Incoloy901合金的热加工图与热变形行为

利用Gleeble-3800热模拟机研究Incoloy901高温合金在变形温度950～1150℃,应变速率0.005～1 s^-1,真应变0.6下的热变形行为。结果表明:变形温度大于1000℃,应变速率大于0.01 s^-1时,Incoloy901合金真应力-应变曲线呈现动态再结晶特征。根据应力-应变曲线构建Incoloy901合金的本构方程与热加工图,得出形变激活能Q=439.401 k J/mol,最佳热加工工艺为:变形温度1050～1150℃,应变速率0.005～0.1 s^-1,在此工艺范围内合金的高温变形功率耗散系数η较高,可达37%,能获得较好的动态再结晶组织。     

High temperature deformation behavior and processing map for a nickel-titanium shape memory alloy

The hot deformation behavior of 49.2Ti-50.8Ni shape memory alloy was studied using hot compressive deformation testing in the temperature range of 1023-1323 K and at strain rates of 0.01-10 s^-1. The work-hardening rate was induced to analyze the stress-strain curves, and the critical stress σc and the dynamic recovery saturation stress σ_sat were measured which can be specified approximately by the expressions: σ_sat-1.12σ_p and σ_c-0.86σ_p. An Arrhenius model was calculated to describe the relationship between peak stress and the Z parameter. The relationship between deformation activation energy, the deformation conditions and the effect of Ni component in a binary TiNi alloy on the activation energy were discussed in this work. With the help of electron backscattering diffraction, a connected mode dynamic recrystallization microstructure was confirmed in peak efficiency regimes (850 °C & 0.01 s^-1 and 1050 °C & 10 s^-1) of the processing map.     

基于热加工图的Cu-Ni-Si-P合金的高温热变形行为

在Gleeble-1500D热模拟试验机上,通过高温等温压缩试验,对Cu-2.0Ni-0.5Si-0.03P合金在应变速率为0.01～5 s-1、变形温度为600～800℃的动态再结晶行为以及组织转变进行了研究。结果表明:在应变温度为750、800℃时,合金热压缩变形流变应力出现了明显的峰值应力,表现为连续动态再结晶特征。同时从流变应力、应变速率和温度的相关性,得出了该合金高温热压缩变形时的热变形激活能(Q)为485.6 kJ/mol和热变形本构方程。根据动态材料模型计算并分析了该合金的热加工图,利用热加工图确定热变形的流变失稳区,并且获得了试验参数范围内热变形过程的最佳工艺参数,温度为750～800℃,应变速率范围为0.01～0.1 s-1,并利用热加工图分析了该合金不同区域的高温变性特征以及组织变化。     

锌合金高温变形行为及加工图

在Gleeble-1500D热模拟机上采用等温压缩实验研究Zn-8Cu-0.3Ti锌合金的高温流变行为,获得锌合金在变形温度为230～380℃、应变速率为0.01～10 s-1和变形程度为50%条件下的真应力—应变曲线,根据动态材料模型(DMM)建立锌合金的热加工图。结果表明:Zn-8Cu-0.3Ti锌合金在实验条件下具有正的应变速率敏感性,流变应力随着应变速率的增大而增大,随着变形温度的升高而减小,该合金的流变应力行为可用Arrhenius方程来描述。在本研究条件下,Zn-8Cu-0.3Ti锌合金在热变形时存在一个失稳区,即应变速率0.2 s-1以上的区域;在应变速率小于0.001 s-1和340～370℃温度范围内,最大功率耗散系数为0.53,该安全区域内合金的变形机制为动态再结晶。     

Cr12合金高温压缩变形行为及热加工图

在TMTS热模拟试验机上对中压转子材料Cr12合金钢进行了实验,研究了Cr12合金钢在温度900～1150℃,变形速度为0.001～10 s-1的变形条件下的热变形行为.结果表明,该合金为热敏感型和应变速率敏感型材料.Cr12合金的热加工图表明,该材料存在两个流变失稳区,在实际生产过程中,变形温度在1000℃以上时,应...     

