Filler metal refers to the filler added in or near the gap for the
purpose of combining two materials (or parts). Filler metal refers
to the filler used to form a weld when brazing. The melting point
of the filler must be lower than that of the welded material.
Suitable for welding of precise, complex, multi - collar joints and
heterogeneous materials. According to the melting point, the solder
can be divided into soft solder (melting point less than 450℃) and
hard solder (melting point more than 450℃) high-temperature solder
(melting point more than 950℃). According to the composition of the
solder solder solder tin base, lead base, zinc base and other
solder. The brazing metals include aluminum base, silver base,
copper base and nickel base. In welding, the filler metal wets the
base material and forms a structure such as solid solution with the
base material to realize the tight bonding of the welding material.
Melting point, wettability, joint strength and other factors must
be considered when choosing brazing metals, which have a direct
impact on brazing quality. Due to the fact that the properties of
brazing alloys not only affect the technological properties of
brazing but also determine the joint properties of brazing to a
large extent, the selection of brazing alloys among various brazing
alloys should be determined from the perspectives of joint use
requirements, mutual matching of brazing alloys and base materials,
brazing heating technology and economic cost. Starting from the
joint use requirements, for the brazing joint strength requirements
are not high, can be brazing with soft solder; for the brazing
joint strength requirements are relatively high, should choose the
brazing solder brazing. For solders brazing at low temperatures,
use a solder with a low tin content or a filler that prevents the
occurrence of cold brittle elements such as antimony. For joints
working at high temperature, solder with good high-temperature
strength and oxidation resistance should be selected, such as
nickel-based solder. The lead base solder containing a small amount
of Ag and Sn has good flooding property and filling capacity, high
melting point, high temperature strength and working temperature up
to 250℃, suitable for soldering iron brazing and flame brazing of
copper, copper alloy and steel. Welding temperature 798℃-850℃.
Depending on the welding temperature, the ratio of tin to copper is
also different Physical: Tin (Sn99.95) : melting point 232℃,
density 7.29g/cm3. Copper: melting point 1083.4℃, density
8.960g/cm.
