冷轧和退火处理对C-276镍合金管材组织与力学性能的影响

对C-276镍合金管材进行冷轧,并进行了不同温度的退火处理,研究了冷轧加工和退火处理对镍合金管材显微组织和力学性能的影响。结果表明:管材经50%变形量冷轧加工后,晶粒破碎,显微组织沿轧制方向呈现纤维状,抗拉强度1210 MPa,屈服强度1000 MPa,伸长率22%;1000℃退火时,显微组织处于回复阶段,仍为拉长的纤维状,抗拉强度为1160 MPa,屈服强度815 MPa,伸长率26%;1050℃退火时,轧制流线消失,部分组织发生再结晶,抗拉强度1050 MPa,屈服强度750 MPa,伸长率32%;1100℃退火时,显微组织发生完全再结晶,抗拉强度868 MPa,屈服强度397 MPa,伸长率53%,强度大幅下降,伸长率大幅上升;1150℃退火时,晶粒与1100℃退火相比没有明显变化,力学性能稳定,抗拉强度、屈服强度和伸长率分别为838 MPa、379 MPa和54.5%。     

冷轧变形量及退火工艺对Gr.39钛合金带卷组织性能的影响

研究了不同冷轧变形量和退火工艺对Gr.39钛合金带卷显微组织和力学性能的影响。结果表明,对于热轧退火态Gr.39钛合金带卷,当冷轧变形量从0升高到59.4%时,显微组织由完全退火的等轴组织逐渐变形为被拉长的纤维状组织,并且随着变形量的增加,材料加工硬化程度逐渐增加。考虑到轧制过程的稳定性,建议单轧程冷轧变形量控制在60%以内。Gr.39钛合金带卷在700℃退火发生完全再结晶,退火温度升高至相变点以上时,显微组织转变为粗大魏氏组织。随着退火温度的升高,抗拉强度和屈服强度逐渐降低,延伸率逐渐升高。推荐冷轧Gr.39钛合金带卷退火制度为700℃/8 h/AC。     

N04400冷轧管材组织与性能

对N04400合金钻孔管坯进行冷轧加工成管材,并进行了不同温度保温90min的真空退火处理,研究了加工态管材的组织与性能及退火温度对管材显微组织和力学性能的影响。结果表明,加工态时管材的显微组织沿轧制方向被拉长,抗拉强度为740MPa,屈服强度为695MPa,伸长率6.5%,屈强比为0.94;经600～650℃退火后,晶界更加清晰,显微组织仍为拉长的纤维状,强度较轧制态略有下降,伸长率稍有上升;700℃退火后,变形晶粒开始发生再结晶,抗拉和屈服强度急速下降,伸长率大幅上升;750℃退火后,组织发生了完全再结晶,力学性能变化缓慢。     

HSn88-1合金冷加工硬化及再结晶温度的研究

对HSn88-1合金进行了不同程度的冷变形,绘制出合金的加工硬化曲线。通过对不同厚度退火后试样的抗拉强度和伸长率的测试和组织观察,得出了合金的再结晶温度。结果表明,合金经冷轧变形后具有明显的加工硬化效果。合金的强度随加工率的增大是先增大然后趋于稳定,而伸长率和电导率呈相反变化规律。此外,冷加工率越大,合金的开始再结晶的温度越低。     

退火处理对LZ91镁锂合金冷轧板材组织与力学性能的影响

采用双辊轧机对热挤压态LZ91镁锂进行冷轧试验,利用OM、SEM、XRD分析了退火处理对LZ91镁锂合金冷轧板材显微组织的影响,并用维氏硬度计和拉伸试验机测试其力学性能。结果表明：200℃/1h退火后α相发生球化反应,β相再结晶完成,此时合金的综合性能最佳;随着退火温度的升高,α相和β相都相继长大;合金的抗拉强度和维氏硬度随着退火温度的升高而逐渐降低,伸长率则先升高后降低;当退火温度高于250℃时,由于α相和β相同时长大,合金的屈服强度急剧降低。     

