Development of two rhenium- containing superalloys for single- crystal blade and directionally solidified vane applications in advanced turbine engines

A team approach involving several turbine engine companies using the concepts of simultaneous engi-neering has been used to successfully develop CMSX-4 ® alloy for turbine blade applications. CMSX-4 al-loy is a second-generation, single-crystal cast nickel-base superalloy containing 3% Re and approximately 70% volume fraction of γ. The high level of balanced properties determined by labora-tory evaluation has been confirmed during field testing of the Solarγ Mars T-14000 industrial gas turbine with CMSX-4 single-crystal (SX) blades in both the coated and bare condition. A similar collaborative ap-proach has resulted in the successful development of CM 186 LCγ alloy for complex, directionally solidi-fied (DS) columnar grain vane segments. CM 186 LC alloy is a second-generation DS columnar grain cast nickel-base superalloy containing 3% Re and approximately 65% volume fraction of γ. Excellent com-ponent producibility and quality is demonstrated. Turbine engine testing is scheduled to commence by the end of 1993.     

基于知识模板的涡轮叶片精铸模设计方法研究

提出了基于知识模板的涡轮叶片精铸模设计方法,介绍了知识模板的定义、构建方法及基于知识模板的设计方法等关键技术。面向装配过程,设计了具有参数化关联的模具模板结构,实现基于模板知识的精铸模自动生成,缩短了精铸模设计周期,提高了精铸模标准化程度和设计知识利用率。     

Influence of service-induced microstructural changes on the aging kinetics of rejuvenated Ni-based superalloy gas turbine blades

Rejuvenation of Ni-based superalloy gas turbine blades is widely and successfully employed in order to restore the material microstructure and properties after service at high temperature and stresses. Application of hot isostatic pressing (HIP) and re-heat treatment can restore even a severely overaged blade microstructure to practically “as-new” condition. However, certain service-induced microstructural changes might affect an alloy’s behavior after the rejuvenated blades are returned to service. It was found that advanced service-induced decomposition of primary MC carbides, and the consequent changes of the γ-matrix chemical composition during the rejuvenation, can cause a considerable acceleration of the aging process in the next service cycle. The paper will discuss the influence of the previous microstructural deterioration on the aging kinetics of rejuvenated gas turbine blades made from IN-738 and conventionally cast GTD-111 alloys.     

An integration system for investment casting mould design of aeroengine turbine blade

An integration system was developed to satisfy the need of information integration in the process of designing, investment casting and monitoring aero-engine＇s turbo blade. The general architecture is detailed presented in this paper. The system mainly comprises of product master model, design information management, anti-deformation design of mould cavity, intelligence mould design and blade testing. The developed system can manage mould design and blade test data flow, optimize mould design process and achieve the goal of integration design.     

热处理对原位自生Mg2Si/Mg-Al基复合材料组织与性能的影响

利用金属型铸造制备了原位自生Mg2Si/Mg-Al基复合材料,研究了热处理对该材料组织与性能的影响。结果表明T4处理改变了Mg2Si/Mg-Al基复合材料中Mg2Si的形貌与分布。随着保温时间的延长,棱状枝晶Mg2Si相发生熔断、球化,最终成为尺寸为10-30μm的颗粒;同时β-Mg17Al12相溶入到α-Mg基体中,在随后的时效过程中发生沉淀析出。由于β-Mg17Al12相的溶解,T4处理会降低该材料的硬度,但随后的时效析出可提高其硬度,415℃×12h固溶处理后175℃×16h(T6)时效,硬度可提高14.9%。热处理过程中棱状枝晶Mg2Si相的粒化可用吉布斯-汤姆逊定理解释。     

Friction and wear properties of casting in-situ silicon particle reinforced ZA27 composites

