锻造零件缺陷分析

介绍了四种典型锻造缺陷案例并进行了详尽的追述，主要从锻造过程中金属流动和冶金缺陷的重新分布的角度对锻造缺陷产生原因作了比较全面的解析，提出了解决这些问题比较成熟的经验和方法。     

高压液氨装置用大型锻件的焊接修复

介绍了大型锻件的焊接修复工艺的制订以及焊后热处理,通过两年的运行表明,该焊接工艺可靠安全。     

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.     

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 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.     

NbTi合金锻造工艺的优化研究

超导材料已广泛应于高技术领域,NbTi合金作为一种典型的低温超导材料,在高技术领域(高能物理、受控热核聚变、储能、磁悬浮等)中占有极其重要的地位,已成为一种不可替代的新材料广泛应用于能源、交通、医疗、高能物理等重要领域。通过模拟仿真(DEFORM计算)结合实际生产,研究了NbTi合金的锻造这一复杂动态的接触过程,得到了 NbTi合金锻造组织的演化规律,确定了组织均匀的NbTi合金锻造工艺。结果表明：通过模拟仿真发现,采用小变形量,三分之一边长下镦的方式并增加换向拔长,可使NbTi合金的不同位置的变形较为均匀,大面积消除满砧镦拔带来的变形死区,通过实验验证最终生产出符合技术标准的NbTi合金棒材。与美国华昌公司的NbTi合金棒材成分、微观组织和XRE作对比,发现成分的极差、微观组织的均匀性和无损探伤均优于美国华昌公司生产的NbTi棒材,为NbTi合金的生产提供实际参考。     

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.     

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。     

通用轴对称锻件锻模CAD系统

论述了开发通用轴对称锻件锻模ＣＡＤ系统的基本原理与方法，提出并解决了锻件圆角过渡的光滑处理问题，从而构造出实用的商品化软件。     

铁素体不锈钢0Cr15Mo锻造工艺研究

通过对铁素体不锈钢0Cr15Mo加热温度、锻造温度控制和退火温度进行研究。制定出了合理的锻造工艺和热处理工艺，在直径为Φ250mm的大棒材上获得了4级以上的晶粒度。