Determination of Elastoplastic Mechanical Properties of the Weld and Heat Affected Zone Metals in Tailor-Welded Blanks by Nanoindentation Test

The elastoplastic mechanical properties of the weld and heat affected zone metals have comparatively major impact on the forming process of tailor-welded blanks. A few scholars investigated the elastoplastic mechanical properties of the weld and heat affected zone, but they only simply assumed that it was a uniform distribution elastoplastic material different from the base materials. Four types of tailor-welded blanks which consist of ST12 and 304 stainless steel plates are selected as the research objects, the elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals are obtained based on the nanoindentation tests, and the Erichsen cupping tests are conducted by combining numerical simulation with physical experiment. The nanoindentation tests results demonstrate that the elastoplastic mechanical properties of the weld and heat affected zone metals are not only different from the base materials, but also varying between the weld metals and the heat affected zone metals. Comparing the Erichsen cupping test resulted from numerical with that from experimental method, it is found that the numerical value of Erichsen cupping test which consider the elastoplastic mechanical properties of the weld and heat affected zone metals have a good agreement with the experimental result, and the relative error is only 4.8%. The proposed research provides good solutions for the inhomogeneous elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals, and improves the control performance of tailor-welded blanks forming accuracy.

Preparation of heat-resistant aluminum alloy pipe blanks by multi-layer spray deposition

A heat resistant aluminum alloy pipe blank with dimensions of d 700/300 mm×1 200 mm was prepared by the multi layer spray deposition technology. Optical microscopy, X ray diffractometry and transmission electron microscopy were used to analyze its morphologies and microstructures. The results show that the microstructures of the pipe blank are homogeneous and the precipitates are uniformly distributed d 25～70 nm spherical or sphere like Al 12 (Fe,V) 3Si particles, its mechanical properties at room temperature and 350 ℃ after densification by extrusion are σ b=412 MPa, δ =7.6% and σ b=187 MPa, δ =7.6%, respectively. The analyses indicate that the proper match of the motion rates of atomizer and substrate can produce deposited blanks with uniform thickness and relatively high cooling rate.

Behaviour of Friction Stir Dissimilar Welded Blanks and The Role of Different Tool Pin Profiles

In this study,the forming behaviour of dissimilar welded blanks was studied.Welded blanks were prepared with friction stir welding processwith different types of tool pin profiles.Welded blanks were developed with fixedfriction stir welding process parameters by varying the tool pin profiles.The forming behaviour of welded blanks were analyzed with the limiting dome height test in biaxial stretch forming condition.The results reveal that the formability of welded joints are made with the square pin tool exhibited a better formabilitybehaviour when compared with other profiled tools,this is due to sufficient amount heat generation and high static volume to dynamic volume ratio.

Research on horizontal electromagnetic continuous casting of copper tube blanks

The effect of commercial frequency electromagnetic field on the solidification structure and mechanical propertiesof copper hollow blanks prepared by horizontal continuous casting method was investigated. The results show thatwhen the electromagnetic field is imposed, columnar grains are evidently refined and fine equiaxed grains areobtained in the inner side of the cross-section. Moreover, with the increase of input current, the equiaxed grain regionwidens and the grains distribute more uniformly in the circumferential direction. Meanwhile, the mechanical properties areremarkably improved by the application of electromagnetic field. When the input current is 140 A, the tensile strengthincreases 15% and the elongation increases 10%. However, the electromagnetic field has no effect on the distribution ofmicroelements.

Joint Performance for Laser Cutting-welding of Zinc-coated Tailored Blanks

The process of laser bull welding of zinc-coated steel（SGCD3 and WLZn）blanks was presented.whose edges were prepared by laser cutting.The properties of the butt joints.such as tensile strength.bending,stamping.weld shape,and corrosion-resisant were tested.The experiments of laser cutting and welding were carried ont on a custom-made system designed.which is a set of equipment for wide sheet butt welding based on a laser cutting-welding combination process.The experiments proved the technological feasibility of laser butt welding for thin zinc coated steel sheets whose edges were prepared by laser cutting on the same equipment.

