1, the welding process, welding area is full of a lot of gas. Acid electrode welding gas composition is CO, H2, H2O; alkaline electrode welding, gas composition of CO, CO2; submerged arc welding, gas composition of CO, H2. Gas welding region mainly from the following aspects: First, in order to protect the welding area from the intrusion of air artificially add a layer of shielding gas in welding area, such as drug skin in the gas-making agent (starch, wood flour, marble etc.) the heat generated by the decomposition of gas, air, gas shielded arc welding, shielding gas (CO2 gas, Ar gas), etc.; followed by wet electrodes or flux welding, the precipitation of gas to protect the lax invasive wire and impurities on the surface of the base metal (greasy dirt, rust, paint, etc.) heated gases, and the gases produced by the evaporation of the metal and slag high temperature. 2, nitrogen, hydrogen and oxygen on weld metal and the impact â‘´ the nitrogen from the welding area around the air. Manual arc welding, deposited metal contains about 0.025% nitrogen. Nitrogen is to improve the weld metal strength and reduce the elements of the ductility and toughness, but also one of the main pores in the weld. (2) hydrogen hydrogen from the electrode drug skin, organic flux in the water, drug skin, dirt on the weldment and the wire surface (rust, oil) and air moisture. Various welding methods to weld the increase of hydrogen, but the increase of hydrogen in varying degrees: manual arc welding with cellulose drug coated electrode welding the weld hydrogen content than the base metal is 70 times higher; only low hydrogen Types Of Welding Wire, the weld hydrogen content is relatively low; CO2 gas shielded arc welding, the lowest hydrogen content. Hydrogen weld metal plastic serious decline, prompting the pores and delay crack in welded joints and also in the formation of white spots in the cross section of tensile specimens. (3) oxygen oxygen from the air, medicine, leather, and the flux in the oxide, water and welding materials, the surface oxide. With the increase of oxygen content in the weld is its strength, hardness and plasticity will be decreased and can cause the metal hot crisp, cold, crisp and age-hardening, and is the main reason for the formation of stomata (CO pores) in the weld a. In short, enter the weld metal nitrogen, hydrogen, oxygen are all harmful elements. 3, the welding area to protect methods of welding The purpose of protection of the weld zone to prevent air intrusion droplet and weld pool to reduce the nitrogen and oxygen content in the weld metal. Protection of the following three kinds: (1) gas shielded for example, Gas Shielded Welding Wire using shielding gas (CO2, H2, Ar) welding zone with air isolation. (2) residue to protect the surface of molten pool of metal covered with a layer of slag it with air to separate isolation, such as electroslag welding, submerged arc welding. â‘¶ gas - slag joint protection to protect the use of shielding gas and slag on the molten metal, such as manual arc welding. 4, reducing the oxygen content of the weld metal in the welding area to protect and prevent air and molten metal contact is an important measure to control the oxygen content of the weld metal, but can not fundamentally solve the problem, because oxygen can also be many other channels into the weld, to completely block these channels is virtually impossible, so it can only take measures, has entered the melting metal in oxygen deoxidation processing. 5, the deoxidation of the weld metal, the use of slag or weld core (wire) metal and molten metal interactions deoxidation is commonly used in weld metal deoxidation way. (1) diffusion deoxidation When the temperature decreases, the original melting FeO in the molten pool will continue to slag diffusion, so that the oxygen content decreased in the weld, this deoxidation method called diffusion deoxidation.
D502 valve surfacing electrode meets GBEDCr-A1-03: D502 1Cr13 valve surfacing electrode is titanium calcium type, AC and DC welding process. The surfacing metal 1Cr13 semi-iron D502 valve surfacing electrode meets GBEDCr-A1-03 Description: D502 1Cr13 valve surfacing electrode is titanium calcium type AC and DC Welding Wires process. The Surfacing metal 1Cr13 semi-ferritic high-chromium steel. Surfacing layer with air quenching characteristics are not generally required to heat treatment, uniform hardness, can also be softened by annealing at 750-800 â„ƒ, when heated to 900-1000 â„ƒ air cooling or oil quenching can be re-hardening.
Uses: This is a common surfacing welding rod, used for surfacing work temperature below 450 â„ƒ carbon steel or alloy steel shaft and valves, etc..
D507 valve surfacing electrode line with GBEDCr-A1-15
Description: D507 1Cr13 valve surfacing electrode low hydrogen sodium type DCRP. The Surfacing metal 1Cr13 semi-ferritic high-chromium steel. Surfacing layer with air quenching characteristics are not generally required to heat treatment, uniform hardness, can also be softened by annealing at 750-800 â„ƒ, when heated to 900-1000 â„ƒ air cooling or oil quenching can be re-hardening.
Uses: This is a common surfacing Welding Rod , used for surfacing work temperature below 450 â„ƒ carbon steel or alloy steel shaft and valves, etc..
Description: D507Mo low hydrogen sodium type of 1Cr13 valve surfacing electrode. The Surfacing metal 1Cr13 semi-ferritic high-chromium steel. Surfacing layer with air quenching characteristics, the the surfacing metal has high-temperature hardness, good thermal stability, erosion resistance. D577 electrode can be obtained with the use of a good anti-abrasion performance. Surfacing process is simple, without preheating before welding without heat treatment after welding using DCRP.
Uses: used for surfacing work temperature below 510 â„ƒ temperature and high pressure shut-off valve sealing surface. Gate valve sealing surface of the electrode with the D577 electrode should be used in conjunction with (valve seat and disc with the above two electrodes). D507MoNb valve surfacing electrode meets GBEDCr-A1-15,
Description: 1Cr13 valve surfacing electrode of the D507MoNb low hydrogen sodium type DCRP drug skin added the right amount of Mo, Nb strengthen the stabilizing element, so the the surfacing metal has better antioxidant activity and crack resistance.
Purposes: for the working temperature below 450 â„ƒ, the low pressure valve sealing surface surfacing.
D512 valve surfacing electrode meets GBEDCr-B-03
Description: D512 2Cr13 valve surfacing electrode is titanium calcium type, AC and DC welding process. The Surfacing metal 2Cr13 martensitic high chromium steel. Surfacing layer with air quenching properties, generally without heat treatment, uniform hardness can be softened by annealing at 750-800 â„ƒ, when heated to 950-1000 â„ƒ air cooling or oil quenching hardening.
Uses: D512 is a generic surfacing electrode the surfacing layer than D502 harder, more wear-resistant and more difficult to process for surfacing carbon or low alloy steel shaft, superheated steam valve parts, mixer paddle, screw conveyor blades.
Description: D516MA high chromium-manganese steel welding electrodes, low hydrogen potassium type coating deposited metal has good abrasion resistance, heat resistance, corrosion resistance, and thermal cracking performance welding process is simple, without preheating before welding, without heat treatment after welding, surfacing layer can be cutting.