时效温度与时间对6005A铝合金挤压型材显微组织与力学性能的影响(英文)

研究时效时间和时效温度对6005A铝合金显微组织与力学性能的影响,对该铝合金挤压型材进行人工时效实验,时效时间分别为4、8和12h,时效温度分别为150、175和200°C。结果表明:随着时效温度和时间增加,挤压过程形成的粗大Al(Fe,Cr)Si析出相形貌由颗粒状向棒状转变,175°C时亚微米级析出相体积分数最大,200°C时在晶界析出1～3μm左右的AlFeSi相。挤压型材的室温力学性能对时效工艺中的温度参数更加敏感,时效工艺为175°C,4～8h时具有最佳的强度和较稳定的力学性能,抗拉强度与屈服强度分别达到300MPa和270MPa以上。     

挤压Mg-8.5Gd-2.3Y-1.8Ag-0.4Zr合金的显微组织与力学性能(英文)

研究铸态和挤压态Mg-8.5Gd-2.3Y-1.8Ag-0.4Zr合金的显微组织、时效强化和力学性能。铸锭在T4处理后分别于400、450和500°C进行挤压,挤压比为10:1。在细晶强化和析出强化的共同作用下,于400°C挤压的样品经T5处理后可以得到最优的力学性能,所得的晶粒尺寸约为5.0μm,其初始和峰值硬度分别为HV109和HV129。室温下的拉伸屈服强度、抗拉强度和伸长率分别达到391MPa、430MPa和5.2%。     

Enhancing room temperature mechanical properties of Mg–9Al–Zn alloy by multi-pass equal channel angular extrusion

Influence of equal channel angular extrusion on room temperature mechanical properties of cast Mg–9Al–Zn alloy was investigated. The results show that room temperature mechanical properties of Mg–9Al–Zn alloy, such as yield strength, ultimate tensile strength and elongation, can be improved heavily by equal channel angular extrusion. Processing routes, processing temperature and extrusion passes have important influence on room temperature mechanical properties of processed Mg–9Al–Zn alloy by equal channel angular extrusion. The optimum room temperature mechanical properties such as yield strength of 209 MPa, ultimate tensile strength of 339 MPa and elongation of 14.1%, can be obtained when Mg–9Al–Zn alloy was processed by equal channel angular extrusion for 6 passes at route B_C at 498 K. Large bulk materials of Mg–9Al–Zn alloy with average grain size of 4 μm and high mechanical properties can be prepared.     

钇含量对Mg-xY-1.5LPC-0.4Zr合金的时效硬化和力学性能的影响(英文)

研究钇含量对Mg-xY-1.5LPC-0.4Zr镁合金的时效硬化、显微组织和力学性能的影响(其中LPC代表富镧混合稀土金属)。当将Y加入Mg-1.5LPC-0.4Zr时,随着Y含量的增加,合金的时效硬化反应相应增强,晶粒尺寸变小,强度增加。当将Y添加到Mg-1.5LPC-0.4Zr合金中时,时效析出相发生改变,由Mg-LPC基合金的稳态Mg12RE相转变为Mg-Y基合金的亚稳态β′相,且随着Y含量的增加,β′相的数量也相应增多。在合金晶界上还发现了稳态立方形的β-Mg24Y5相。对于Mg-Y-LPC-Zr合金,拉伸性能的改善主要归功于均匀、弥散分布的β′相,在晶界上的β-Mg24Y5相对合金的晶界也有明显的强化作用。当Y含量达到6%时,合金的拉伸强度最大,合金在室温和250°C的抗拉强度分别是250 MPa和210 MPa。     

多级时效对低压铸造A356.2轮毂力学性能的影响

研究了多次人工时效对低压铸造A356.2铝合金轮毂力学性能的影响.结果表明,T6处理后,再经过3次人工时效,合金的抗拉强度、屈服强度、硬度有所提高,但伸长率有所下降;随人工时效次数的继续增多,力学性能变化幅度渐小,组织结构趋于稳定;轮辐部位的晶粒较轮缘部位的晶粒粗,二者屈服强度和硬度的差别不大,但轮辐部位的抗拉强度和伸长率比轮缘部位低.     