Preparation of tube blanks by atomization deposition process

By using the method of mathematical calculation combined with experiment, the technological conditions of atomization deposition process for making tube blanks with even thickness were studied. The results show that in the case of the substrate rotating and translating simultaneously, when the ratio of the rotation frequency to the translational velocity is very large, and the other deposition conditions are suitable, tube blanks with even thickness and high density can be produced, and the actual deposition efficiency will be highest.

Modeling Target Detection and Performance Analysis of Electronic Countermeasures for Phased Radar

Interference is a key factor in radar return misdetection.Strong interference might make it difficult to detect the signal or targets.When interference occurs in the sidelobes of the antenna pattern,Sidelobe Cancellation(SLC)and Sidelobe Blanking are two unique solutions to solve this problem(SLB).Aside from this approach,the probability of false alert and likelihood of detection are the most essential parameters in radar.The chance of a false alarm for any radar system should be minimal,and as a result,the probability of detection should be high.There are several interference cancellation strategies in the literature that are used to sustain consistent false alarms regardless of the clutter environment.With the necessity for interference cancellation methods and the constant false alarm rate(CFAR),the Maisel SLC algorithm has been modified to create a new algorithm for recognizing targets in the presence of severe interference.The received radar returns and interference are simulated as non-stationary in this approach,and side-lobe interference is cancelled using an adaptive algorithm.By comparing the performance of adaptive algorithms,simulation results are shown.In a severe clutter situation,the simulation results demonstrate a considerable increase in target recognition and signal to noise ratio when compared to the previous technique.

Application of Blank Symbols in Japanese Architecture and Indoor Designs

A symbol is an expression of meaning,while blank symbols express special meanings.By focusing on the application of blank symbols in Japanese architecture and indoor designs,we analyzed the aesthetic principles in Japanese architecture and indoor designs from the perspective of semiotics,such as“Kongji,”“Emptiness,”and“Dying out,”and their minimalist and pure design concepts.Traditional Chinese culture was also further explored,especially the profound influence of the“Chan sect”and the philosophy of“unity of heaven and mankind”on Japanese architecture and designs.This study aims to facilitate the coexistence and mutual appreciation of Chinese and Japanese architectural designs.

Research on microstructure and properties of boron/Q235 steel laser welded dissimilar joints under synchronous thermal field

The mechanical mismatch effect frequently occurs in the dissimilar materials welded joints, thus leading to plastic gradient at the interface between the weld and heat-affected zone(HAZ). In this work, the boron steel and Q235 steel were selected for laser tailor welding,which obtained boron/Q235 steel tailor-welded blanks(TWBs). The method of welding with synchronous thermal field(WSTF) was utilized to eliminate the mismatch effects in TWBs. The WSTF was employed to adjust cooling rates of welded joints, thereby intervening in the solidification behaviors and phase transition of the molten pool. Boron/Q235 steel was welded by laser under conventional and WSTF(300-600 ℃) conditions, respectively. The results show that the microstructure of weld and HAZ(boron) was adequately transitioned to ferrites and pearlites instead of abundant martensite by WSTF. Meanwhile, the discrepancy of microhardness and yield strength between various regions of welded joints was greatly reduced, and the overall plasticity of welded joints was enhanced by WSTF. It is indicated that WSTF can effectively contribute to reducing plastic gradient and achieving mechanical congruity in welded joints by restraining the generation of hardbrittle phase, which could significantly improve the formability of TWBs in subsequent hot stamping.

基于变厚板(VRB)的汽车前纵梁内板开发

使用变厚板零件是实现汽车轻量化的有效方法之一。针对变厚板的板厚及材料力学性能非均一性,文章采用数字散斑单向拉伸试验对变厚板等厚区和厚度过渡区的力学性能进行研究,探讨退火工艺对变厚板不同厚度区域材料性能的影响,提出结合数字散斑单向拉伸试验和厚度分区离散的变厚板过渡区力学性能表征;仿真分析某汽车前纵梁内板变厚板冲压成形性,并与试制样件进行对比,结果表明,采用该文提出的变厚板过渡区表征方法正确可靠,且变厚板制作的汽车前纵梁内板件成形性良好。

