The Reserch Of Step Ageing Processes Of 00Cr13Ni7Co4Mo4Ti Maraging Stainless Steel

With thermodynamic simulation software Jmatpro, the curve of the amount of precipitation with the change of temperature in the process of solution treatment was simulated and the Ms temperature was obtained. By means of OM,SEM,TEM,SAED and XRD,the organizational structure and the major precipitate of 00Cr13Ni7Co4Mo4 Ti maraging Stainless Steel were investigated; The step ageing process and the traditional single-stage aging on the material were compared by the test of tensile strength,elongation and hardness of 00Cr13Ni7Co4Mo4 Ti maraging stainless Steel. The influences of time and temperature on the properties of 00Cr13Ni7Co4Mo4 Ti maraging stainless Steel were studied in the process of step aging. The corrosion resistance of 00Cr13Ni7Co4Mo4 Ti maraging stainless Steel after different heat treatment processes were compared with artificial sea water corrosion and 6% Fe Cl3 solution corrosion.The results of thermodynamic simulation show : all the precipitate phases dissolve in austenite when the solution temperature exceeds 930?, the only phase is austenite and Ms is 116.3?.To ensure solid solution transfers completely, the solution temperature is 1050?.The results of mechanics experiments show:the best heat treatment process of 00Cr13Ni7Co4Mo4 Ti maraging stainless steel is 1050 ? solution temperature for1 h and aging process is 430? 30min(air-cooling)+470? 720 min. Through this process,the 00Cr13Ni7Co4Mo4 Ti maraging stainless steel obtains 1450 MPa tensile strength,13.3% elongation and 50 HRC.The uniform corrosion immersion tests show:covered in artificial sea water for90 days,the materials show good corrosion resistant properties; With the lowest corrosion rate 26.95 g/(m2.h),the step aging process of 430 ? 30 min+470 ? 720 min shows the best corrosion resistant property in 6% Fe Cl3 solution.The results of micro-analytic experiments indicate: analyzing metallographic structure of 00Cr13Ni7Co4Mo4 Ti maraging stainless steel under different heattreatment processes,many dispersed lath martensite are found;The result of SEM indicates that the type of fracture of 00Cr13Ni7Co4Mo4 Ti maraging stainless steel is dimple fracture,which belongs to ductilerupture; The result of XRD shows that the matrix structure of 00Cr13Ni7Co4Mo4 Ti maraging stainless steel is martensitic structure;The result of TEM shows that precipitate is R phase.