Effects of processing parameters in P/M steel forging on part properties: A review part III analysis methods

In the last decade, powder metallurgy (P/M) technology has made marked advances in competitive manufacturing. P/M offers design opportunities that are not possible with other methods, as well as significant cost savings. The processing parameters, material characteristics, individual stages of parts production, deformation and densification mechanics and tooling, and preform design influence the properties of the P/M part and related economics. Therefore, a review of the various parameters involved in the different stages of P/M steel forging in net-shape manufacturing and their implications on resulting properties of P/M parts is presented in a three-part review. Part I discusses the stages of preparing a sintered compact, and Part II identifies key parameters in forging the sintered compact that influence the properties of the powder forged part. Part III reviews the different analysis methods available to study P/M processing.     

Effects of processing parameters in P/M steel forging on part properties: A review part I powder preparation,compaction, and sintering

In the last decade, powder metallurgy (P/M) technology has made marked advances in competitive manufacturing. P/M offers design opportunities that are not possible with other methods, as well as significant cost savings. In the automotive industry, P/M forgings are being developed for applications requiring good high- cycle fatigue properties. The processing parameters, material characteristics, individual stages of compaction and parts production, deformation and densification mechanics and tooling, and preform design influence the properties of the P/M part and related economics. Therefore, a review of the various parameters involved in the different stages of P/M steel forging in net-shape manufacturing and their implications on resulting properties of the P/M parts is presented in a three part review. Key parameters in steel powder preparation, compaction, and sintering of P/M forging and their effect on part properties are described in Part I. Part II discusses issues of forging the sintered compact, and Part III reviews currently available analysis methods for studying the powder forging process.     

The powder sintering and isothermal forging of Ti-10V-2Fe-3Al

The synthetic technology of powder sintering and isothermal forging was explored to prepare a powder Ti-10V-2Fe-3Al (Ti-1023) alloy. Hydride-dehydride powder was provided from unqualified Ti-1023 ingot alloy because of “beta fleck” defect. After cold isostatic pressing and sintering, the compact presented uniform chemical composition, but lamella alpha microstructure. Isothermal forging technology was used to further densify the sintered compact and improve the microstructure and properties. The final forged compact exhibited equiaxed, recrystallized, and fined alpha phase microstructure, and excellent tensile properties at room temperature.     

Densification laws and properties of sintered powder compacts in rotary forging process

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圆环零件液态模锻研究

通过圆环零件的液态模锻成形实验,对在不同比压和浇铸温度条件下,锻件的微观组织形貌和力学性能进行了分析研究.结果发现,在不同比压下,随着比压值的增加,α枝晶长度随之减小,枝晶被破碎,锻件力学性能也随之升高;在不同浇铸温度条件下,锻件微观组织也有着较大的差异,且随着浇铸温度的升高,粗大树枝晶被打断、破碎细化现象较为明显,锻件组织致密,力学性能逐渐上升.     

炮弹壳体液态模锻模设计

采用液态模锻工艺生产杯形、薄壁深筒形炮弹壳体,依据零件图设计了液态模锻工艺用锻件图、试验用模具,并生产出试验产品。经过试验产品分析,最终设计制造出生产用模具。模具结构简单、紧凑,工作平稳,生产的零件符合设计要求。     

The microstructure and properties of ultra-fine grained Ti-17 powder compact improved through isothermal forging

The microstructure and properties of hot isostatic pressed (HIP-ed) Ti-17 powder compact were improved through isothermal forging with preferable deformation parameters provided by processing map. The processing map was established based on isothermal compression experiments which were conducted at temperatures from 810 °C to 920 °C and strain rates from 0.001 s^?1 to 1 s^?1. The established processing map ascertained the value of the efficiency of power dissipation, the flow stability region and the flow instability region at different deformation conditions. Based on processing map, the isothermal forging was conducted above and below beta transus temperature to fully densify the powder compact and simultaneously improve the microstructure. After isothermal forging in flow stability regions with preferable deformation parameters, the primary coarse grains of HIP-ed Ti-17 powder compact were thoroughly broken. Many ultra-fine dynamic recrystallized grains formed and uniformly distributed in beta matrix. Both experiment data and fracture morphology of tensile sample proved that the microstructure and properties of HIP-ed Ti-17 powder compact were largely improved during isothermal forging. Final properties of prepared ultra-fine grained Ti-17 powder compact even exceeded conventional casting and forging Ti-17 alloy.     

