Bonding strength in carbon steel sandwich panels under condition of diffusion-rolling with small reduction

One of the key problems by diffusion-rolling bonding with small reduction for carbon steel plates is the bonding assistant coat. Abonding assitant coat used below 850℃ was developed. It contained copper as basic element and zinc as main alloy element. Other small elements and rear metals were added to decrease the melting point and to obtain a better clouding and bigh plasticity. Based on the theory of brazing and transient liquid diffusion welding, two carbon steel plates were rolled with small reduction by using self-made bonding assistant coat. Temperature, pressure and holding time are the main technology parameters for controlling the process of diffusion-rolling. The results show that the bonding strength is the greatest when the bonding temperature is 830℃, holding time is 3 min and the reduction rate is 9%.     

High temperature plastic deformation behavior of non-oriented electrical steel

High temperature plastic deformation behavior of non-orientated electrical steel was investigated by Gleeble 1500 thermo-mechanical simulator at strain rate of 0.01−10 s⁻¹ and high temperature of 500–1 200 °C. The stress level factor (a), stress exponent (n), structural factor (A) and activation energy (Q) of high temperature plastic deformation process of non-orientated electrical steel in different temperature ranges were calculated by the Arrhenius model. The results show that, with dynamic elevation of deformation temperature, phase transformation from α-Fe to γ-Fe takes place simultaneously during plastic deformation, dynamic recovery and dynamic recrystallization process, leading to an irregular change of the steady flow stress. For high temperature plastic deformation between 500 and 800°C, the calculated values of a, n, A, and Q are 0.039 0 MPa⁻¹, 7.93, 1.9×10¹⁸ s⁻¹, and 334.8 kJ/mol, respectively, and for high temperature plastic deformation between 1 050 and 1 200 °C, the calculated values of a, n, A, and Q are 0.125 8 MPa⁻¹, 5.29, 1.0×10²⁸ s⁻¹, and 769.9 kJ/mol, respectively. Foundation item: Project(2005038560) supported by the Postdoctoral Foundation of China; Project(05GK1002-2) supported by Key Program of Hunan Province     

真空热轧不锈钢复合板界面结合行为的研究

为了研究真空热轧不锈钢复合板的结合行为,本文以热轧304不锈钢／Q345低碳钢复合板为研究对象,通过剪切试验及组织分析等手段研究了变形量及真空度对不锈钢复合板结合性能的影响规律．结果表明,轧制总变形量从35％增加到75％之后复合板的剪切强度大约可增加100MPa．真空度降低会导致结合界面氧化程度增加,进而降低复合板的结合性能,当真空由0.1Pa变为20Pa时,界面氧化物的比例由约10％提高到约50％,剪切强度由440MPa降低到了350MPa左右．最后根据试验结果提出了热轧不锈钢复合板的结合行为．     

The Influence of Preheat Temperature of Steel Plate on Steel-mushy Cu-graphite Bonding

The pressing bonding of steel plate to QTi3.5-3.5 graphite slurry was conducted. Under the conditions of 530 ℃ for the preheat temperature of dies, 45% for the solid fraction of QTi3.5- 3.5 graphite slurry, 50 MPa for the pressure and 2 min for the pressing time, the relationship between the preheat temperature of steel plate and interfacial mechanical property of bonding plate was studied. The results show that when the preheat temperature of steel plate is lower titan 618 ℃ , the interfacial shear strength of bonding plate increases with the increasing of the preheat temperature of steel plate. When the preheat temperature of steel plate is higher than 618 ℃ , the interfacial shear strength decreases with the increasing of the preheat temperature of steel plate. When the preheat temperature of steel plate is 618 ℃ , the highest interfacial shear strength of bonding plate of 127.8 MPa can be got.     

粘钢加固混凝土梁挠度和裂缝的研究

针对9根粘钢加固钢筋混凝土梁的试验结果。对梁的挠度和裂缝进行了非线性理论分析。采用无滑移理论计算结果与实验结果比较吻合．     

压缩变形对BNbRE钢组织的影响

利用Gleeble-1500热模拟试验机研究了变形量、变形道次数等对BNbRE钢组织形态的影响.利用光学显微镜和扫描电子显微镜,观察了BNbRE钢试样的组织形态,利用洛氏硬度计测试了试样的硬度值.结果表明,随着变形量的增加,BNbRE钢显微组织明显变细.变形量越大,珠光体的片间距就越小,珠光体的强度和硬度就越高.在其他条件相同时,变形道次数对BNbRE钢显微组织影响不大.     

