Immersing Treatment of Steel Plate Surface in Steel-Aluminum Solid to Liquid Bonding

The interfacial status of the steel-aluminum solid to liquid bonding plates (their steel plate surfaces were or were not immersed in flux aqueous solution) were measured by using SEM (Scanning Electron Microscope) and X-ray diffraction . The results showed that the layer of flux (the minimum thickness was 15 μm on the steel plate surface) could protect the steel plate surface from oxidizing effectively at high temperature in solid to liquid bonding. The melt temperatUre of the flux should be lower than 580 ℃ so that it could be melted and removed completely. No. 1 flux (patent product made by the author) made up of halogeindes could also force liquid aluminum to infiltrate into steel plate surface and thus the interfacial shear strength of the bonding plate was rather large.

Microstructure and properties of S30403+Q345R roll-bonded clad steel plate for pressure vessels

To meet the demand of the domestic pressure vessel industry for roll-bonded clad steel plates, Baosteel has developed an S30403 ＋ Q345R roll-bonded clad steel plate. Comprehensive inspections of the composition, microstructure, and properties are made to systematically evaluate the steel plate in the normalized and normalized ＋ stress relieved states. The results show the cladding interface of the S30403 ＋ Q345R roll-bonded clad steel plate has high shear strength, the base metal has good properties, and the mechanical properties of the steel plate head and tail are uniform. The performance is fully consistent with the technical requirements of the roll-bonded clad steel plate for pressure vessels.

Development of S11306+SA516Gr70 roll-bonded clad steel plate for pressure vessels

To meet the demand of the pressure vessel industry, Baosteel has developed an S11306 ＋ SA516Gr70 roll-bonded clad steel plate. Comprehensive inspections of the composition, microstructure, and properties are performed to systematically evaluate the steel plate in normalized state and normalized ＋ stress relieved state. The results show the cladding interface of the Sl1306 ＋ SA516Gr70 roll-bonded clad steel plate has high shear strength, and the base metal has good mechanical properties. The performance is fully consistent with the technical requirements of the roll-bonded clad steel plate for pressure vessels.

Effect of plastic deformation on diffusion-rolling bonding of steel sandwich plates

Diffusion bonding is one of the most important techniques for composite materials, while bonding temperature, holding time,and rolling reduction are the key parameters that affect the bonding strength of sandwich plates. To study the effect of plastic deformation on the bonding strength, laboratory experiments were carried on a Gleeble Thermal Simulator to imitate the diffusion-rolling bonding under different reductions for steel sandwich plates. The bonding strength and interlayer film thickness were measured, and the element diffusion was analyzed using line scanning. The relationship between the bonding strength and “diffused interlayer” thickness was investigated. It has been found that the bonding strength increases with reduction, whereas the interlayer film thickness decreases gradually as the reduction increases. The diffusion under plastic deformation is obviously enhanced in comparison with that of nil reduction. The mechanism of plastic deformation effect on the diffusion bonding and related models have been discussed.

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.

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.

Semi-solid Processing of Steel-Al-7 Graphite Binding Plate

The bonding of steel plate to Al 7graphite slurry was studied for the first time. The relationship model about preheat temperature of steel plate,solid fraction of Al 7graphite slurry, rolling speed and interfacial shear strength of bonding plate could be established by artificial neural networks perfectly.This model could be optimized with a genetic algorithm.The optimum bonding parameters are:516℃ for preheat temperature of steel plate,32.5% for solid fraction of Al 7graphite slurry and 12mm/s for rolling speed,and the largest interfacial shear strength of bonding plate is 70.6MPa.

The Bonding Properties of Solid Steel to Liquid Aluminum

The bonding of solid steel plate to liquid al uminum was studied using rapid solidification. The relationship models of interf acial shear strength and thickness of interfacial layer of bonding plate vs bond ing parameters (such as preheat temperature of steel plate, temperature of alumi num liquid and bonding time) were respectively established by artificial neural networks perfectly.The bonding parameters for the largest interfacial shear stre ngth were optimized with genetic algorithm successfully. They are 226℃ for preh eating temperature of steel plate, 723℃ for temperature of aluminum liquid and 15.8s for bonding time, and the largest interfacial shear strength of bonding pl ate is 71.6 MPa . Under these conditions, the corresponding reasonable thickne ss of interfacial layer (10.8μm) is gotten using the relationship model establi shed by artificial neural networks.

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

The bonding of solid steel plate to liquid aluminum was studied using rapidsolidification. The surface of solid steel plate was defatted, descaled, immersed (in K_2ZrF_6 fluxaqueous solution) and stoved. In order to determine the thickness of Fe-Al compound layer at theinterface of steel-aluminum solid to liquid bonding under rapid solidification, the interface ofbonding plate was investigated by SEM (Scanning Electron Microscope) experiment. The relationshipbetween bonding parameters (such as preheat temperature of steel plate, temperature of aluminumliquid and bonding time) and thickness of Fe-Al compound layer at the interface was established byartificial neural networks (ANN) perfectly. The maximum of relative error between the output and thedesired output of the ANN is only 5.4%. From the bonding parameters for the largest interfacialshear strength of bonding plate (226℃ for preheat temperature of steel plate, 723℃ for temperatureof aluminum liquid and 15.8 s for bonding time), the reasonable thickness of Fe-Al compound layer10.8 μm was got.

