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累积叠轧焊温度和循环道次对AZ31镁合金组织和性能的影响 总被引:1,自引:0,他引:1
研究了累积叠轧焊温度变化和循环道次对AZ31镁合金板材组织和性能的影响,分析了累积叠轧焊工艺细化AZ31镁合金晶粒的机理.试验结果表明,加热温度从250℃增加到400℃时,第一个道次后的平均晶粒尺寸逐渐减小;在400℃保温5min、道次压下量为50%时,第二个道次的板材平均晶粒尺寸可以细化到1.3μm,抗拉强度为300MPa,伸长率达到25.2%. 相似文献
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通过光学显微镜、室温拉伸试验、显微硬度计、X射线衍射仪、扫描电镜等方法研究了累积叠轧温度对AZ31镁合金晶粒尺寸、基面织构、界面结合情况及力学性能的影响。结果表明:3道次累积叠轧后的AZ31镁合金晶粒细化效果明显,硬度增大,随着累积叠轧温度的升高,晶粒细化效果减弱,硬度增加趋势减弱。累积叠轧温度升高有弱化基面织构的作用。AZ31镁合板材在450 ℃累积叠轧3道次,综合力学性能最佳,为显微硬度70.64 HV0.05,抗拉强度288.64 MPa,屈服强度203.76 MPa,伸长率16.96%,界面结合强度21.53 MPa。 相似文献
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以热挤压材为坯料,经多道次热轧制备AZ40Mg合金板材。研究热轧变形对合金组织、力学性能与断裂行为的影响。结果表明:随着热轧道次的增加,通过动态再结晶,材料的组织均匀性得到逐步改善,晶粒尺寸持续细化。相应地,热轧板材的力学性能与挤压态坯料相比得到显著改善。经过5道次以上热轧制备的AZ40Mg合金板材,其平均晶粒尺寸细化到10μm以下,轧向及横向的室温拉伸屈服强度与伸长率均可分别达到175MPa和20%以上。 相似文献
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利用累积叠轧焊制备了LZ91和AA1050相间隔的层状复合板材,采用拉伸机、光学显微镜、扫描电镜和X射线衍射仪研究了叠轧次数对该层状复合板材力学性能和显微组织的影响。结果表明,3次叠轧后两种板材层厚非常接近,LZ91层中的α相沿轧延力方向的平均粒径由2μm减小至0.3μm,叠轧晶粒细化效果不明显;随着叠轧次数增多,制备的LZ91/AA1050层状复合板材抗拉强度先增大后减小,3次叠轧材料抗拉强度、屈服强度和硬度(HV)最高,分别比未叠轧材料提高了42.11 MPa、71.93 MPa和16.5;累积叠轧LZ91/AA1050复合板材层间无新的金属间化合物生成。 相似文献
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纯镁大比率挤压棒材的组织与性能及其随后的退火处理(英文) 总被引:1,自引:0,他引:1
以纯镁铸锭作为坯料,经过两道次累计大比率挤压制备了棒材,并对最终的棒材进行退火处理。通过光学显微镜(OM)、力学性能测试和扫描电子显微镜(SEM)研究了挤压变形和退火处理对纯镁组织、性能以及断裂行为的影响。结果表明:在挤压变形过程中,由于动态再结晶的作用,材料的晶粒尺寸得到明显细化,从而显著地改善了材料的室温力学性能和断裂方式。经过一次挤压后,粗大的铸态晶粒细化到35μm,屈服、抗拉强度和伸长率分别达到84MPa、189MPa和12%,所得棒材经再次挤压后,屈服强度超过120MPa,但是,由于加工硬化的作用,伸长率有所下降。对最终棒材进行退火处理后,平均晶粒尺寸为9~10μm,屈服强度、抗拉强度分别达到124MPa、199MPa,伸长率为10.7%,材料的组织和性能得到明显改善。 相似文献
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研究了板坯加热温度、退火温度以及冷轧道次加工率对AZ31变形镁合金轧制能力的影响.结果表明,当加热温度为350℃,轧制速度为0.4m/s时,AZ31镁合金板材的热轧道次极限加工率可以达到34.62%(无裂纹)和59.23%(无表面裂纹);将热轧态板材分别在250℃~350℃温度,退火40min后,板材显微组织中晶粒大小均匀,维持在5μm~6μm水平;板材具有良好的综合力学性能,其抗拉强度为:230Pa~240MPa,屈服强度为:135MPa~175MPa,延伸率为:12%~15%.当采用350℃×40min退火后,板材在冷轧道次加工率为5%~10%时,总加工率可以达到40%以上. 相似文献
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工业纯钛在120°模具中的多道次ECAP室温变形组织与性能 总被引:4,自引:0,他引:4
在室温,采用通道夹角为120°的变形模具对工业纯钛(Commemial Pure Titanium,CP-Ti)以Bc方式实施四道次ECAP(EqualChannel Angular Pressing)挤压变形,成功获得表面光滑无裂纹的变形试样.文中主要研究了工业纯钛在室温下进行ECAP多道次变形的组织结构演变,并测试了变形试样的力学性能.微观结构显示工业纯钛在室温下进行多道次ECAP变形时,只在前两道次产生了大量的变形孪晶,且随道次增加变形孪晶逐渐消失.最终获得的试样晶粒平均尺寸由最初的约28μm细化到约250 nm,试样断裂强度和显微硬度分别提高到773和2486 MPa,而试样仍保持较好的延伸率(可达16.8%). 相似文献
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The microstructure and tensile properties of Ti-44Al-6V-3Nb-0.3Y (at.%) alloy after canned forging were investigated. SEM results showed that the TiAl pancake exhibits inhomogeneous microstructure, which can be ascribed to the temperature drop and friction between billet and outer pack during forging, as well as the intrinsic anisotropy of lamellar colony. By means of TEM observation and EBSD analysis, the microstructure in the dominant area of the pancake was further characterized. This deformation area consists of 87.7% content of γ grains plus some refined