【摘要】 通过冲击性能试验、光镜、透射电镜和扫描电镜等方法对超超临界机组用新型奥氏体耐热钢HR3C经650℃时效不同时间后的冲击韧度和显微组织变化进行了研究。结果表明,HR3C钢在650℃时效过程中具有较明显的时效脆化倾向,时效500 h后冲击韧度由时效前的351.7 J/cm2降低到40 J/cm2以下,而后随着时效时间的延长(直至6000 h),冲击韧度基本稳定在20～25 J/cm2;HR3C钢长时时效后的断裂形式主要是以沿晶断裂为主的脆性断裂;时效初期HR3C钢冲击韧度降低的主要原因是由于沿晶析出较多网状M23C6和少量σ沉淀相造成的;时效后期,M23C6出现聚集、球化、长大,但由于σ相的析出量增加,使该钢时效6000 h后的冲击韧度仍保持在较低的水平。更多还原

【Abstract】 The impact toughness and microstructure variation of new type austenitic heat resistant steel HR3C used in USC boilers aging at 650 ℃ for different time were studied through impact property test,OM,TEM and SEM.The results show that the aging embrittlement of HR3C steel is obvious,the impact toughness decreases to below 40 J/cm2 after aging at 650 ℃ for 500 h from 351.7 J/cm2 before aging treatment and with the continuation of aging time,the impact toughness changes between 20 J/cm2 and 25 J/cm2.The fractography of impact specimen is intergranular brittle fracture.The microstructure results indicate that the main reasons for the impact toughness degradation are the dispersion of net-like M23C6 and a little amount of σ phase along grain boundary at early stage,at later stage,the combination of M23C6’s spheroidizing,congregation and coarsening and the amount of σ phase increasing is responsible for the embrittlement of HR3C steel.更多还原