E-mail: sxthsteel@sxth-group.com   Tel: +86-29-89636557
Home > Knowledge > Content

Product Categories

Contact Information

  • Shaanxi Tonghui Steel Co., Ltd.

  • E-mail: sxthsteel@sxth-group.com

  • Tel: +86-29-89636557

  • Add: 1st Building Of Jinqiao International, Xi'an, Shaanxi,China

  • What is the intergranular corrosion of austenitic stainless steel?(1)
    Aug 03, 2018

    Since the adoption of austenitic stainless steel in industrial circles in the 20s of last century, it was found that after the welding of this kind of steel, intergranular corrosion was produced in the heat affected zone at temperature of 450 to 800 C in many media. These mediums are mainly nitric acid containing 50% ~ 65% of heat, sulfuric acid containing copper and ferric oxide, and thermal organic acids. It was found that this kind of steel works at 450 ~ 800 C, or at the temperature of aging (or heat preservation or slow cooling), the same effect will be obtained because of welding heating. This aging treatment will lead to the sensitivity of intergranular corrosion of stainless steel, so it is also called sensitization treatment. The temperature range which is easy to cause intergranular corrosion is 450 to 800 degrees, which is called sensitized temperature.

    Recent studies have shown that this corrosion form exists not only in chromium steel and Chromium-Nickel steel, but also in nickel, copper and aluminum-based alloys. The cause of intergranular corrosion is the chemical composition inhomogeneity in grain boundaries and crystals.

    In stainless steel and nickel based alloys, the mechanism of intergranular corrosion can be divided into three basic types: one is that corrosion and the corrosion resistant elements in the medium are associated with the dilution of the grain boundary region; the two is that corrosion is related to the chemical stability of the precipitates along the grain boundary, and the three is the surface active elements that reduce the corrosion resistance of the substrate along the grain boundary. It is caused by segregation.

    (to be contunued...)

    Please Click to learn more.