Study On Structure Uniformity Control And Strength And Toughening Mechanism Of Maraging Steel

Maraging steel is a kind of ultra-high strength steel with ultra-low carbon martensite as matrix and intermetallic compound precipitation and strengthening in aging process.This steel has some unique properties:A good combination of high strength and acceptable ductility,low hardening index,good formability,simple heat treatment process,no deformation during aging process and good welding performance.Therefore,it is widely used in aviation,ocean,nuclear energy and other high-end scientific and technological fields,and has become a very potential steel.An custom455 of maraging steel is studied in this paper,to study the effects of heat treatment,heat treatment and long-term aging on the microstructure and properties of different systems,according to Gleeble-3800 Thermal Compression Simulation Experiment,Thermo-Calc software thermodynamic calculations,STA449F3 of Ultra High Temperature Integrated Thermal Analyzer make use of Differential scanning calorimetry DSC method,Smart Lab X diffraction instrument,RB2000 Rockwell hardness tester,Z050 universal testing machine,Olympus GX53metallographic microscope,S4800 field emission electron microscopy,FEI QUANTA 450SEM,Tecnai G2 20 Transmission electron microscopy and APT various methods of microstructure observation and experimental analysis of mechanical properties,find out the parameters of heat processing and heat treatment custom455 maraging steel,control the uniformity of microstructure of custom455 maraging steel hot working,analysis of strength and toughening mechanism of custom455 maraging steel.According to the micro organization observation and data analysis,the custom455 maraging steel treated with high temperature homogenization at 1200°C before heat addition,hot working temperature not less than 1000°C can make its structure have good uniformity;have high hardness,yield strength and tensile strength,solid solution at 830°C aging at 480°C hardness up to52 HRC,tensile strength up to 1800MPa,yield strength up to 1700MPa,and has certain toughness;The higher the aging temperature,the lower the hardness,these two properties are effected by the size of the primary phase（?）-Ni₃Ti and the secondary phaseε-Cu and austenite content;Analysis sampie changes in organization and performance deal with solid solution at 830°C aging at480°C again long-tern aging at 450°C and 480°C,with the prolongation of aging time,the strength hardness decreases,the plasticity changes little,the austenite content increases,and the strengthening phase size increases.