US2390775A - Brazing alloys - Google Patents

Description

Other objects of this invention Patented Dec. 11, 1945 ur ferries Baume mors Joseph G. Christ, Wilkinsburg, a., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation oi Pennsylvania Application March 25, i944, Serial No. 528,085

(CH. "Z-153) 4 Claims.

This invention relates to alloys and in particular to copper base brazing alloys. A

An object of this invention is to produce a copper base brazing alloy having high strength and good ductility. v will become apparent from the following description when taken in conjunction with the accompanying drawing, the single figure of which is a graph the curves oi which illustrate the eiect of changes in the alloying content on the tensile strength, elongation and reduction of area of the alloy of this invention.

The alloy of this invention consists of 0.25% to 2.5% silver, 1% to 3% tin, 6% to 7.5% phosphorus and the balance copper with not more than ..5% incidental impurities. The alloys within this range have low melting ranges andl good ductility combined with excellent ow, Wetting and self-iiuxing characteristics. The alloys containing from .5% to 2%A silver, 1%-to 3% tin,

6.5% to 7.5% phosphorus and the balance cop-V ,ranging between .5% and 1.5% has unusual characteristics as is illustrated by reference to the following table:

Table I Tensile Elongation Reduction Ag strength, in 1% p. s. i. inches of area o auw' 2.a 2.9

In the foregoing table the silver and copper contents are the only variables, the tin and phosphorus contents being held constant with the alloy containing not over\.5% incidental impurities. The data given in the table is the average of a number oi tests conducted for each of the valloys containing the silver content as given in 'the table.

, Examining the data given in the tableand rev Vierring to the curves of the accompanying drawing, it is evident that thel maximum characteristics of the alloy within the range given is obtainedwhere the silver content-is about 1% and the tin content about 2%. In the drawing, curve It is illustrative of the tensile strength, curve i2 is illustrative of the elongation, and curve itis illustrative of the reduction in area obtained and recorded in the foregoing table. As clearly illustrated in the drawing the addition of more than 2% silver does not have any benecial eiect on `the alloy. However, silver contents of up to 2.5%

do not have any detrimental effect upon the resulting alloy and are contemplated Within the scope of this invention. y I

By utilizing both tinl and silver within the ranges given, alcopper base brazing alloy Vcontaining phosphorus is produced which has unusual properties. The tin content of the alloy has the eiect of lowering the melting point and improving the ductility. However, 1% is given as-the lower limit of the tin content, as the effect of tin on the ductility is negligible if less than 1% tin is utilized. The tin has the eect of increasing the ductility if up to 3% of tin is employed, but beyond 3% tin the brittleness of the alloy increases to a detrimental degree. The silver content further lowers the melting range, improving the duc'tility and facilitating'the manufacture of the alloy by decreasing the hot shortness of the alloy. Ihe eect of the silver content on the physical characteristics of the resulting alloy is apparent from the foregoing table and the accompanying drawing.

The phosphorus content of the alloy of thisl invention has a` denite effect on the ductility oi the resulting alloy in that 4the lower the phosphorus content the more ductile the resulting alloy. Referring to the following table, the eiect of the phosphorus on the ductility and tensile strength of the alloy is readily apparent, the

results recorded therein being obtained with copper base brazing alloys having a 1% silver and a 2% tin content with the phosphorus varying as indicated in the table:

By lowering the phosphorus content 'of the alloy, improved ductility is obtained. However the melting range of the alloys having the lower',

phosphorus content is wider. Thus, while it is contemplated to include alloys having a phosphorus content as low as 6% as given in the broad range hereinbefore referred to, it is preferred that the lower limit of the phosphorus 'such good ductility that if they are in rod or wire form such rod or wire can be bent to any desired shape for preplacing of the brazing alloy on assemblies which are to be furnace-brazed. The resulting joints are exceptionally strong and ductile.

As stated hereinbefore, the alloy of this invention may contain up to 25% of incidental impurities without detrimental effect on the resultingv alloy. In practice, it is found that these impurities may comprise cadmium, zinc, antixnony, bismuth, nickel, iron, arsenic, lead and tellerium which are sometimes present in the alloying ingredients. In the claims where the lterm balance copper is employed, it is intended that this term include as a maximum not more than .5% of such incidental impurities as are referred to hereinbefore and which may be present in the resulting alloy without changing the desirable characteristics of the alloyureferred to hereinbefore.

While this invention has been described with reference to a particularembodiment thereof, it

is, of course, not to. be limited thereto except in so far as is necessitated by appended claims.

I claim as my invention:

1. A brazing alloy consisting of, 0.5% to 2% silver, 1% to 3% tin, 6.5% to 7.5% phosphorus, and the balance copper. y

2. A brazing alloy consisting of, about 1% silver, about 2% tin, from 6.5% to 7% phosphorus, and the balance copper.

3. A brazing alloy consisting of, about 1% silver, about 2% tin, about 6.75% phosphorus, and the balance copper.

4. A brazing alloy consisting of, about 1.5% silver, about 2% tin, about 6.75% phosphorus, and the balance copper.

the scope of the JOSEPH G; CHRIST.

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