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一、选材依据 目前,世界各国在运输机的设计和制造方面,部在朝高速、大型、远程方向发展。因而对起落架所采用的大型锻件提出了越来越高的要求。锻件的选材除了保证常规的机械性能、冷热加工工艺性能外,还应考虑对零件的重量和使用寿命以及安全可靠性方面的要求。 1.要求材料有较高的比强度 材料的比强度直接关系到零件的重量和体积。多年来飞机设计者和冶金工作者都在追求这个指标的提高,以美国常用的航空结构钢4340钢为例,起初(约三十年代初)它的使用强度在105公斤/毫米~2左右,到第二次世界大战期间及战后数年中,用于飞机起落架的使用强度一般在126～142公斤/毫米~2。可是,到了五
I. Selection Basis At present, all countries in the world have been moving toward high-speed, large-scale and long-range transport aircraft design and manufacturing. Therefore, the landing gear used for large forgings have put forward higher and higher requirements. In addition to ensure the selection of forgings conventional mechanical properties, hot and cold processing performance, but also should consider the weight of the parts and service life and safety and reliability requirements. 1. Require materials have higher specific strength than the strength of the material directly related to the weight and volume of the parts. Aircraft designers and metallurgists have been pursuing this indicator over the years. Taking the 4340 steel, a structural steel commonly used in the United States, for example, its strength was initially at about 105 kg / mm ~ 2 (about the early 1930s) During World War II and the years after the war, the strength of the landing gear for aircraft was generally 126 to 142 kg / mm2. However, to five