Effect Of Aging On Microstructure And Properties 05Cr15Ni5Cu4Nb

In this paper, research effect of aging process for05Cr15Ni5Cu4Nb precipitation hardening stainless steel mechanical properties, and application of transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy spectrum, X ray diffraction, etc. Observation and analysis microstructure and precipitated phase, and explored the internal relationship between the aging process and room temperature mechanical properties and microstructure, compared the corrosion resistance of typical aging process, for the engineering application of the steel provides experimental data and technical support.Results show that with the aging temperature rising up and prolong aging time, the tensile strength gradually decline, reduction of area, elongation, impact absorption power gradually increases, the strength decline slower within482℃to579℃, when aging temperature up to579℃strength decline faster, at621℃dropped to the lowest, and the toughness is the maximum, impact fracture morphology from quasi cleavage gradually transform to a predominantly dimple nest morphology, indirectly confirmed that with the increase of aging temperature increasing toughness.With aging temperature rising up, reverse austenite content gradually increased, in the579℃austenite content is up to4.84%, when the aging temperature higher than579℃the austenite content sharply increase to20%, which up to maximum27%at621℃, the increase of austenite volume fraction reduces the strength and improve the plasticity and toughness of steel; after aging at552℃for4hours, the state membrane reverse austenite precipitation from the lath martensite interface, martensite and austenite maintained a K-S orientation:(011) M//(111)γ,[111]//[011]γ; At this point, quantities small rich Cu precipitation phase dispersion in lath and maintained crystallography orientation relationship with substrate for (111) Cu//(011)M,[011] Cu//[001]M, which is the main strengthening phase in steel, is one of the biggest factors to enforce strength of steel.Phase structure analysis show that, only a little amount of M23C6and NbCN phase in steel, with the aging temperature rising up and prolong aging time of the amount of M23C6and NbCN phase percentage increase gradually, the quality of the Chrome in the M23C6phase formula is gradually replace the iron atoms, in NbCN phase formula nitrogen atoms is gradually replace carbon atoms.With the aging temperature rising up, the pitting corrosion and crevice corrosion resistance of steel gradually decreases, the corrosion resistance is the worst in593℃, at621℃corrosion resistance improved compared with593℃, aging at482℃by1hour corrosion resistance is best, and552℃by4hour have the same point and crevice corrosion resistance of621℃; Aging at482℃prolong the heat time, the stress corrosion resistance of steel Kiscc also gradually increased.