Effect of carbon content on microstructure and properties of 00Cr22Ni5Mo3N duplex stainless steel
In duplex stainless steel, the main elements are Cr, Si, Ni, Mn, Mo, C, rare earth elements, and so on. These alloying elements mainly affect the structure of the dual-phase steel, and then have an effect on the performance of the dual-phase steel. Some of them promote each other, and some restrict each other. Therefore, in each dual-phase steel, the determination of alloying elements and their content can meet reasonable conditions such as corresponding mechanical properties, process properties, and corrosion resistance. In this experiment, the influence of different addition amounts of C on the microstructure, phase comparison, mechanical properties, and corrosion resistance of 00Cr22Ni5Mo3N duplex stainless steel was compared to optimize the best C content in the duplex stainless steel.
It is smelted in an intermediate frequency furnace and poured into plum blossom samples. In the smelting process, decarburization, deoxidation, and desulfurization cannot be carried out, so high-quality raw materials are used. This test uses 00Cr22Ni5Mo3N duplex stainless steel with different C content, the chemical composition is (mass fraction, %): Cr22, Ni5, Mo3, N2.5, Cu0.6, Si0.6, Mn0.9, RE0.2, P≤ 0.040, S≤0.020, C content is 0.012, 0.022, 0.032, 0.042, 0.052, respectively.
Carry out solution treatment on the sample with water cooling at 1070℃×4h. The microstructure was observed and photographed with an OLYMPUSGX71 electron microscope. The tensile test was carried out on the WDW3300 micro-control electronic universal testing machine. The hardness test is carried out on the HB-3000C electronic Brinell hardness tester. The room temperature impact test is carried out on the JBN-300B impact testing machine, and the impact sample is a Charpy V-notch standard sample. Use CS350273A potentiostat for electrochemical corrosion test. The stress corrosion test is carried out in accordance with GB/T17898-1999 “Test Method for Stress Corrosion of Stainless Steel in Boiling Magnesium Chloride Solution”. The sample is processed into a standard stress corrosion sample with a wire cutting machine.
The results show that as C increases from 0.012% to 0.052%, austenite slightly increases, ferrite gradually decreases, yield strength and tensile strength change little, elongation after fracture continues to increase, and the reduction of area is first After increasing, it fluctuates in a small range, the impact absorption energy is significantly reduced, and the hardness gradually decreases. When the C content is 0.012%, the performance required for electrochemical corrosion resistance and stress corrosion fracture resistance is the best. When the C content is 0.012%, 00Cr22Ni5Mo3N duplex stainless steel has the best overall performance.