铜与铝异质搅拌摩擦焊的工艺研究

采用不同的工艺参数对3 mm厚的T2纯铜板材与5383铝合金板材进行了对接搅拌摩擦焊试验,并对焊接接头的显微组织、拉伸性能和耐腐蚀性能进行了测试与对比分析。结果表明,选择适当的工艺参数,可以实现T2纯铜板材与5383铝合金板材的对接搅拌摩擦焊,搅拌头旋转速度、焊接速度和轴肩压力都会影响接头的拉伸性能和耐腐蚀性能,其优选的工艺参数为:搅拌头旋转速度ω=950 r/min、焊接速度v=140 mm/min、ω/v=6.79、轴肩压力P=8 kN。     

旋转速度对汽车用5052铝合金板材高速搅拌摩擦焊接接头组织及性能的影响

高速搅拌摩擦焊是铝合金板材在汽车领域大规模应用的保障。采用五种不同的旋转速度进行了焊接速度恒定为3 000 mm/min的汽车用5052铝合金板材高速搅拌摩擦焊试验,并对焊接接头的显微组织与拉伸性能进行了测试与分析。结果表明,当旋转速度为300 r/min和900 r/min时,接头存在孔洞缺陷,接头系数低于70%;当旋转速度在500 r/min~700 r/min之间时接头无缺陷,接头系数高于85%;当旋转速度为500 r/min时,接头系数最大,为96.1%。旋转速度优选为500 r/min。     

7B04高强铝合金搅拌摩擦焊搭接接头界面成形与力学性能

为了研究7B04高强铝合金搅拌摩擦焊搭接接头的界面成形与力学性能,对2 mm厚薄板搭接接头进行了不同工艺参数的搅拌摩擦焊接。试验结果表明:当旋转速度和轴肩下压量不变,焊接速度在50~300 mm/min之间变化时,接头的抗拉强度先增后减;当旋转速度和焊接速度不变,轴肩下压量在0.1~0.4 mm之间变化时,接头的抗拉强度逐渐增大;当焊接速度和轴肩下压量不变,旋转速度在400~1000 r/min之间变化时,接头的抗拉强度先增后减。当旋转速度为600 r/min、焊接速度为200 mm/min、轴肩下压量为0.3 mm时,接头强度最高。     

搅拌头旋转速度对2024-T3铝合金搅拌摩擦焊接接头腐蚀行为的影响

在不同的搅拌头旋转速度v(400 r/min、600 r/min、800 r/min、900 r/min)下搅拌摩擦焊接2024-T3铝合金,研究了搅拌摩擦焊接接头的力学性能和电化学腐蚀行为。研究结果表明:当v=600 r/min时,焊接接头具有最佳的力学性能,焊核区和热影响区均呈现最高的腐蚀电位和最低的腐蚀电流密度,表明v=600 r/min时焊接接头的耐蚀性最佳,但焊接接头不同区域耐蚀性均低于母材的。     

7075铝合金搅拌摩擦焊接头组织与力学性能研究

利用搅拌摩擦焊方法对7075铝合金板进行焊接,探讨了焊接速度和搅拌头旋转速度等焊接工艺参数对焊缝成形及接头力学性能的影响,并对焊接接头的显微组织进行了分析.结果表明:采用搅拌摩擦焊焊接7075铝合金时,焊接接头具有较好抗拉性能.当旋转速度为750r/min、焊接速度为95 mm/min时,焊接接头的强度最高,达到母材抗拉强度(487 MPa)的97.4％,并且其伸长率也较高(为3.1％);当旋转速度为950 r/min、焊接速度为150 mm/min时焊接接头的伸长率最好,为4.7％.总体上看,焊接接头的伸长率和母材相比较低.     

LF21板搅拌摩擦焊接头组织与焊接工艺关系的研究

利用搅拌摩擦焊方法对LF21铝合金板进行了焊接实验。分析了接头组织分区情况，探讨了搅拌头尺寸及焊接工艺参数对其接头组织的影响。经过实验得知：焊接时，搅拌头旋转速度为950～1500r／min，焊接速度为23．5-375mm／min，皆可获得接头性能尚可的焊接接头。同时发现，搅拌头旋转速度与焊接速度越小焊缝组织越细小：当两焊板间留有间隙时对焊缝孔洞的形成有一定的影响。     

L6-LY12异种材料搅拌摩擦焊接技术

通过SN比试验设计和方差分析研究了L6-LY12异种材料搅拌摩擦焊接工艺参数对焊接接头成形及力学性能的影响。参数显著性顺序为：焊接压力、焊接速度、搅拌头旋转转速。试验表明，对于5mm厚L6-LYl2板材，搅拌摩擦焊接工艺参数范围是：焊接压力2000～3000N；焊接速度37．5～60mm／min；搅拌头旋转速度950～1500r／min。优化的最佳工艺参数为2500N、37．5mm／min、950r／min。获取了等强或超强的搅拌摩擦焊接头。     

MB3镁合金搅拌摩擦连接工艺研究

针对工业用MB3镁合金进行了搅拌摩擦焊接试验。分析了各工艺参数及搅拌头形状对焊缝质量的影响。经过力学测试表明；对于3mm厚的MB33镁合金，采用搅拌头旋转速度为1500r／min，焊速48mm/min时焊接接头成形良好，性能优良。     

焊接参数对5A06铝合金搅拌摩擦焊接头性能的影响

采用搅拌摩擦焊工艺对10 mm厚的5A06铝合金板进行焊接,研究了搅拌头转速(150～400 r/min)、焊接速度(50～200 mm/min)对接头显微组织、拉伸性能和硬度的影响。结果表明:在试验参数范围内焊接均可获得无宏观缺陷且成形良好的搅拌摩擦焊接头;接头焊核区晶粒细小、组织均匀,热机影响区晶粒相比焊核区的粗大,当搅拌头转速为400 r/min、焊接速度为50 mm/min时,接头焊核区和热机影响区的组织明显粗大;当焊接热输入特征值,即焊接速度与搅拌头转速的比值在0.3～0.5 mm/r时,焊接接头的拉伸性能与母材相当,其抗拉强度最高可达381 MPa,断后伸长率可达25.4%;接头焊核区硬度最高,热影响区硬度最低,当搅拌头转速为250 r/min、焊接速度为100 mm/min时,焊核区硬度较高。     

搅拌摩擦焊工艺参数对6005A/6082铝合金接头搭接界面形貌和性能的影响

对12 mm厚6005A-T6铝合金型材和6082-T6板材组合的对搭接接头进行了搅拌摩擦焊接,通过改变焊接转速和焊接速度,研究了搅拌摩擦焊工艺参数对接头搭接界面形貌和力学性能的影响规律。试验结果表明,焊接前进侧和后退侧的不同工艺设计选择对接头搭接界面形貌性能具有一定的影响。当焊接工艺参数匹配合理时,接头热输入量适当,获得成型良好、表面光滑、无隧道孔和沟槽缺陷的焊接接头。在一定范围内,选择型材侧为前进侧,在搅拌头旋转速度为750 r/min,焊接速度为250 mm/min工艺条件下接头强度为229 MPa,达到母材强度的73.9%。     

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。     

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.