定向凝固镍基高温合金的反常屈服和中温脆性行为（英文）

采用真空冶炼和定向凝固工艺制备一种具有优异抗腐蚀性能的镍基高温合金,并利用光学显微镜、扫描电镜和透射电镜研究合金的微观组织,分析合金在不同温度下的拉伸性能。结果表明,除γ′颗粒和γ基体外,在合金晶界上析出了一些MC碳化物、M3B2硼化物和Ni5Hf相。合金拉伸性能对温度有很强的依赖性,并呈现明显的的反常屈服和中温脆性行为。在650°C以下,合金的屈服强度随着温度的升高而略微降低,但抗拉强度几乎没有变化。当温度在650°C和750°C之间时,合金的屈服、抗拉强度快速升高,但拉伸塑性显著降低,并在700°C时达到最低值。当温度进一步升高时,合金的屈服、抗拉强度逐渐降低,塑性升高。透射电镜观察发现,在低温条件下,位错切割γ′是主要的变形机制;在高温条件下,位错绕过γ′是主要的变形机制;由位错切割γ′转变至位错绕过γ′的温度约为800°C。合金的反常屈服和中温脆性行为主要归因于合金中高的γ′含量。此外,碳化物和共晶组织对合金的中温脆性行为也有影响。     

冷轧与退火对LA91合金显微组织和力学性能的影响

对热挤压态LA91合金进行了冷轧及退火处理,研究了不同冷轧变形量与退火温度对合金显微组织和力学性能的影响。结果表明,总轧制变形量为76.7%的LA91合金薄板具有较高的强度和良好的塑性(抗拉强度为177 MPa,伸长率为37.4%)。在200~300℃范围内退火,冷轧LA91合金发生回复和再结晶,β相逐渐变为等轴状,α相逐渐球状化。因此,随退火温度升高,合金薄板的抗拉强度先降低后升高,伸长率则先升高后降低。同一变形量下,合金中的α相再结晶温度略高于β相;经1h退火,不同变形量的冷轧LA91合金开始再结晶的温度略微不同,约为250℃,退火温度为300℃时,再结晶完成。     

退火对LZ91镁锂合金冷轧板材组织与力学性能的影响

采用双辊轧机对热挤压态LZ91镁锂进行冷轧试验,利用OM、SEM、XRD分析了退火处理对LZ91镁锂合金冷轧板材显微组织的影响,并用维氏硬度计和拉伸试验机测试其力学性能。结果表明,200℃×1 h退火后α相发生球化反应,β相再结晶完成,此时合金的综合性能最佳;随着退火温度的升高,α相和β相都相继长大;合金的抗拉强度和维氏硬度随着退火温度的升高而逐渐降低,伸长率则先升高后降低;当退火温度高于250℃时,由于α相和β相同时长大,合金的屈服强度急剧降低。     

退火处理对TiZrAlV合金组织与力学性能的影响

采用X射线衍射仪、光学显微镜、扫描电镜、硬度测试和拉伸试验等方法研究退火处理对TiZrAlV合金的显微组织和力学性能的影响。结果表明:锻造态TiZrAlV合金由α相、β相以及少量fcc相组成;退火处理后,合金发生α+β+fcc→α+β的相变过程,并且β相含量随退火温度升高而增加;TiZrAlV合金锻造态和退火态的微观组织特点为典型的网篮组织,并且随着退火温度的升高,α相片层的厚度逐渐增大;锻造态TiZrAlV合金的屈服强度、最大抗拉强度、伸长率以及硬度分别为833、955 MPa、13.08%以及36.5 HRC;退火处理后合金的屈服强度得到提升,400℃退火的屈服强度为982 MPa,抗拉强度为1136 MPa,而伸长率和硬度变化不大;退火处理后合金的拉伸断口由大量大小不等的韧窝组成,呈现塑性断裂特征。     

Cu-Ag合金的冷加工硬化及再结晶温度

对Cu-Ag合金进行了不同程度的冷变形,绘制出了合金的加工硬化曲线。通过对不同厚度退火后试样的抗拉强度和伸长率进行测试和组织观察,得到了合金的再结晶温度。结果表明,合金经冷轧变形后,具有明显的加工硬化效果。合金的强度随着变形量的增大,呈先增大后趋于稳定的趋势,而伸长率、电导率与变形量呈相反的变化规律。冷变形程度越大,合金的再结晶温度越低。但当变形量超过60%时,再结晶温度趋于一个稳定值(300~400℃)。     

Microstructures of Ti–Ni–Fe wire after severe cold-drawing and annealing

The microstructures and mechanical properties of Ti–47 at%Ni–3 at%Fe shape memory alloy wire under the condition of severe cold-drawing at room temperature and different postdeformation annealing processes were intensively investigated using transmission electron microscope(TEM),X-ray diffraction(XRD),Vickers microhardness tester and electron tensile tester.It is indicated that the structure of the alloy evolves into a predominant amorphous structure with a trace of nanocrystalline B2 phase after the cold-drawing of 76%areal reduction.Postdeformation annealing process exerted significant influence on the microstructure and mechanical properties.Crystallization occurs when the cold-drawn wire was annealed at 300℃ for 30 min.The ultimate tensile strength and ductility as well as the superelasticity of the wire are improved significantly by cold-drawing plus postdeformation annealing.     