基于遗传程序设计的作物水分生产函数研究

利用遗传程序自动搜索模型结构能力强的优点,建立了基于遗传程序设计的作物水分生产函数模型。该方法通过演化计算自动寻找最优的模型结构,比传统统计方法具有较大的灵活性和智能性,避免了预先建立具体数学表达式的不便。将基于遗传程序设计作物水分生产函数模型同BP神经网络模型、Jensen模型以及Blank模型进行比较,实例表明,遗传程序设计的作物水分生产函数模型适应性强,拟合精度高,为作物水分生产函数的计算提供了新的有效方法。

番茄产量对各生育阶段土壤水分的响应分析

为了解不同生育阶段土壤水分状况对番茄产量的影响,根据番茄第一穗果的发育情况,将番茄全生育期划分为苗期、始花结果期、果实生长初期、快速膨大期和品质形成期五个生育阶段,采用五元二次通用旋转组合设计进行盆栽试验,建立产量与土壤含水率间回归模型,对各单一因素效应及两两因素的耦合效应进行分析,并基于Jensen和Blank模型,分析产量对各阶段耗水的敏感性。结果表明,在其它生育阶段土壤含水率为中间水平时,番茄产量随果实生长初期、快速膨大期、品质形成期土壤含水率的增加呈上升趋势,随始花结果期增加呈开口向下的抛物线变化,不随苗期而变化。始花结果期与果实生长初期和品质形成期、果实生长初期与快速膨大期土壤含水率间的交互作用均表现为促进番茄产量的提高。番茄产量对各生育阶段水分亏缺的敏感性依次为品质形成期、果实生长初期、始花结果期、快速膨大期、苗期,相应的Jensen模型水分敏感指数为0.1658、0.1275、0.0941、0.0448、-0.1813。当苗期、始花结果期、果实生长初期、快速膨大期与品质形成期土壤相对含水率分别为50%∽60%、90%∽100%、90%∽100%、90%∽100%、90%∽100%时,番茄可达最高单株产量1 406.04 g。综合分析表明,保证果实生长初期、品质形成期和快速膨大期灌水,减少苗期灌水,适当控制始花结果期灌水可有效提高番茄产量。

基于春玉米微咸水灌溉的水盐生产函数研究

在石羊河流域开展微咸水灌溉试验,综合考虑水分与盐分因素对春玉米生长的影响,以国际上通用的水分生产函数Blank模型和Jensen模型为基础进行作物水盐模型的构建,通过引入盐分胁迫因子,将水分生产函数转变为水盐生产函数。通过2009年和2010年春玉米不同矿化度微咸水灌溉试验,结合函数求解,探求春玉米各生育阶段的盐分敏感指数,得出春玉米的盐分敏感程度顺序为苗期>拔节期>抽雄灌浆期>成熟期。同时以交替灌溉试验进行验证,结果表明微咸水安排在盐分敏感程度小的生育阶段更有利于作物的生长。

提升CDMA1x网络容量-1x增强技术研究、试验及策略

文章重点介绍了cdma2000网络的增强技术—Smart Blanking、FET、EVRCNW、PC Enhancement、QOF、EQLIC和RLIC的实现原理,以及各种技术对网络的改造要求和终端要求,并对采用增强技术后的CDMA1x网络容量增益进行了测试,测试结果表明,采用这些增强技术,可以获得约130%～140%的容量增益。

设施延迟栽培葡萄不同水分生产函数比较

为了探究设施延迟栽培葡萄生育期灌溉水量的优化配置,根据2013—2014年设施延迟栽培葡萄不同生育期水分胁迫处理下的耗水量与产量关系的资料,分别分析了Stewart模型、Blank模型和Jensen模型3种不同水分生产函数对设施延迟栽培葡萄的适应性,计算了不同模型对应的设施延迟栽培葡萄不同生长阶段的水分敏感指数。结果表明,设施延迟葡萄水分敏感指数在果实膨大期最大,该时期为需水关键期,亏水处理会明显降低产量;萌芽期最小,该时期适度亏水对产量提高有积极影响。确立了Stewart模型和Blank模型为适用于设施延迟栽培葡萄的水分生产函数模型,在灌溉水量有限的条件下,应采取萌芽期适度亏水,将灌溉水量调配给果实膨大期的灌溉水配置方式,以期在合理调配灌溉水量的同时获得最佳经济效益。

