Influence of processing parameters and sintering atmosphere on the mechanical properties and microstructure of porous 316L stainless steel for possible hard-tissue applications

The 316L stainless steel has been widely used in both artificial knee and hip joints in biomedical applications. The average lifetime of artificial hip joints is about 10 years due to aseptic loosening of the femoral stem attributed to polymeric wear debris; however, there is a steadily increasing demand from younger osteoarthritis patients aged between 15 and 40 years for a longer lasting joint of 25 years or more. This paper studies the properties changes of powder metallurgy 316L stainless steel, depending on the compacting pressure, sintering temperature, and the sintering atmosphere. All samples have been compacted at 150, 250, and 350 MPa, and sintered at 1200, 1250, and 1300 C. In order to analyze the sintering atmosphere, three different media were used: nitrogen, pure argon, and vacuum. The properties of the materials are evaluated. The study covered sintering density, compressive strength, hardness, wear resistance and microstructure analysis. The results show that the porous 316L stainless steel can be used as hard tissue implant.