Ti49.4Ni50.6超弹性弹簧的相变和形变特性

用示差扫描量热仪、拉伸实验和应力-应变循环实验系统研究了退火温度、变形温度以及热循环和室温应力-应变循环对Ti49．4Ni50．6超弹性(SE)弹簧的相变和形变特性的影响。冷加工加中温退火态Ti49．4Ni50．6合金冷却→←加热时的相变类型为母相B2→←R相→←马氏体B19′。随退火温度升高，马氏体转变温度升高，R相转变温度降低。623-773K退火态Ti49．4Ni50．6弹簧室温下可获得SE特性，随变形温度升高，SE弹簧剐度增加；当退火温度超过823K后，SE持性变差。热循环时SE弹簧的切变量取值越小，其应变恢复率越高。预循环训练可增强SE的稳定性。     

Microstructures and mechanical properties of laser-welded TiNi shape memory alloy and stainless steel wires

The Nd:YAG laser welding was used to join the TiNi shape memory alloy and AISI304 stainless steel wires. The microstructural features of the dissimilar material joint were analyzed. The tensile and hardness tests were carried out to examine the mechanical properties and microhardness distribution of the welded joint. The results show that the joint has the non-homogeneous microstructure and element distribution. The brittle phases such as Fe2Ti, FeTi, Cr2Ti, Ti3Ni4, Fe0.2Ni4.8Ti5 and TiN mainly segregate in rich Ti region of fusion zone. The laser-welded joint has the tensile strength of 298 MPa with the elongation of 3.72% and exhibits the brittle fracture features on the fracture surfaces. The reasons for low joint strength were discussed in this investigation.     

退火温度对CrFeCoNiTi1.5高熵合金微结构与性能的影响

为研究中低温热处理对CrFeCoNiTi_1.5高熵合金性能的影响,分别在200、400及600 ℃下对高熵合金进行10 h退火处理。通过X射线衍射仪、扫描电镜(SEM)、能谱仪(EDS)、显微硬度计和电化学工作站对高熵合金的组织结构、表面形貌以及元素的偏析程度进行分析,并测试了高熵合金的动电位极化曲线以及维氏硬度。结果表明:退火温度的提高有利于CrFeCoNiTi_1.5高熵合金中HCP结构相的析出;随着温度的升高Cr、Fe、Co和Ni逐渐向晶内聚集分布,Ti逐渐向晶间聚集。600 ℃中低温退火处理时合金耐腐蚀性能最好,硬度为914 HV0.5。     

Microstructure and tensile properties of isothermally forged Ni–43Ti–4Al–2Nb–2Hf alloy

NiTi-Al-based alloys are promising high-tem- perature structural materials for aerospace and astronautics applications. A new NiTi-Al-based alloy Ni--43Ti-4AI- 2Nb-2Hf （at%） was processed via isothermal forging. The microstructure and mechanical properties at room temperature and high temperature were investigated through scanning electron microscope （SEM）, X-ray diffraction （XRD）, and tensile tests. Results show that the micro- structure of as-forged Ni-43Ti--4AI-2Nb-2Hf alloy con- sists of NiTi matrix, Ti2Ni phase, and Hf-rich phase. The simultaneous addition of Nb and Hf, which have strong affinities for Ti sites, promotes the precipitation of Hf-rich phases along the grain boundaries. The tensile strengths of Ni-43Ti-4A1-2Nb-2Hf alloy are dramatically increased compared with the ternary Ni-46Ti-4A1 alloy. At room temperature and 650℃, the yield stress of Ni--43Ti-4Al- 2Nb-2Hf alloy reaches 1,070 and 610 MPa, respectively, which are 30 % and 150 % higher than those of Ni--46Ti- 4Al alloy. The improved tensile property results from the solid solution strengthening by Nb and Hf, as well as the dispersion hardening of the Ti2Ni and Hf-rich phases.     

