Surface remelting of 316 L + 434 L sintered steel: microstructure and corrosion resistance

Abstract

This study presents arc surface remelting of three types of sintered stainless steels carried out in order to constitute a homogeneous microstructure in the surface layer which is free from open and interconnected porosity. The main aim of this treatment was to improve functional properties of the sinters analysed, especially their resistance to pitting corrosion. The sinters were obtained from powders of 316 L and 434 L steels. The PM austenitic-ferritic stainless steels are used mainly in the automotive industry, but their general application is still limited due to relatively poor corrosion properties when compared to casts or wrought components. This study used the gas tungsten arc welding (GTAW) process as a method of economical surface treatment. The effect of surface treatment was evaluated based on macro-and microstructural observations, energy-dispersive X-ray spectroscopy (EDX) analysis, X-ray phase analysis, measurements of surface roughness and electrochemical examinations. It was found that a cellular or mixed cellular and dendritic structure was formed in the remelted zone of the sinters after remelting. X-ray analysis demonstrated that application of remelting contributes to formation of the austenitic phase in the surface layer. The corrosion resistance of the remelted surface layers was evaluated using polarization tests in 0.5 M NaCl solution. It was found that arc surface remelted layers exhibit much better anticorrosive properties than sinters without surface treatment. Microstructural observations of the surface of specimens after electrochemical tests showed only a few single pits in the remelted layer, while the surface of initial sinters was much more corroded.

Influence of patient position and implant material on the stress distribution in an artificial intervertebral disc of the lumbar vertebrae

“…However, in order to optimise the proposed design, it is crucial to perform further simulations using different materials like porous titanium and titanium-nickel (shape memory) alloys or implants with modified surface properties [1,3,[9][10][11]13].…”

“…In such cases, one of the first stages of treatment is to design an artificial intervertebral disc. However, various biomaterials are available that could be considered for implant applications [1,3,[9][10][11][12][13], and FEM simulations are helpful in proper material selection.…”

The effect of alloying method on the structure and properties of sintered stainless steel

“…Selection of an alloy for a specific application depends on a number of factors, with the most important criterion usually being corrosion resistance. Furthermore, other criteria that are taken into account during alloy selection are mechanical properties, thermal and magnetic properties, resistance to oxidation and creep, and costs [1,6].Nowadays, a very interesting and promising material is sintered duplex stainless steels (SDSSs). They are characterized by a two-phase structure consisting of approximately equal content of ferrite and austenite [7][8].…”

Corrosion Rate of the X2CrNiMoN22-5-3 Duplex Stainless Steel Annealed at 500 cc

“…Main grades of these steels are ferritic, austenitic and martensitic steels microstructure. High chromium and molybdenum contents provide excellent resistance to pitting and crevice corrosion [1][2][3][4][5]. They are used in a wide range of industrial applications, but their properties are continuously studied to improve the quality of properties [6][7][8][9].…”