The effects of silicon particle content and testing temperature on friction and wear properties of casting in-situ silicon particle reinforced ZA27 composites were investigated. The wear mechanisms were mainly discussed by observations of both worn surfaces and their side views. The results indicated that the variations of wear resistance with increasing of silicon particle content, at all of the testing temperatures applied, showed a similar tendency with a manner of non-monotonous change. It was surpdsed that the wear resistance decreased with the increase of silicon particle content from 2 vol.% to 5 vol.%, while it increased when the content was less than 2 vol.% or more than 5 vol.%. Similarly, the friction coefficient also did not change monotonously. The dominative wear mechanism changed from a relatively severe regime of plastic deformation accompanied by adhesion wear to a mild regime of smear, then to a very severe regime of severe plastic deformation induced wear, and finally again to a relatively mild regime of smear accompanied by abrasive wear as the silicon content increased. The wear resistance always decreased with elevating testing temperature, but the decrease ranges were different for the composites with different silicon contents. The friction coefficients changed irregularly for the different composites with the increase of testing temperature. Correspondingly, the wear mechanism alternated from a mild regime of smear accompanied by abrasive wear to a severe regime of plastic deformation accompanied by adhesion wear.     

Influences of processing parameters on microstructure during investment casting of nickel-base single crystal superalloy DD3

The effects of solidification variables on the as-cast microstructures of nickel-base single crystal superalloy DD3 have been investigated by using the modified Bridgman apparatus.The experiments were ...     

Geometric analysis of investment casting turbine blades based on digital measurement data简

A turbine blade is one of the key components of the aero-engine.Its geometric shape should be inspected carefully in the production stage to ensure that it meets the tolerance specification.In the present paper,an approach for investment turbine blade geometric shape analysis based on multi-source digital measurement is presented.Its key technologies,such as measurement data collection,blade model reliable alignment,geometric shape deviation fast calculation and visualization,were investigated.Actual measurement data from a structure light measurement device and a Coordinate Measuring Machine （CMM） for turbine blades were used to validate the presented method.The experimental results show that the proposed method is accurate,quick and effective to implement.     

微合金化对Cu-15Cr原位复合材料组织和性能的影响

研究了合金元素Zr对Cu-15Cr原位复合材料微观组织、力学性能、导电性能及热稳定性的影响规律。用SEM和TEM分别观察了材料的微观组织演变和析出相形貌,测试了不同应变下材料的抗拉强度和导电率,测定了材料的抗软化温度。结果表明:Zr促进Cr的析出,保持了微合金化Cu-15Cr复合材料的导电性;添加少量Zr可使Cu-15Cr-0.1Zr的抗拉强度提高约15%;Zr的加入使复合材料的抗软化温度提高了50℃左右。     

精铸涡轮叶片蜡模模具型面优化设计方法

提出一种基于有限元法的精铸涡轮叶片蜡模模具型腔优化设计方法。首先,计算出涡轮叶片在凝固和冷却过程中的非均匀、非线性收缩变形量;然后,基于本文提出的位移场反向迭代算法,确定优化的蜡模模具型腔。以A356合金涡轮叶片为例,采用提出的涡轮叶片模具型腔优化设计系统,经过精度评估,尺寸误差得到了大幅度降低。数值模拟与实验结果吻合良好,经过4次迭代优化,涡轮叶片的总体形状误差从0.515815mm降低至0.001978mm。     

Multiscale modelling and simulation of single crystal superalloy turbine blade casting during directional solidification process

