共查询到19条相似文献,搜索用时 31 毫秒
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应力三轴度和应变率对6063铝合金力学性能的影响及材料表征 总被引:6,自引:0,他引:6
对6063铝合金试样在不同应力三轴度和不同应变率下进行拉伸试验,得到了该合金在这两种情况下的力学性能.研究结果表明:随着应力三轴度的减小,材料的等效弹性模量、等效屈服应力减小,但等效断裂应变增大;随着应变率逐渐增大,材料的屈服强度和断裂强度略有增大;断裂应变明显减小;抗拉强度基本不变.Johnson-cook本构模型及其断裂应变模型可以用来描述6063铝合金在不同三轴应力度和不同应变率下的本构及失效关系.通过材料表征,得出了Johnson-cook本构模型及其断裂应变模型中各个参数,为有限元(ABAQUS)模拟提供帮助. 相似文献
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本文研究了 10钢在 H2 SO4溶液和 Na Cl溶液中渗氢后 ,在不同应变速率下其氢脆敏感性 .结果表明 :在 H2 SO4溶液中渗氢后 ,10钢具有明显的氢脆特征 ,应变速率从 3.33× 10 -1.sec-1~ 3.33×10 -6 .sec-1范围内 ,截面收缩率Ψ从 35 .36%降至 18.35 % ;延伸率δ从 2 9.34 %降至 14 .95 % ,10钢显示出最大的氢脆敏感性 相似文献
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采用末端淬火-硬度测试、差示扫描量热法、透射电镜、扫描电镜等方法,研究了固溶处理对Al-7.9Zn-2.5Mg-1.0Cu合金淬火敏感性的影响。结果表明:随着距淬火端面距离的增加,合金试样的硬度逐渐降低,处理制度为475℃/2h试样的淬火敏感性明显比处理制度为450℃/8h+475℃/2h试样的低,其淬透层深度超过100mm,而处理制度为450℃/8h+475℃/2h试样的淬透层深度仅为65mm。固溶处理制度对合金过饱和度的影响不大,但是与处理制度为475℃/2h的试样相比,处理制度为450℃/8h+475℃/2h试样的再结晶晶粒和(亚)晶界数目大大增加,促进了慢速淬火过程中η平衡相的析出,且尺寸相对粗化,导致了淬火敏感性的提高。 相似文献
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通过电化学充氢、慢拉伸实验并结合XRD、SEM、TEM和EBSD等显微组织表征方法,研究了显微组织对两种不同强度级别贝氏体钢筋氢脆敏感性的影响。结果表明:PSB1080钢筋强度高,但氢脆敏感性却低于PSB830钢;PSB830钢筋的组织分布不均匀,马氏体块尺寸差异较大,马氏体中高密度的位错为可逆氢陷阱,充氢之后氢分布不均匀,在拉伸的过程中,氢原子随位错迁移,扩散富集至裂纹尖端,裂纹在脆性大的马氏体和强度低的铁素体中扩展迅速,氢脆敏感性大。PSB1080钢筋板条间的残留奥氏体为不可逆氢陷阱,阻碍了氢原子的扩散富集,此外其组织的均匀性使钢中氢的分布也相对均匀,氢脆敏感性小。亚微米、纳米级的残留奥氏体同时具有良好的机械稳定性和化学稳定性,缓解了应力集中,阻碍了裂纹的扩展。 相似文献
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为了研究在低周大应变循环作用下钢材损伤对钢构件及钢框架抗震性能的影响,该文在Bao-Wierzbicki的等效塑性应变与应力三轴度路径的基础上,提出了符合钢材微观机制的应力三轴度起始损伤准则。随后通过10组Q235钢板拉伸试验确定了钢材的损伤演化准则。为了验证这些准则在描述钢构件及框架损伤破坏方面的正确性与适用性,该文采用有限元软件ABAQUS对一组型钢梁、钢框架梁柱节点及一榀钢框架的典型循环加载试验进行了损伤模拟分析。分析结果显示,考虑损伤准则的有限元曲线与试验曲线吻合一致,能较为准确的描述钢构件及钢框架在循环加载下承载力与刚度退化的现象,并能直观地模拟各结构的损伤部位及损伤程度。该文研究为分析钢构件及钢框架在低周大应变循环作用下的性能退化提供较为便捷的方法。 相似文献
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为了研究渗氮处理对钢的氢脆敏感性的影响,对气体渗氮处理的普通碳素钢进行了拉伸试验,对其断口进行了扫描电镜观察和显微组织分析。结果表明:渗氮层发生了氢脆延迟断裂,未渗氮部位发生了韧性断裂;渗氮处理增加了钢的氢脆敏感性。 相似文献
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利用氢渗透试验、慢应变速率拉伸试验(SSRT)研究了1 000MPa级高强钢(HSS)焊接件在海水中的氢渗透行为及其应力腐蚀敏感性,结合SEM观察了试样的断口特征,并利用电化学试验和显微组织观察分析了焊接件不同区域的氢脆特征。结果表明:相对于焊缝区(WM)和母材区(BM),热影响区(HAZ)的自腐蚀电位最负、析氢电位最正,更容易发生腐蚀和析氢行为。热影响区的氢扩散系数最大,具有较强的吸氢倾向。动态电化学充氢对高强钢焊接件的影响主要体现在对塑性的损减方面;随着极化电位的负移,高强钢焊接件的强度没有明显变化,但断面收缩率、断后延伸率均减小,断裂方式逐渐由韧性断裂变为解理断裂;当极化电位约为-930mV(vs SCE)时,高强钢焊接件的氢脆系数达25%;在不同充氢极化电位下,焊接件试样的断裂位置多在热影响区。 相似文献
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ABSTRACT Exact simulations of engineering practice are often difficult to accomplish with test methods of materials performance against hydrogen embrittlement (HE). Instead, it is proposed that assessment of the intrinsic susceptibility to HE be adaptable to diverse usage environments and loading modes. This notion is based on recent findings concerning the predominant role of strain-induced vacancies and their involvement in characteristic features of HE such as microstructural effects and dependence on strain rates and temperatures. The function of hydrogen in enhancing the generation of strain-induced vacancies operates throughout the entire process of fracture, and the density of vacancies is detectable using hydrogen as a tracer. A method is proposed here for using as the parameter the difference in the amounts of tracer-hydrogen between specimens given cyclic stressing with and without hydrogen. 相似文献
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An Overview of Hydrogen Interaction with Amorphous Alloys 总被引:2,自引:0,他引:2
