Cracking morphology in the fusion zone of HQ130 high strength steel was researched by 'the y-slit test' and 'three-point bend test', ultrasonic test and microscope. HQ130 and QJ63 high strength steel w...Cracking morphology in the fusion zone of HQ130 high strength steel was researched by 'the y-slit test' and 'three-point bend test', ultrasonic test and microscope. HQ130 and QJ63 high strength steel was welded by Ar+CO2 gas shielded arc welding under the condition without preheating. Experimental results indicated that welding cracks were produced in the partially melted zone of the weld root of HQ130 steel side and propagated parallel to the fusion zone. The cracks were developed alternatively between the weld and the partially melted zone, and are not strictly ruptured at W/F (weld metal/fusion zone) boundary surface. Controlling weld heat input (E) about 16 kJ/cm could make the cracking rate lowest and satisfy the performance requirement of welded joint zone.展开更多
Tensile and hardness values for 7075-T651 aluminum alloy in the as welded and post weld heat treated conditions（solubilization and artificial aging-T6）,obtained using GMAW and modified indirect electric arc（MIEA）w...Tensile and hardness values for 7075-T651 aluminum alloy in the as welded and post weld heat treated conditions（solubilization and artificial aging-T6）,obtained using GMAW and modified indirect electric arc（MIEA）welding processes are presented.Results showed that the base material along rolling direction exhibited a tensile strength of around 600 MPa and elongation of 11%.For the as welded condition,tensile strength was 260 MPa and elongation percent of 3%.This behavior was attributed to brittleness induced by the microstructural characteristics of the welded alloys,as well as high porosity.Hardness profiles along the welds were obtained and different welded zones were identified.A soft zone（＊100 HV0.1） in the heat affected zone for GMAW and MIEA was observed,the minimum hardness corresponding to weld metal（＊85 and ＊96 HV0.1for GMAW and MIEA,respectively）.The high dilution between filler and base metal during welding in MIEA allows to the Zn and Cu to flow from the base metal into the weld metal,inducing hardening by solution and subsequent artificial aging.In this regard,the hardness of the weld metal for MIEA increases by 56%,while the tensile strength reaches a value close to 400 MPa.For GMAW,non-favorable hardening effect was observed for the weld metal after solution and artificial aging.展开更多
Microstructure and alloy element distribution in the welded joint between austenitic stainless steel (1Cr18Ni9Ti) and pearlitic heat-resistant steel (1Cr5Mo) were researched by means of light microscopy, scanning elec...Microstructure and alloy element distribution in the welded joint between austenitic stainless steel (1Cr18Ni9Ti) and pearlitic heat-resistant steel (1Cr5Mo) were researched by means of light microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Microstructure, divisions of the fusion zone and elemental diffusion distributions in the welded joints were investigated. Furthermore, solidification microstructure and S-ferrite distribution in the weld metal of these steels are also discussed.展开更多
Characterization of the microstructure of the fusion zone of an Alloy 600-82 weld joint was conducted, with focus on the weld residual strain distribution and the comparison of the microstructure of heat affected zone...Characterization of the microstructure of the fusion zone of an Alloy 600-82 weld joint was conducted, with focus on the weld residual strain distribution and the comparison of the microstructure of heat affected zone （HAZ） with that of cold worked alloy. Peak of the residual strain was observed to approach to the fusion boundary in HAZ while the strain increased from the top of the weld to the root. Strain distribution in the HAZ was found to be concentrated adjacent to grain boundaries （GBs）, with a peak of approximately three times of that in grain. Further, triple junctions of the GB appear to cause a higher strain concentration than single GBs. The microstructure of HAZ consists of partially tangled dislocations, which is different from slip bands of high density dislocations in cold worked alloy. This may cause a relatively higher intergranular cracking resistance of HAZ due to the difficulty in transferring tangled dislocations to GB in HAZ under deformation.展开更多
