| 18Ni300 maraging steel is widely used in aviation,aerospace,ship,nuclear power and other fields.In general,the volume of parts in this field is large and the structure is complex.There are many problems in traditional casting,forging,heat treatment manufacturing process,such as long production cycle,high material consumption rate,and many processing procedures.In this paper,18Ni300 maraging steel is manufactured by 3D printing technology(hereinafter referred to as 3D-M300)to evaluate the the basic performance of3D-M300 by being compared with 18Ni300 maraging steel manufactured by traditional technology(hereinafter referred to as M300).For further,the aging heat treatment of 3D-M300 was carried out to analyze the relationship between the structure and properties of 3d-m300 in the aging process.The specific conclusions are as follows:(1)Through the contrast between 18Ni300 maraging steel made by 3D printing and traditional technology,the relative density,roughness,microstructure,phase,hardness,tensile properties,friction and wear properties and corrosion resistance of 3D printing18Ni300 maraging steel were analyzed objectively and deeply.It was found that the relative density of 3D-M300 is 99.18%,the roughness is 5.760?m and the roughness is one thirteenth of the traditional machining process(EDM).The microstructure showed a semi-arc structure,mainly composed of 98.03%martensite and 1.97%austenite.The tensile strength of 3D-M300 was 1060MPa,the modulus of elasticity was 115.7GPA,the yield strength was841.3MPa,the microhardness was 349.2HV,and the elongation was 13.4%.Compared with the traditional M300,the tensile strength of 3D-M300 was increased by 2%,13.7%,45%,5.6%,306%,respectively.In contrast,3D-M300 was superior to M300 in friction and wear resistance and corrosion resistance..(2)The 3D-M300 was solution treated(820?×2h,air-cooled)in vacuum,and then aged at 420?,440?,460?,480?,500?and 550?for 4h.The microstructure after aging treatment was martensite+precipitate+retained austenite.The transformation of martensite into austenite occured at 500?.Compared with the original 3D-M300,after being aged at 460?,the hardness,tensile strength,elastic modulus,yield strength increased by 72.3%,75.5%,197.6%,112.3%respectively;however,the elongation of the samples decreased by 92.8%.The tensile fracture mechanism was ductile fracture,and the fracture section is mostly dimple.(3)The friction and wear properties of the aged 3D-M300 martensitic steel were evaluated.The data showed that the wear coefficient and wear amount of the aged steel decreased firstly,then increased with the aging temperature increase.The wear mechanism of the samples was abrasive wear and oxidation wear.The best friction performance was obtained when the aging temperature was 460?.The friction coefficient was 0.5060,which is 26.9%lower than 3D-M300 and the wear amount is 0.0048g,which is 63.9%lower than that of 3D-M300.(4)The 3D-M300 martensitic aging steel was tested for corrosion resistance after aging treatment.Compared with the original 3D-M300,the corrosion resistance was improved when the aging temperature was 460?and 480?by polarization curve and corrosion morphology.When the aging temperature was 460?,the self-corrosion potential increased by 32.7%to-0.608V,the self-corrosion current density decreased by 0.2%to-7.889A/mm~2,and the breakdown potential increased by 16.8%to-0.262V being compared with 3D-M300.When the aging temperature rised to 480°C,the self-corrosion potential increased by 2.5%to-0.880V,self-corrosion current density decreased by 1.7%to-7.764A/mm~2,breakdown potential increased by 18%to-0.258V being compared with3D-M300.Combining the self-corrosion potential,self-corrosion current density and breakdown potential,the sample has the best corrosion resistance when aged at 460°C. |
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