Intergranular corrosion test in Shandong
Tianjin Rong Da Testing Co., Ltd. contact: Wang Jingfu
Cell phone: 13102238283 QQ:3144667033
Telephone: 022-23892103
Metal corrosion test method is designed to test the susceptibility of metallic materials to intergranular corrosion under specific medium. The purpose is to know whether the chemical composition, heat treatment and machining process are reasonable. The principle is to adopt the corrosion potential of metals in the constant test solution potential polarization curve of a specific interval, the use of metal grains and grain boundaries of intergranular corrosion accelerated display significant differences in the potential range of corrosion current. Standard Test methods for intergranular corrosion of stainless steel and aluminum alloys have been standardized in many countries. Each standard has detailed provisions on the details of the test.
Common intergranular corrosion method:
(1) sulfuric acid - sulfuric acid - Copper - copper chip method. The intergranular corrosion resistance of almost all types of stainless steel and some nickel based alloys due to carbon and nitride precipitation was tested. The corrosion potential of austenitic stainless steel in this solution is in the activation passivation region. The test results by bending specimen crack or magnification metallographic evaluation under microscope. This method has a slight corrosion, the test conditions are stable, but the determination of the crack need to have experience.
(2) nitric acid method. The intergranular corrosion resistance of stainless steel and nickel based alloys can be tested due to carbide, O phase separation or solute segregation. The corrosion potential of austenitic stainless steel in this solution is in the passivation passivation zone. The corrosion rate was evaluated by the test results. The test period is long.
(3) nitric acid hydrofluoric acid method. Apply to the inspection of austenitic stainless steel containing molybdenum due to carbide precipitation caused by the corrosion of the crystal. The corrosion potential of austenitic stainless steel in this solution is in the activation passivation region. The test cycle is short, but the overall corrosion is serious. The test results shall be evaluated by the ratio of the corrosion rate of the homogeneous material to the solid solution and the solid solution.
(4) ferric sulfate. Apply to the inspection of nickel based alloy, stainless steel due to carbide precipitation caused by intergranular corrosion. The corrosion potential of austenitic stainless steel in this solution is in the passivation region. The test results are compared with the corrosion rate and the corrosion rate of solid solution samples.
(5) the oxalic acid etching method. Screening test for testing the intergranular corrosion of austenitic stainless steel. The corrosion potential in the passivation region during electrolytic etching. After etching with metallographic etching tissue classification evaluation of microscope