In this paper, the common heat source model of point and linear heat source in the numerical simulation of electron beam welding （EBW） were summarized and introduced. The combined point-linear heat source model was ...In this paper, the common heat source model of point and linear heat source in the numerical simulation of electron beam welding （EBW） were summarized and introduced. The combined point-linear heat source model was brought forward and to simulate the welding temperature fields of EBW and predicting the weld shape. The model parameters were put forward and regulated in the combined model, which included the ratio of point heat source to linear heat source Qpr and the distribution of linear heat source Lr. Based on the combined model, the welding temperature fields of EBW were investigated. The results show that the predicted weld shapes are conformable to those of the actual, the temperature fields are reasonable and correct by simulating with combined point-linear heat source model and the typical weld shapes are gained.展开更多
The concept of shape factors of the fusion-solidification zone is proposed to describe the weld cross section geometry. According to these shape factors, the electron beam weld fusion-solidification zone is divided in...The concept of shape factors of the fusion-solidification zone is proposed to describe the weld cross section geometry. According to these shape factors, the electron beam weld fusion-solidification zone is divided into four typical shapes and the classification criterion for these typical shapes is suggested. An integrated parameter n, combining the line power density of electron beam and material thermal properties is proposed to describe the relative power input, and another integrated parameter n2 combing the accelerating voltage and focusing current is proposed to reflect the power distribution in the keyhole. A series of new expressions, which can reflect the influence of focusing current, accelerating voltage, beam current, and material thermal properties, are developed to predict the fusion-solidification zone shape based on experimental results nonlinear fitting of n1 and n2.展开更多
A laser fusion experiment was performed based on the Shenguang II facility. An image of thermonuclear burning region was obtained with a Fresnel zone plate-coded imaging technique, where the laser-driven target was se...A laser fusion experiment was performed based on the Shenguang II facility. An image of thermonuclear burning region was obtained with a Fresnel zone plate-coded imaging technique, where the laser-driven target was served as an o-particle source, and the coded image obtained in the experiment was reconstructed by a numerical way.展开更多
城市功能区识别可为城市建设决策提供技术支撑。本研究提出了面向城市功能区识别的多源场景特征Transformer融合方法。利用路网构建交通分析区(Traffic Analysis Zone,TAZ),采用Delaunay三角网创建POI(Point of Interest)数据的图结构,...城市功能区识别可为城市建设决策提供技术支撑。本研究提出了面向城市功能区识别的多源场景特征Transformer融合方法。利用路网构建交通分析区(Traffic Analysis Zone,TAZ),采用Delaunay三角网创建POI(Point of Interest)数据的图结构,通过TAZ获得遥感数据的影像对象;利用图卷积网络提取POI图结构的社会场景特征,由ResNet-50编码遥感数据的自然场景特征;基于Transformer的多头注意力机制融合多维特征,依托SoftMax实现功能区识别。以沈阳市主城区为例,以2021年的OpenStreetMap、POI和遥感数据为数据源。该方法的总体精度和Kappa系数为82.2%和70%,Kappa系数较单一数据方法和其他融合方法至少提高18%和9%。本研究采用Transformer融合社会场景特征和自然场景特征,解决了多源数据难以集成表达的问题,为城市功能区识别提供了新的技术路径。展开更多
准确的地表覆盖信息是陆地过程模拟与生态系统管理的重要基础。近年来多种地表覆盖产品相继发布,但因分类体系、数据源与算法差异,在区域尺度应用中存在较大不确定性,而现有研究多关注产品间的精度差异,较少探讨如何整合多源产品优势以...准确的地表覆盖信息是陆地过程模拟与生态系统管理的重要基础。近年来多种地表覆盖产品相继发布,但因分类体系、数据源与算法差异,在区域尺度应用中存在较大不确定性,而现有研究多关注产品间的精度差异,较少探讨如何整合多源产品优势以构建高精度融合产品。本文以气候变化倡议(climate change initiative,CCI)、中国土地覆盖数据集(China land cover dataset,CLCD)、全球地表覆盖30 m分辨率精细分类系统(global land cover with fine classification system at 30 m resolution,GLC_FCS30)和MCD12Q1四套地表覆盖产品为基础,设计一种兼顾一致性与精度的多源地表覆盖产品融合方法。通过提取各产品一致区域作为共识区;随后结合F1分数对不一致区域进行加权判别,优选最可信类别,生成精度更高的融合产品;为验证方法可行性,在川滇生态屏障区进行验证。结果显示:不同产品具有较高的一致性,但分类精度差异明显;融合产品的空间分布与原始产品相似,但整体分类精度更高,总体精度提高了约8.04%,达到81.34%,Kappa系数提高了约14.13%,达到69.1%,并在森林、草地等关键地类上表现更优,有效降低了类别间的混淆程度。展开更多
