TC8合金转子叶片锻造工艺研究

为研制一项TC8合金转子叶片,并达到提高锻造生产效率、降低生产成本的目的,进行了锻造工艺性试验、工艺参数试验,研究了TC8合金锻造工艺适应性以及加热温度、变形程度对低倍组织、显微组织及力学性能的影响.结果表明,TC8合金十分适合锻造工艺,采用较低的锻造加热温度能够获得初生α相含量更高的等轴组织,变形程度在40%以内所获得的组织均匀性较好.在此基础上,依据TC8合金转子叶片单榫头、小尺寸的结构特点,采用了高效的挤压制坯+终锻成形工艺,通过叶片锻造成形试验,试制出了具有均匀且状态理想的金相组织、良好表面质量的TC8合金转子叶片锻件,表明了所制定的叶片成形工艺及工艺参数合理可行.     

TiAl基合金双温热处理的研究

研究了双温热处理对ＴｉＡｌ基合金的显微组织和室温拉伸性能的影响。试验结果表明，适当的双温热处理工艺能够减小或消除等温锻ＴｉＡｌ基合金因变形不均匀而遗留下的粗大组织，细化晶粒尺寸，从而提高合金的室温力学性能。     

TC17合金β锻管形件近等温挤压成形工艺研究

目的 研究β锻管形件近等温挤压成形工艺对TC17合金显微组织和力学性能的影响。方法 采用DEFORM–3D软件模拟分析了实心挤压和空心挤压成形TC17合金管形件的变形特征,模拟分析2种挤压方式成形下TC17合金管形件在固溶处理过程中的冷却效果。对空心挤压成形的锻件进行金相组织表征和力学性能测试。结果 模拟结果表明,相较于实心挤压的方式,空心挤压方案整体应变较大、变形均匀、材料利用率高、固溶冷速较快且均匀性较好。试验结果表明,空心挤压成形的锻件质量良好,整体的宏观/微观组织均匀,室温拉伸性能和断裂韧性一致性好,且满足相关指标要求。结论 空心挤压方案满足该管形锻件研制要求,研究结果可以为类似管形件制备提供依据。     

钛合金双安装板静子叶片精锻成形工艺优化

为了缩短双安装板结构的TC4合金低压第二级静子叶片精锻工艺流程,并得到更优的金相组织、力学性能,首次将等温锻造方法引入叶片精锻工艺中,采用一火次等温预锻代替两火次普通预锻.利用刚粘塑性有限元法模拟等温预锻过程,分析了金属流动规律、应变场等的变化情况.结果表明,所成形的等温预锻件应力较低、应变分布比较均匀.经叶片成形工艺试验,得到了采用等温预锻的叶片精锻件,将采用普通预锻的叶片精锻件与之对比,发现采用等温预锻的叶片较采用普通预锻的叶片金相组织均匀性好,而两者的力学性能相当.     

GH4720Li合金细晶棒材制备的热加工工艺研究

通过合理的热加工工艺获得组织均匀细小的棒材是难变形高温合金GH4720Li研制成功的关键和难点。通过对变形高温合金开坯工艺调研以及在GH4720Li合金MTS热模拟实验和数值模拟基础上,对开坯工艺参数进行了初步确定,据此采用2000t快锻机对406mm的GH4720Li合金铸锭进行了开坯试制,获得的棒材组织均匀、细小,性能优良。实验结果表明,得到的GH4720Li合金开坯工艺参数合理可行。     

微量Mn元素对超高强铝合金锻件平面力学性能各向异性的影响

通过金相显微镜、扫描电镜、XRD 衍射仪以及拉伸力学性能测试研究了微量 Mn 元素对 Al-Zn-Mg-Cu超高强铝合金挤压带板及其制备的等温模锻件的平面力学性能各向异性的影响。结果表明,微量 Mn 元素的加入可以产生大量含 Mn 第二相,促进超高强铝合金锻件的再结晶,使变形织构强度减弱,再结晶织构强度增加,降低高强铝合金锻件的平面力学性能各向异性。此外,弥散细小的含锰相使合金断裂形式转变为穿晶延性断裂,提高了合金的延伸率。     

大变形量近等温锻造开坯对TiAl合金组织与性能的影响

采用近等温锻造开坯工艺实验定量研究了增大变形量对Ti-46.5Al-2.5V-1.0Cr-0.3Ni合金变形组织均匀性和力学性能稳定性的作用。通过锻坯组织观察分析及硬度、强度分布测试,揭示了TiAl合金近等温锻造过程中变形量与宏观组织和微观组织均匀性的基本关系。结果表明:近等温锻造变形量为65%,70%,75%,80%,85%时,随着变形量的增大,TiAl合金锻坯内的宏观变形流线分布趋于均匀,均匀变形区域面积不断增大,变形量85%时均匀变形区面积增加至68.0%,微观变形组织由等轴的γ和α2,以及很少量的残余层片团组成,晶粒尺寸明显细化,且等轴组织在合金中占到了绝大部分;锻坯硬度分布测试表明随着近等温锻造变形量的增大,均匀变形区域的硬度变化基本趋于均匀一致,且硬度平均值也在不断增高;锻坯难变形区和均匀变形区经1250℃/15h/AC热处理后取样进行室温压缩测试,随着近等温锻造变形量的增加锻坯各部位室温压缩应力应变数据分散度降低,性能稳定性提高。     