Study of residual stresses in tailor rolled blanked Al5J32-T4 sheets

Several automotive parts such as door panels have been manufactured by using load-adapted blanks for crash optimization and weight minimization. Recently, Tailor Rolled Blanks (TRB) has been introduced to remove the disadvantages of a welding process which was used in joining panel components. TRB offers better structural design capabilities due to the seamless transitions on the panels with different thicknesses. In spite of the advantages of the process, TRB leaves internal stresses in the panel. This residual stresses lower the formability of Tailor Rolled Blanked (TRBed) parts and cause cracks near severe curvature during subsequent forming processes. In this research, the residual stresses of TRBed Al5J32-T4 sheets were studied by X-ray stress analysis, and also microstructure was observed along the rolling direction. In addition, heat treatment was done after TRB process in order to compare the residual stresses to that of the TRBed sheets before the heat treatment.

Fluid Flow and Solidification Simulation in Beam Blank Continuous Casting Process With 3D Coupled Model

Based on turbulent theory, a 3D coupled model of fluid flow and solidification was built using finite difference method and used to study the influence of superheating degree and casting speed on fluid flow and solidification, analyze the interaction between shell and molten steel, and compare the temperature distribution under different technological conditions. The results indicate that high superheating degree can lengthen the liquid-core depth and make the crack and breakout possible, so suitable superheating should be controlled within 35℃ according to the simulation results. Casting speed which is one of the most important technological parameters of improving production rate, should be controlled between 0. 85 m/min and 1.05 m/min and the caster has great potential in the improvement of blank quality.

Technology and Experiments of 42CrMo Bearing Ring Forming Based on Casting Ring Blank

Bearing ring is the crucial component of bearing. With regard to such problems as material waste, low efficiency and high energy consumption in current process of producing large bearing ring, a new process named ＂casting-rolling compound forming technology＂ is researched by taking the typical 42CrMo slew bearing as object. Through theoretical analysis, the design criteria of the main casting-rolling forming parameters are put forward at first. Then the constitutive relationship model of as-cast 42CrMo steel and its mathematical model of dynamic recrystallization are obtained according to the results of the hot compression experiment. By a coupled thermal-mechanical finite element model for radial-axial rolling of bearing ring, the fraction of dynamic recrystallization is calculated and recrystallized grains size are predicated. Meanwhile, the effects of the initial rolling temperature and feed rate of idle roll on material microstructure evolution are analyzed. Finally, the industrial rolling experiment is designed and performed, based on the simulation results. In addition, mechanical and metallographic tests are conducted on rolled bearing ring to get the mechanical parameters and metallographic structure. The experimental data and results show that the mechanical properties of bearing ring produced by casting-rolling compound forming technology are up to industrial standard, and a qualified bearing ring can be successfully formed by employing this new technology. Through the study, a process of forming large bearing ring directly by using casting ring blank is obtained, which could provide an effective theoretical guidance for manufacturing large ring parts. It also has an edge in saving material, lowering energy and improving efficiency.

NUMERICAL SIMULATION OF THE THERMO-MECHANICAL PROCESS FOR BEAM BLANK CONTINUOUS CASTING

The aim of this study was to simulate the solidification process of beam blank continuous casting, and then find the reasons for the typical defects of the beam blank. A two-dimensional transient coupled finite element model has been developed to compute the temperature and stress profile in beam blank continuous casting. The enthalpy method was used in the heat conduction equation. The thermo-mechanical property in the mushy zone was taken into consideration in this calculation. It is shown that at the mold exit the thickness of the shell had its maximum value at the flange tip and its minimum value at the fillet. The temperature had a great fluctuation on the surface of the beam blank in the secondary cooling zone. At the unbending point, the surface temperature of the web was in the brittleness temperature range under the present condition. To ensure the quality, it is necessary to weaken the intensity of secondary cooling. At the mold exit the equivalent stress and strain have higher values at the flange tip and at the web. From the spray 1 to the unbending point, the maximum values of stress and strain gradually moved to the internal section of the flange tip and the web. However, whenever, there were bigger stress and strain values near the flange tip and the web than in the other parts, it must be very easy to generate cracks at those positions. Now, online verification of this simulation has been developed, which has proved to be very useful and efficient to instruct the practical production of beam blank continuous casting.