Abstract
Mechanical properties of a REX734 austenitic stainless steel were examined through compression testing over a wide range of temperatures (1173 K to 1373 K (900 °C to 1100 °C)) and strain rates (0.1 to 40 s−1) that cover deformation conditions encountered in different metalworking processes. The evolution of microstructure was studied using electron microscopy combined with electron backscatter diffraction and energy-dispersive spectroscopy. Partially recrystallized microstructures were obtained after compression testing at 1173 K (900 °C), while after deformation at 1273 K and 1373 K (1000 °C and 1100 °C), the material was fully recrystallized almost in all examined cases. The role of dynamic and metadynamic restoration processes in the formation of final microstructure was investigated. Σ3 twin boundaries lost their twin character and transformed into general high-angle grain boundaries as a result of deformation, while during recrystallization new Σ3 twin boundaries formed. The evolution of precipitates during compression testing and their role in the recrystallization process was also discussed.
Highlights
AUSTENITIC stainless steels are widely used to manufacture orthopedic implants.[1,2] In the early 1980s, REX734 nitrogen- and niobium-bearing stainless steel was introduced for the fabrication of femoral prosthesis for a total hip replacement; this alloy is still one of the most common materials used for the fabrication of femoral stems.[3,4] REX 734 stainless steel for femoral stems is marketed under several brand names by different manufacturers and is standardized by both ISO (5832-9) and ASTM (F1586) standards
Varying the grain orientation spread threshold between 1 and 2 deg had a negligible effect on recrystallized fraction for the as-received material and other samples examined in the present study
Compared to high-temperature mechanical properties reported for a REX734 austenitic stainless steel [1 and 10 sÀ1 at 1173 K, 1273 K, and 1373 K (900 °C, 1000 °C, and 1100 °C)],[11] flow stress values obtained in this study are about 20 pct higher
Summary
AUSTENITIC stainless steels are widely used to manufacture orthopedic implants.[1,2] In the early 1980s, REX734 nitrogen- and niobium-bearing stainless steel was introduced for the fabrication of femoral prosthesis for a total hip replacement; this alloy is still one of the most common materials used for the fabrication of femoral stems.[3,4] REX 734 stainless steel for femoral stems is marketed under several brand names by different manufacturers and is standardized by both ISO (5832-9) and ASTM (F1586) standards. The addition of nitrogen in REX734 stabilizes austenite, improves resistance to crevice and pitting corrosion, as well as strength during both monotonic and cyclic loading. Compared to another austenitic stainless steel grade 316L commonly used in implants, REX 734 provides superior corrosion resistance and mechanical properties.[1,2].
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