The addition of chromium improves the corrosion resistance of nickel in oxidizing media, including oxidizing acids (HNO3,H2CrO4,H3PO4), oxidizing acid salts, and oxidizing alkaline salts. When the alloy contains more than 10% chromium, the corrosion resistance and oxidation resistance of the nickel-chromium alloy are significantly improved. In different environments, the critical chromium content for improving the corrosion resistance of nickel-chromium alloys is different. To achieve different corrosion resistance targets, a series of nickel-chromium corrosion-resistant alloys have been formed. It can be seen from the binary phase diagram of Fig. 0-1 (Fig. 6-1) that if the alloy of 1^-0 is kept as a single austenite structure, the chromium content in the alloy can be up to 47%0 when cut (0) At 47%, the alloy will have a 7 + ^ dual phase structure. The highest chromium content of corrosion-resistant alloys currently used in industry (00% is 50%, and the high chromium content is no longer in the category of nickel-based alloys. In order to reduce or inhibit the precipitation of chromium-rich carbides and improve the strength and resistance of alloys. Abrasive and oxidation resistance, some alloys contain different amounts of elements such as AL, Ti, Nb, etc. Under the premise of not changing the basic corrosion resistance of the alloy, in order to reduce the cost, some grades have a mass fraction of 3%~20. %. The grades and chemical compositions of commonly used corrosion resistant alloys are shown in Table 6-1.
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Post time: Aug-11-2018