BT22钛合金及其大型锻件的研究进展

综述了国内外BT22合金及其改型合金的应用现状,归纳介绍了BT22合金的锻造加工及热处理工艺.结果表明,BT22合金在两相区低于β_转15～50℃的温度范围内多火次锻造,每火次变形量不低于60%.通过严格控制变形速率和终锻温度可制备出组织均匀、晶粒细小的锻件,经两阶段整体热处理后可获得强度、塑性和韧性的最佳匹配.针对我国的研究现状指出了BT22合金大型锻件制备方面亟待解决的问题和未来研究发展的方向.     

复合包套轧制工艺对难变形高温合金GH720Li组织的影响

研究了复合包套轧制工艺对难变形高温合金GH720Li组织的影响.结果表明:采用复合包套变形可以有效控制合金的轧制温度,减少轧辊与钢锭的摩擦力,改善难变形合金的表面质量及变形组织均匀性,防止轧制过程开裂.随着轧制变形量的增大,铸态GH720Li合金粗大的柱状树枝晶组织充分破碎,热变形后合金轧态晶粒度为ASTM5级,一次γ′相尺寸约为0.46μm,同时消除了低倍粗晶现象.经过热处理后GH720Li合金晶粒度为ASTM4级,改善了强化相γ′相的大小、数量及其分布状态,获得了良好的力学性能.     

Ti-6-22-22S合金大棒的显微组织与力学性能

研究了6种热处理制度对Ti—6—22—22S合金棒材显微组织和力学性能的影响。结果表明，该合金锻态为细网篮组织，在接近相变点温度固溶并经低温时效后，得到杂乱网蓝组织 少量初生等轴α或晶界条状α的混合网篮组织，三重热处理后得到针状网篮组织。选择适当的热处理制度，可以得到较佳的综合性能。     

Ti-1023合金的研究现状

Ti-1023合金是一种为适应损伤容限性设计原则而生产的高结构效益、高可靠性和低制造成本的锻造钛合金。本文主要介绍了Ti-1023合金组织性能、工艺性能及应用现状。     

Effect of processing parameters on shear bands in non-isothermal hot forging of Ti -6Al -4V

Abstract

The alloy system Ti- 6Al- 4V is the prominent Ti alloy system for aerospace and biomedical applications, as a result of its mechanical property balance and biocompatibility. Since the mechanical characterisation of Ti- 6Al- 4V is strongly sensitive to processing parameters there is relationship between processing variables, i.e. strain rate and temperature, microstructure, and properties under different loading conditions. Two phase (α + β) titanium alloys undergo flow instabilities and are susceptible to shear bands or regions of localised deformation crossing many grains during hot forging under non-isothermal conditions (dies and workpiece at different temperatures). Under such conditions shear bands can be generated even in materials without flow softening attributes. This occurs if the forging parameters lead to large amounts of heat transfer between the dies and the workpiece. This study investigates the occurrence of shear bands during non-isothermal, hot forging of Ti -6Al- 4V in order to evaluate the process parameters that generally lead to shear bands in conventional hot forging of metals. Upset compression tests on cylindrical specimens were conducted in a mechanical press and lateral side pressing tests on long, round bars were performed in either a mechanical press or a hydraulic press. The tests ranged from axisymmetric to plane strain compression. In upset specimens shear bands occurred at an angle of 45° to the compression axis and bands of intense deformation separated chill zones from the deforming bulk. Observation also demonstrated that the fracture might be owing to microvoids nucleated at weak points in sections of the shear surfaces. For plane strain deformation, shear bands were found to initiate along zero extension directions in a manner analogous to the formation and propagation of shear bands in isothermal hot forging. Although the shear band features at hot forging temperatures were similar to each other, there was a difference in the hardness and thickness of the shear bands depending on deformation mode, amount, and temperature.     

