Friction Stir Processing of Stainless Steel for Ascertaining Its Superlative Performance in Bioimplant Applications

Area of Science:

• Biomaterials Science
• Materials Engineering
• Surface Science

Background:

• Bioimplant performance and longevity depend critically on surface properties, as degradation via wear and corrosion leads to metallosis.
• Surface engineering offers a pathway to enhance implant durability and reduce revision surgery rates.

Purpose of the Study:

• To investigate the effects of submerged friction stir processing (FSP) on the surface characteristics and performance of stainless steel for bioimplants.
• To evaluate the microstructural, mechanical, tribocorrosion, and biological properties of FSP-modified stainless steel.

Main Methods:

• Stainless steel was processed using submerged friction stir processing (FSP), a severe plastic deformation technique.
• Microstructural analysis, hardness testing, wear and corrosion evaluations in simulated body fluid, and in vitro biocompatibility assays (MTT, hemolysis, fibrinogen adsorption, platelet adhesion) were performed.

Main Results:

• FSP refined the grain size from 22 μm to 0.8 μm, increasing hardness by 1.5 times.
• The processed sample exhibited significantly improved wear and corrosion resistance due to surface strengthening and a stable passive layer.
• Enhanced cell attachment and proliferation with minimal toxicity and hemolysis were observed, alongside reduced platelet and fibrinogen adhesion, indicating improved thromboresistance.

Conclusions:

• Friction stir processing is a versatile technique for tailoring stainless steel surfaces to enhance bioimplant performance and reliability.
• The improved properties suggest FSP-treated implants may offer greater longevity and reduced complications in vivo.
• This surface modification strategy holds promise for developing next-generation bioimplants with superior biocompatibility and durability.