文摘Cracking morphology in the fusion zone of HQ130 high strength steel was researched by 'the y-slit test' and 'three-point bend test', ultrasonic test and microscope. HQ130 and QJ63 high strength steel was welded by Ar+CO2 gas shielded arc welding under the condition without preheating. Experimental results indicated that welding cracks were produced in the partially melted zone of the weld root of HQ130 steel side and propagated parallel to the fusion zone. The cracks were developed alternatively between the weld and the partially melted zone, and are not strictly ruptured at W/F (weld metal/fusion zone) boundary surface. Controlling weld heat input (E) about 16 kJ/cm could make the cracking rate lowest and satisfy the performance requirement of welded joint zone.
文摘Tensile and hardness values for 7075-T651 aluminum alloy in the as welded and post weld heat treated conditions（solubilization and artificial aging-T6）,obtained using GMAW and modified indirect electric arc（MIEA）welding processes are presented.Results showed that the base material along rolling direction exhibited a tensile strength of around 600 MPa and elongation of 11%.For the as welded condition,tensile strength was 260 MPa and elongation percent of 3%.This behavior was attributed to brittleness induced by the microstructural characteristics of the welded alloys,as well as high porosity.Hardness profiles along the welds were obtained and different welded zones were identified.A soft zone（＊100 HV0.1） in the heat affected zone for GMAW and MIEA was observed,the minimum hardness corresponding to weld metal（＊85 and ＊96 HV0.1for GMAW and MIEA,respectively）.The high dilution between filler and base metal during welding in MIEA allows to the Zn and Cu to flow from the base metal into the weld metal,inducing hardening by solution and subsequent artificial aging.In this regard,the hardness of the weld metal for MIEA increases by 56%,while the tensile strength reaches a value close to 400 MPa.For GMAW,non-favorable hardening effect was observed for the weld metal after solution and artificial aging.
基金The work was supported by the Foundation of KeyLaboratory of Liquid Structure and Heredity of Materi-als, Ministry of Educat
文摘Microstructure and alloy element distribution in the welded joint between austenitic stainless steel (1Cr18Ni9Ti) and pearlitic heat-resistant steel (1Cr5Mo) were researched by means of light microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Microstructure, divisions of the fusion zone and elemental diffusion distributions in the welded joints were investigated. Furthermore, solidification microstructure and S-ferrite distribution in the weld metal of these steels are also discussed.
基金financially supported by the Hundred-Talent Program of Chinese Academy of Sciences
文摘Characterization of the microstructure of the fusion zone of an Alloy 600-82 weld joint was conducted, with focus on the weld residual strain distribution and the comparison of the microstructure of heat affected zone （HAZ） with that of cold worked alloy. Peak of the residual strain was observed to approach to the fusion boundary in HAZ while the strain increased from the top of the weld to the root. Strain distribution in the HAZ was found to be concentrated adjacent to grain boundaries （GBs）, with a peak of approximately three times of that in grain. Further, triple junctions of the GB appear to cause a higher strain concentration than single GBs. The microstructure of HAZ consists of partially tangled dislocations, which is different from slip bands of high density dislocations in cold worked alloy. This may cause a relatively higher intergranular cracking resistance of HAZ due to the difficulty in transferring tangled dislocations to GB in HAZ under deformation.
