Sukmanyuk O.M.
Zhytomyr
National Agreecological University, Ukraine
The
materials’ development for the fusion under the sphere of the flux
The development of the modern fusion
methods is connected with the electrical arc and gas flame appearance. M. G.
Slavyanov considered “the filling of the layer of metal to the worn surfaces or
for any other purpose” to be one of the most important the arc welding usage.
Under his management it was carried out the fusion of different alloyed steels,
cast iron, bronze and others, and it was also made a number of the complex
repair works.
In 30th of the last century manual
arched fusion by the coated electrodes became more widely spread appearance of
which with the alloying coating made it possible to renew the worn or damaged
machine parts.
Gradually the deficiencies in the manual
fusion occurred: low productivity and heavy working conditions, the inconstant
quality of layer, which depended on the personal skill of the worker. Therefore
the mechanization of arched fusion was and is the important condition for its
subsequent development and improvement.
New stage of the fusion development
began at the end of the 40th years, when for fulfilling the fused works they
began to use submerged-arc welding. The key problem,
that needed to be solved was the creation of layers with the assigned
technological properties which would allow fusion continuously for a long time,
to obtain the high quality of weld metal and the high productivity.
In order to obtain the desired
properties of the weld metal - the high wear and corrosion resistance, and also
its endurance under the effect of high temperatures, it was necessary to find
the acceptable way of the alloying for it. The suitable alloyed wire was let out
in the small quantities and therefore only sometimes it was possible to use it
in the finished form also of the necessary composition however, in the majority
of the cases for this they adapted the wire, whose composition was as far as
possible at least close to necessary one.
The attempts to finish mixing to the molten flux mashed ferro alloys
proved to be unsuccessful: separation with the overfilling passed, the layer
was rather heterogeneous, appeared cracks and others. The more advanced results
it was possible to obtain after mixing the powdery slag-forming, alloying, and
deoxidizing constituents with the liquid glass, with the following granulation,
drying, and frying.
But the research showed that the
alloying through the flux leads to the significant dependence of the quality of
the weld metal composition on the regime of the fusion: the mass ratio of the
slag, which is fallen per unit of the molten wire mass, according to the regime
can vary from 0,4 to 4,0. And the
composition of weld metal changes, therefore the range of the permissible
regimes of fusion is very narrow with the alloying through the flux, which
limits the possibilities of its use.
It was possible to overcome these
difficulties as a result of the new form of the electrode materials
creation - the powder wire. The electrical material in this case was convoluted from the metallic tape (continuous steel tube)
of that filled with the powder, which consists of the mixture of the necessary
materials - metals, the ferro alloys, gas-forming and other substances. The
powder wire with a diameter of from 2,0 to 6,0 mm was manufactured via the wire
drawing of soft tape with the simultaneous filling with the mixture of powders.
The development of the methods of
alloying had practical embodiment for obtaining the alloyed weld metal of the
assorted composition both the renovating fusion and for the fusion of the
wear-resistant layer, however, electrode wire made of high-alloy steel was used
with the fusion of anticorrosive layer.
Fusion under the layer of flux was noted
by high productivity and reliability and it contributed to the widespread
introduction of this method in machine building where as an electrode they began to use a tape of small
thickness and large width. The layer of the stainless steel sufficiently
reliably and productively was melted on the internal surfaces of chemical,
petrochemical and power reactors with the help of the electrode tape.
Automatic fusion under the layer of flux
also becomes effective technological process, also, during the production of
the bimetallic elements. The possibility to simultaneously increase sizes and
fitness for work of the deposited components appeared with the aid of it. This
found its use in many branches, in particular in the metallurgical industry -
for increasing the durability of rolling rollers, rollers and many other
components, for the agricultural machines adapts the
technology of the fusion of components with the use of the alloyed wire of
small diameter developed in the institute of electro-welding by E.O. Paton.
The wide spectrum of the works, which
were carried out by institute in the branch of fusion, led to the solution of
the alloying of weld metal problem for the purpose of obtaining metal with the
special properties, which was achieved because of the powder electrodes usage.
Automatic fusion under the layer of flux
as one of the methods of the renewal of components had a number of the
advantages: high productivity and the stability of the quality of process, and
layer (uniformity, density); a good adhesion of base layer with the base metal;
the possibility of obtaining the layers of the significant thickness (to 8 mm
and more); the possibility of obtaining the layer with the necessary chemical
composition and the properties.
Scientific developments in the branch of
the hard-facing of metals did not lose their urgency and at present, since the
rapid technological development of human society constantly requires the
decision of new tasks on these questions.