Status of nickel free stainless steel in biomedical field: A review of last 10 years and what else can be done

A new smelting method to synthesize high-nitrogen nickel-free austenitic stainless steel was suggested. The synthesized steel completely consists of austenite and represents more brilliant anti-corrosion ability both in salt solution and sulfuric acid solution. The brilliant anti-corrosion ability is retained even after severe cold-rolling deformation, which ensures its workability in practice. The potentiodynamic polarization curves, electrochemical impedance spectroscopy, and passivating treatment were used to characterize its corrosion properties and uncover its corrosion mechanism in salt solution. X-ray photoelectron spectroscopy was used to clarify the mechanism of passivation. The results demonstrate that the steel has a more uniform and thicker passive film than traditional stainless steel due to the cooperation of nitrogen and chromium.

The Synthesis and Electrochemical Behavior of High-Nitrogen Nickel-Free Austenitic Stainless Steel

UNS S32707 hyper-duplex stainless steel processed by powder injection molding and supersolidus liquid-phase sintering in nitrogen sintering atmosphere

A high-nitrogen, low-nickel powder metallurgy austenitic stainless steel was studied and compared with a conventional powder metallurgy austenitic stainless steel. Three different sintering processes were applied by controlling the sinter-cooling rate (furnace, gas, and water). Nitrogen was chosen as the sintering atmosphere. A microstructural study was performed and the corrosion behavior was evaluated in terms of anodic polarization measurements and an electrochemical potentiokinetic reactivation test. It was found that the water-cooling process is advisable for good corrosion behavior. The results were correlated with the microstructural features.

Influence of Sinter-Cooling Rate on the Corrosion Behavior of High-Nitrogen, Low-Nickel Powder Metallurgy Austenitic Stainless Steel

This chapter reviews the topic of stainless steels manufactured with MIM technology The following questions are considered What is a stainless steel? What is the place of stainless steels in the MIM world? What are the special characteristics of the different steps of MIM technology (kinds of powders used, feedstocks, debinding methods, sintering problems and new technologies)? The chapter finishes with a description of some applications

Metal injection molding (MIM) of stainless steel

The effects of various sintering parameters (temperature, time and nitrogen pressure) on the density, nitrogen content and the mechanical properties of high nitrogen nickel free austenitic stainless steel (0Cr–17Mn–11Mo–3N) prepared by powder injection moulding were investigated, and the influence of solution annealing on the microstructure and mechanical properties was also discussed. The results show that the optimal sintering conditions are as follows: sintering temperature 1300°C, sintering time 2 h and nitrogen pressure 0·1 MPa, under which a favourable combination of the relative density of 99·1% and the nitrogen content of 0·78 wt-% can be obtained. After solution annealing at 1150°C for 90 min, the yield strength and ultimate tensile strength can reach 580 and 885 MPa respectively, which are about 2·9 and 1·7 times greater than those of 316L Metal Injection Molding (MIM) stainless steel. Before solution annealing, the sintered specimens mainly consist of γ-austenite, α-ferrite and network ...

P. Guo

Papers

Sintering optimisation and solution annealing of high nitrogen nickel free austenitic stainless steels prepared by PIM