Drug by the welding electrode core and skin of two parts. The metal core Welding Electrodes are outside the paint (drug skin) evenly to carefully pressure
applied to the welding core. Different types of Tungsten Electrodes, welding core is different. Welding electrode metal core that is the core, in order to ensure the weld
quality and performance, the core butt in the content of the metal elements have strict rules, especially for harmful impurities (such as sulfur, phosphorus,
etc.) the content, there should be strict restrictions, better than the base metal. Direct impact on the core components of welding the weld metal
composition and performance, so the harmful elements in the core welding to as little as possible.
Welding carbon and low alloy steel welding core, low-carbon steel is generally used as a welding cell, and fill up the manganese, silicon, chromium, nickel
and other elements (see the national standard GB1300 a wire 77). The reason the one hand, low-carbon low carbon steel wire plastic, wire drawing easier, on
the other hand can reduce the CO content of reducing gas to reduce splashing or pores, and higher weld metal solidification temperature, beneficial to the
overhead position welding. Adding other alloying elements mainly to ensure the weld mechanical properties, while the welding process performance and to
remove impurities, also have a role.
High alloy steel and aluminum, copper, iron and other metal materials, the core component of its welding and the welded metal in addition to
requirements similar to, but also have control of impurities, according to process requirements often by adding certain alloying elements.
Electrode is coated with a medicine for skin use welding arc melting electrode, which is welded by the drug skin and core composed of two parts. Drugs
in front of the skin with electrodes of about 45 ° chamfer, which is to facilitate the arc. In the rear there is a bare-core welding, electrode length about 1 /
16, easy to maintain and facilitate the welding clamp conductive. Electrode diameter of core Chung actually refers to the weld diameter) is usually 2,2. 5,3 2 or
4, 5 or 6mm and other types of specifications, used a small 3.2, small 4, 5 three small species, its length "L" is generally between 250 ^ -450 mm.
1 welding core
Medicine bag was covered electrode the metal core is called core welding. Welding cell is generally a certain length and diameter of the wire. Welding,
welding core has two effects: first, conduction welding current, arc to convert electrical energy into heat energy, and second, the core itself is melted as
welding filler metal and base metal fused to form the liquid weld.
Electrode welding, weld metal core part of the total weld metal. Therefore, the {welding core chemical composition directly affect weld quality.
Therefore, as the electrode wires are single-core potential with the unique requirements of its grade and composition. If used for submerged arc welding,
electroslag welding, gas welding, gas welding method for welding filler metal, then known as the wire. (1) in the core welding welding of alloy elements on
the
1) carbon (C) carbon is the main alloying elements in steel, when the carbon content increases, the steel {strength, hardness significantly increased,
while the plasticity decreased. In the welding process, the carbon oxygen play a role in the arc under high temperature and oxygen compounds, generating
carbon monoxide and carbon dioxide gas, the arc and weld pool ambient air exclusion zone to prevent air oxygen and nitrogen gases adverse impact on the
pool, reducing the weld metal oxygen and nitrogen content. If the carbon content is too high, to restore the role of severe, will cause a larger splash and
pores. Taking into account the carbon steel hardened to the crack and its increased sensitivity to the effects of low-carbon steel welding general carbon
content of the core cluster 0.1%.
2), manganese (Mn) of manganese in steel is a good alloying agent, as the manganese content increases, its strength and toughness will be increased.
In the welding process, the manganese is also a good deoxidizer, can reduce the oxygen content in the weld. Together with the formation of manganese
sulfide in the slag floating manganese sulfide, thereby reducing the weld hot cracking tendency. It is generally the core of carbon structural steel welding
manganese content of 0.30% ~ 0.55%, some special purpose welding wire, the manganese content up to 1.70% a 2.10%.
3) Silicon (Si) alloy of silicon is a good agent in the steel by adding an appropriate amount of silicon can improve steel yield strength, flexibility and acid
resistance; if the content is too high, then reduce the ductility and toughness. In the welding process, the silicon also has good oxygen capacity, and oxygen
to form silicon dioxide, but it will increase the viscosity of slag, easy to promote non-metallic inclusions generated.
4) Chromium (Cr) chromium steel to improve hardness, wear resistance and corrosion resistance. For low carbon steel, the chromium is a kind of
accidental impurities. The main features of Chrome is easy to rapid oxidation of metallurgy, the formation of refractory oxides of chromium oxide (Cr203),
thereby increasing the likelihood of weld metal inclusions. Transition to the chromium oxide slag, the slag viscosity can increase, decrease liquidity.
5) Ni (NO nickel on the toughness of the steel have more significant effects, generally require a higher temperature impact value, the appropriate
incorporation of some of the nickel.
6) Sulfur (S) S is a harmful impurity, with the sulfur content increases, will increase the tendency of hot cracking of weld, thus welding the core sulfur
content of no greater than 0.04%. Important in the soldering structure, the sulfur content of no greater than 0.03%.
7) P
(2) the classification of welding core
Welding core is based on national standards, "welding wire" (GB 1300-77) classification requirements for welding steel wire can be divided into carbon
steel, alloy steel, stainless steel categories.
2 drug skin
Pressure applied to the welding cell surface coating as drug skin. The drug electrode welding process in the skin plays an extremely important role. The
use of a drug-free light skin electrode welding, the welding process, the oxygen and nitrogen in the air will be a substantial intrusion of molten metal, the
metal iron and beneficial elements carbon, silicon, manganese oxide and nitride formation of various oxides and nitride, and left in the weld, causing the weld
slag or cracks. And melt into the molten pool in gas welding may produce a large number of pores, these factors can make the weld mechanical properties
(strength, impact value, etc.) greatly reduced, while the weld brittle. In addition, the use of optical electrode welding, the arc is very unstable, serious splash,
poor weld.
It found that in practice outside if the electrode coated with a layer of light mineral composed by a variety of drug skin, make the arc combustion
stability, improved weld quality, this is called electrode coated electrodes. With the continuous development of industrial technology, people created a now
widely used high-quality thick coated electrodes.
