含铝奥氏体不锈钢的强化相析出调控和蠕变性能研究进展

Research Progress on Strengthening Phase Precipitation Regulation and Creep Properties of Aluminum-Containing Austenitic Stainless Steel

根据我国的能源结构,发展大容量、高参数的超(超)临界火电机组和高效的先进核能是解决能源短缺与环境污染之间矛盾的主要途径。为了能够长期在高温、高压的恶劣环境下服役,对发电机组和核能系统结构用材料提出了更苛刻的要求。含铝奥氏体不锈钢兼具优异的抗氧化性能和高温强度,可作为超(超)临界电站及超临界水堆等先进能源系统关键部位的候选材料。蠕变性能是含铝奥氏体不锈钢应用于先进能源系统的重要服役性能,其与析出相(包括碳化物M_(23)C_(6)及MC、Laves相、NiAl相、FeCr相等)的种类、尺寸和分布状态关系密切。如果析出相能以有效钉扎位错的合适尺寸均匀弥散分布于基体中,且具有较好的高温稳定性,那么合金就能获得优异的高温蠕变性能。总结现有的研究成果可知,含铝奥氏体不锈钢的主要发展方向和调控思路是以Super304H、HR3C和TP347HFG为基体,进一步调整Al、N、Si、Ni、V、B等合金元素含量,研究合金在服役过程中纳米级别析出相的分布情况、高温蠕变性能等变化规律。主要研究目标是在控制成本的前提下通过析出相的有效调控,提升合金的高温蠕变性能和抗氧化性能。因此,对析出相的调控方法进行总结和归纳对开发和设计出性能优异的含铝奥氏体不锈钢具有重要的指导意义。本文主要综述了含铝奥氏体不锈钢主要析出相的调控方法,包括调控合金元素和优化热机械处理工艺,进而分析了析出相调控与蠕变性能之间的关系。

According to China’s energy structure,the development of ultra-supercritical thermal power plants and advanced nuclear energy with high efficiency is an effective way to solve the contradiction between energy shortage and environmental pollution.In order to meet the requirement of long term service in the harsh environment of high temperature,high pressure and corrosive medium,it is urgent to develop new grade material with improved high temperature mechanical properties and oxidation resistance.The newly developed aluminum forming austenitic(AFA)stainless steel shows excellent oxidation resistance and high temperature strength,which is considered as a promising candidate material for key components of advanced energy systems such as ultra-supercritical power plants and supercritical water-cooled reactor.Creep is an important service property for AFA steels application in advanced energy systems,which is closely related to the feature of precipitated phases(including M_(23)C_(6) and MC carbide,Laves phase,NiAl phase and FeCr phase),including phase type,size and distribution of precipitates.If the precipitates with good high temperature stability can be controlled to disperse uniformly in the matrix with appropriate size for dislocation pinning effect,then the alloy can obtain excellent high temperature creep properties.AFA was developed based on Super304H,HR3C and TP347HFG.The idea is through adjusting the alloying elements,such as Al,N,Si,Ni,V and B,and controlling the feature of nanoscale precipitated phases,to improve high-temperature creep properties at a low cost.Therefore,it is of great significance to summarize and generalize the control methods of precipitates in order to the development and design of aluminum-containing austenitic stainless steel with better creep properties.In this paper,the control methods of main precipitates in austenitic stainless steel containing aluminum are reviewed,including the regulation of alloying elements and the optimization of thermal mechanical treatment process,and then the relationship between the regulation of precipitates and creep properties is discussed.