Mechanical properties and fracture upon static tension of the high-carbon steel with different types of pearlite structure

The hardness and mechanical properties of the U10 steel (1.03 wt % C) with pearlite structures that were formed by isothermal decomposition at temperatures of 650°C (coarse-lamellar pearlite) and 500°C (fine-lamellar pearlite) as well as upon subsequent annealing of fine-lamellar pearlite at a temperature of 650°C for 10–300 min have been studied upon tensile tests. Fractures of the steel with different types of pearlite structure have been examined using scanning electron microscopy. The interrelation between the mechanical properties and the structural features and character of fracture has been analyzed for this steel with pearlite structures differing in the dispersity, morphology, and defect structure of cementite, and in the levels of solid-solution strengthening and microdistortions of the ferrite-constituent lattice.     

Properties of Ti−V and Ti−V−Al alloys with oxygen

Metal Science and Heat Treatment -     

The effect of copper content and heat treatment on the hydrogen embrittlement of 7050-type alloys

The effect of copper content (0.01 and 2.1%) and microstructure on the intrinsic hydrogen embrittlement susceptibility of unl nercially-processed AI---6Zn---2Mg---XCu alloys was investigated. (The alloy with 2.1 Cu corresponds to 7059). Hydrogen was introduced into the alloys using cathodic charging, both with and without concurrent plastic straining. The copper-free alloy in both the under-aged and peak-aged conditions was embrittled by hydrogen and the effect was enhanced by concurrent plastic strain. The copper-containing alloy (7050) was susceptible to hydrogen embrittlement when under-aged, but once the peak-strength microstructure had been developed, the alloy in the longitudinal direction showed no embrittlement even under severe hydrogen-entry conditions. Similar beneficial effects have been reported for copper additions in imparting resistance to humid air and stress-corrosion cracking for high strength AI-Zn-Mg alloys, and the results are discussed with emphasis on the parallel nature of the phenomena of stress-corrosion cracking and hydrogen embrittlement.     

Corrosion resistance of austenitic stainless steel separator for molten carbonate fuel cell

STS310S and SC-STS310S (simultaneously co-deposited chromium and aluminum onto 310S austenitic stainless steel substrate by pack-cementation process) were used as separator materials on the cathode side of a molten carbonate fuel cell. With the STS310S, corrosion proceeded via three steps; a formation step of unstable corrosion product, a protection step against corrosion until breakaway, and an advance step of corrosion after breakaway. The final corrosion product was LiFeO₂ and the loss of mass was 6.5 mg/cm² after a corrosion test of 480 hr at 650°C. The SC-STS310S showed more effective corrosion resistance, however, than did common STS310S. There was especially no corrosion loss on the SC-STS310S after the 480 hr corrosion test. It is anticipated that it will be very useful as an alternative separator on the cathode side off the MCFC in the future.