lamellar colonies and the rest of B2 grains. The grain size ranges between 1 μm and 8.5 μm. High-angle boundaries dominate the deformation microstructure, several substructures and twins are observed as well. Additionally, current forged alloy exhibits excellent high temperature tensile strength and noteworthy yield stress anomaly (YSA), with ultimate tensile strength 680 MPa and yield strength 620 MPa at room temperature, increasing to 850 MPa and 750 MPa at 700 °C, respectively. The anomalous strengthening of current TiAl alloy is temperature dependent and can be interpreted by the dislocation cross-slip pinning mechanism. 相似文献
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V. I. Zel’dovich E. V. Shorokhov S. V. Dobatkin N. Yu. Frolova A. E. Kheifets I. V. Khomskaya P. A. Nasonov A. A. Ushakov 《The Physics of Metals and Metallography》2011,111(4):421-429
The macro- and microstructure have been analyzed and the tensile mechanical properties have been measured for commercial titanium
subjected to dynamic channel angular pressing (DCAP) at high temperatures using one or two passes, as well as to additional
warm rolling and low-temperature annealing. The structure of titanium after DCAP at a high temperature consists of a dispersed
mixture of fine recrystallized grains (1 to 2 μm in size) and deformed nonrecrystallized regions. The deformed regions have
a subgrain structure with sub-grains 200–300 nm in size. After the second pass, the size of the recrystallized grains becomes
less by two times as compared to their size after one-pass DCAP, the subgrains in the deformed regions acquire a more equiaxed
shape, and the microstructure becomes more uniform. The warm rolling of the samples subjected to DCAP at high temperatures
increases the total density of dislocations and provides a high level of internal stresses. After two-pass DCAP at 530°C,
the ultimate strength of titanium was 650MPa and the relative elongation was 19%. Additional rolling to 50% at 300°C and low-temperature
annealing increases the ultimate strength to 790 MPa, while the relative elongation is retained at a high level of 15%. 相似文献
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《Intermetallics》1999,7(8):875-879
A Ti–40Al–10V (at%) intermetallic compound has been developed using vacuum arc remelting and hot-isostatic pressing (HIP), followed by isothermal hot-forging (IHF). The alloy, composed mainly of B2 and γ phases with equiaxial grains of several μm in average diameter and a small amount of α2 phase with equiaxial grains of smaller size, shows excellent tensile properties; it has an elongation larger than 6% on average and yield strength larger than 700 MPa at low (ambient temperature) to intermediate temperatures, although the strength decreases rapidly at temperatures higher than 600°C. 相似文献
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Microstructure and tensile properties of ultrafine grained copper processed by equal-channel angular pressing 总被引:4,自引:0,他引:4