基金co-supported by the National Basic Research Program (No.61362)the National Natural Science Foundation of China(No. 50935008 and 10902113)Science Foundation of Aeronautics (No. 2010ZE25006)
文摘In this paper, the common heat source model of point and linear heat source in the numerical simulation of electron beam welding （EBW） were summarized and introduced. The combined point-linear heat source model was brought forward and to simulate the welding temperature fields of EBW and predicting the weld shape. The model parameters were put forward and regulated in the combined model, which included the ratio of point heat source to linear heat source Qpr and the distribution of linear heat source Lr. Based on the combined model, the welding temperature fields of EBW were investigated. The results show that the predicted weld shapes are conformable to those of the actual, the temperature fields are reasonable and correct by simulating with combined point-linear heat source model and the typical weld shapes are gained.
文摘The concept of shape factors of the fusion-solidification zone is proposed to describe the weld cross section geometry. According to these shape factors, the electron beam weld fusion-solidification zone is divided into four typical shapes and the classification criterion for these typical shapes is suggested. An integrated parameter n, combining the line power density of electron beam and material thermal properties is proposed to describe the relative power input, and another integrated parameter n2 combing the accelerating voltage and focusing current is proposed to reflect the power distribution in the keyhole. A series of new expressions, which can reflect the influence of focusing current, accelerating voltage, beam current, and material thermal properties, are developed to predict the fusion-solidification zone shape based on experimental results nonlinear fitting of n1 and n2.
基金This work was supported by National High Technique Development Project (863) Fund No. 2002AA84ts12 Innovative Fund of Research Center of Laser Fusion No. 9111.
文摘A laser fusion experiment was performed based on the Shenguang II facility. An image of thermonuclear burning region was obtained with a Fresnel zone plate-coded imaging technique, where the laser-driven target was served as an o-particle source, and the coded image obtained in the experiment was reconstructed by a numerical way.
文摘城市功能区识别可为城市建设决策提供技术支撑。本研究提出了面向城市功能区识别的多源场景特征Transformer融合方法。利用路网构建交通分析区(Traffic Analysis Zone,TAZ),采用Delaunay三角网创建POI(Point of Interest)数据的图结构,通过TAZ获得遥感数据的影像对象;利用图卷积网络提取POI图结构的社会场景特征,由ResNet-50编码遥感数据的自然场景特征;基于Transformer的多头注意力机制融合多维特征,依托SoftMax实现功能区识别。以沈阳市主城区为例,以2021年的OpenStreetMap、POI和遥感数据为数据源。该方法的总体精度和Kappa系数为82.2%和70%,Kappa系数较单一数据方法和其他融合方法至少提高18%和9%。本研究采用Transformer融合社会场景特征和自然场景特征,解决了多源数据难以集成表达的问题,为城市功能区识别提供了新的技术路径。
文摘准确的地表覆盖信息是陆地过程模拟与生态系统管理的重要基础。近年来多种地表覆盖产品相继发布,但因分类体系、数据源与算法差异,在区域尺度应用中存在较大不确定性,而现有研究多关注产品间的精度差异,较少探讨如何整合多源产品优势以构建高精度融合产品。本文以气候变化倡议(climate change initiative,CCI)、中国土地覆盖数据集(China land cover dataset,CLCD)、全球地表覆盖30 m分辨率精细分类系统(global land cover with fine classification system at 30 m resolution,GLC_FCS30)和MCD12Q1四套地表覆盖产品为基础,设计一种兼顾一致性与精度的多源地表覆盖产品融合方法。通过提取各产品一致区域作为共识区;随后结合F1分数对不一致区域进行加权判别,优选最可信类别,生成精度更高的融合产品;为验证方法可行性,在川滇生态屏障区进行验证。结果显示:不同产品具有较高的一致性,但分类精度差异明显;融合产品的空间分布与原始产品相似,但整体分类精度更高,总体精度提高了约8.04%,达到81.34%,Kappa系数提高了约14.13%,达到69.1%,并在森林、草地等关键地类上表现更优,有效降低了类别间的混淆程度。
