Effect of Aging Temperature on the Microstructure, Local Mechanical Properties, and Wear Behavior of a UNS S32750 Super Duplex Stainless Steel

In this paper, the effect of aging temperature on the microstructure, local mechanical properties and wear behavior of a UNS S32750 super duplex stainless steel is investigated. A massive preferential precipitation of σ phase and Cr2N is detected at the periphery of ferrite with an increase in their extent as aging temperature increases. Simultaneously, the δ phase decomposition is accentuated with temperature and reaches its maximum at 850 °C. This behavior results in an enhancement in hardness and Young’s modulus accompanied by a higher plasticity ratio. The wear resistance of the aged samples is investigated in terms of friction coefficients and wear rates against two counterparts. The wear performance follows σ phase presence, the higher σ phase extent, the higher the wear resistance. It is found that the change in wear mechanisms in the 850 °C aged samples from abrasive against AISI-304L counterpart to adhesive-oxidative against Al2O3 counterpart is responsible in the increase in wear resistance.