Cold Welding Electrodes, Cast Iron, Providing the Receipt of the Weld Metal Color

for joints having sufficient ductility in the cold state, apply the electrodes to ensure receipt of the weld metal alloys based on copper and nickel

Cold welding electrodes, cast iron, providing the receipt of the weld metal non-ferrous and special alloys

For joints that have a sufficiently high ductility in the cold state, apply the electrodes to ensure receipt of the weld metal alloys based on copper and nickel. Copper and nickel do not form compounds with carbon, but their presence in the alloy reduces the solubility of carbon in iron and promotes graphitization. So, getting into the zone of partial melting, adjacent to the seam, they reduce the probability of bleaching. In addition, the ductility of the weld metal contributes to a partial relaxation of welding stresses, and therefore reducing the likelihood of cracking in the HAZ. For welding of cast iron used mednozheleznye, mednonikelevye and iron-nickel electrodes.

There are several types of copper and iron electrodes.

One. The copper rod with a braided sheet thickness 0.25 - 0.3 mm, which is in the form of 5-7 mm width tape wound on a core of the helix. Applied to the ionizing electrode or a thick coating. The electrode with a rod made of a combination of wire, which is a core of steel wire, tightly pressed into a copper tube manufactured on the machines for the production of cored wire.

It may also be another option: a copper core with a steel shell. All varieties of iron content in the weld metal should not exceed 10-15%, because otherwise the seam formed (in large quantities) is very solid inclusions of iron with high carbon content, adversely affect the workability and reduce the ductility of the joint.

Two. The beam of the electrodes, consisting of one or two copper rods and a steel electrode with a protective coating of any brand. The beam connected to the four or five places and the copper wire on the end inserted into the electrode, we catch for a good contact between all the bars.

Three. The most advanced among the copper-iron electrodes - electrodes OZCH grade-1, representing a copper rod with a diameter of 4-5 mm, on which a coating consisting of a dry powder coating SSSI-13 (50%) and iron powder (50%), zameshennyh on liquid glass.

Copper-iron alloy in the joint can also be obtained when welding copper electrodes on a special layer of flux, which consists of calcined borax (50%), caustic soda (20%), iron scale (15%) and iron powder (15%). Flux poured a layer thickness of about 10 mm, the arc melted, continue stirring as the arc between copper electrode and the molten flux.

Welding electrodes, copper and iron of all kinds should be carried out in such a way as to avoid strong heating of the welded parts: the lowest possible currents, providing a stable arcing, short sections of randomly, with interruptions for cooling the workpiece.

The main advantage of these electrodes - the possibility of forging weld metal in the hot state to reduce the level of welding stresses. Forging is required, since this decreases the risk of cracking in the weld zone.

The general lack of copper-iron electrodes - a heterogeneous structure of joint: soft copper base and a solid component of the inclusion of iron, hinder or prevent the processing of obtaining a high purity of the treated surface. Some have better machinability joints, electrodes made of mark Anch-1, a core consisting of austenitic steel grade St-04H18N9 and the copper shell. The electrode coated ftoristokaltsievogo type.

The most efficient use of copper-iron electrode for welding defects not through individual or small leaks, creating a leak responsible for casting purposes, including working under pressure (flanges, bearings).

Copper-nickel electrodes in production is mainly used for welding casting defects detected during the machining of cast iron on the working surfaces, where the local increase in hardness is not allowed. The positive properties of these electrodes is that the nickel and copper do not dissolve carbon and do not form a structure having a high hardness after heating and rapid cooling. Whitening zone of partial melting at small sizes it is virtually absent, as copper and nickel - elements - grafitizatory, getting into this area to have a positive effect: at the same time, nickel and iron have unlimited solubility, facilitating reliable fusion.

For the manufacture of electrodes and the use of copper-nickel alloys: Monel - Metal containing 65-75% Ni, 27-30% Cu, 2-3% Fe and 1.2-1.8% Mn (eg, NMZhMts 28-2, 5-1,5), Constantan, containing ~ 60% Ni and ~ 40% Cu (MNMts 40-1,5), nichrome (Cr20Ni80).

The disadvantages of these alloys - their high cost and scarcity, as well as a large shrinkage, leading to the formation of hot cracks. Hot cracks sometimes look like a solid mesh, which reduces the strength of the weld. In this regard, these alloys are not recommended for welding cracks in the products that carry the power load. Welding same individual small bowls can get good results, as it provides a possibility of subsequent machining.

Are used in industrial electrodes makes MOF-1 with the rod of monel metal, and MOF-2 with a rod of constantan. Both brands have a kind of Electrode coatings F. Weld perform electrodes with a diameter of 3-4 mm, thread, seam, short sections, with the reciprocating movement of the electrode, preventing overheating of parts, which are recommended to cool breaks. Bead while hot should be carefully prokovyvat light strikes the hammer. For welding some small defects on the machined surfaces of castings responsible use of gray and ductile cast iron defects identified on the machined surfaces of products and equipment for repair of cast iron, iron-nickel electrodes are also used with the core of an alloy containing 40-60% Ni and 60 -40% Fe.

When welding electrodes so provided a sufficiently high strength and a toughness of the weld metal. Iron-nickel electrodes offer certain advantages, among which, besides high strength can be attributed less than that of copper-nickel alloys, casting shrinkage, surfacing with a one-color iron. An example of this type of electrode can serve as electrodes TSCH brand-OF rod with wire Sv-08N50 and coated with dolomite (35%), fluorspar (25%), graphite, black (10%) and ferrosilicon (30%), liquid zameshennyh glass.

You should always keep in mind that all the electrodes containing nickel, scarce and can be used for welding cast iron is limited, such as welding of small shells, exposed in the last machining operation, the details of large size and high stiffness.

See also:
Welding of Cast Iron
Composition and Properties of Iron
Marking of Iron
Basic Information on Weldability and Technological Advice
Structural Transformations in the Heat Affected Zone during Welding of Cast Iron
Effect of Cooling Rate on the Structure of the Weld Metal and Heat Affected Zone
The Technological Process of Hot Welding
Cold Welding of Cast Iron with Simple Electrodes
Cold Welding Electrodes, Cast Iron, Providing the Receipt of the Weld Metal Color