焊接焊缝变形的测量研究

针对目前无法采用先进的测量手段获取精确的焊接焊缝变形规律,使得焊接矫正工艺往往不能达到预期效果,提出一种非接触在线全场测量焊接焊缝变形的方法。基于数字图像相关技术,结合传统氩弧焊焊接工艺,对焊缝关键点进行全程跟踪测量并获取变形规律。此方法对焊接变形机制研究提供依据,提供焊接矫正方法思路,对焊接工艺具有重要的指导意义。     

在线测量薄板焊缝区的变形

针对薄板在堆焊过程中焊缝区发生较大塑性变形的问题,提出一种基于数字图像弱相关技术的光学非接触在线测量焊接变形的方法,在焊接及冷却过程对焊缝区域全场及关键点的变形状态进行跟踪测量,获取变形规律.对Q235薄板进行钨极惰性气体保护焊（TIG）堆焊试验,结果表明,垂直于薄板方向上的变形量远大于其余两个方向;薄板焊缝区在焊接过程中先呈凸起状,逐渐冷却后呈马鞍状;薄板焊缝关键点及焊缝区的面外变形量随焊接电流的增大而明显增大.此方法对验证薄板焊接变形的数值模拟预测和揭示焊接变形机理等具有重要的指导意义.     

焊接顺序对某飞行器叉形结构焊接变形的影响

焊接变形影响了结构的承载能力和精密性,尤其对飞行器等精密结构将造成非常严重的后果.为了对某钛合金飞行器叉形结构的焊接变形进行精确测量从而达到控制焊接变形的目的,制作了简化的1:3钛合金模型,根据不同测量方法的特点,对钛合金模型采用数值仿真计算对整体变形进行了模拟,采用数字图像相关技术对远焊缝区域进行检测,并采用三维扫描对工作臂变形角度测量等三种方法,对焊接变形进行测量分析,较于传统测量,采用模拟和试验测试相结合的方法能够紧密联系工程实际,更加全面准确,量化了焊接顺序对焊接变形的影响,找到最佳焊接顺序方案.     

板料焊接屈曲变形测量

板料屈曲变形在焊接工艺中不可避免且难以控制矫正,采用先进的测量手段获得焊接屈曲变形规律进而揭示变形机理是目前研究焊接变形的难点问题.文中拟采用一种基于数字图像相关法的非接触测量方法获取板料焊接屈曲变形的全场全过程变形状态.首先,提出了一种针对弱相关和大变形的对应点匹配算法;其次,建立试验平台并利用DIC测量系统对平板堆焊变形进行测量;最后,在平板堆焊试验的基础上,通过分析变形数据,揭示屈曲变形规律.结果表明,低碳钢在板料焊接与冷却过程中均发生屈曲变形,分别呈碟形与马鞍形;板料焊接产生的应变主要分布在焊缝周围;焊缝纵向收缩是引起板料塑性屈曲变形的主要原因.板料焊接屈曲变形规律试验不仅能验证焊接变形预测有限元理论,而且对焊接矫正方法提供依据和思路,同时对板料焊接工艺的发展具有积极的促进和指导作用.     

薄板焊接热变形的视觉检测方法研究

在焊接过程中,焊件易受热变形,降低了构件安装精度以及结构的承载能力,导致焊件不符合设计和使用要求。精确测量焊接过程中焊件的热变形具有重要的意义。针对焊接过程中焊件热变形测量的问题,结合数字图像相关方法,提出一种基于时序匹配的散斑图像视觉检测方法,提高了图像的采集质量;通过有限元仿真,验证了该方法测量焊接变形的精度较高。该方法实现了薄板焊接热变形的高精度视觉检测     

薄板激光焊接热变形的检测

主要对5052铝合金薄板在激光焊接中的变形过程进行了全程监控,对焊接变形量进行了精确测量并得到焊接过程中待测点的变形量随时间变化的曲线.相对于传统的变形测量而言,采用独特的非接触数字图像相关技术全场测量法对激光焊接变形进行精确的测量,使用三维云图再现了变形量,并在不同焊接参数下对焊接变形量进行研究,得到焊接变形量随激光功率的增加而增加,随焊接速度的增加而减小,随着离焦量负值变为正值而减小.待测点的变形量在焊接过程中呈现持续增长的趋势,但是在不同的时间增长的速度不同.     

薄板单面密集焊缝焊后弯曲变形分析

针对2 mm的316L薄板单面密集焊缝结构,采用数值模拟的方法分析了两种焊接方案下的薄板焊接弯曲变形. 利用高度测量装置建立了薄板弯曲变形测量方法,进行了两种焊接方案的工艺试验,对焊后弯曲变形进行了测量. 在此基础上,对数值模拟和工艺试验的结果进行了对比. 结果表明,薄板单面密集焊缝结构焊接后呈船形变形,拉通焊弯曲变形中心接近于板中心,而两端向中间焊弯曲变形中心偏向板的先焊位置. 两端向中间焊在长度方向弯曲变形量小于拉通焊,两端向中间焊的焊接方案较优.     

数字图像相关技术在材料变形研究中的应用

数字图像相关技术只需白光照明,操作简单,可以在非接触条件下进行全场变形测量。它不仅能够实现变形量从显微应变到2000%大变形的测量范围,也可以实现高温环境下的测量,而且对试验材料、加载形式、加载速率等没有严格要求。本文介绍了近些年数字图像相关技术在材料变形研究中的应用,概述了数字图像相关法的适用范围。根据不同的测量要求总结了相应的解决方法。并且利用数字图像相关技术研究了泡沫铝材料的压缩变形行为,分析了裂纹萌生与扩展,证明了数字图像相关法的优越性。     

厚板对接接头多层多道焊有限元模拟研究

以X70钢厚板对接接头多层多道焊为研究对象,利用MARC软件中的生死单元技术对厚板多层多道焊焊接过程进行模拟,经分析得到了厚板多层多道焊取样点的热循环曲线、试样件的变形和应力曲线,然后对其进行分析,并采用塞尺测量验证仿真结果。结果表明,每个焊缝都会受到后焊接过程的热作用,有多次热循环;沿焊接方向对接接头的自由端发生了明显的角变形,焊接变形最大值为4.984 mm;焊接仿真变形结果与测量结果趋势一致,误差最大为4.54%;焊缝受到其后焊接的多次热循环作用,有多次应力循环,对生产有重要的指导意义。     

T形焊接接头固有变形逆解析方法的开发

基于固有应变方法的弹性有限元方法是适用于大型复杂焊接结构件变形预测的有效方法,但这一方法得以运用的必要条件是必须已知存在于焊缝附近的固有变形.文中利用物理试验和数值模拟技术相结合的研究手段开发了典型焊接接头固有变形的逆解析数值计算方法.利用逆解析得到的固有变形值,采用固有应变弹性有限元方法对T形焊接接头的焊接变形进行了预测.通过比较数值模拟结果和试验测量值,验证了基于数值模拟技术的逆解析方法的求解精度.结果表明,T形焊接接头固有变形的逆解析算法是正确有效的.     

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.     

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。     

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.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

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.     

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.     

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.