Al-Zn-Mg-Sc-Zr合金的热变形行为及加工图

在Gleeble-1500热模拟试验机上对Al-5.5Zn-1.5Mg-0.2Sc-0.1Zr铝合金进行高温等温压缩实验,研究该合金在变形温度为300～500℃、应变速率为0.01～10s-1条件下的流变行为,建立合金高温变形的本构方程和加工图,采用电子背散射衍射(EBSD)分析变形过程中合金的组织特征.结果表明流变应力随变形温度的升高而降低;当应变速率ε=10s-1,变形温度为300～500℃时,合金发生了动态再结晶.Al-5.5Zn-1.5Mg-0.2Sc-0.1Zr合金的高温流变行为可用Zener-Hollomon参数描述.在热变形过程中,随着真应变增加,合金的变形失稳区域增大.该合金适宜的变形条件如下变形温度300～360℃、应变速率0.01～0.32s-1,或变形温度380～500℃、应变速率0.56～10s-1.     

Cu-Ni-Si-P合金热变形行为及热加工图

采用高温等温压缩试验,对Cu?Ni?Si?P合金在应变速率0.01~5?1、变形温度600~800°C条件下的高温变形行为进行了研究,得出了该合金热压缩变形时的热变形激活能Q和本构方程。根据实验数据与热加工工艺参数构建了该合金的热加工图,利用热加工图对该合金在热变形过程中的热变形工艺参数进行了优化,并利用热加工图分析了该合金的高温组织变化。热变形过程中Cu?Ni?Si?P合金的流变应力随着变形温度的升高而降低,随着应变速率的提高而增大,该合金的动态再结晶温度为700°C。该合金热变形过程中的热变形激活能Q为485.6 kJ/mol。通过分析合金在应变为0.3和0.5时的热加工图得出该合金的安全加工区域的温度为750~800°C,应变速率为0.01~0.1 s?1。通过合金热变形过程中高温显微组织的观察,其组织规律很好地符合热加工图所预测的组织规律。     

Pb-Mg-Al合金的热变形行为与加工图

采用Gleeble-1500热模拟试验机研究Pb-Mg-Al合金在变形温度453～613 K、应变速率0.01～1 s-1条件下的热压缩流变行为,计算应力指数和变形激活能,采用Zener-Hollomon参数法构建合金的高温变形的本构关系,基于Murty准则,建立Pb-Mg-Al合金的加工图。结果表明:Pb-Mg-Al合金为正应变速率敏感材料;该合金的热压缩变形流变应力行为可用双曲正弦函数本构方程和Zener-Hollomon参数来描述,其平均变形激活能为149.524 4kJ/mol;从加工图分析并结合激活能,确定Pb-Mg-Al合金的最优变形温度和应变速率分别为533 K和0.1 s-1。     

ZA27合金的热变形及加工图

采用Gleeble-1500热模拟实验机进行热压缩试验,研究ZA27合金的热变形行为,在变形温度为200~350℃、应变速率为0.01~5 s-1、工程应变为60%,基于Murty准则,建立ZA27合金的加工图。结果表明:流变应力随变形温度的升高而减小,随应变速率的提高而增大;在变形温度为200~210℃、应变速率为0.01~0.1 s-1和变形温度为250~350℃、应变速率为1~5 s-1的2个区域内易产生流变失稳现象;动态再结晶是导致流变软化及稳态流变的主要原因,ZA27合金的安全热加工区域的变形温度在250~350℃之间、应变速率在0.1~1 s-1之间。     

Ti6242合金的热变形行为及加工图

利用Gleeble-3800对Ti6242合金进行热模拟压缩试验。研究了压缩量为60%、应变速率分别为0.01、0.1、1、10 s-1,变形温度分别是900、950、1000、1050、1100℃条件下试样的热变形行为。根据试验参数得出Ti6242合金本构方程,绘制Ti6242合金真应力-应变曲线,基于动态材料模型建立热加工图。结果表明,流变应力随着变形温度的升高而下降,随着应变速率的增加而升高,变形激活能Q=453.74 k J/mol,最佳热加工工艺为变形温度1000~1050℃应变速率0.1 s-1左右。     

Cu-Cr-Zr-Y合金热压缩力学行为及热加工图

利用Gleeble-1500D热模拟试验机对Cu-Cr-Zr-Y合金进行高温等温压缩试验,变形温度和应变速率分别为650~850℃和0.001~10 s-1,对合金高温热压缩过程中的变形行为进行研究。结果表明:其流变应力随应变速率的提高而增大,随变形温度的升高而减小。并根据动态材料模型绘制和分析了该合金的热加工图,得出了热变形过程的最佳工艺参数为:温度为800~850℃,应变速率范围为0.001~0.1 s-1。     

