① of weld metal mechanical properties and chemical composition For normal structural steel, weld metal and often require the base material of equal strength, tensile strength of weld metal should be used is equal to or slightly higher than the base metal electrode. For alloy steel, sometimes also called the base metal alloy composition and the same or close. In welded structures rigid, high stress joints, weld cracks easily under adverse conditions, consider choosing a low intensity than the base metal electrode. When the base material of carbon, sulfur, phosphorus and other elements at high levels, prone to weld cracking, good crack resistance should be used in basic low-hydrogen electrodes. ② consider the performance of welded components and working conditions with To withstand load and impact load on the weldment, in addition to meet the strength requirements, should primarily ensure that the weld metal has a high impact toughness and plasticity, the choice of plastic, the toughness index higher low hydrogen type electrode. Contact with corrosive media weldment should be based on the nature of media use and corrosion characteristics of stainless steel or other corrosion-resistant type electrode welding. In the heat, cold, wear or other special work under conditions of welded parts, should use the appropriate heat-resistant steel, cold steel, welding, or other special purpose Welding Rods. ③ consider the structural characteristics of welding and stress conditions Complex shape of the structure, rigidity of the Heavy welded, the welding process produces a large internal stress, easy to weld cracks, good crack resistance should be used in basic low hydrogen electrodes. Of discontinuity large, difficult to clean up the welding parts welding parts, should be used for rust, oxide, oil is not sensitive to the acidity of electrodes. Conditions imposed can not turn on the weldment should be used for all position welding electrode. ④ construction conditions and economic considerations Product to meet the performance requirements of the case, should be used in electrode technology and good acidity. In small or poorly ventilated situations, should be used in acidic or low dust welding electrode. The structure of the large amount of welding work, conditions should maximize the use of high efficiency electrodes, such as iron electrodes, welding and other high-efficiency gravity, or use welding vertical down welding of the underlying class-specific electrode, in order to improve welding productivity.
for weld repair and welding of structural steel welding electrodes include, heat-resistant steel electrode, stainless steel welding rod, welding electrodes, cast iron welding rod, nickel and nickel alloys and special purpose welding electrodes and so on.
Welding electrode model is based on national standards, reflecting the main characteristics of a welding rod representation. Electrode models include the following meanings: electrode type, electrode characteristics (such as welding core metal type, temperature, chemical composition of deposited metal or tensile strength, etc.), drug skin type and welding power supply. Models of different types of electrodes, said method is also different.
1, carbon steel electrode model
According to GB/T5117-95 "carbon electrode" standard, carbon steel electrode type according to the mechanical properties of deposited metal, drug skin type, welding position and type of welding current to be divided. The first letter "E" said electrode; first two numbers indicate the minimum tensile strength of deposited metal, in units of kgf / mm ² (1kgf/mm ² = 9.81MPa); the third digit welding position, "0 "and" 1 "applies to all welding positions (ie flat, vertical, overhead, horizontal welding)," 2 "applies to a flat butt and fillet weld," 4 "applies to a downward vertical position welding; third, fourth-digit combinations, said welding current range and type of drug skin. In the fourth digit after the letters have special provisions attached electrode, such as "R" means resistance to moisture absorption electrode; additional "-1" indicates that the impact of special provisions of the electrode performance.
2, low-alloy steel welding rod model
According to GB/T5118-95 "low-alloy steel welding rod" standard, low-alloy steel welding rod model based on the mechanical properties of deposited metal, chemical, drug skin type, location and current of each type of welding. The first letter "E" said electrode, the first two numbers indicate the minimum tensile strength of deposited metal; the third digit welding position, "0" and "1" applies to all welding positions (flat welding, vertical Flux Cored Welding Wire , Yang welding and horizontal welding), "2" applies to a flat butt and fillet weld; third and fourth digit indicates the welding current range and combination skin types of drugs; suffix letter for the chemical composition of deposited metal classification code, and with a dash "-" and in front of numbers separately. If there are additional chemical composition, the additional chemical element symbols directly, and a dash "-" in front of the suffix letters and separated.
3, stainless steel welding rod model
According GB/T983-95 "stainless steel electrode" standard, stainless steel welding rod according to the chemical composition of deposited metal, drug skin type, welding position and welding current of each type of model. The first letter "E" said electrodes, "E" behind the numbers indicate the chemical composition of deposited metal classification code, there are special requirements of the chemical composition of elemental symbols on the figure behind. Dash "-" followed by two numbers indicate the electrode drug skin type, welding position and welding current types. Stainless steel electrode append the suffix models (15,16,17,25,26), said drug skin type and electrode type welding power source, the table below 1 - 1. Suffix 15, said alkaline, level of anti-DC welding; extension 16 that can be alkaline, it can be titanium or titanium calcium type coating, both AC and DC; suffix 17 is a drug and the skin type 16 variant, said titanate type coating (SiO2 instead of drug use in some skin types 16 TiO2), solder melting fast, excellent anti-redness, AC and DC. Suffix 25 and 26 of drug ingredients and operating characteristics of skin and skin type of drug the electrodes 15 and 16 similar drugs skin types 15 and 16 electrodes are also suitable for description of drug skin types 25 and 26.
Stainless steel electrode with the new national standard GB983-85 GB/T983-95 changes compared to the larger. Stainless steel electrode original model (GB983-85) in the first letter "E" said electrode, the carbon content of deposited metal with the "E" behind one or two digits, "00" indicates that the carbon content of not more than 0.04%, "0,1,2,3", respectively, the carbon content of not more than 0.10%, 0.15%, 0.20%, 0.45%. Carbon numbers behind the numbers, respectively, deposited metal Cr, Ni content of the approximate percentage. If the deposited metal alloy that contains other important elements, elements in the model coupled with the note symbols and their average levels.
4, the welding electrode type
According to GB984-85 "Welding Rods" standard, welding electrodes deposited metal type by the chemical composition and the type of drug into the skin. The letters "ED", said welding electrode, the third model in the third to last, said electrode characteristics, chemical element with symbol alphabet or surfacing electrode model classification.