大规格高强度钛/纯钛/不锈钢爆炸焊接复合板性能研究

通过爆炸焊接工艺制备出大规格(大面积、大厚度)的化工用高强度钛/纯钛/不锈钢(Gr12/Gr1/316L)爆炸焊接复合管板,并对其结合质量、力学性能、结合界面形态进行研究。结果表明,复合板的结合质量良好,钛/不锈钢界面的剪切强度达到290 MPa以上,其力学性能也达到ASTM B898-2011(2016)标准要求和客户的验收指标;结合界面形态分析表明,钛/钛(Gr12/Gr1)界面呈现近似于直线状结合,钛/钢(Gr1/316L)界面呈现波纹状结合。     

TA1/Q235R爆炸焊接复合板界面组织及力学性能

通过扫描电子显微镜（SEM）和能谱扫描仪（EDS）等分析方法，结合力学性能试验，研究了TA1/Q235R爆炸焊接复合板的界面组织与力学性能。结果表明：TA1/Q235R在爆炸焊接后形成了规律的波状结合界面以及不均匀的漩涡状组织。漩涡组织主要由TiFe、TiFe2等脆性金属间化合物组成，漩涡组织中裂纹、夹杂物、脆性金属间化合物等缺陷导致界面的破坏易沿波形轨迹发生；钛/钢界面拉伸剪切强度达194 MPa，复合板的最大抗拉强度为440 MPa；拉剪断口表现为以脆性断口为主的混合断裂特征，断口特征表明漩涡组织中金属熔化层对钢侧的结合强度高于钛侧。板材拉伸断口为韧性断口。     

钛铝复合板热加工图及热轧实验

采用Gleeble-3500热模拟试验机进行高温等温压缩实验,研究了爆炸焊接钛铝复合板在变形温度为300~500 ℃、应变速率为0.1~10 s^-1条件下的热变形行为,利用动态材料模型构建了钛铝复合板热加工图,并基于热加工图进行了钛铝复合板热轧工艺验证实验。结果表明：钛铝复合板属于正应变速率敏感材料;在热加工图中变形温度为420~460 ℃、应变速率为1.6~6.3 s^-1时,功率耗散效率达到0.64~0.72,该区域对应的工艺参数适合进行钛铝复合板热轧;热轧后实验板材界面结合良好,具有良好的力学性能和钣金成形性能。钛铝复合板在热轧过程中的变形机制为：变形抗力低、流动快的铝层在自身发生塑性变形的同时牵引着钛层一起发生塑性变形,其中铝层是热变形,钛层为冷变形。     

爆炸焊接装药方式对钛/钢复合板组织及性能的影响

分别采用等厚度装药及分段装药两种不同的装药方式制备了钛/钢复合板,研究了金属复合板在爆炸焊接过程中爆炸压力分布及覆层金属变形规律,并对所制备的Gr1/Gr70爆炸复合板结合界面的微观组织特征和力学性能进行了分析。结果表明,采用分段装药工艺所制备的大面积钛/钢复合板界面无分层、夹杂等缺陷,且各项力学性能均符合ASTM B898—2005标准,能够满足装备的使用要求。     

铝/钛/钢爆炸复合板性能研究

通过试验加工了船用铝/钛/钢(5083/1060/TAl/CCS-B)爆炸焊接复合板,并对其结合质量、力学性能及界面形态进行了研究.结果表明,将纯铝板1060和钛板TA1作为中间过渡层后,复合板的结合质量良好,且铝/钛界面的剪切强度达到85 MPa以上,其力学性能也均达到了相应标准;钛/钢界面呈规则的正弦波形,产生了较明显的塑性变形;铝/钛界面比较平直,波长较大,波幅较小.     

