Depending on the circumstances, welding, there are three classifications: Classification by use of welding, according to the main chemical ingredient drug classification of skin, the skin melted slag by drug classification features.
According to the use of welding, welding can be divided into: structural steel welding rod, heat-resistant steel electrode, stainless steel welding rod, Welding Electrodes, low temperature steel electrodes, cast iron welding rod, nickel and nickel alloy electrodes, copper and copper alloy rod, aluminum and aluminum alloys and special purpose welding rod.
If the drug under the skin of the main electrode to classify the chemical composition, welding can be divided into: titania type electrode, titanium calcium type electrode, ilmenite-type electrode, iron oxide-based electrodes, cellulose type electrode, low hydrogen type electrode ,
Type of base electrode and graphite electrode.
If the drug under the skin electrode melting, slag characteristics to classify, welding can be divided into acidic and basic welding electrodes. Acidic drug electrode main component of skin acidic oxides such as silica, titanium dioxide, iron oxide and so on. Basic electrode for the main component of skin medicine alkaline oxides, such as marble, fluorite.
Compile brazed joints within the common defects and their causes are as follows: today 1 interstitial bad, part of the gap is not filled Reason: (L) unreasonable joint design, assembly gap is too large or too small, crooked quarter ramp assembly parts. (2) flux is inappropriate, such as the activity difference, flux and solder melting temperature difference is too large, Yee agent caulking and poor; or gas purity and low gas brazing, vacuum brazing vacuum is low. (3) improper selection of solder, such as poor solder wetting, solder fluxes inadequate. Mongolia (4) improper placement of solder. (5), poor preparation before brazing, such as not washing the net and so on. Set (6) soldering temperature is too low or unevenly distributed. 2. Brazing seam vents causes: (1) joint gap inappropriate choice. (2) parts clean before brazing without a net. (3) flux to the membrane or protective role of oxide gas to the role of the weak. (4) solder in the soldering or brazing at precipitated gas overheating. 3. Brazing seam slag Reason: (1) flux use too much or too little. (2) joint gap inappropriate choice. (3) solder joints on both sides from the caulk. (4) solder and flux melting temperature does not match. (5) flux ratio is too large. (6) uneven heating. 4 solder joints cracking Reason: 1> Because heterogeneous parent material of different coefficient of thermal expansion and cooling process of the formation of excessive stress. (2) of the same material brazing uneven heating, resulting in contraction of the cooling process is inconsistent. (3) solder solidification, the part of mutual dislocation. (4) solder the crystallization temperature interval is too large. (4) solder the crystallization temperature interval is too large. (5) brittle solder joints too. 5. Brazing loss Reason: <1) brazing temperature or holding time is too long. (2) improper placement of solder from the capillary action is not so. (3) The local gap is too large. 6 base metal is dissolved Reason: (1) The brazing temperature, holding time is too long. (2) base metal and filler metal between the role is too dramatic. (3) excessive solder. Brazed defect inspection method Brazed flawed testing methods can be divided into non-destructive testing and destructive testing. 1. Visual inspection . Visual inspection is the disorder with the naked eye or low magnification magnifying glass to inspect the surface quality of brazed joints, such as whether to fill the gap brazing, brazing seam is exposed at one end to form rounded off is uniform, the surface is smooth, whether there are cracks, holes and other external defects. 2. Surface defect inspection Cooked surface defect inspection and test methods including fluorescence, color testing and magnetic particle inspection. They checked with the appearance of foam and inspection of solder joint surface can not be found in defects such as cracks, holes and so on. Ying sleep test is generally used for small parts inspection, testing a large piece coloring method is used, only used for magnetic particle inspection method Sung-magnetic metal. 3 internal defects inspection Jazz X-ray and using the general, ray, ultrasound and dense test. Hole X-ray and y-ray inspection is an important piece of internal defects commonly used method, which can be displayed solder cracks pores, slag, and did not drill through the brazing seam and base metal cracking, ultrasonic inspection can find the range and ray defects the same test. Exclusion of the structure of compact brazed test methods are commonly used in general water pressure tests, air tightness test Qian, "through the test, kerosene penetration testing and test methods such as mass spectrometry, where the high-pressure hydraulic test Guang containers, leak test and gas permeability test for low container, kerosene penetration test for non-pressure containers Yi; MS test for vacuum sealing joints.