累积叠轧温度对AZ31镁合金组织和性能的影响

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。     

等通道转角挤压Mg-3.52Sn-3.32Al合金的组织与力学性能

采用等通道转角挤压（ECAP）Bc路径对固溶态Mg-3.52Sn-3.32Al合金分别挤压1、4和8道次。利用光学显微镜、扫描电子显微镜、透射电子显微镜和X射线衍射仪分析合金的组织和相组成,并测试了其室温拉伸力学性能。结果表明,经ECAP挤压后,固溶态合金组织中析出大量细小的Mg2Sn相和极少量的Mg17Al12相。随挤压道次增加,合金的综合力学性能先提高后降低。经4道次挤压后,合金的综合拉伸力学性能相对较佳,抗拉强度、伸长率和硬度分别达到250 MPa、20.5%和61.3 HV9.8,较未ECAP时分别提高43.7%、105%和26.9%。经ECAP挤压的合金室温拉伸断口均呈韧性断裂。等通道转角挤压Mg-3.52Sn-3.32Al合金的力学性能受晶粒尺寸、析出相以及组织织构的共同影响。     

RECIPROCATING EXTRUSION OF IN SITU Mg2Si REINFORCED Mg-A1 BASED COMPOSITE

Mg2Si reinforced Mg-Al based composite with high amount of silicon was prepared by permanent mould casting, and then extruded by reciprocating extension (RE) after the composite was processed by homogenization heat treatment. The effect of RE processing on the morphology and size of Mg2Si and the mechanical properties of the composite were investigated, to develop new ways to refine the Mg2Si phase and improve its shape. The result showed that RE was very useful in refining the Mg2Si phase.The more the RE processing passes, the better the refining effect would be. Moreover,the uniform distribution of Mg2Si phases would be more in the composite. After the composite was processed by RE for 12 passes, most Mg2Si phases were equiaxed, with granular diameter below 20 μm, and distributed uniformly in the matrix of the composite. The mechanical properties of the composite could be increased prominently by RE processing, and were much higher than that in the as-cast state. As the temperature rises, the tensile strength is reduced. For the composite RE processed for 12 passes, the tensile strength, yield strength, and elongation are 325.9 MPa, 211.4 MPa,and 3.3% at room temperature, whereas, 288.2 MPa, 207.7 MPa, and 7.8%, respectively, at 150° C. In comparison with the properties at room temperature, the tensile strength and yield strength are high and only decrease by 11.6% and 1.8% at 150°C. The Mg2Si reinforced Mg-Al based composite possesses good heat resistance at 150° C. The excellent resistance to effect of heat is attributed to the high melting temperature and good thermal stability of fine Mg2Si phases, which are distributed uniformly in the composite, and effectively hinder the grain boundary gliding and dislocation movement.     

Twin-Induced Plasticity of an ECAP-Processed TWIP Steel

The TWIP steels show high strain hardening rates with high ductility which results in high ultimate tensile strength. This makes their processing by equal channel angular pressing very difficult. Up to now, this has only been achieved at warm temperatures (above 200 °C). In this paper, a FeMnCAl TWIP steel has been processed at room temperature and the resulted microstructure and mechanical properties were investigated. For comparison, the material has also been processed at 300 °C. The TWIP steel processed at room temperature shows a large increase in yield strength (from 590 in the annealed condition to 1295 MPa) and the ultimate tensile strength (1440 MPa) as a consequence of a sharp decrease in grain size and the presence within the grains of a high density of mechanical twins and subgrains. This dense microstructure results also in a loss of strain hardening and a reduction in ductility. The material processed at 300 °C is more able to accommodate deformation and has lower reduction in grain size although there is a significant presence of mechanical twins and subgrains produced by dislocation activity. This material reaches an ultimate tensile strength of 1400 MPa with better ductility than the room temperature material.     

低温形变热处理制备Mg-6Gd-1Y-0.5Zr合金的力学性能(英文)

对固溶态的Mg-6Gd-1Y-0.5Zr合金进行低温形变热处理,处理工艺包括不同应变量的冷拉伸和随后在200°C进行的峰值时效。结果表明:低温形变热处理合金的时效硬化动力学显著加速,随变形量增大,合金的峰值时效时间大幅度缩短。冷拉伸变形量为10%的合金在200°C峰值时效后的屈服强度、抗拉强度和伸长率分别达到251MPa、296MPa和8%,这些性能大大超过传统商业牌号的耐热镁合金WE54,尽管其总的稀土含量高于GW61K合金。     

Mechanical properties at room temperature of an Al-Zn-Mg-Cu alloy processed by equal channel angular pressing

