共查询到20条相似文献,搜索用时 62 毫秒
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本工作研究了7005铝合金在应变速率为(1~5)×103s-1条件下的力学行为。结果表明,7005铝合金有明显的应变速率敏感性。利用最小二乘法求得了材料的Johnson-Cook本构参数;应用ABAQUS软件,研究了高应变速率下的帽型试样的绝热剪切变形历程。数值模拟得到的应力-应变曲线与实验结果吻合。温度场的计算为绝热剪切带内微观组织是否发生动态再结晶提供了依据,当应变速率为15 000 s-1时,在120~240μs内,相比初始温度,试样的平均温升达到405℃。通过对冲击后试样的微观组织观测发现,绝热剪切带中有大量的等轴晶,具有典型的再结晶组织特征。7005铝合金在高应变速率下的变形温升和动态再结晶软化行为,将为其在汽车碰撞构件中的应用提供指导作用。 相似文献
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采用慢应变速率法SSRT(Slow Strain Rate Test)测试了在含H2S的介质中不同冷变形度条件下管线钢X70的硫化氢应力腐蚀开裂(SCCC)性能.结果表明,冷变形度是影响国产X70管线钢SSCC的重要因素之一.冷变形促进了材料局部微观缺陷内能的增加,这些缺陷所在的位置,往往是氢易被捕捉的地方,造成氢的聚集,微观变形将会促进裂纹的萌生和扩展.同时,随着冷变形度的增加,冷变形造成的位错等缺陷使强度进一步增大而韧性降低.最终氢与应力的交互作用导致X70管线钢抗SSCC性能下降. 相似文献
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Ti-15-3钛合金超塑行为研究 总被引:2,自引:0,他引:2
为系统了解Ti-15-3合金的超塑性,研究了固溶态和两种不同变形量冷轧态的Ti-15-3合金板材在700~800 ℃和1×10-4 ~3×10-3s-1应变速率范围内的超塑性行为.结果表明:Ti-15-3合金具有较好的超塑性能,冷轧态合金的延伸率均优于固溶态,且随着板材冷轧变形量的增大而增大;各应变速率下,该合金都在780 ℃时获得最大延伸率和应变速率敏感性指数.在780 ℃和1×10-4s-1条件下拉伸时,冷轧变形量为52%的Ti-15-3合金板材获得了370%的延伸率,m值为O.56;变形温度和速率对合金的超塑性能影响很大,合金的延伸率在730~780 ℃范围内随温度的升高和应变速率的降低而升高,合金的流变应力则随之下降. 相似文献
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在Gleeble-1500热模拟机上进行了Ti6213合金热模拟压缩试验,变形温度范围为800-1050℃,应变速率范围为0.001-10 s-1,最大变形量为60%,并根据动态材料模型建立了加工图。结果表明,合金在高温变形时主要有2个合适的加工区域,一个是变形温度800-950℃,应变速率0.01 s-1以下区域;另一个在相变温度以下40℃内,应变速率10 s-1以上区域。在900-930℃和0.001 s-1的变形条件下,出现耗散率峰值为65%,高m值,S形应力和应变速率对数曲线的现象,合金表现出超塑特性。拉伸实验进一步表明,延伸率可达512%,组织为两相混合组织。另外,合金在800-930℃和大于0.01 s-1的条件下出现集中变形带,表现为局部流变特征。 相似文献
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采用分离式Hopkinson压杆试验技术,对山西黑花岗岩进行了一系列不同应变率(315.53s-1~1349.87s-1)的动态压缩试验。试验结果表明:山西黑花岗岩在高应变率条件下,动态抗压强度表现出突变特性:应变率从460.09s-1上升到860.20s-1的时候,山西黑花岗岩的动态抗压强度从272.33MPa提高到371.78MPa;在高应变率条件下,山西黑花岗岩材料的破碎机理为在初始冲击波作用区先产生体积破碎,而后在试样后半部分产生赫兹破碎;山西黑花岗岩在高应变率下的弹塑性变形能随应变率的增大而减小,高应变率条件下材料失效和裂纹扩展消耗更多能量,对应更加严重的材料破碎。 相似文献
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PENG Yong SHI Haisheng 《材料导报》2004,18(Z3):161-162
就喷射成形GCr15钢的显微组织及晶粒大小对其超塑性的影响进行了研究.结果显示,喷射成形GCr15钢具有细小等轴晶组织.喷射态GCr15钢在790℃C和2.5×10-4s-1应变速率条件下进行拉伸,延伸率为119%.喷射态GCr15钢经过淬回火处理,晶粒明显细化,在700℃C和2.5×10-4s-1条件下拉伸,其延伸率可达671%.淬回火处理试样再经过等温锻造加工,晶粒显著长大,在同样的700℃C和2.5×10-4s-1条件下拉伸,延伸率由原先的671%下降到392%.由此可见,超塑性与晶粒大小的变化确实密切相关,本研究的TEM观察结果亦已证实晶粒大小的变化. 相似文献
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在MTS809材料试验机和自行研制的旋转盘式间接杆杆型冲击拉伸试验机上,对聚碳酸酯板材进行了准静态0.001s-1、0.01s-1、0.1s-1和高应变率400s-1、800s-1、1700s-1加载条件下的单向拉伸试验,得到了不同应变率下聚碳酸酯板材的拉伸工程应力-工程应变曲线。试验结果表明:聚碳酸酯的拉伸力学行为呈现明显的非线性变形特征;在文中实施的0.001s-1~1700s-1应变率加载范围内,聚碳酸酯拉伸力学性能具有明显的应变率相关性,其屈服应力和与屈服应力相对应的失稳应变均随应变率的增加有显著的增大。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ... 相似文献
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《中国标准化(英文版)》2014,(4)
正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from 相似文献
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《中国标准化(英文版)》2014,(5)
正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively. 相似文献