As the key parts of an aero-engine,single crystal（SX）superalloy turbine blades have been the focus of much attention.However,casting defects often occur during the manufacturing process of the SX turbine blades.Modeling and simulation technology can help to optimize the manufacturing process of SX blades.Multiscale coupled models were proposed and used to simulate the physical phenomena occurring during the directional solidification（DS）process.Coupled with heat transfer（macroscale）and grain growth（meso-scale）,3D dendritic grain growth was calculated to show the competitive grain growth at micro-scale.SX grain selection behavior was studied by the simulation and experiments.The results show that the geometrical structure and technical parameters had strong influences on the grain selection effectiveness.Based on the coupled models,heat transfer,grain growth and microstructure evolution of a complex hollow SX blade were simulated.Both the simulated and experimental results show that the stray grain occurred at the platform of the SX blade when a constant withdrawal rate was used in manufacturing process.In order to avoid the formation of the stray crystal,the multi-scale coupled models and the withdrawal rate optimized technique were applied to the same SX turbine blade.The modeling results indicated that the optimized variable withdrawal rate can achieve SX blade castings with no stray grains,which was also proved by the experiments.     

温度和压力对1Cr12Mo钢汽轮机叶片微观组织的影响

为了研究服役条件下的汽轮机叶片的微观组织演化行为,利用X射线衍射仪、光学显微镜、扫描电镜和透射电镜等手段详细表征了退役1Cr12Mo钢高压动叶片的微观组织结构,进而分析了不同温度和压力对微观组织的影响规律。试验结果表明,适当的应力能促进板条内部尤其是边界析出相弥散分布,维持细小组织特征;细小弥散的析出相能够延缓位错束集和位错胞亚晶的形成。位错胞亚晶的形成显著地降低位错密度;温度对马氏体及位错结构影响不大,但显著提高碳化物的长大速度。     

A Comparison of Aging Kinetics of New and Rejuvenated Conventionally Cast GTD-111 Gas Turbine Blades

Two industrial gas turbine blades made from a conventionally cast Ni-base superalloy GTD-111, one new and the other rejuvenated, were removed from the same machine after a particular operational cycle for an examination in order to determine the effect of rejuvenation on the material’s behavior during service. It was found that service-induced changes in the microstructure, such as γ′-phase coarsening and coalescence, excessive grain-boundary secondary M₂₃C₆ carbides formation, and primary MC carbides decomposition, were noticeably more advanced in the rejuvenated blade. The stress-rupture life of the rejuvenated blade decreased significantly compared to that of the new blade after the same number of hours in service. The cause of this decrease appears to be related to a release of additional amounts of carbon and carbide-forming elements into the matrix during rejuvenating heat treatment as a result of the primary MC carbide decomposition.     

Evaluation of service-induced damage and restoration of cast turbine blades

Conventionally cast turbine blades of Inconel 713C, from a military gas turbine aircraft engine, have been investigated with regard to service-induced microstructural damage and residual creep life time. For cast turbine blades, service life is defined by statistical values. The statistical methods can prove to be uneconomical, because safe limits must be stated with regard to the statistical probability that some blades will have higher damage than normal. An alternative approach is to determine the service-induced microstructural damage on each blade, or a representative number of blades, to better optimize blade us-age. Ways to use service-induced γ rafting and void formation as quantified microstructural damage pa-rameters in a service lifetime prediction model are suggested. The damage parameters were quantified, in blades with different service exposure levels, and correlated to remaining creep life evaluated from creep test specimens taken from different positions of serviced blades. Results from tests with different rejuvenation treatments, including hot isostatic pressing andJor heat treatment, are discussed briefly.     

Cu-Cr原位复合材料组织性能研究

采用感应加热熔炼及通过热锻和线拉变形结合中间热处理制备了Cu-15％Cr原位复合材料，用SEM和TEM等技术对形变Cu—Cr原位复合材料的Cr纤维形成过程、立体形态进行了分析。结果表明，在变形过程中Cr树枝晶发生转动，平行于线轴方向排列；Cr纤维立体形态则为卷边的薄片状。测定了形变Cu—Cr原位复合材料的抗拉强度，分析表明，强度随变形量的增加而提高，与纤维相间距呈Hall—Patch关系。     

