Effect of Nickel Content on Mechanical Property and Microstructure for Sulfide Stress Corrosion High-Strength Steel

Abstract

Two types of steels which are different in Ni content were tested in three groups of different quenching temperatures and same tempering temperature respectively under the same conditions, and then tested the mechanical properties and observated the microstructure, comparing with the effects of different Ni content on the microstructure and properties. When 1Ni-steel is under the different quenching temperature, its tensile strength range is 1269-1290MPa and changes subtlely. The yield strength and impact energy reach the highest at 910°C, and the mircostructure is fine and uniform. With the quenching temperature increasing, the strength of 3Ni-steel decreases ,but the toughness increases comparing with both kinds of the steels, the microstructure of 3Ni-steel has much more hard phases in its tempered martensite microstructure. Its tensile strength, yield strength and toughness are higher than 1Ni-steel at the lower quenching temperature. The inclusions of 3 Ni-steel are characterized by spheroidization and refinement. In the NACE-A test, the SSC resistance of 3Ni-steel is better than that of 1Ni-steel, which indicates that the high Ni steel has better comprehensive properties.

Effect of Coating Damage on the Micro Area Corrosion Performance of HDR Duplex Stainless Steel

“…Such fillers could enhance the shielding property of the coating and shield water and oxidation outside the substrate. The improved corrosion resistance of the substrate material [24] might also be due to the reported complex reaction between Fe ions and groups in the coating that improved the corrosion resistance of the substrate [25,26]. The ferritic structure is the preferred pitting corrosion in coating damage, which indicates that the ferrite of HDR duplex stainless steel is a weak phase in a 3.5% NaCl solution and easily corrodes [27,28].…”