The heat generation device of the electric heating mesh belt furnace usually adopts a radiant tube, which is composed of a metal outer tube and a built-in squirrel-cage heating element. Depending on the operating temperature, the material used in the radiant tube is also different. The metal outer tube material of the quenching furnace radiant tube is SUS310S, and the maximum service temperature can reach 1 200 ℃;AUTOMATIC FEED DRILLING MACHINE the metal outer tube material of the tempering furnace radiant tube is SUS304, and the maximum service temperature can reach 800 ℃. The heating element with built-in squirrel-cage structure is composed of metal electric heating elements and corundum insulating ceramic sheets. The metal heating element is a resistance wire, and its commonly used materials are nickel-chromium alloy wire and iron-chromium-aluminum alloy wire.BENCH STRONG DRILLING MACHINE After the nickel-chromium alloy wire is heated in the air, a layer of hard Cr, 03 protective film is formed on the surface and adheres to the alloy substrate. The melting point is higher than that of the alloy substrate. It can withstand alternating heating and cooling and has strong corrosion resistance. Good mechanical properties at high temperature, easy to process and weld at room temperature, high resistivity, small temperature coefficient of resistance, and stable power. Cr20Ni80 alloy wire is commonly used in quenching furnaces, which contains more nickel, and its price is higher than that of iron-chromium-aluminum alloy wire.Application of Pressureless Sintering of Silicon Carbide Ceramics The melting point of iron-chromium-aluminum alloy wire is higher than that of nickel-chromium alloy wire, and a layer of hard Al,03 protective film is formed on the surface after heating in air, and its melting point is higher than that of the alloy body. Iron-chromium-aluminum alloy wire has high resistivity and small temperature coefficient of resistance, but it is brittle, has poor processability, low strength at high temperature, and easily deforms and collapses components. Therefore, it is often used in tempering furnaces, and OCr25Al5 alloy wire is commonly used.Analysis of carbon content on the surface of carburized parts