Material for joining and product produced therewith

Abstract

An iron based brazing material for joining of objects by brazing represents an alloy, which apart from iron contains maximum 40% Cr, maximum 16% Mn, maximum 40% Ni and maximum 7% Mo, all stated in weight percent and 6-40% Si, which Si-addition lowers the liquidus temperature, that is the temperature at which the brazing material is completely melted. A brazed product is manufactured by brazing of iron based objects with an iron based brazing material which is alloyed with a liquidus lowering element as Si, possibly also with B or P.

1 . Iron based brazing material for joining objects by brazing characterized in that the brazing material consists of an alloy which contains at least 50% Fe and includes 0-30% Cr, preferably 9-30% Cr, maximum 5% Mn, 0-25% Ni and maximum 7% Mo, 0-1% N and 6-20% Si, all stated in weight percent, which Si-addition lowers the liquidus temperature, that is the temperature when the brazing material is completely melted.  
     
     
         2 . Iron based brazing material according to  claim 1 , characterized in that the brazing material apart from Si also contains B as a melting point lowering supplement to Si, at which the amount of B is below 2%, preferably below 1.5%, which addition also increases the wettability of the brazing material.  
     
     
         3 . Iron based brazing material according to  claim 1 , characterized in that the amount of Si is 7-16%, preferably 8-12%.  
     
     
         4 . Iron based brazing material according to  claim 1 , characterized In that the brazing material apart from Si also contains P as a melting point lowering supplement to Si, at which the amount of P is maximum 15%.  
     
     
         5 . Iron based brazing material according to any of the preceding claims, characterized in that the brazing material is produced by gas- or water atomising or melt-spinning.  
     
     
         6 . Brazed product manufactured by brazing the objects with an iron based brazing material according to  claim 1 , characterized in that the material in the objects to be brazed is iron based.  
     
     
         7 . Brazed product according to  claim 6 , characterized in that the product is a plate heat exchanger intended for at least two heat exchanging media, which comprises at least one plate package manufactured by brazing together a number of thin walled heat exchanger plates of an iron based material brazed by means of a iron based brazing material, at which the heat exchanger plates between themselves define plate inter spaces intended for the heat exchanging media, at which the brazing joints have a metallurgical composition close to the composition of the iron based plate material with locally higher amounts of Si in and around the brazing joints in comparison with the iron based plate material.  
     
     
         8 . Brazed product according to  claim 7 , characterized in that the iron based heat exchanger plates are brazed together with an iron based alloy containing B or P apart from Si.