝锂合金FSW焊焊缝成形良好,接头组织细小,且焊缝强化相并未溶解,接头拉伸强度达到母材的82.6%,焊缝显微硬度高达115 HV,接头表现出良好的塑性。     

核工程中一种全熔透钢筋锚固式预埋件焊接接头性能研究

我国相关标准规范规定全熔透钢筋锚固式预埋件均采用穿孔塞焊接头形式进行焊接,文中选取直径分别为16, 32 mm的HRB400钢筋,采用K形坡口全熔透+角焊缝组合焊的焊接接头形式进行焊接试验,焊后对焊缝进行了VT, PT, RT检测,以及对焊接接头及附近区域对应位置的钢板进行了UT检测,最后对接头进行拉伸、弯曲、宏观金相及微观金相试验测试。结果表明:全熔透钢筋锚固式预埋件采用K形坡口全熔透+角焊缝组合焊的焊接接头完全满足质量要求,可推广应用到核工程建造中。     

焊后热处理对铝锂合金激光焊接头微观组织的影响

采用Nd:YAG激光对3 mm厚5A90铝锂合金薄板进行激光焊接,焊后对接头进行了固溶-时效处理,对热处理前后接头微观组织和显微硬度的分布进行了对比研究。研究结果表明,焊态5A90铝锂合金激光焊焊缝组织晶粒形态为等轴枝晶,未观察到强化相;经过焊后处理后,接头不同区域组织均呈现明显的晶界,焊缝金属晶粒形态转变为等轴晶,焊缝组织均匀性得到改善,并且焊缝金属晶粒内部弥散析出较多的δ'强化相。焊态下5A90铝锂合金激光焊焊缝的显微硬度低于母材,焊后热处理使焊缝金属中δ'强化相析出从而使焊缝的硬度显著提高。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.     

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality of the slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in mold.This technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, thereby controlling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle and partly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structure and angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower than that without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at the top surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial to the growth of equiaxed crystal and decreased element segregation.