Study On Plasticity Forming Performance Effect Of Cu-15Ni-8Sn Alloy With Dendrite Spacing And Alloy Elements

This paper adopts intermediate frequency induction furnace and high frequency induction furnace for melting Cu-15Ni-8Sn alloys,and explore the influence of different dendrite spacing on the microstructure and properties at subsequent heat treatment process;Trace Cr?Zr?Si?Nb?Ti and Mn elements were respectively added,and the effects of these trace alloy elements on the transformation of microstructure and property of Cu-15Ni-8Sn alloy during homogenization annealing,solid solution treatment,cold deformation and aging treatment were studied.Determine the conditions which can delay the precipitation of the low melting point discontinuous precipitationandimprove the formability of the alloy.At the same time,the effect of alloy element content on the spinodal decomposition structure and properties of Cu-15Ni-8Sn alloy was studied.The results show that the Cu-15Ni-8Sn alloy which have11?m dendrite spacing and was treatedby 840?×8h homogenization annealing and 800?×1hsolid solution,the microstructure has tended to be uniform.While the dendrite spacing in Cu-15Ni-8Sn alloy reached 50?m,the diffusion of the solutes is not uniform after the same heat treatment condition.And the residual undissolved structure is still visible while the primary bright white insoluble tissue is tin rich phases.Cu-15Ni-8Sn alloy which haveuneven diffusion solutesafter 80% and 60% cold rolling deformation,the 80% cold rolling sample reached the hardness peak of 394 HV after 400?×0.5h aging,and the 60% cold rolling sample reached the hardness peak of 392 HV,and with the extension of the aging time,the hardness decreased sharply.While the Cu-15Ni-8Sn alloy with homogeneous microstructure reached the peak of 395 HV after 60%cold upsetting deformation and 400?×5h aging.Trace Nb and Si can retardthe diffusion of the solutesin Cu-15Ni-8Sn alloy at the homogenization annealing process.The edge of the sample causes crack after 60% upsetting deformation.The discontinuous precipitation showed the trend of precipitation at aging process.The hardness were respectively 300 HV and 365 HV after 400 ? ×5h aging.The edge of the Cu-15Ni-8Sn alloy which had added trace Zr does not causes crack after 60% upsetting deformation,but a lot of discontinuous precipitation had be precipitated after 400?×5h aging,and the hardness is only 287 HV.The edge of the Cu-15Ni-8Sn alloy which had added trace Ti although causes crack after 60% upsetting deformation,the precipitation of the discontinuous precipitationis proportional to the deformation.Theprecipitation and growth of the high deformation area in the edge of the sample is rapid,the precipitation and growth ofthe center areain the sample is stable,and the hardness reached 393 HV after 400?×5h aging.The edge of the Cu-15Ni-8Sn alloy which had added trace Mn not only did not crack,but also did not precipitate much of discontinuous precipitation in the high deformation area of the edge of the sample after 400?×5h aging.The hardness is 387 HV.Themicrostructure and properties of Cu-15Ni-8Sn alloywhich had added trace Cr are worse than the alloy which had added trace Mn after 400?×5h aging,and the hardness is only 369 HV.The microstructure and properties of Cu-15Ni-8Sn alloywhich had added more content of Mn was studied.The results show thatthe effect of 0.87wt%Mn content and 0.38wt%Mn contentdelay the discontinuous precipitation precipitate is similar.But the age hardening effectwas delayed in the Cu-15Ni-8Sn alloy with the increase of Mn content.Therefore,the addition of 0.38wt%Mn contents of the Cu-15Ni-8Sn alloy have the best comprehensive process performance.