Hot deformation and processing maps of an Fe3Al intermetallic alloy

The deformation behavior of an Fe–28Al–5Cr–0.08Zr–0.04B (at.%) intermetallic alloy under hot compression conditions was characterized in the temperature range of 600–1100 °C and strain rate range of 0.001–100 s⁻¹. Processing maps were calculated to evaluate the efficiency of the hot working and to recognize the instability regions of the flow behavior. The investigated alloy possesses the optimum hot-working conditions at 1100 °C and 0.001 s⁻¹, since the material undergoes dynamic recrystallization to produce a fine-grained structure with a high fraction of high-angle boundaries (∼70%). At lower temperature the material exhibited “large grained superplasticity” with a peak efficiency of ∼60% at 1000 °C and 0.001 s⁻¹. These parameters are the optimum ones for superplastic working of that alloy. The occurrence of large grained superplasticity is attributed to the formation of a subgrain structure within the large original grains and higher strain-rate sensitivity. The material also exhibits flow instabilities due to flow localization at lower temperatures (<700 °C) and higher strain rates (>0.1 s⁻¹).     

Deformation characteristics of the intermetallic alloy 60NiTi

The deformation behavior of a Ni-rich Ni₅₅Ti₄₅ (at.%) alloy, commonly known as 60NiTi (as designated in wt.%), was analyzed using neutron and synchrotron x-ray diffraction during in situ isothermal tension and compression loading, and pre and post-test electron microscopy. The alloy was shown to exhibit remarkable strength and high hardness resulting from a high density of fine Ni₄Ti₃ precipitates (size ∼67 nm), which were uniformly dispersed throughout the matrix after a solution treatment and oil quench. The precipitate volume fraction was 55 ± 3%, determined from both the neutron Rietveld refinement and conventional x-ray measurements. Non-linear stress-strain behavior was observed in tension (but not in compression) and was attributed to reversible stress-induced martensite (SIM) that forms to accommodate the stress as revealed by neutron diffraction measurements. The tensile and compressive neutron data also showed peak broadening and residual lattice strains. Transmission and scanning electron microscopy revealed stress-induced coarsening of Ni₄Ti₃ precipitates in both tension and compression tested samples, but precipitation and growth of the stable Ni₃Ti phase was observed only after tensile testing. Finally, the potential ramifications of these microstructural changes are discussed.     

High temperature strengthening of the FeAl intermetallic phase-based alloy

The cause of the positive temperature dependence of the yield stress B2 FeAl alloys is still controversial. In the literature several models have been proposed but none of them fully accepted. In the present work results of studies of the yield stress, long range order parameter, magnetic susceptibility and structure versus temperature for the multi-component alloy on base of the B2 FeAl phase are presented.Results of TEM and HREM observations excluded precipitation hardening and the presence of antiphase domains as the reasons for the thermal hardening of the studied material. Detailed studies of the dislocation structure after small deformation of the alloy did not reveal the reaction of massive decomposition of the 〈1 1 1〉 superdislocation for the 〈1 0 0〉 and 〈0 1 1〉 in the temperature range of the anomaly occurrence.The plastic deformation process up to 1073 K proceeded by movement of the 〈1 1 1〉 type dislocations. For the first time a clear dependence of the yield stress temperature changes on the long range order parameter for the alloy on base of the B2 FeAl phase was obtained.     

TC4钛合金EB炉扁锭高温压缩变形行为和热加工图

采用Gleeble-3500热/力学模拟试验机对电子束冷床炉(EB炉)熔炼的TC4钛合金扁锭进行高温压缩实验,研究了TC4钛合金扁锭在变形量为40％,温度为1023～1173 K,应变速率为0.001～1 s-1的条件下热压缩变形行为.通过使用双曲正弦形式修正的Arrhenius关系来描述TC4钛合金高温压缩变形时最大...     

