| The precipitation behavior of00Cr13Ni7Co5Mo4W maraging stainless steelwas analyzed and studied by using the thermodynamic calculation software Thermo-Calc; by means of metallographic microscope (OM), transmission electron microsco-py (TEM), selected area electron diffraction (SADP) and other test methods, theorganizational structure of00Cr13Ni7Co5Mo4W maraging stainless steel wasinvestigated; the seawater corrosion resistance performances of00Cr13Ni7Co5Mo-4W maraging stainless steel were contrastively researched by using potentiodynamicpolarization curves and uniform corrosion immersion test, the corrosion morphologyof00Cr13Ni7Co5Mo4W maraging stainless steel were analyzed by using scanningelectron microscopy.The results of thermodynamic calculations showed that the R phase is thestrengthening phase during the aging process; the heat treatment process of maragingstainless steel was determined based on the matrix organization in the differenttemperatures and the precipitation phase changes.The results of the microstructure analysis indicated that the organization of00Cr13Ni7Co5Mo4W maraging stainless steel after solution treatment is uniformand fine lath martensite; the microstructure of maraging stainless steel after agingtreatment is the thin lath martensite and small amount of reverted austenite. Theaging precipitation phase of00Cr13Ni7Co5Mo4W maraging stainless steel afteraging treatment was R phase; this is consistent with thermodynamic calculationresults.The result of seawater corrosion resistance property studies showed that the00Cr13Ni7Co5Mo4W maraging stainless steel after solution treatment have theability of organization electrochemical uniformity, this makes it a good seawater corrosion resistance. The annual corrosion rate of00Cr13Ni7Co5Mo4W maragingstainless steel after solution treatment at1100℃for1h immersed in artificialseawater after90days was1.0872μm/a, the breakdown potential was276mV.The00Cr13Ni7Co5Mo4W maraging stainless steel after different agingtemperature treatment occurred to the self-passivation, the relationship between thebreakdown potentials are E470℃>E490℃>E510℃>E450℃, due to the precipitation phaseis not conducive to the corrosion resistance during aging process, the corrosionresistance of maraging stainless steel after solution treatment and aging treatmentwere reduced.The breakdown potential of00Cr13Ni7Co5Mo4W maraging stainless steel aftersolution treatment at1100℃for1h and aging treatment at490℃for8h is252mV,and its the annual average rate of corrosion is1.2590μm/a, in this condition, the00Cr13Ni7Co5Mo4W maraging stainless steel has good resistance to seawatercorrosion. |
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