Temperature Effects on the Microstructures of Mg-Gd-Y Alloy Processed by Multi-direction Impact Forging

A high strain rate multi-directional impact forging(MDIF) was applied to a solutionized Mg-Gd-Y-Zr alloy in the temperature range of 350-500℃.Results demonstrate that the dominant deformation mode is twinning at a temperature below 400℃,whereas at a medium temperature of 450℃ considerable continuous dynamic recrystallization was promoted by{10-12} extension twins.At a higher temperature of 500℃,twinning activation was suppressed.New DRX grains were observed but their sizes were much bigger than those resulting from the MDIFed 50 passes at 450℃,which are ascribed to the larger grain boundary mobility and atomic diffusion at 500℃.Moreover,a non-basal weak texture was gained afterward MDIF at each temperature,which is credited to the MDIF process and the minor strain applied in each pass.     

锻造操作机液压缓冲系统建模与仿真研究

根据锻造操作机高速、高精度和高可靠性的要求,进行了锻造操作机液压缓冲系统的设计,并在此基础上利用AMESim对液压系统进行了仿真研究,分析了不同溢流压力对缓冲系统的影响。同时利用MATLAB的Simulink模块对锻造操作机的缓冲系统进行了总体建模,分析了缓冲系统的动态响应情况。仿真结果表明:系统设计能满足操作机的工作要求,为锻造操作机液压系统设计提供了参考。     

碳钢锻件的超声波检测

对碳钢锻件在不同加工阶段进行超声波检测,做到及早发现缺陷,及时处理缺陷,从而达到减少损失、降低损害、保证锻件质量的目的。     

Image-based measurement of the dimensions and of the axis straightness of hot forgings

Non-contact measurement of shapes and dimensions is currently quite a common issue. A lot of systems with different speeds and accuracies are in the market. Measurement of high temperature objects is, however, a very special task which ensures a specific solution. This paper presents a measurement system composed of two high resolution single-lens reflex cameras and a software application, which is designed for the fast measurement of shapes and dimensions of rotationally symmetric forgings. The software computes the length, diameter, and straightness of the axis, based on a 3D model constructed from four boundary curves of the forging captured in two images. Experimental measurements have shown an error of up to 2% for the length measurement and 1% for the diameter measurement. Results are available in a few seconds. The proposed measurement approach based on boundary curves shows a great potential for practical use in forging plants.     

Effect of cast and extruded stock on grain structure of EN AW 6082 alloy forgings

Abstract

There has been a rapid increase in the use of aluminium forgings in the automotive industry, where weight savings is a critical requirement for reduced fuel consumption and exhaust emissions. Extruded bar is the typical forging stock particularly in the manufacture of suspension components. There has been a great interest to replace the extruded forging stock with cast billets of the same diameter. The casting and extrusion routes for the manufacture of EN AW 6082 alloy forging stock were compared in the present work. The control arm produced via forging of the cast stock offers a very uniform grain structure and much superior surface quality with respect to its counterpart produced by the forging of the extruded stock owing to a much smaller grain structure at the surface of the forged component after the T6 heat treatment.     

Effect of the cooling rate in the corrosion behavior of a hot worked Ti-6Al-4V extra-low interstitial alloy

This work discusses the effect of the cooling rate during a forging process on the microstructure and corrosion behavior of a Ti–6Al–4V extra-low interstitial (ELI) alloy, which is commonly used as biomaterial. The samples were hot forged at two different temperatures, both of them within the dual phase field (α + β) and a constant strain rate of 4 × 10⁻³ s⁻¹ was employed during the tests. The samples were cooled in three different cooling media (water, air and clay) and the microstructure was analyzed using scanning electron microscopy (SEM). The corrosion resistance was determined by cyclic polarization tests in Ringer’s solution at 37 °C. Comparison between the results obtained for forged and commercial samples allowed to establish some correlations between cooling rate, microstructure and corrosion resistance. It was found that the clay as a cooling medium is a good candidate to obtain a proper microstructure and properties for biomedical applications, eliminating the requirement of subsequent heat treatment and reducing costs.     

台阶孔锻造工艺改进相关问题综述

讨论了采用台阶孔锻造法锻造缸体锻件在生产缸体锻件时的优势，提出了对原工艺的改进方法．改进后的工艺减少了缸体锻件的锻造火次，提高了锻件的成材率，降低了生产成本，取得较好的经济效益。     

Comparative study of direct and indirect forging processes for rheological material of A356 aluminium alloy

Abstract

Using a vacuum electromagnetic stirring system, a high quality rheological material is developed in order to fabricate the engineering components without defects like internal porosities, which are caused by the entrapment of external air into the melt and impurities arising from the penetration of surface oxides by vacuum electromagnetic stirring. For practical application in vehicle industry, forming of the knuckle component that is used in automobiles was demonstrated by both direct and indirect type rheoforging processes. Here, insufficient filling behaviour occurred during direct forging processes, whereas indirect rheoforging of material with a solid fraction of 30–40% produced a completely formed knuckle component; thus, an indirect forging process may be suitable for forming the knuckle part. Through microstructural investigations and tensile tests before and after T6 heat treatment of the material, mechanical properties were characterised. By obtaining data about the rheoforging process and material properties of the rheoforged product associated with microstructural features, feasibility for future practical application was investigated. Moreover, the die structure for direct and indirect rheological forging processes was comparatively studied.     

Prediction of hot compression flow curves of Ti–6Al–4V alloy in α + β phase region

Prediction of material flow behavior is essential for designing the forming process of any material. In this research, experimental flow curves of Ti–6Al–4 V alloy were obtained using the isothermal hot compression test done at 750–950 °C with 50 °C intervals and constant strain rates of 0.001, 0.005 and 0.01 s⁻¹. For prediction of hot deformation flow curves two methods of modeling were applied. In the first method, an entire flow curve was modeled using Sellars equation. In the second one, modeling of a flow curve up to the peak point was carried out with Cingara model, and modeling beyond that was performed with a model developed based on the Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory. The accuracy of each model was examined through a statistical method. Results showed that flow curve modeling using Cingara model and JMAK theory leads to results that are more consistent with the experimental data.     

3O钨-铜爆炸成形弹丸（EFP）药型罩制备技术研究

本文研究了30w—CuEFP药型罩的制备及成形性能。研究采用了普通钨粉、铜粉和超细钨铜复合粉制备两种不同的棒材,然后测试棒材的锻造性能,最后选用普通钨铜材料制备EFP药型罩。结果表明,采用普通钨粉、铜粉刺备的材料具有较好的压力加工性能。制备的30W—CuEFP药型罩的材料的致密度达98％理论密度,退火后材料的抗拉强度达到320MPa,延伸率达17％。