| The powder metallurgy technology used to prepare stainless steel parts has cost-effectiveadvantages, compared with traditional casting and forging technology, its parts are near to net shapeand high dimensional accuracy, which has been widely used. The relationship among composition,manufacturing process, microstructure, mechanical properties and corrosion resistance of316Lstainless steel has been systematically investigated in this dissertation by thermal analysis (DTA),optical microscopy (OM), scanning electron microscope (SEM) and energy dispersive X-ray analysis(EDS).In the first part of this dissertation, the present research situation of P/M stainless steel wascritically overviewed, including the general development situation in domestic and abroad, theresearch development of forming and sintering technology, the role of alloying elements in thepre-alloyed stainless steel powder, and the influence of addition of sintering additive andstrengthening phase powder on the microstructure and properties of the P/M stainless steel; Based onthe above work, the purpose and significance of the dissertation had been pointed out.The vacuum sintering craft of stainless steel matrix and added with sintering additive had beenstudied systematically, the conclusions were obtained as follows: for the matrix composition ofstainless steel, when sintered at1380℃of supersolids liquid-phase sintering for60minutes, sinteringbody had homogeneous microstructure with high density and low porosity which exhibiting the bestmechanical properties and corrosion resistance; for the stainless steel added with1wt.%FeB sinteredat1250℃, through the rapid spread of liquid phase at the particle contact areas and the grainboundaries, near full densification was obtained of the sintering body which made its tensile-strengthand corrosion resistance of the best, elongation and hardness of high; for the stainless steel added with2wt.%Sn, when the sintering temperature reached1325℃, favoring the classical phenomenon ofliquid phase sintering, which made the sintering body had high densification and best tensile-strength,corrosion resistance and excellent elongation and hardness. Comparison of the three sintering craft insummary, the stainless steel adding with1wt.%FeB sintered at1250℃demonstrates the bestdensification, corrosion resistance and high mechanical properties.The influence of different balling techniques and different ceramic strengthening phases on themicrostructure and properties of the stainless steel had been studied, the conclusions were obtained asfollows: compared with ordinary dry-mixing, the stainless steel particles and ceramic phase particles were significantly refined by high-energy ball milling method, which also improved the distributionuniformity of ceramic particles in the stainless steel substrate; when added with2wt.%TiC and TiNpowders in stainless steel individually, the tensile-strength and hardness of stainless steels had bothbeen greatly improved, however, its elongation and corrosion resistance declined because of a certainincreasement of porosity in the sintering body. |
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