等轴组织TC21合金高温变形本构模型和热加工图

对等轴组织TC21合金在Gleeble-1500热模拟实验机上进行了等温压缩实验,变形温度为760、800、840、880、920和960℃(α+β相区),应变速率为0.001、0.01、0.1、1和10.0 s-1.结果 表明:TC21合金的流动应力随应变速率降低和变形温度升高而降低;随应变的增加,变形激活能从570 kJ·mol-1减少到410 kJ· mol-1.基于应变补偿的Arrhenius方程建立TC21合金高温变形本构模型,该模型可以精确地预测流动应力随工艺参数的变化.基于动态材料模型建立了TC21合金的热加工图;热加工图中的能量耗散效率和非稳态成形区域随着应变增加而改变.     

Cu-Cr-Zr-Ce合金的高温热变形行为

在Gleeble-1500D热模拟试验机上通过高温等温压缩试验,对Cu-0.4Cr-0.15Zr-0.05Ce合金在应变速率为0.01 ～5 s-1、变形温度为600 ～800℃的动态再结晶行为以及组织转变进行了研究.结果表明:流变应力随变形温度的升高而减小,随应变速率的提高而增大.同时从流变应力、应变速率和温度的相关性,得出了该合金高温热压缩变形时的热变形激活能Q为495.8 kJ/mol,同利用逐步回归的方法建立了该合金的流变应力方程.利用光学显微镜分析了形变温度对该合金在热压缩过程中的组织演变及动态再结晶形核机制的影响规律.     

锻态C-276镍基合金热变形行为及热加工图

为研究锻态C-276镍基合金的热变形行为,采用Gleeble-3180D热模拟试验机对该合金在变形温度950～1200℃以及应变速率0.01～10 s^-1条件下进行一系列热压缩实验。结果表明,合金的流变应力曲线都呈现明显的动态再结晶特征,并且流变应力随变形温度的提升或者应变速率的下降而降低。根据Arrhenius模型构建该合金峰值应力下的本构方程,得出合金的变形激活能为510.484 kJ/mol。依据材料动态模型绘制合金在0.6应变下的热加工图,并结合组织分析提出该合金最优的热加工参数为(1100℃,0.01 s^-1)以及(1150℃,0.01～1 s^-1)。另外,合金的组织变化规律表明,温度的增加或应变速率的降低能够促进合金的动态再结晶晶粒的形核与长大。     

High-temperature deformation behavior and processing map of the as-cast Inconel 625 alloy

A short process of Inconel 625 alloy tube was developed to solve the problems of the traditional extrusion process, and particular attention was paid on the hot deformation behavior of the as-cast Inconel 625 alloy. The hot compression experiments were performed to study the hot deformation behavior of Inconel 625 in the temperature range of 900–1200 °C and strain rate range of0.01–10.00 s~(-1) by Gleeble-3500. The hot compressed microstructure was examined to study the effects of temperature and strain rate on the microstructural characteristic by electron backscatter diffraction(EBSD). The results show that the processing maps were greatly influenced by the temperature rather than the strain rate. It is found that with the strain increasing, the instability zone gradually turned to the low-temperature and low strain rate area,while the range of high-temperature instability area shrank.The optimum condition of the as-cast Inconel 625 alloy was determined as high strain rate region(temperature of1100–1200 °C, strain rate of 1.00–10.00 s~(-1)) with the dissipation efficiency of above 0.28. As illustrated by microstructural characteristic of EBSD analysis, the perfect dynamic recrystallization occurred and fine grain structure was obtained under this deformation conditions.     

热等静压态FGH96合金的热变形行为及热加工图

采用Gleeble-3800热模拟压缩试验机对热等静压态FGH96合金进行了不同温度和应变速率的等温热压缩试验,研究了FGH96合金在变形温度分别为1040、1070、1100、1130 ℃,应变速率为0.001、0.01、0.1和1 s^-1,最大真应变为0.7条件下的高温热变形行为,分析了真应力-真应变曲线,建立了本构方程,并利用Origin软件构建了热加工图,结合变形温度和应变速率对组织的影响确定了FGH96合金合适的热加工参数。结果表明,热等静压态FGH96合金的真应力-真应变曲线呈现典型的动态再结晶特征,其峰值应力随变形温度的降低和应变速率的增加而增加,结合本构方程、热加工图以及微观组织确定了FGH96合金合适的热加工区域为变形温度1060~1080 ℃,应变速率0.0001~0.004 s^-1。