Tensile tests were conducted to evaluate the influence of equal-channel angular pressing (ECAP) on the mechanical properties at room temperature of overaged Al 7075-O alloy. ECAP processing was performed using route B_C at different temperatures and number of passes, i.e. different processing severity conditions. The maximum load (F_max) recorded during the last pass of each ECAP path considered in this study is a very good estimation of the processing severity. The mechanical properties were studied in terms of the balance between tensile strength and ductility. In the processed Al 7075-O alloy, the grain size was reduced down to ∼150 nm. Consequently, tensile testing at room temperature revealed a significant increase in the maximum tensile strength after ECAP with respect to the as start material. In the present study, as the processing severity increases with the number of ECAP passes or with the decrease in processing temperature, there is a consistent trend of increment in ultimate tensile strength with minor decrease in uniform plastic elongation respect to the first ECAP pass at room temperature. This is in contrast to the behaviour after more severe plastic deformation conditions, where an increase in strength together with a strong decrease in elongation would be expected.     

Influences of aging temperature and time on microstructure and mechanical properties of 6005A aluminum alloy extrusions

The influences of aging time and aging temperature on the microstructure and mechanical properties were investigated on the 6005A aluminum alloy extrusions. Artificial aging was performed on the alloy extrusions. The aging times were 4, 8 and 12 h, and the aging temperatures were 150, 175 and 200 °C. The results show that the morphologies of the coarse Al(Fe,Cr)Si particles formed in the extrusion process are evolved from granular to rod-like particles with the increase of the aging temperature or the aging time. The volume fraction of the submicron precipitates reaches the maximum value at the aging temperature of 175 °C. AlFeSi particles in size of 1-3 μm are precipitated at the grain boundaries at the aging temperature of 200 °C. The room temperature mechanical properties of the extrusions are more sensitive to the aging temperature than to the aging time. The optimum and stable mechanical properties are achieved when the aging procedure 175 °C, 4-8 h has been performed on the extrusions. The tensile strength and the yield strength in the longitudinal direction of the aged extrusions are more than 300 MPa and 270 MPa, respectively.     

Processing of AZ31 magnesium alloy by accumulative roll-bonding at gradient temperature

In the present investigation a wrought magnesium alloy AZ31 was successfully processed by the accumulative roll-bonding (ARB) at gradient temperature up to six cycles with the lowest temperature of 250 °C. This is performed through different thermomechanical processing routes (different ARB cycles at different temperatures of 350-200 °C). The microstructures and mechanical properties were investigated. The results indicate that significant grain refinement is observed after the first two cycles at the highest ARB temperature as a result of dynamic recrystallization, which is necessary for the subsequently ARB cycles at relatively lower temperature with the aim to restrict grain growth. No significant finer grain size was observed through the fifth and sixth cycles while the microstructure homogeneity is further improved. The grain structure can be effectively refined at lower ARB processing temperature and higher cycles. The resulting material exhibited high strength and relatively high ductility at ambient temperature when ARB deformed above 250 °C. The mechanical properties of the ARB deformed materials are strongly dependent on several main factors: the amount and the homogeneity of strain achieved, grain size and microstructure homogeneity, textures developed during ARB and interface bonding quality.     

Effects of die angle on microstructures and mechanical properties of AZ31 magnesium alloy processed by equal channel angular pressing

1　INTRODUCTIONMagnesiumalloysarethelightestmetallicstruc turalmaterialsandhencetheyprovidegreatpotentialintheweightsavingofautomotiveandaerospacecomponents ,materialhandlingequipment ,portabletoolsandevensportinggoods[1,2 ] .Duetotheirhexago nalclose packed (HCP)crystalstructure ,magnesiumalloysperform poorformabilityandlimitedductilityatroomtemperature ,thustheirproductsaremainlyfabricatedbycasting ,inparticular ,die casting ,andtheapplicationsofwroughtmagnesiumalloysarelim ited .Nowit…     

The influence of multi-pass friction stir processing on the microstructural and mechanical properties of Aluminum Alloy 6082

