Effect Of Pb And Heat Treatment On Microstructure And Properties Of Mn-Cu Damping Alloy

Mn-Cu damping alloy has excellent damping properties,and at the same time has good mechanical properties,economy,safety and other advantages,and has been widely used in modern society.According to actual needs,the optimization of the structure and mechanical properties,corrosion resistance and damping performance of damping alloys has been done,but there is a lack of research on the compound damping mechanism.In this paper,a damping alloy of Mn-Cu-Pb alloy system was developed by introducing Pb element.Discuss the influence of Pb element gradient and heat treatment process system on the morphology,mechanical properties,phase transformation mechanism,corrosion resistance and damping properties of Mn-Cu-Pb alloy.The study on the microstructure,phase transformation mechanism and mechanical properties of Mn-Cu-Pb alloy shows that the introduction of Pb element will form a monotectic structure in the alloy,and its quantity and size will continue to increase with the increase of Pb element content increase.The phases of the Mn-Cu-Pb alloy in the as-cast structure are both ?-Mn and Pb phases.The heat treatment process makes the Mn-Cu-Pb alloy undergo martensitic transformation,resulting in peak separation.And the increase of Pb element content only produces Pb phase in the alloy,and does not significantly change the lattice distortion of the alloy.The introduction of Pb element significantly reduces the hardness,tensile strength and elongation of Mn-Cu-Pb alloy.When the content of the added Pb element exceeds 15 wt.%,the brittleness of the material changes significantly,and the mechanical properties of the alloy will decrease significantly.Pb element reacts in NaCl medium to form protective lead hydroxide,and the corrosion products of Mn and Pb element on the surface prevent the peeling of the substrate surface.With the continuous increase of Pb element content,the corrosion performance of Mn-Cu-Pb alloy shows a trend of first increase and then decrease,and the inflection point appears when the mass fraction is 10 wt.%.The heat treatment process will promote the segregation of Mn elements in the Mn-Cu-Pb alloy,thereby accelerating the corrosion reaction rate and reducing the corrosion resistance of the alloy.The results of finite element simulation show that the damping performance of Mn-Cu-Pb alloy is better.The heat treatment process promotes the distribution of Pb in the Mn-Cu alloy more uniformly,and the increase of the holding time will cause the depletion effect of the Mn dendrites,which makes the damping performance of the Mn-Cu-Pb alloy weakened to a certain extent.In addition,when the content of Pb element content exceeds the threshold value of 15 wt.%,the phase transformation mechanism of the Mn-Cu-Pb alloy will be completely invalid.With the increase of holding time,the damping performance of Mn-Cu-Pb alloy will be greatly improved,and the degree of improvement will be reduced by the increase of Pb element content.The change of frequency will not affect the change law of Mn-Cu-Pb alloy internal friction curve with temperature,but the damping performance has been reduced to a certain extent with the increase of frequency.