Yg15 Carbide And 40cr Matrix High-frequency Induction Brazing

Tamping tine as a kind of easy wearing tool using by tamping express, which is a kind of large railroad maintain mechanical.Tamping tine with move and vibration insert stones under the base of railroad,which made them more closely and solidly.Prolong tamping tine's service life we can improve efficiency of tamping work,save energy soufce and reduce the cost.Wearing out is the main reason for expiration of the tamping tine.The key to prolong tamping tine's service life is improve wearable ability of it's surface.Using hard alloy cover the easily worn parts of tamping tine can enhance it's wearable ability and prolong it's service life.Covering hard alloy on the surface of tamping tine,we usually can't obtain high conjunction strength brazing seam.Because this is belongs to welding between different kind of material.The difference of line expansion coefficient between steel and hard alloy is very large. Great inner stress will produce around the brazing seam,when steel and hard alloy shrink in the process of cooling.In the serious condition,it can lead to crack in the hard alloy.This paper searched and summarized the way of exhibitions and technology of brazing hard alloy to the surface of tamping tine,base on analysis the brazing characteristic both of YG15 hard alloy and 40Cr alloy steel,also of the import tamping tine.A series of experimental analysis and comparison showed that,for brazing 40Cr alloy steel and YG15 hard alloy under an unprotected ambience,the roughness of hard alloy'surface,the preheat time of brazing and brazing time only have a littlr influence to the welding quality.However,keeping the temperature and time after brazed,pressure and surface of hard alloy with corrosion are important factors of influence to the welding quality.Giving about 15kg pressure at brazing process is suitable,great pressure may lead to brazing seam too thin and increase it's inner stress.After brazing,at 400℃keep about 8 hours,brazing seam usually have a high strength combined.At that condition,the macrosegregaion and spread of Ag,Cu and Zn elements in the brazing seam are serious,but W and Co elements spread are slowly. The macrosegregaion and spread of elements lead to reduce the level of Ag neare the interface of brazing seam,but the level of Cu,Zn and Fe elements are increase,which easily produce brittle organization.Especially,the element of Fe easily gather in the brazing seam neare the hard alloy,which usually form the brittleη phase.This is the main reason for lower strength and brittle fracture of brazing seam.Using sour corrode the surface of hard alloy can effectively wipe the oxidation film,but will lower the welding strength. For brazing 40Cr alloy steel and YG15 hard alloy use Ag-Cu alloy sandwiching three layers solder is superior to the silver base solder.