变形方式对Cu-8.3Fe-1Ag形变原位复合材料组织性能的影响

分别采用冷拉拔和冷轧变形并结合中间退火工艺,制备了丝状和带状形变Cu-8.3Fe-1Ag原位复合材料。用SEM、精密万能试验机、显微硬度计和电阻测量仪对两种变形方式下试样的微观组织、力学性能和导电性能进行了比较研究。微观组织观察表明:冷拉拔和冷轧变形试样的横截面组织形貌有显著差异,前者为基体上分布着弯曲、扭折、交叠的蠕虫状相,后者为基体上定向排列着与冷轧方向平行的平直颗粒相。力学性能和导电率测试结果表明:相同应变量下,冷拉拔变形的抗拉强度、硬度均高于冷轧变形,但二者的导电率几乎相同。应变量达到6.70时,二者的抗拉强度/硬度/导电率分别达到838 MPa/149 HV/58%IACS和924 MPa/160 HV/58%IACS。     

Microstructure and properties of deformation-processed Cu-Fe in-situ composites

The effects of intermediate annealings on the microstructure, the strength and the electrical resistivity of deformation-processed Cu-Fe in-situ composites were studied. The results show that intermediate annealings favour the formation of uniform tiny fibres from the iron dendrites but they have no obvious effect on the strength of the composite. The bigger the strain is, the higher the strength is. As the strain increases, the resistivity increases due to the increase of interface density. Intermediate annealings result in notable decreasing resistivity due to the precipitation of the iron atoms from the Cu matrix and decrease of solute scattering resistivity. The doping with Zr improves the strength of the composite slightly and the ultimate tensile strength（UTS） increases about 10%. The colligated performances of deformation-processed Cu-11.5 % Fe and Cu-11. 5% Fe-Zr composites at strain η=5.37 are 64.6% IACS/752 MPa and 61.4% IACS/824 MPa respectively.     

Processing and microstructure of alumina-based composites

A study of powder structure and its effect on the sintering tendency of certain alumina-based ceramic systems, that is, Al₂O₃-SiO₂ and Al₂O₃-ZrO₂, was carried out to improve their mechanical strength and fracture toughness. The compacting behavior and the sintering characteristics were optimized through control of various parameters such as composition, compaction pressure, sintering temperature, and time. Best densification was obtained for mixtures prepared using very fine and deagglomerated alumina powders.     

Ti-Si-Mg-Al焊丝对SiC_p/Al基复合材料等离子弧原位焊接焊缝组织和性能的影响(英文)

研究Ti-Si-Mg-Al焊丝对等离子弧原位合金化焊接制备SiC颗粒/铝金属基复合材料的微观结构和力学性能的影响。以氩氮混合气体为离子气,采用Ti-Si-Mg-Al药芯焊丝作为填充材料,对焊接接头进行拉伸试验,并对宏观形态和微观组织进行分析。结果表明:以Ti-Si-Mg-Al药芯焊丝作为原位反应填充材料,可以有效抑制针状脆性相Al4C3的生成。以15Ti-5Si-5Mg-Al药芯焊丝作为填充材料时,焊接接头的最大抗拉强度为267MPa,达到退火条件下基体材料强度的83%。     

Effects of temperature on fracture behavior of Al-based in-situ composites reinforced with Mg2Si and Si particles fabricated by centrifugal casting

An aluminum-based in-situ composites reinforced with Mg₂Si and Si particles were produced by centrifugal casting Al–20Si–5Mg alloy. The microstructure of the composites was examined, and the effects of temperature on fracture behavior of the composite were investigated. The results show that the average fraction of primary Si and Mg₂Si particles in the composites is as high as 38%, and ultimate tensile strengths (UTS) of the composites first increase then decrease with the increase of test temperature. Microstructures of broken specimens show that both the particle fracture and the interface debonding affect the fracture behavior of the composites, and the interface debonding becomes the dominant fracture mechanism with increasing test temperature. Comparative results indicate that rich particles in the composites and excellent interface strength play great roles in enhancing tensile property by preventing the movement of dislocations.