The .00 Cr13ni5co9mo5 Maraging Stainless Steel Toughening Technology

00Cr13Ni5Co9Mo5 is a kind of casting maraging stainless steels with excellent properties, which has well Corrosion Resistance as stainless steels, the strength and toughness are no less than 18Ni. It has been systematically studied that the effects of Chemical Compositions and Heat Treatment Processes on, especially the low temperature impact toughness of 00Cr13Ni5Co9Mo5 maraging stainless steel. The correlation of mechanical properties, microstructures such as morphology of precipitation phase and austenitic volume fraction has been researched by transmission electron microanalysis and x-ray diffraction analysis. The toughening mechanism and the approach of toughness improvement has been explored, and the following major results has been obtained:The tensile strength curve of 00Cr13Ni5Co9Mo5 maraging stainless steel had an aging peak during 510-540℃. Theα→γphase transition which with the temperature increasing made strength decrease. Austenitic volume fraction reached the highest value 49.08% when the aging temperature is 625℃. But the formation of secondary martensite with the temperature increasing made austenitic volume fraction decrease.An appropriate residual austenitic volume fraction(15-25%) is the essential prerequisite to improve the low temperature impact toughness. Though theα→γphase transition increased the residual austenitic volume fraction during overaging temperature process, the low temperature impact toughness couldn't be improved as there were brittle precipitate phase during the process. There were higher strength but extremely low impact toughness especially room temperature impact toughness at the aging peak of 510-540℃. Aging at temperatures lower than 480℃didn't change the residual austenitic volume fractions, it made the steel has the higher room temperature and low temperature impact toughness but the lower strength. Comprehensive analysis of strength, room temperature and low temperature impact toughness,480℃became the proper aging temperature.The correlation of microstructures and mechanical properties of 11 heat steels with different chemical compositions indicate that:the contents of C, N and Ni were the primary elements to control the residual austenitic volume fractions and distributions.It lowered significantly ductile-brittle transition temperature when the austenitic volume fraction in the range of 15-25%.Thus,control the residual austenitic volume fractions through adjustment of alloy composition was the key to improve the material low temperature impact toughness.Besides, the content of Ti which is strong carbide forming element also had effect-on the mechanical properties of 00Cr13Ni5Co9Mo5 maraging stainless steel besides the contents of C, N and Ni. The research showed that appropriate Ti could refine grain size. But when there was the more content of Ti, Ti could combined with C and N to form large inclusion Ti(C,N), which induced cleavage fracture.And the effective content of C and N in martix can be reduced obviously by the formation of Ti(C,N), which may significantly decrease the residual/austenite content after solution and aging treatment, and the ductile-brittle transition temperature may be raised obviously which could reduce the material impact toughness rapidly.