Mg-13Gd-4Y-0. 5Zr 镁合金多向锻造组织和性能研究

由于锻坯的组织和力学性能对其后续成形过程具有重要的影响,研究锻坯的组织和力学性能均匀性具有重要实用价值。利用实验的方法,对比研究了Mg-13Gd-4Y-0.5Zr合金材料的三次多向锻造后的组织演变和力学性能的不同。实验结果表明:随着锻造次数的增加,动态再结晶明显,Mg-13Gd-4Y-0.5Zr镁合金晶粒逐渐细化,析出相逐渐增多;并且,随着锻造次数的增多,硬度变化呈小幅波动的趋势,且第一次多向锻造后的硬度最大。     

Investigation on microstructure and mechanical properties of Ti14 alloy after semisolid deformation

Abstract

This study details the development of microstructure of Ti14 alloy as a function of the forging temperature and forging ratio in semisolid state and influence of resulting microstructure on the mechanical properties. The results reveal that dynamic recrystallisation occurred during semisolid forging, and the grain refinement was attained. Grain size increased in the forging temperature and decreased in the forging ratio. High ultimate tensile strengths and low elongation have been achieved after semisolid forging. The strength decreased with increasing forging temperature, while the ductility increased with increasing forging ratio. The relative contributions of tensile properties were attributed to the varieties of grain size obtained by thixoforging.     

Effect of pulse-current heating multiple forging on mechanical properties of Mg–Nd–Zn–Zr alloy

The effects of pulse current heating on microstructure evolution and mechanical property of Mg–Nd–Zn–Zr magnesium alloy during multiple forging are investigated. The results of uniaxial tensile test show that tensile strength, yield strength and elongation of the alloy are improved with the increasing of forging passes. Moreover, under the condition of pulse current heating, this promotion effect is more obvious. The results of microstructure analysis show that recrystallisation occurs during the deformation, and the recrystallisation is obviously accelerated by pulse current. The magnesium alloy billet with fine grains is obtained eventually. Theoretical analysis shows that pulse current can increase the recrystallisation nucleation rate and reduce the rate of grain growth, which is helpful to refine the grains of alloy.     

烧结温度对TC4合金的微观结构和力学性能的影响

将TiH₂、Al-V粉末压制成型后进行真空烧结,制备出Ti6Al4V(TC4)合金,使用XRD、金相和SEM断口形貌观测以及力学性能测试等手段对其表征,研究了烧结温度对合金力学性能的影响。结果表明：烧结样品由密排六方α-Ti和体心立方β-Ti双相组成,其形貌呈等轴、网篮或板条(片状、针状)状,随着烧结温度的提高和保温时间的延长等轴组织减少,片状组织和针状组织增加且其组织粗化,在1150℃烧结的样品具有较好网篮结构组织;用该方法可制备相对密度为96.9%~99.6%、抗拉强度为719.3~914.1 MPa、延伸率为6.2%~9.4%、硬度为313.2~364.8HV的TC4合金试样;在1150℃保温1.5 h的样品性能较好,其抗拉强度最高(914.1 MPa),对应的延伸率和硬度分别为7.6%和355.5HV;用纯TiH₂粉末烧结样品的断口呈韧性断裂;加入合金元素的样品其断口逐渐由韧性断口变为韧性和脆性混合的断口,其强度提高、延伸率下降。     

TiAl基合金包套锻复合热机械处理工艺的研究

针对用于ＴｉＡｌ基合金的常规热机械处理的局限性，提出了包套锻复合热机械处理新工艺。详细地研究了此项新工艺的工艺参数对Ｔｉ－３３Ａｌ－３Ｃｒ－０．５Ｍｏ合金显微组织及锻坯表观质量的影响。     

Influence of deformation process on microstructure and properties of 2014 aluminium alloy

The comparisons of forging-extrusion multistage hot deformation, forging and extrusion hot deformation processes on microstructure, mechanical property and impact toughness of 2014 Al alloy have been investigated. Results showed that the strength and impact toughness of the samples under forging-low extrusion multistage deformation process were significantly improved compared with that under forging deformation process due to the formation of smaller insoluble particles, finer grains and higher density of matrix precipitates. However, the strength and impact toughness of the samples under forging-extrusion multistage hot deformation process are lower than that under extrusion hot deformation process. The strengthening and fracture mechanisms with different deformation process have been discussed in detailed.     

Microstructure and mechanical properties of TA15 titanium alloy under multi-step local loading forming

In this paper six different local loading processes were proposed to study the effects of local loading conditions (temperature, deformation degree, loading pass, heats, cooling modes and heat treatment) on the microstructure and mechanical properties of TA15 titanium alloy workpieces including room and high temperature tensile properties, impact property, fracture toughness and high temperature duration property.It is found that it is better to finish the local loading forming in one heating time, if multi-fire forging needed the optimal forging technique as follows: adopting conventional forging (950 °C) at first and then following near-beta forging to control the proportion of the equiaxed primary α phase and the transformed β phase, allocating deformation degree of each loading pass rationally and using WQ cooling mode. Thus the workpiece with good compositive mechanical properties can be obtained.