S32168 stainless steel is used in the manufacture of petroleum gas combustion pipes, shells, heat exchangers, heating furnace components and other equipment in a very harsh working environment, and domestic and foreign often seen on the S32168 stainless steel stress corrosion fracture reports. In this paper, the application of slow strain rate tensile test method to study the S32168 stainless steel in the chlorine ion environment, temperature and pressure on its stress corrosion effect.
S32168 austenitic stainless steel grade 06Cr18Ni11Ti, chemical composition is shown in Table 1. S32168 austenitic stainless steel material is processed into NACE standard test sheep. The specimen surface with sandpaper sanding to replace the smooth after the specimen in turn into the ethanol and acetone solution for ultrasonic cleaning and then rinse with deionized water and blow-dry, remove the specimen surface oil and debris.
S32168 chemical composition
The test solution was NACE standard solution. Specimen clamped in the kettle located in the fixture in the kettle to add NACE standard solution in the kettle after tightening the upper end cap and sealing to open the exhaust valve into the N, discharging the kettle air, close the exhaust valve to increase the pressure in the kettle when the pressure reaches a predetermined value to stop the ventilation at the same time to close the air inlet valve. The temperature required for the test was controlled by a heating jacket set outside the kettle. The tensile rate of the test was set at 1.9×10-6 s . The combinations of temperature and pressure in the corrosive environments for the five sets of tests were determined based on the highest operating parameters of the equipment made by S32168 as reported in the current literature, and the fractured specimens were compared with the air-drawn specimens. The test environments for each specimen are shown in Table 2.
The stress corrosion properties of S32168 austenitic stainless steel in different environments are shown in Table 3.
In the test condition, S32168 austenitic stainless steel does not have stress corrosion sensitivity in air, and has stress corrosion sensitivity in NACE solution. In the test conditions, S32168 austenitic stainless steel in NACE solution with the increase in ambient temperature and pressure, the specimen stress corrosion characteristics more and more obvious, when in the 260 ℃, 11MPa environment when the stress corrosion susceptibility index reaches its maximum value, at this time, the specimen's stress corrosion resistance is the worst. In the test conditions, the same temperature, the higher the pressure, the higher the stress corrosion sensitivity of S32168 austenitic stainless steel