钛-钢-钛三层爆炸复合板的界面及性能研究

为了研究钛-钢-钛三层复合板的微观界面和力学性能,在对两次爆炸焊接的动能损耗进行计算的基础上,利用扫描电镜及能谱分析仪对两次爆炸焊接的界面进行了研究比较;对复合板进行了显微硬度测试、弯曲强度试验和剪切强度试验。结果表明:第二次爆炸焊接时的动能损耗更大,动能经过复板向基板传递,导致首次爆炸结合界面缺陷较明显,其熔化层和熔化块数量较多,体积较大;二次爆炸结合界面呈较好的波状结合。首次爆炸焊接界面处的显微硬度高于二次爆炸焊接界面,说明首次爆炸焊接界面的塑性变形更为严重;复合板在弯曲试验中未断裂和分离,抗弯性能良好;首次爆炸焊接界面处的结合强度低于二次爆炸焊接界面,但均满足复合板强度标准。     

钛/铝复合板爆炸焊接技术研究进展

通过爆炸焊接技术制备的钛/铝复合板可兼具钛合金耐腐蚀性和铝合金低成本的优点。对钛/铝复合板爆炸焊接技术的研究进展进行介绍,论述了炸药种类、质量比R、基覆板间距及爆炸焊接窗口等主要工艺参数对钛/铝复合板组织和性能的影响;分析了影响钛/铝复合板结合界面的主要因素——金属间化合物种类、扩散层和界面波形;对钛/铝复合板硬度、抗剪切强度、抗拉强度及拉伸断口的研究进行了汇总分析。最后,指出了钛/铝复合板爆炸焊接工艺研究的重点发展方向。     

热加工工艺对钛-钢复合板界面力学性能和显微组织的影响

研究了热加工工艺对钛-钢复合板界面力学性能和显微组织的影响。测试了在A，B，C，D4种温度下热轧复合板界面的力学性能，用金相显微镜及扫描电镜观察了界面显微组织并分析了界面的成分。结果表明，在A，B2种温度下轧制的钛-钢复合板界面机械性能良好，延伸率高，其剪切强度不但可保持坯料原有的水平，甚至还略有增加。在C，D2种温度下轧制的钛-钢复合板界面机械性能相对较低，延伸率较高，但剪切强度要比爆炸复合坯料低，尤其是D加热温度，轧制后界面剪切强度急剧下降。热轧的终轧温度也是影响钛-钢复合板界面结合性能的重要因素。在低于相转变温度的合适温区热轧，且终轧温度合适，获得的钛-钢复合板结合界面无爆炸波纹，没有污染，生产的脆性化合物极细小，组织类同于钛材完全退火的等轴组织。     

R60702/TAI/16MnⅢ复合板爆炸焊接数值模拟与试验

随着爆炸焊接技术的发展,锆-钢复合板作为一种特殊的耐蚀复合材料,结合了锆优良的耐蚀性能和钢的高强度的优点,在工业中的需求量也逐步增加.以爆炸焊接理论为基础,采用数值模拟和试验分析相结合的方法,在ANSYS/LS-DYNA软件中模拟R60702/TAI/16MnⅢ复合板不同间隙值组合下爆炸焊接的动态过程.分析间隙值对整个R60702/TAI/16MnⅢ复合板爆炸焊接成形的影响.结果表明,当锆-钛间距/钛-钢间距取值为12/6 mm时,可以实现良好焊接.对试验焊接后R60702/TAI/16MnⅢ复合板上不同位置处的试样进行扫描电镜分析,观察复合板界面的结合状况,为选择更合适的工艺条件提供数据支撑,有利于指导生产实践.     

3 mm厚钛/钢复合板低爆速炸药稳定爆轰的研究

研究3 mm厚的钛/钢复合板在爆炸焊接工艺技术条件下,采用不同药量的低爆速炸药,通过从起爆端开始沿爆轰长度方向对结合界面进行波纹检测及氧化和熔化研究,研究低爆速炸药不同用药量时在钛/钢复合板的稳定爆轰长度,为长度≥4 m钛/钢复合板爆炸焊接工艺参数的制定建立基础.     

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.     

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.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

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.     

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.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.