1, the welding system The welding system consists of welding power source and welding torch, TIG welding machine, CO2 welding, MIG / MAG welder, plasma welder, submerged arc welding machine. Of course, there are in the form of resistance welding, flame welding, laser welding, electron beam welding and other welding, due to limited space, we only describe the most commonly used in front of several welding power source. The foregoing several welding power source, argon arc welding machine and welding machine can weld metal, the fusion of the two workpieces are welded together, can also be added automatically to fill the wire feeder, to complete the welding of thick workpiece. CO2/MIG/MAG welding and submerged arc welding machine has its own wire feeding system, to send the wire through the end of the torch center. The welding parameters are adjusted by the control knob on the welder. 2, the mechanical system Mechanical systems, mainly by the bed institution, fixture and workpiece auxiliary support agencies, the gun fine-tuning institutions, welding workpiece or Welding Cable moving mechanism. Such as the right icon for the tube sheet automatic welding machine. Tube sheet automatic welding machine Due to the different types of welding workpiece shape, size, weld location, and so on, different design ideas for each design, so the Welding Rod style also varied, with the right equipment, we explain in detail to constitute ideas.
Flux Core Welding Wire for gas shielded welding gas protection factors need to be considered of welding cost, welders preferences, and weld quality
Flux-cored gas shielded welding (referred to as FCAW-G) is a widely used welding process, as shown in Figure 1. It is widely used in heavy manufacturing, construction, shipbuilding, offshore installations and other industries, low carbon steel, low alloy steel welding and a variety of other alloy materials. FCAW-G welding process is often used to 100% pure CO2 or 75% to 80% Ar and 20% to 25% CO2 mixed gas as protective gas.
Implementation of theWelding Fluxshielded arc, what the select what kind of protective gas, CO2 or Ar/CO2 mixed gas? Each type of shielding gas has its own advantages and disadvantages. Choose when welding gases, cost, quality, productivity and other factors are important considerations. Sometimes the choice of protective gas, and these factors are in contradiction. This article discusses the advantages and disadvantages of FCAW-G shielding gas in welding steel of two basic choice.
Select the pros and cons of protective gas is discussed in detail, it is best to review some basic knowledge. It should be noted that this article just discuss a few protective gas. More comprehensive introduction, please refer to ANSI/AWSA5.32 / A5.32M, shielding gases for welding specification specifies the protection gas technical requirements, including testing, packaging, identification, acceptance. In addition, it also includes some useful information in the welding process ventilated, take full account of the security requirements.
Protective gas works
A main role of the protective gas is isolated from the air, oxygen, nitrogen and water vapor, and to protect the weld pool and the electrode. Protective gas through the torch enters ejected from the tip, to displace the air around the electrode surrounded by the periphery of the electrode, to form a temporary protective hood, in the bath and around the arc. CO2 gas and Ar/CO2 mixture can achieve this goal.
These protective gas to promote the formation of arc plasma area, arc plasma area is the current path of the welding arc. The type of protective gas also affects the the arc heat conduction as well as the size of the arc force is applied to the bath. CO2 and Ar/CO2 mixed gas is not the same performance on these issues.
The protection of the characteristics of gas
CO2 and Ar arc enthusiastic reactions vary. The analysis of these differences can help to understand the characteristics of each gas is how it affects the welding process and weld deposit.
The ionization potential. The ionization potential is the size of the energy required for gas ionization (For instance, the gas is converted into a state of charged ions), so that gas can be conductive. The ionization potential is lower, the arc is more easily ignited and remain stable. The ionization potential of CO2 as 14.4eV the Ar ionization potentials 15.7eV. Therefore, CO2 shielding gas than Ar shielding gas is more likely to ignite the arc.
Thermal conduction. The thermal conductivity of the gas means the size of the gas conduction heat capacity, it is good or bad will affect droplet transfer mode (such as jet transition and large drops of transition), the arc shape, the weld penetration and the arc temperature distribution. CO2 gas having a higher thermal conductivity than the mixed gas of Ar and Ar/CO2.
Reactivity. The reaction gas is a gas whether a chemical reaction with the molten weld puddle. The gas can be roughly divided into two categories: an inert gas and reactive gas. Inert gases, and other elements in the weld puddle does not react. AR belonging to the inert gas. The reactive gas, in the molten weld pool will be in combination with other elements or reaction, to form new compounds. At room temperature, CO2 is an inert gas, but in the arc plasma, CO2 will be decomposed to form carbon monoxide (CO), oxygen (O2) and some independent of the oxygen atoms (O). Thus, CO2 in the arc into a reactive gas, the oxidation can occur with other metals. Ar/CO2 mixed gas also belong to the reactive gas, but to be lower than the activity of the CO2.