Fabrication and compressive performance of plain carbon steel honeycomb sandwich panels

Plain carbon steel Q215 honeycomb sandwich panels were manufactured by brazing in a vacuum furnace.Their character- istic parameters,including equivalent density,equivalent elastic modulus,and equivalent compressive strength along out-of-plane (z-direction)and in-plane(x- and y-directions),were derived theoretically and then determined experimentally by an 810 material test system.On the basis of the experimental data,the compressive stress-strain curves were given.The results indicate that the meas- urements of equivalent Young's modulus and initial compressive strength are in good agreement with calculations,and that the maximum compressive strain near to solid can be up to 0.5-0.6 along out-of-plane,0.6-0.7 along in-plane.The strength-to-density ra- tio of plain carbon steel honeycomb panels is near to those of Al alloy hexagonal-honeycomb and 304L stainless steel square-honeycomb,but the compressive peak strength is greater than that of Al alloy hexagonal-honeycomb.     

The Bonding Properties of Solid Steel to Liquid Aluminum

The bonding of solid steel plate to liquid aluminum was studied using rapid solidification. The relationship models of interfacial shear strength and thickness of interfacial layer of bonding plate vs bonding parameters ( such as preheat temperature of steel plate, temperature of aluminum liquid and bonding time ) were respectively established by artificial neural networks perfectly. The bonding parameters for the largest interfacial shear strength were optimized with genetic algorithm successfully. They are 226℃ for preheating temperature of steel plate, 723℃ for temperature of aluminum liquid and 15.8s for bonding time, and the largest interfacial shear strength of bonding plate is 71.6MPa. Under these conditions, the corresponding reasonable thickness of interfacial layer (10.8μm) is gotten using the relationship model established by artificial neural networks.     

45号钢在往复冲击载荷作用下的塑性变形

摘要：采用钢球冲击45号钢盘,观测了在不同接触条件、冲击次数及载荷条件下钢盘表面的塑性变形情况．发现在低冲击次数条件下,使用低黏度油的凹坑深度与干接触相近,但在高次数冲击条件下,冲击深度与干接触条件下相比大幅度变浅．而高黏度油条件下的凹坑深度一直最浅．在其他条件相同时,冲击深度随载荷的增加而增加．冲击时,由于凹坑中心产生的热量不断向边缘传递,使凹坑边缘形成凸起即形成所谓彩虹环．彩虹环随润滑油黏度的增加及载荷的增加而高度增加．润滑油的使用可以降低材料表面的塑性变形和磨损．对于干接触条件,凹坑内部发生微细颗粒碎化．而油润滑时凹坑内部出现微裂纹．微细颗粒碎化及微裂纹的程度均随冲击次数和载荷的增加而增加．     

滑移线在塑性变形中的应用

本文利用塑性变形过程的特点，建立了滑移线场，由滑移线的几何性质来确定应力分力。它避开了直接用非线性塑性本构关系，因此极大简化了计算过程。     

Acoustic emission study of the plastic deformation of quenched and partitioned 35CrMnSiA steel

Acoustic emission （AE） monitored tensile tests were performed on 35CrMnSiA steel subjected to different heat treatments. The results showed that quenching and partitioning （Q-P） heat treatments enhanced the combined mechanical properties of high strength and high ductility for commercial 35CrMnSiA steel, as compared with traditional heat treatments such as quenching and tempering （Q-T） and austempering （AT）. AE signals with high amplitude and high energy were produced during the tensile deformation of 35CrMnSiA steel with retained austenite （RA） in the microstructure （obtained via Q-P and AT heat treatments） due to an austenite-to-martensite phase transformation. Moreover, additional AE signals would not appear again and the mechanical properties would degenerate to a lower level once RA degenerated by tempering for the Q-P treated steel.     