TRANSFORMATION HYSTERESIS AND STABILITY OF STRAIN MARTENSITE IN A Ni_(47)Ti_(44)Nb_9 ALLOY

The transformation hysteresis and stability of strain martensite in Ni_(47)Ti_(44)Nb_ alloy have been studied by means of tensile tests at various temperatures and electrical resistance measurements as well as TEM observations.It was shown that there is a characteristic deformation temperature and a strain range,in which the critical yield stress for stress-in- duced transformation acquires optimum matching with the yield strength of the β-Nb parti- cles.In this case,deformatian can effectively increase the transformation hysteresis,while the strain recovery ratio remains usefully high.The martensite with irreguldar fine.twin substructure and martensite containing some dislocations as well as martensite intersected by the β-Nb particles possess high stability.     

退火工艺对激光选区熔化成形Ti6Al4V合金组织及室温力学性能的影响

以Ti6Al4V球形粉末为原料,利用激光选区熔化成形方法制备了Ti6Al4V合金试样,采用光学显微镜、扫描电镜及力学性能测试等手段,研究了退火工艺对Ti6Al4V合金室温力学性能及组织的影响规律。结果表明: SLM成形沉积态Ti6Al4V合金室温抗拉强度超过1200 MPa,而平均断后伸长率仅为4.0%;在650 ℃下进行真空退火处理,合金的抗拉强度仍保持在1200 MPa左右,规定塑性延伸强度R_p0.2高于1150 MPa,但试样的断后伸长率<10%;而在750及800 ℃下进行真空退火处理,合金试样的抗拉强度降至1100 MPa左右,规定塑性延伸强度高于1050 MPa,伸长率达到甚至超过10%,材料的综合强韧性得到明显提升。随着真空退火加热温度和保温时间的增加,SLM成形Ti6Al4V合金原始β晶界逐渐变模糊,晶粒趋向于等轴化。与此同时,快速冷却转变的α′针状马氏体未出现明显地粗化。     

添加Cr对Ti-Ni形状记忆合金相变和低温形变特性的影响

用示差扫描量热仪和拉伸试验研究了添加Cr对形变退火态Ti-Ni形状记忆合金相变和低温形变特性的影响。结果表明,添加微量Cr后,Ti-Ni合金的R、马氏体(M)相变温度θR和θM大幅度降低,M相变热滞?θM增加,应力-应变曲线的平台应力σM显著提高,超弹性(SE)改善,塑性变差。添加微量Cr后,Ti-Ni合金的低温SE特性大幅改善。室温下,Ti-50.8Ni合金呈现形状记忆效应(SME)+SE,而Ti-50.8Ni-0.3Cr合金则呈现SE。退火温度也显著影响Ti-Ni合金的低温形变特性。在10℃变形时,400～500℃退火态Ti-50.8Ni合金呈现SME,550～650℃退火态Ti-50.8Ni合金呈现SME+SE,而400～650℃退火态Ti-50.8Ni-0.3Cr合金则持续呈现SE。     

Transformation behavior and mechanical properties of a nanostructured Ti−50.0Ni(at.%) alloy

Transformation behavior, the shape memory effect and the superelasticity of an equiatomic 40% cold worked Ti−Ni alloy followed by annealing at various temperatures have been investigated by means of differential scanning calorimetry (DSC), transmission electron microscopy, thermal cycling tests under constant load and tensile tests. The B2-R-B19 transformation occurred in all samples, and the R-B19’ transformation occurred in a wide temperature range. The B2-R transformation start temperature kept constant with raising annealing temperature. The average grain size increased from 23 to 80 nm with raising annealing temperature from 523 to 673 K. Transformation hysteresis increased rapidly with raising annealing temperature up to 623 K, above which they almost keep constant, which was ascribed to the small grain size and large constraints of grain boundaries.     

退火温度对Ti-Ni-Cr低温超弹性合金组织和拉伸性能的影响

用光学显微镜和拉伸试验研究了退火温度(Ta)对Ti-50.8Ni-0.3Cr合金显微组织和拉伸行为的影响。结果表明,合金原始态为拉拔纤维组织,退火时发生回复与再结晶。Ta=350～500℃时,为回复阶段,组织呈纤维状。Ta=550～590℃时,为再结晶阶段,纤维组织逐渐变成无畸变等轴晶粒,再结晶温度在570℃左右。Ta=600～800℃时,为晶粒长大阶段,显微组织呈粗大不均匀等轴晶。Ta对合金在低温(8℃)下的拉伸行为有显著影响,随Ta升高,应力诱发马氏体相变临界应力先降低后升高;350～500℃退火态合金的加工硬化能力和抗拉强度大于550～700℃退火态合金,而后者的延伸率则显著大于前者。当Ta大于650℃后合金的延伸率因晶粒粗化而减小。