Study On The Strengthening And Toughening Of Low-temperature High Strength Maraging Steel

With the development of science and technology, more and more liquefied gas isproduced and used. On the petrochemical and air separation unit oxygen generationequipment, as well as some special fields, the structure is not only asked for adequate strengthand toughness and corrosion resistance, but also can be used in very low temperature safety,all of this demands better component materials. This article studies on as high strengthmaraging stainless steel 00Cr13Ni6Co9Mo5 and corrosion resistance maraging steel00Cr9Ni9Co5Mo3, focus on improving test of low temperature toughness of steel, with thehelp of metallographic microscope, scanning electron microscope, X-ray diffraction methodcarry on thorough analysis of the factors that affecting the properties of materials at lowtemperature, got the best treatment of test steel to obtain the best mechanical properties.First we studied of austenite temperature impact on high strength maraging stainlesssteel 00Cr13Ni6Co9Mo5. The results show that treatment with low austenite temperaturecaused large amounts of excess intermetallics in the steel, such asμphase, laves phase andχphase, and carbonitride such as Cr₂₃C₆, NbC, Ti（C,N）. When austenite temperature up to1130℃, most of the intermetallic compounds and carbonitride were soluble in the substrate,remaining only a small amount of TiN distribution in the crystal, and the grain size reaches aminimum 15μm and size uniform, have a beneficial effect on strength and toughness of thematerial. Taking all these factors, we finally confirmed that the best solution temperature ofhigh strength maraging stainless steel 00Cr13Ni6Co9Mo5 was 1130℃.Second we studied of austenite temperature and pretreatment temperature impact oncorrosion resistance maraging steel 00Cr9Ni9Co5Mo3. Test steel treatment with lowaustenite temperature inherited the forging state deformation grain, the austenite is formed bynon-diffusionα′â†'γtransformation. The martensite which change on the cooling processinherited the harden austenite, lead to a higher strength, and suppression the ability that austenite turn to martensite in cooling process, caused more residual austenite, makesmaterial for good impact performance in low temperature. With increase pretreatment the testeliminate the coarse grain which remnants of the forging process, improved low temperaturetoughness of the material, make the material obtain excellent comprehensive mechanicalproperties.