Study On Aged Toughness Of Heat Resistence Steel At The Condition Of Serving

The important performance index of steel member is strength and toughness. Its safety design contains not only strength design but also resistance to brittle failure design. Fracture toughness is often important basis of structural design of materials. Large construction often encounters some dynamic load .The effect of dynamic load should be also considered at static environment.So the study on dynamic fracture toughness of steel member is important specially.The safe period of important project is usually more than 10 years.Thus the performance index of long-term and after elevated temperature aging different terms is required for safety design.In this paper the heat resistence steel for stream-turbine cylinder body is studied ,which is introduced freshly by nation.The data and basis of safety design for this material may be provided by studying the performance index—dynamic fracture toughness and strength after elevated temperature aging.In this paper The impact toughness(A_k,), dynamic fracture toughness (K_Id),and tensile performance of the heat resistence steel for stream-turbine cylinder body afer 593 ℃ aging different terms is tested at different temperatures.The creep rupture test is proceeded at 593 ℃ .The microstructure is analysed by metalloscope,scanning electron microscope, energy spectrum,and the method of phase analysis by physics and chemistry.The result is followed.Compared with no aging ,after 593℃ aging5600h,the impact toughness does not chang ,the dynamic fracture toughness decreases by a narrow range (the change of K_Id is in conrrespondence with the change of shear lip thickness and side-swell value), the tensile strength increases in some sort ,and the plasticity decreases a little.After aging 5600h,micro phase of M₂₃C₆,in which the...