WEI Wei ) CHEN Guang) WANG Jingtao) and CHEN Guoliang) ) Department of Materials Science Engineering Jiangsu Polytechnic University Changzhou China ) Department of Materials Science Engineering Nanjing University of Science Technology Nanjing China 《稀有金属(英文版)》2006,25(6):697-703
1. Introduction There has been an interest in the research of spe- cific microstructure and unique mechanical proper- ties in ultrafine-grained (UFG) materials [1]. Equal-channel angular pressing (ECAP) process has been successfully applied to obtain UFG structure in numerous metals and alloys [2-6]. However, there are some deficiencies on copper deformed to large shear strains. Ferrasse et al. [6] argued that intense simple shear promotes dynamic rotation recrystalli- zation during ECAP… 相似文献
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对高铝双相合金Mg15Al在553K以Bc路线进行了不同道次的等通道挤压(ECAP),获得了超细晶高铝镁合金。通过OM,SEM,TEM分析了ECAP前后合金的微观组织结构及断口形貌,并测试了不同挤压道次后合金的硬度和室温拉伸性能,分析了ECAP细化晶粒机理及其性能改善原因。结果表明,随挤压道次增加,累计形变增强,网状硬脆相β-Mg17Al12破碎,合金晶粒显著细化,但对单相区和两相混合区细化效果不同。在α、β两相共存区内,4道次ECAP后形成100nm~200nm的细晶粒;在α单相区,4道次ECAP后晶粒为1μm以下,且在初晶α-Mg内析出弥散细小的β相,起到细晶强化和弥散强化作用。8道次ECAP后,晶粒略有长大。ECAP使合金的硬度、抗拉强度和延伸率同时得到提高,尤其是4道次ECAP后,硬度提高了32.04%,抗拉强度σb从150MPa提高到269.3MPa,延伸率δ由0.05%提高到7.4%;8道次ECAP后,硬度、抗拉强度略有下降,延伸率略有上升。SEM断口观察显示ECAP使合金拉伸断口形貌由铸态的解理断裂特征转变为延性韧窝断裂特征。 相似文献
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Jong Un Lee Sang-Hoon Kim Wan-Kuen Jo Won-Hwa Hong Woong Kim Jun Ho Bae Sung Hyuk Park 《Metals and Materials International》2018,24(4):730-737
Grain-refined AZ92 (GR-AZ92) alloy with superior tensile properties is developed by adding 1 wt% Zn and a very small amount of SiC (0.17 wt%) to commercial AZ91 alloy for enhancing the solid-solution strengthening effect and refining the crystal grains, respectively. The homogenized GR-AZ92 alloy with an average grain size of 91 μm exhibits a tensile yield strength (TYS) of 125 MPa, ultimate tensile strength (UTS) of 281 MPa, and elongation of 12.1%, which are significantly higher than those of AZ91 alloy with a grain size of 420 μm (TYS of 94 MPa, UTS of 192 MPa, and elongation of 7.0%). The peak-aging time of GR-AZ92 alloy (8 h) is significantly shorter than that of AZ91 alloy (32 h) owing to a larger amount of grain boundaries in the former, which serve as nucleation sites of Mg17Al12 precipitates. A short-aging treatment for less than 1 h of the GR-AZ92 alloy causes an effective improvement in its strength without a significant reduction in its ductility. The 30-min-aged GR-AZ92 alloy has an excellent combination of strength and ductility, with a TYS of 142 MPa, UTS of 304 MPa, and elongation of 8.0%. 相似文献
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用OM,SEM和XRD等方法研究了挤压态Mg-Al-Ca-x Nd(x=0~1.76,质量分数,%)合金的显微组织和析出相以及该合金在室温和高温下的力学性能。结果表明,Nd的添加会使基体中形成Al2Nd和Al11Nd3相,并且细化Mg-Al-Ca合金的晶粒。随着Nd添加量的增加,Al2Nd和Al11Nd3相的数量也随之增加。当添加1.76%Nd时,合金的平均晶粒尺寸从不含Nd的4.80μm变为2.39μm。由于第二相的析出和晶粒细化,室温下的力学性能也得到改善。随着Nd元素含量的增加,合金的室温抗拉伸强度由267MPa提高到304 MPa,屈服强度从144 MPa提高到203 MPa,延伸率从20.0%下降到16.9%。在150℃时,随着Nd含量的增加,拉伸强度从192 MPa增加到229 MPa,屈服强度从140 MPa增加到159 MPa,伸长率从48.6%下降到29.3%。 相似文献