Mechanical relationship in steel-aluminum solid to liquid bonding

The bonding of solid steel plate to liquid aluminum was studied by using rapid solidification. The relationship between the bonding parameters such as preheat temperature of steel plate, temperature of aluminum liquid and bonding time, and the interfacial shear strength of bonding plate was established by artificial neural networks perfectly. This relationship was optimized with a genetic algorithm. The optimum bonding parameters are: 226 ℃ for preheat temperature of steel plate, 723 ℃ for temperature of aluminum liquid and 15.8 s for bonding time, and the largest interfacial shear strength of bonding plate is 71.6 MPa.

Study on process of roll bonding stainless and carbon steel under non-vacuum condition

The non-vacuum roll bonding method of nickel plating on the base materials is put forward in accordance with the primary problems existed in the roll bonding of stainless/carbon steel. After nickel plating test on the base materials, the microstructure of nickel cladding is observed by scanning electron microscopy （SEM） at high, and room temperature, and the results show that the nickel cladding on base material can be protected from oxidation in the high temperature. Non-vacuum roll bonding tests of nickel plating on base materials are done by the roll bonding equipment, and the roll bonding plates of stainless/carbon steel are obtained. The microstructure and the elements distribution of non-vacuum roll bonding interface are analyzed by optical microscope （OM） and SEM. The results reflect that the nickel plating layer and the base materials bond well.

既有RC变截面柱加固前后的力学性能

针对变截面柱加层改造处存在的外力损伤、混凝土强度变低等问题,采用增大截面法、CFRP包裹法及粘钢加固法对构件进行加固并分析其受力性能。结果表明:增大截面法、CFRP加固法及粘钢加固法使原构件轴压承载力分别提升了113%、128%、112%,使侧压承载力分别提升了105%和192%及154%,但在周期荷载作用下粘钢加固法具有较大优势;增大截面法适用于提升变截面柱轴压承载力,CFRP加固适用于提升侧压承载力及轴压承载力,但两者均不适用于提升变截面柱抗震能力。而粘钢加固法相较于前两种方法均具有普适性。

水工混凝土结构修补加固关键技术探析

我国多数水库大坝建设年代早,水工混凝土结构存在各种老化安全问题,亟待采取修补加固处理。针对水工混凝土结构缺陷类型较多,缺陷修补加固技术复杂,本文根据水工混凝土结构的运行环境和常见缺陷类型,对其修补加固方案、加固材料及施工工艺等进行了技术总结,结合漳河水库水工混凝土结构缺陷问题,详细阐述混凝土裂缝、混凝土表面剥蚀、局部结构强度不足等缺陷产生原因和最新加固技术,相关研究成果和实践经验可供类似工程借鉴。

C型外包花纹钢-混凝土界面粘结强度推出试验研究

为探究带拉条式C型外包花纹钢-混凝土的粘结强度及粘结滑移性能,考虑钢板的花纹高度、混凝土强度、拉条间距、截面宽度和翼缘截面形式对试件粘结强度的影响,设计制作了12个带拉条的C型外包花纹钢-混凝土推出试件。分析各试件的破坏过程、荷载-滑移曲线、钢板应变沿纵向分布规律及特征粘结强度;综合考虑各影响因素,统计回归得出特征粘结强度的计算公式。研究结果表明:增大花纹高度是改善粘结性能最有效的途径;特征粘结强度随着混凝土强度的增大呈增大趋势,随着截面宽高比和拉条间距的增大呈减小趋势;在同等条件下,翼缘内翻试件的粘结性能优于翼缘外翻试件;特征粘结强度的回归公式能够较好地拟合试验结果。

粘贴钢板加固偏压H型钢长柱承载力试验研究

为了研究粘贴钢板加固对H型钢长柱承载力的影响,以粘贴钢板厚度和施加荷载偏心距为变量,制作了3根未粘贴钢板加固H型钢长柱和6根在翼缘纵向通长粘贴钢板加固的H型钢长柱,加固前后钢柱长细比均大于30,并对其进行压弯试验。通过对试验测得的柱中腹板应变、柱中翼缘应变、柱中侧向位移及试验现象进行分析,研究粘贴钢板加固对于H型钢长柱受力稳定性能的影响。结果表明:未经加固的H型钢长柱稳定性较差,在荷载下降段时发生空间弯扭破坏;经过加固的H型钢长柱试件稳定承载力提升显著,胶层在达到极限承载力之前粘接牢固,在荷载下降段时胶层发生剥离,试件发生平面内整体弯曲失稳破坏;并且在其他条件相同情况下,加固试件的偏心距越小,承载力越高,粘贴钢板厚度越大,承载力提升幅度越大。

