Brazing of Copper and Copper Alloys

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1. Brazing Materials

(1) Several commonly used soft brazing materials are used for copper and brass soft brazing and then strength as shown in Table 1.

Solder grade	Shear strength/MPa		Tensile strength/MPa
	copper	brass	copper	brass
S-Pb80Sn18Sb2	20.6	36.3	88.2	95.1
S-Pb68Sn30Sb2	26.5	27.4	89.2	86.2
S-Pb58Sn40Sb2	36.3	45.1	76.4	78.4
S-Pb97Ag3	33.3	34.3	50.0	58.8
S-Sn90Pb10	45.1	44.1	63.7	68.6
S-Sn95Sb5	37.2	–	–	–
S-Sn92Ag5Cu2Sb1	35.3	–	–	–
S-Sn85Ag85B7	–	42.3	–	–
S-Cd96Ag3Zn1	57.8	–	73.8	–
S-Cd95Ag5	44.1	46.0	87.2	88.2
S-Cd92Ag5Zn3	48.0	54.9	90.1	96.0

Table 1 The strength of the copper and brass soft brazing heads

When brazing copper with tin lead brazing, non-corrosive brazing agents such as rosin alcohol solution or active rosin and ZnC12-Nh4C1 aqueous solutions can also be used for brazing brazing in brass, bronze and palladium bronze. When brazing aluminum brass, aluminum bronze and silicon brass, the brazing agent can be a zinc chloride hydrochloric acid solution. When brazing manganese white copper, the needle can be used to select a phosphoric acid solution. The zinc chloride solution can be used as a brazing agent when brazing with lead-based brazing material, and FS205 brazing agent can be used when brazing with cadmium-based brazing material.

(2) When brazing materials and brazing agents for brazing, silver-based brazing materials and copper phosphorus brazing materials can be used. Silver-based brazing material has moderate melting point, good process, and has good mechanics and conductive thermal conductivity, is the most widely used hard brazing material. For workpieces that require high conductivity, a B-Ag70CuZn brazing material with a high silver content should be selected. Brazing in a vacuum brazing or protective atmosphere furnace should be made using brazing materials such as B-Ag50Cu and B-Ag60CuSn without volatile elements. Low silver content brazing material, cheap, high brazing temperature, brazing head toughness is poor, mainly used in brazing requirements of low copper and copper alloys. Copper phosphorus and copper phosphorus silver brazing material can only be used for brazing copper and its copper alloy, of which B-Cu93P has good fluidity, for mechanical and electrical, instrumentation and manufacturing industry without impact load parts brazing, the most suitable clearance of 0. 003 to 0.005mm, copper phosphorus silver brazing material (e.g. B-Cu70Pag) toughness and conductivity are better than copper phosphorus brazing material, mainly used in high conductivity requirements of electrical connectors. Several commonly used hard brazing materials are used in copper and brass brazing joints. Performance is shown in Table 2.

Solder grade	Shear strength/MPa		Tensile strength/MPa		Bending angle/º	Impact absorption energy/J
	copper	brass	copper	brass	copper	copper
H62	165	–	176	–	120	353
B-Cu60ZnSn-R	167	–	181	–	120	360
B-Cu54Zn	162	–	172	–	90	240
B-Zn52Cu	154	–	167	–	60	211
B- Zn64Cu	132	–	147	–	30	172
B-Cu93P	132	–	162	176	25	58
B-Cu92PSb	138	–	160	196	–	–
B-Cu93Pag	159	219	225	292	120	–
B-Cu8OPag	162	220	225	343	120	205
B-Cu90P6Sn4	152	205	202	255	90	182
B-Ag70CuZn	167	199	185	321	–	–
B-Ag65CuZn	172	211	177	334	–	–
B-Ag55CuZn	172	208	174	328	–	–
B-Ag45CuZn	177	216	181	325	–	–
B-Ag25CuZn	167	184	174	316	–	–
B-Ag10CuZn	158	161	167	314	–	–
B-Ag72Cu	165	–	177	–	–	–
B-Ag50CuZnCd	177	226	210	375	–	–
B-Ag40CuZnCd	168	194	179	339	–	–

Table 2 Performance of copper and brass brazing heads

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