Effect of Copper Content and Heat Treatment Schedules on Mechanical Properties, Cold Resistance, and Microstructural Constituent Morphology in Precipitation-Hardened Steel

The article delves into the impact of copper content and heat treatment schedules on the mechanical properties, cold resistance, and microstructural characteristics of precipitation-hardened steel. It highlights the need for new steel compositions to meet the demands of high-strength, high-thickness pipeline fittings. The research involves developing three steel compositions with varying copper content and subjecting them to different heat treatment regimes. The study reveals that the optimal mechanical properties are achieved with a tempering temperature of 550°C, with the highest strength levels corresponding to strength class K60. Additionally, the impact strength and cold resistance of the steels are evaluated, showing that steels with lower copper content exhibit better cold resistance. Microstructural analysis using SEM and TEM reveals the formation of copper-containing particles and their influence on steel properties. The research concludes that these steels can provide high yield strength and good impact strength, making them a viable alternative for pipeline fittings and other critical structures.