Design of forging process variables under uncertainties

Forging is a complex nonlinear process that is vulnerable to various manufacturing anomalies, such as variations in billet geometry, billet/die temperatures, material properties, and workpiece and forging equipment positional errors. A combination of these uncertainties could induce heavy manufacturing losses through premature die failure, final part geometric distortion, and reduced productivity. Identifying, quantifying, and controlling the uncertainties will reduce variability risk in a manufacturing environment, which will minimize the overall production cost. In this article, various uncertainties that affect the forging process are identified, and their cumulative effect on the forging tool life is evaluated. Because the forging process simulation is time-consuming, a response surface model is used to reduce computation time by establishing a relationship between the process performance and the critical process variables. A robust design methodology is developed by incorporating reliability-based optimization techniques to obtain sound forging components. A case study of an automotive-component forging-process design is presented to demonstrate the applicability of the method.     

Deformation characteristics and fracture mechanisms during the cold forging of metal powder preforms

The paper reports on an investigation into the various aspects of cold forging of iron powder preforms which have been compacted and sintered from atomised iron powder. The influence of particle size, compacting pressure, sintering temperature and forging parameters on relative density of the preform was investigated. Experiments were conducted and measurements were made on the development of barrelling and strain variations at the free surface. Cracks were also observed at the free surface of the perform. The deformation characteristics and fracture mechanism is discussed critically to illustrate the interaction of various parameters involved and the results are presented graphically.     

基于ANN的涡轮盘等温成形过程模拟电路模型

为提高锻件质量和成品率,有必要建立一种适合于实时控制的锻件成形过程模型.利用有限元模拟技术对涡轮盘的等温成形过程进行了虚拟正交试验,通过对成形过程的载荷--行程曲线的分析,建立了粉末高温合金涡轮盘件等温成形过程的人工神经网络(ANN)模型,并将其映射成模拟电路模型.以此模拟电路模型为参考模型,应用于模型参考自适应控制(MRAC)系统,对涡轮盘件等温成形过程进行控制.结果表明,所建立的ANN模型及其模拟电路模型对粉末高温合金涡轮盘件等温成形过程的拟合精度很高,且控制参数始终与模型输出相吻合,为实现盘件成形过程的实时控制奠定了基础.     

Process design and control in cold rotary forging of non-rotary gear parts

This paper is aimed to investigate the process design and control method in cold rotary forging of parts with non-rotary upper and lower profiles. Using the analytical and FE simulation methods, three critical technological problems in the cold rotary forging process of this kind of parts are resolved reasonably. The first one is that an accurate design method of the non-rotary upper die is presented based on the geometrical and kinematic relationship between the upper die and upper profile of parts. The second one is that the interference judgment between the upper die and upper profile of parts can be achieved by analytically obtaining the trajectory of any point in the upper die. The third one is that the metal flow and geometrical accuracy of the non-rotary upper profile of parts can be effectively controlled through optimizing the process parameters. On the basis of the above research, the cold rotary forging process of a typical gear part, both the upper and lower profiles of which are non-rotary, is investigated numerically and experimentally. The results indicate that the desirable geometrical accuracy of the non-rotary upper profile of the gear part can be obtained, which verifies that the process design and control method presented in this paper is valid and cold rotary forging can thus be used to manufacture the parts with non-rotary upper and lower profiles.     