胶栓组合连接加固钢板疲劳性能试验研究

为了对比高强螺栓栓接加固和胶栓组合连接加固带初始缺陷钢板的疲劳性能,制作9个试件,试验采用MTS进行压弯疲劳加载,对加载过程中的应力变化和试件的破坏模式进行监测和分析。研究表明:胶栓组合连接加固中胶体的存在可有效降低螺栓孔附近的应力水平,延缓疲劳裂纹的产生;单侧栓接加固使带初始缺陷钢板的疲劳寿命增加了11.5倍,而单侧胶栓组合连接加固增加了15.3倍,单侧胶栓组合连接加固较单侧栓接加固提升了30%。

SUS441不锈钢/Al金属间化合物微叠层复合板的界面结构与力学性能

采用“表面预处理—交替层叠—热轧复合—热处理”的工艺流程制备了SUS441不锈钢/Al金属间化合物微叠层复合板。利用光学显微镜、X射线衍射仪、扫描电子显微镜等检测与表征方法研究了热处理温度对复合板界面形貌、微观组织、物相组成、维氏硬度、拉伸性能的影响。结果表明:复合板界面结合良好;热处理后,固–液反应界面氧化严重,易导致界面分层而开裂;固–固、固–半固、固–液热处理后,金属间化合物层由均匀层和两相层组成,均匀层的物相组成为Fe_(2)A_(15),两相层的物相组成为Fe_(4)Al_(13)和Al_(13)Cr_(2),且两相层具有韧性特征,固–半固反应所得到的复合板的综合力学性能最佳。

铣削型钢纤维与超高性能混凝土的界面粘结性能研究

超高性能混凝土(UHPC)优异的性能主要取决于钢纤维与基体的协同工作,为探讨铣削型钢纤维在UHPC中的适用性,本工作通过钢纤维拉拔试验,研究了铣削型钢纤维与UHPC的界面粘结性能,分析了纤维埋深、纤维有无端勾、基体有无纤维、养护条件四个因素的影响及其机理,并与镀铜微丝钢纤维进行对比。结果表明:四种类型的钢纤维(镀铜平直型S、镀铜端钩型H、铣削平直型MS和铣削型MH)在UHPC中的粘结强度大小顺序为H型>MH型>MS型>S型;随着纤维埋深增加,S型、H型和MS型钢纤维在UHPC中的粘结强度减小,而MH型钢纤维则增大;端勾有助于提升钢纤维在UHPC中的粘结强度和拉拔能,并影响拉拔荷载-位移曲线的形状;基体掺入2%(体积分数)钢纤维亦能略微提高钢纤维在UHPC中的粘结强度和拉拔能;与蒸养条件相比,标养条件下界面粘结强度降低,但也使得铣削型钢纤维的拔出行为更明显,提高了拉拔能。铣削型钢纤维与UHPC界面粘结强度较高,但其较低的纤维抗拉强度影响了粘结性能的发挥,建议开发适用于UHPC的高强铣削型钢纤维。

不同损伤程度下公路隧道粘钢加固效果试验研究

衬砌裂损是隧道常见病害形式,直接影响到结构承载力,粘钢加固作为结构补强的方式应用较多,但公路隧道粘钢加固后结构的承载性能和不同损伤程度下的粘钢加固效果研究较少。采用1∶10模型加载试验,研究了公路隧道在不同损伤程度下加固后结构的承载性能、受力变形特征和破坏过程,分析了粘钢加固效果、加固时机。研究结果表明:(1)原结构和加固结构在松动荷载作用下的变形过程均可分为4个阶段,但破坏特征及形态存在差异。(2)剩余承载力为50%F,30%F(F为原结构极限承载力)时加固,破坏荷载相对原结构提升50%,51%。在结构失效前施作钢板可有效提升其极限承载力,且受加固点荷载影响较小。剩余承载力为50%F,30%F时加固,最终变形量比原结构增加59%,56%,可降低脆性破坏风险。(3)加固结构破坏模式为拱顶大偏心受压破坏。(4)加固过晚时,钢板会因衬砌的表面裂缝及变形速度而难以有效黏结或长时间协同变形,导致加速破坏。建议将结构剩余承载力介于62%F至50%F作为公路隧道合理加固时机。

电磁感应加热轧制制备钛/钢复合板性能研究

采用电磁感应加热对加入不同厚度纯铁中间层的钛/钢组坯进行加热,并单道次热轧复合,短时高效地制备出高质量钛/钢复合板。研究了在快速电磁感应加热至钢板居里点770℃的条件下,不同厚度纯铁中间层对钛/钢复合板界面组织和结合性能的影响。结果表明,随着中间层厚度的降低,复合板剪切强度逐渐提高,加入0.3 mm厚纯铁中间层复合板的剪切强度达到215.05 MPa。感应加热低温轧制条件下,减少了复合板界面脆性金属间化合物的生成。纯铁中间层有效地促进了结合界面两侧基体的协调变形,同时增加了界面处基体元素间的相互扩散距离,使复合板实现了良好的冶金结合,获得了综合性能较好的钛/钢复合板。