Stainless steel pipe intergranular corrosion test method

The intergranular corrosion test of stainless steel pipe shall comply with the requirements of Method E in GB/T 4334-2008. According to the requirements of the purchaser, the supplier shall negotiate with the supplier and the buyer, and indicate in the contract that the intergranular corrosion test of the nuclear safety 2 and 3 steel pipes may be Use one of the methods specified in A.3 or A.4. The intergranular corrosion test of stainless steel pipe shall comply with the following requirements. The other requirements shall comply with the requirements of GB/T 4334-2008 Method E: when the diameter of the stainless steel pipe is not less than 38 mm, the sample shall be a whole pipe length of 25 mm; the diameter of the steel pipe is greater than 38 mm. At the time, the 75mm arc should be cut on the whole pipe section of 25mm length; the ultra-low carbon (C<0.035%) and the stabilized steel grade, the sensitization treatment of the sample is kept at 675 °C for 1 hour; the corrosion test, the same Three samples can be tested in the vessel and the ratio of surface area to solution is maintained at least 8 mL / 20 cubic centimeters. The distance between the two plates of the flattening test of the whole pipe section shall comply with the standards.

The intergranular corrosion test of stainless steel pipe should meet the following requirements. The other requirements should meet the requirements of GB/T 4334-2008 Method E: When the diameter of stainless steel pipe is not more than 30mm, the sample should be a whole pipe length of 30mm. When the diameter of the steel pipe is greater than 30mm, the specimen shall be a longitudinal specimen with a width of 10mm; when the wall thickness is not greater than 4mm, the thickness of the specimen shall be the original wall thickness, and when the wall thickness is greater than 4mm, the surface to be inspected shall be retained, from the other The surface is machined to a thickness of 4 mm. Ultra-low carbon (C<0.035%) steel with no molybdenum and steel grade stabilized with titanium ruthenium, the sensitization temperature of the sample is 700 °C; ultra-low carbon (C<0.035%) steel with molybdenum, The sensitization temperature of the sample was 725 °C. The heating time is not more than 5 min, the temperature is kept for 30 min, and the furnace is slowly cooled to 500 ° C at a rate of 60 ° C (± 5 ° C) per hour, and then cooled in the air. For other steel grades, the sensitization temperature of the sample was 650 ° C, held for 10 minutes and then immersed in human water for cooling.

Solution formula for corrosion test of stainless steel tube: 10% sulfuric acid + 10% crystalline copper sulfate + 80% distilled water; each sample is completely immersed in a separate flask containing copper scrap and not less than 250 mL of solvent, boiling corrosion 24 hour. After the corrosion test, the sample is slowly bent 90° around the mandrel, and the diameter of the mandrel is not more than twice the thickness of the sample before the corrosion test; the whole pipe section is subjected to the flattening test, and the crushing pitch is equal to 4 times the thickness of the pipe wall.