Theories, experimental results and applications associated with hydrogen behavior in amorphous metals and alloys are reviewed. An emphasis is made on the potential use of these advanced materials for hydrogen storage technology. Therefore, several properties that are especially relevant for such applications are assessed. These include structural models for hydrogen occupancy, sorption characteristics, solubility, diffusion behavior and thermal stabilities. Hydrogen effects on the mechanical properties and fracture modes of glassy metals are also presented, and possible mechanisms of hydrogen embrittlement are discussed. Similarities and differences between hydrogen behavior in amorphous and crystalline metals and alloys are discussed in detail. 相似文献
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Equivalent Hydrogen Fugacity during Electrochemical Charging of 980DP Steel Determined by Thermal Desorption Spectroscopy
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Qinglong Liu Evan Gray Jeffrey Venezuela Qingjun Zhou Clotario Tapia‐Bastidas Mingxing Zhang Andrej Atrens 《Advanced Engineering Materials》2018,20(1)
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采用正电子湮没技术结合透射电镜,考察了Ti含量对一种Fe-Ni-Co基合金的微观结构及氢脆敏感性的影响结果表明:改变合金的Ti含量,会使合金中第二相的尺寸、数量、分布及种类发生变化,合金的强度、塑性及氢脆敏感性均随之发生改变;大尺寸的γ′颗粒及η相与基体间的界面是一种较强的缺陷,可以促进氢的局部聚并,从而导致合金氢脆敏感性的升高研究表明,合金的氢脆敏感性与合金强度之间并不存在必然的联系,而是取决于合金的微观结构,即随着合金中利于氢原子局部聚并的缺陷浓度的升高而增大 相似文献
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Jeffrey Venezuela Qingjun Zhou Qinglong Liu Mingxing Zhang Andrej Atrens 《Advanced Engineering Materials》2018,20(1)
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《中国工程学刊》2012,35(1):58-66
ABSTRACTSeveral advanced nickel-chromium-molybdenum high strength lowalloy steels newly developed by our research team exhibit excellent mechanical strength, toughness and hardenability. However, the phenomenon of hydrogen-induced embrittlement will easily occur for these high strength steels. In this research, the hydrogeninduced embrittlement of 8625-Modified steel (8625M steel) was studied. Experimental results show that the dominant hydrogen trapping site of the 8625M steel is dislocation, of which trapping energy is about 20 kJ/mol, indicating that the hydrogens trapped in the dislocations are diffusible. The as-quenched 8625M steel has the highest dislocation density and accordingly the highesthydrogen content after hydrogen charging. This makes the asquenched 8625M steel exhibit severe hydrogen embrittlement. After tempering at 200°C and 300°C, the dislocation density drops, and hence these tempered specimens have lower ultimate tensile strength loss. After 400°C tempering, the hydrogen embrittlement phenomenon becomes serious again, being ascribed to the formation of needlelike and film-like cementite which will weaken the strength of martensite. After 500°C tempering, the 8625M steel has the lowest dislocation density, and the inter-lath cementite become discontinuous and spheroidal, making the 500°C tempered specimen have the lowest ultimate tensile strength loss and the highest elongation after hydrogen charging in this study. 相似文献
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Failure of ductile materials is often related to coalescence of microscopic voids. The stress triaxiality is one of the primary
factors that influence the coalescence. In the present work, a 3D unit cell model is employed to investigate this effect.
The cell model contains two aligned voids. A coalescence criterion is proposed in which the critical void volume fraction
is expressed in terms of stress triaxiality. 相似文献