铝/钢异种金属惯性摩擦焊接过程中IMCs生成机理与调控

我国航天大推力液体发动机推进剂输送管路为铝合金/不锈钢(铝/钢)连接管件，但现有连接工艺因接头耐腐蚀性低而不满足加注长期贮存的要求。项目根据铝/钢异种金属焊接冶金特点，采用惯性摩擦焊实现铝/钢输送管路高强可靠焊接制造，通过研究基础科学问题突破核心技术瓶颈：理论上，建立合乎物理本质的铝/钢摩擦副和焊接数理模型，数值分析铝/钢惯性摩擦焊接温度场、塑性流变场及应力应变场演变过程，揭示铝/钢惯性摩擦焊接热力耦合机制；以此为基础，采用物理模拟试验研究确定铝/钢摩擦界面上Fe-Al金属间化合物(IMCs)生成的能量和力学条件，阐释在短时、低温、高速相对运动条件下IMCs生成机理，特别是塑性流变对其生成的作用机制；应用基础上，探索铝/钢惯性摩擦焊接头组织性能调控的工艺和冶金措施并阐明强化机理，掌握铝/钢输送管路惯性摩擦焊接核心技术，为新型航天大推力液体发动机输送管路的研制和制造提供理论支撑和技术支持。

High thrust liquid rocket engine is the development foundation for the space industry, which indicates the high-technology level and comprehensive national strength of a country. In order to reduce the weight, the dissimilar metals pipeline made of Al alloy and stainless steel(Al/steel) is used to feed liquid propellent in high thrust liquid rocket engine. So the welding of Al alloy to stainless steel with high strength and reliability is important for the R&D and manufacturing of high thrust liquid rocket engine which need to be kept in long term. In this project, according to the problems in friction welding manufacturing of lightweight Al/steel feeding pipeline of liquid propellent, and metallurgical characteristics of welding of Al alloys to steel, the key scientific problems were studied to breaking bottleneck of manufacturing the welded lightweight Al/steel feeding pipeline. In theoretical studies, the mathematical and physical models of friction pair and inertia friction welding are founded, respectively, which are in accordance well with the physical nature of inertia friction welding process of Al alloy to steel, and applied to numerical simulation of the thermal process, plastic flow behavior and the evolution of stress-strain field in inertia friction welding process, and the mechanism and rules of the thermo-mechanical coupling field in inertia friction welding process of Al/steel will be revealed from the aspects of thermal process, plastic flow behavior and stress-strain evolution. By using the physical simulation and emergency stop and rapid cooling technology of welding process, the formation conditions of Fe-Al IMCs in friction interface are studied from the energy and mechanical aspects, and the formation mechanism of Fe-Al IMCs(InterMetallic Compounds) in inertia friction welding process of Al/steel will be interpreted. In studies of applied foundation, based on the studied results of IMCs formation, the process measures and metallurgical measures will be taken to control the IMCs and strengthen the mechanical properties of the inertia friction welded joint of Al/steel, the strengthening mechanism of process and metallurgical measures are revealed and the tensile strength of the joint can be equivalent to that of the Al alloy base metal. At last, based on the theoretical and experimental studies, the inertia friction welding manufacturing process of lightweight Al/steel feeding pipe of liquid propellent for high thrust liquid rocket engine is developed and the properties of the welded lightweight Al/steel feeding pipe are tested and evaluated. The studies in this project can provide the theoretical and technological supports for R&D and manufacturing the liquid propellent feeding pipeline system in high thrust liquid rocket engine.