粘钢加固钢筋混凝土梁仿真软件编制初探

以粘钢加固混凝土梁的仿真分析为例,研究仿真模拟的失败原因。研究结果表明：仿真模拟受材料本构关系、有限元模型、网格尺寸、边界约束条件和荷载步及收敛准则等因素影响,计算前提的微小改动都能导致仿真分析的不收敛。对此,文章在结论中对后续仿真软件的编制提出若干建议。     

不锈钢复铝板结合强度和延伸率的实验研究

实验研究了N2 气保护下加热轧制复合和辊板轧制工艺对不锈钢和铝复合板材界面结合强度及复合板深加工性能的影响。结果表明 ,N2 气保护下加热轧制复合和辊板轧制可有效提高复合板界面结合强度 ,同时使达到界面良好结合的临界变形率明显降低 ;这两种轧制工艺不仅在小变形的条件下即可实现不锈钢和铝复合界面的良好结合 ,而且能明显降低复合过程中不锈钢的变形率分配 ,有利于改善复合板的深加工性能     

Influence of aluminum solid fraction on property of steel-mushy aluminum bonding plate

The interfacial shear property of steel-mushy aluminum bonding plate was studied, and the relationship between aluminum solid fraction and the interfacial shear strength of bonding plate was determined. The results showed that when aluminum solid fraction is 34.3 %, the maximum interfacial shear strength of bonding plate is 71 .0 MPa.     

形变热处理对Cr12MoV钢的变形量及碳化物的影响

研究了Ｃｒ１２ＭｏＶ钢形变热处理对其变形量和碳化物的影响,结果表明,利用锻后余热进行调质处理工艺比锻后球化退火工艺优越,采用新工艺的生产试验,提高效率５０－６０％左右。     

Thickness of compound layer in steel-aluminum solid to liquid bonding

The bonding of solid steel plate to liquid aluminum was studied using rapid solidification. The surface of solid steel plate was defatted, descaled, immersed (in K2ZrF6 flux aqueous solution) and stoved. In order to determine the thickness of Fe-AI compound layer at the interface of steel-aluminum solid to liquid bonding under rapid solidification, the interface of bonding plate was investigated by SEM (Scanning Electron Microscope) experiment. The relationship between bonding parameters (such as preheat temperature of steel plate, temperature of aluminum liquid and bonding time) and thickness of Fe-AI compound layer at the interface was established by artificial neural networks (ANN) perfectly. The maximum of relative error between the output and the desired output of the ANN is only 5.4%. From the bonding parameters for the largest interfacial shear strength of bonding plate (226℃for preheat temperature of steel plate, 723℃ for temperature of aluminum liquid and 15.8 s for bonding time), the reasona     

塑性变形对单晶铜线材导电性影响的研究

为了研究塑性变形对单晶铜线材导电性的影响，以及电阻率与塑性变形量之间的定量关系，将Φ8mm的工业单晶铜线材冷拔后，得到塑性变形量不同的试样，用四端引线法精确测量其电阻率、结果表明，单晶铜线材的电阻率随塑性变形量的增加而上升，其原因是由于单晶铜线材的微观组织畸变程度随塑性变形量的增加而加剧。     

Effect of weld on design of steel moment-resisting connection reinforced with steel plates

The foreign experimental and FEM research of steel moment-resisting connection reinforced with steel plates are introduced. The effect of weld on the connection design is studied in two ways including weld detail and geometrical detail of steel plates contrast to the reference drawing of connection design in China. The research shows that the weld plays an important role in the design of connections. The welds connecting reinforced plates and beam/column flange and the plate geometry have direct influence on the performance of the connections reinforced with plates. The study is helpful to the application of design of steel moment-resisting connection with steel plates.     

Effect of weld on design of steel moment-resisting connection reinforced with steel plates

The foreign experimental and FEM research of steel moment-resisting connection reinforced with steel plates are introduced. The effect of weld on the connection design is studied in two ways including weld detail and geometrical detail of steel plates contrast to the reference drawing of connection design in China. The research shows that the weld plays an important role in the design of connections. The welds connecting reinforced plates and beam/ column flange and the plate geometry have direct influence on the performance of the connections reinforced with plates. The study is helpful to the application of design of steel moment-resisting connection with steel plates.