铁粉烧结圆环开式热锻综合试验研究

采用烧结圆环开式热锻试验方法,综合考察了中碳合金钢粉烧结材料热锻过程的摩擦因子、断裂应变极限和致密情况。提出了一种烧结－喷丸、－热锻新工艺、用以有效提高材料的断裂应变极限和锻后材料的表面密度。     

Optimization of Binder Jetting Using Taguchi Method

Among several additive manufacturing (AM) methods, binder-jetting has undergone a recent advancement in its ability to process metal powders through selective deposition of binders on a powder bed followed by curing, sintering, and infiltration. This study analyzes the impact of various process parameters in binder jetting on mechanical properties of sintered AM metal parts. The Taguchi optimization method has been employed to determine the optimum AM parameters to improve transverse rupture strength (TRS), specifically: binder saturation, layer thickness, roll speed, and feed-to-powder ratio. The effects of the selected process parameters on the TRS performance of sintered SS 316L samples are studied with the American Society of Testing Materials (ASTM) standard test method. It was found that binder saturation and feed-to-powder ratio were the most critical parameters, which reflects the strong influence of binder powder interaction and density of powder bed on resulting mechanical properties. This article serves as an aid in understanding the optimum process parameters for binder jetting of SS 316L.     

高速切削技术在连杆锻模制造中的研究和应用

阐述了现阶段连杆锻模加工的主要方法,系统介绍了高速切削技术在加工连杆锻模中的应用。从高速切削技术加工连杆模具的优点着手,介绍了高速加工机床的特点,CAD/CAM设计、制造的优势,加工中关键技术工艺和参数的研究,并通过实际加工出的模具,进一步说明了高速切削的优势,包括生产时间短,产品表面精度高等,最后提出了我国在连杆锻模高速加工中存在的问题和解决方法。     

管坯镦粗工艺

管坯成形过程容易失稳，产生折纹；同时因管壁厚度公差大，坯料体积不易控制，使得锻件成形困难，质量难以控制。本针对我厂生产的一种管坯锻件的成形工艺，结合有限元模拟与实际生产情况，着重分析了第一道聚集工步的特点，型腔设计的基本原则，并对一些工艺参数进行了探讨。     

Material adapted tool design in cold forging exemplified by powder metallurgical tool steels and industrial ceramics

The advantages of today’s cold forging technology, such as excellent mechanical properties of the workpiece and minimum waste of material together with energy saving via near net shaping increase its competitiveness against other production methods. However, as a result of extremely high loading of the tools when compared with warm and hot forging, tool life is distinctly more confined resulting in increased production costs. Due to separately or concurrently emerging damaging mechanisms of fatigue and wear at different sections of a cold forging die, process specific tool material selection and design of cold forging dies play a decisive role in near-net-shape forging of various parts. Two case studies utilizing powder metallurgical tool steel and ceramic as tool materials are presented in this paper. Successful adaptation of these materials with the help of FE simulations led to increased tool life and workpiece quality.     

激光烧结工艺参数对Fe-16%Ni合金致密度的影响

采用激光烧结成形技术研究了不同工艺参数对Fe-16%Ni金属粉末选区激光烧结成型件微观结构和致密性的影响。结果表明,随着脉冲宽度、扫描速度和铺粉厚度的增加,烧结后试样的密度先增加然后减少,随着扫描间距的增加,烧结后试样的密度减小。当脉冲宽度0.7 ms,扫描速度1000 mm/min,铺粉厚度0.15 mm,扫描间距0.15 mm时,烧结成型件成型质量较好。     

锻锤用圆模体使用寿命的影响因素及提高方法

通过对锻锤用圆模体本体制造阶段、投入生产阶段影响圆模体使用寿命因素等的分析,有针对性地提出了正确选材并科学设计锻造工艺、严格控制加工和热处理工艺、合理设计模具和制订工艺、正确使用模具等全程控制的有效措施,达到了提高圆模体使用寿命和模锻件质量、缩短生产周期和降低模锻件成本的目的。     

工程陶瓷注射成型的研究与发展

综述了陶瓷注射成型目前的发展状况以及该成型方法的优点。详细论述了陶瓷粉体性质、有机载体组成特别是表面活性剂对于陶瓷喂料和注射成型所成坯体性质的影响。分析了混炼顺序、注射工艺参数、脱脂对陶瓷喂料的流变性以及所成型坯体性质的影响。