Samples with one through three passes with 100% overlap were created using friction stir processing (FSP) in order to locally modify the microstructural and mechanical properties of 6082-T6 Aluminum Alloy. A constant rotational speed and three different traverse speeds were used for processing. In this article, the microstructural properties in terms of grain structure and second phase particles distribution, and also the mechanical properties in terms of hardness and tensile strength of the processed zone were addressed with respect to the number of passes and traverse speeds. The parameter combination which resulted in highest ultimate tensile strength was further compared with additional two rotation speeds. FSP caused dynamic recrystallization of the stir zone leading to equiaxed grains with high angle grain boundaries which increased with increasing the number of passes. The accumulated heat accompanying multiple passes resulted in increase in the grain size, dissolution of precipitates and fragmentation of second phase particles. Increasing the traverse speed on the other hand did not affect the grain size, yet reduced the particles size as well as increased the particle area fraction. Hardness and tensile test results of the stir zone were in good agreement where increasing the number of passes caused softening and reduction of the ultimate tensile strength, whereas, increasing the traverse speed increased the strength and hardness. Increasing the tool rotational speed did not have a significant influence on particle mean diameter, ultimate tensile strength and hardness values of the stir zone, whereas, it caused an increase in mean grain size as well as particle area fraction.     

表面机械研磨对5052铝合金表面纳米化与性能的影响

研究了表面机械研磨处理(SMAT)对传统轧制和连铸连轧5052铝合金显微组织、物相组成、硬度和拉伸性能的影响.结果表明:进行SMAT前,连铸连轧5052铝合金的晶粒尺寸(7μm)要小于传统轧制5052铝合金的晶粒尺寸(13μm);进行SMAT后,传统轧制和连铸连轧5052铝合金在表层均会形成细小的晶粒尺寸梯度分布,而且...     

不同热成形工艺下TA32钛合金的流变性能及组织演变

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%。     

流变轧制AZ91合金的热处理和组织性能调控

本文对连续流变轧制AZ91合金在热处理过程中的组织和力学性能演化进行了研究。热处理后两种析出相在基体中出现：一种是晶界处的非连续析出相,另一种是从过饱和基体中析出的小尺寸连续析出相。随着时效温度升高,原子扩散速度也随之提高,导致更多的析出相生成和长大。合金的维氏硬度和拉伸强度峰值在16小时时效后出现,而合金的延伸率随着时效时间的延长和时效温度的提高呈下降趋势。经过对实验结果的分析,适合提升合金综合力学性能的热处理制度为415°C固溶20小时加220°C时效16小时。经热处理后得到的维氏硬度、拉伸强度和延伸率分别为：99 HV,251 MPa和4.5%,各项性能均显著优于流变轧制态合金。相对于传统成型手段,流变轧制加热处理方法成型的AZ91合金展现了优异且均衡的综合力学性能。     

Evolution of Microstructure,Residual Stress,and Tensile Properties of Mg–Zn–Y–La–Zr Magnesium Alloy Processed by Extrusion

The microstructure, texture, residual stress, and tensile properties of Mg–6 Zn–2 Y–1 La–0.5 Zr(wt%) magnesium alloy were investigated before and after extrusion process, which performed at 300 °C and 400 °C. The microstructural characterizations indicated that the as-cast alloy was comprised of α-Mg, Mg–Zn, Mg–Zn–La, and Mg–Zn–Y phases. During homogenization at 400 °C for 24 h, most of the secondary phases exhibited partial dissolution. Extrusion process led to a remarkable grain refi nement due to dynamic recrystallization(DRX). The degree of DRX and the DRXed grain size increased with increasing extrusion temperature. The homogenized alloy did not show a preferential crystallographic orientation, whereas the extruded alloys showed strong basal texture. The extrusion process led to a signifi cant improvement on the compressive residual stress and mechanical properties. The alloy extruded at 300 °C exhibited the highest basal texture intensity, the compressive residual stress and hardness, and yield and tensile strengths among the studied alloys.     

热处理工艺对Inconel 617合金管组织性能的影响

利用光镜(OM)、硬度测试、室温拉伸试验等方法,研究了Inconel 617合金管的微观组织和力学性能在不同热处理工艺参数下的变化趋势。通过光镜对合金组织进行表征,分析了温度为1120～1200 ℃,保温时间为10、30 min时合金晶粒尺寸的变化规律,同时建立了晶粒尺寸长大的动力学模型。结果表明,随着温度的不断提高,晶粒的平均尺寸不断增大,并且晶粒内部逐渐出现较多的孪晶。同时,随着热处理温度的不断提高,合金的硬度变化趋势与抗拉强度变化趋势相同,二者都随着温度的升高,呈现下降的趋势;合金的伸长率随着温度的升高不断增加。Inconel 617合金的晶界迁移表观激活能Q为651.82 kJ/mol。