Quenching of aerospace forgings from high temperatures using air-assisted, atomized water sprays

The nickel-based superalloy or titanium materials used in the aerospace industry are cooled from high temperatures during the heat treatment process to obtain appropriate strength properties. However, unacceptably high residual stresses can be developed in some situations if the rate of cooling is too high so that air-assisted, atomized water sprays have been suggested as an alternative to the widely used techniques of quenching in oil or water. Thus, this article examines two aspects of the use of air-water sprays for quenching aeroengine forgings. First, basic experimental heat transfer data are presented for a wide range of water flows and for surface temperatures up to approximately 850 °C, for both plane and recessed surfaces. Second, the heat transfer data are used in numerical simulations to study the influence of nonuniform spray distributions on the residual stress patterns in a typical forging. This paper was presented at the ASM Third International Conference on Quenching and Control of Distortion, 24–26 March 1999, in Prague, Czech Republic.     

压方圆角对长轴类大锻件质量影响研究

长轴类大锻件的锻造过程一般分为压方、拔长和倒棱滚圆三大步骤,目前对锻造工艺研究较多的是拔长和倒棱滚圆的优化,很少有对压方工艺优化的研究。本文从V型砧边缘的圆角半径的大小来对长轴类大锻件的压方过程进行模拟优化,从锻件内部应力、应变及破坏因子三个方面进行对比分析。结果表明,适当增大V型砧边缘的圆角半径可以有效防止锻件裂纹的产生,为锻件的质量提高和结构设计提供一种有效、可靠的分析方法。     

Preparing the entry-level materials professional in the 1990s

It is time that universities stop using the excuse that industry does not want a five-year-engineering-degree graduate. Industry does not have any choice since it can only select from the available talent pool. At present, materials graduates with four-year degrees often lack the critical tools necessary to perform the non-engineering jobs that are frequently offered. Courses such as statistics, process control and management will help remedy this situation. Today, the individual with a master of science degree, having spent over five years in school, still lacks many essential non-engineering skills. Worse, many students in master’s degree programs graduate with a primarily science background and have not taken the full basic engineering curriculum. For this reason, there is no comparison between the current, research-oriented M.S. degree and the proposed master of engineering degree. The outlined curriculum allows for a continuation of many current programs in materials while providing a transition to a five-year, first professional degree. The program allows the student to choose, after four years of education, whether he or she really wants to obtain a professional degree. Further, the four-year degree recipient enters the field with a better education than is available at present, and industry is supplied with a better-educated mix of degree recipients.     

Phase transformations in large forgings

Conclusions To study the kinetics of phase transformations and develop a heat treatment to prevent shattercracks in large forgings it is expedient to use diagrams of the isothermal and athermal decomposition of supercooled austenite plotted with use of double austenitizing of the samples — first at the forgoing temperature and then at a temperature of Ac₃+30–50°.Scientific-Research and Planning-Technological Institute of Machine Construction, Kramatorsk. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 52–54, August, 1981.     

90年代铸渗工艺新进展

回顾了９０年代以来国内外铸渗工艺研究的新进展;对铸渗条件下的铸件表面合金化及材料表层复合进行了综合述评;分析了新近开发的一些改善效果的工艺措施,并提出了今后研究中值和诉几个方向。     

Modeling the heat treatment of superalloy forgings

In the quest for higher operating temperatures, aircraft engine designers seek to improve properties of existing superalloys through a variety of different means. The heat treatment of superalloy forgings, particularly the cooling rate from solutioning temperature, is a key factor in their final properties. Modeling the cooling rate can be used to optimize the properties of a forging, and can help designers avoid quench cracks and residual stresses as well.     

For predicting the structure of die forgings

Formation of structure and properties of an aluminum alloy is considered on an example of wheel forging with the use of the Zener-Hollomon parameter. Parts of a forging most dangerous from the standpoint of coarsening of the structure are considered, namely, the web, the thread, and the upper and lower rims. A predicting technique is suggested and implemented for the case of die forging of a car wheel from aluminum alloy of grade AB in a split die. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 49–52, July, 2006.     

九十年代我国铝电解技术新进展

论述了９０年代以来我国铝电解技术在基础技术研究、生产工艺、过程控制、配套技术与辅助设备以及在吕电解槽开发试验等方面取得的新进展,即从理论研究到工业试验完成大容量铝电解槽开发的全过程。在设计、建设与工业生产领域已形成我国铝电解新技术体系,２１世纪的中国铝工业将进入一个新时代。     

Polyamides in aerospace industry

Abstract

Polyamides were one of the earliest powder coatings invented for metal protection and soon established recognition for their physical toughness, visual attractiveness and compatibility with potable water and foodstuffs. The available polyamides today can be derivatives from both crude oil and castor oil refining processes. A short review of established applications and recent developments in both coatings and non-coatings uses is given.