Investigation of effects on the properties of high strength low alloy steel for various percent nickel content and powder metallurgy parameters

Abstract

Powder metallurgy (P/M) is familiarly known as one of the main critical manufacturing processes for making numerous industrial products. The production of powder metallurgy component has been expanding at a significantly faster rate because of the advantages associated with it. The reward includes compositional flexibility, minimized segregation, and ability to produce graded microstructures with varying physical and mechanical properties. This will improve quality, precision, productivity, optimized material utilization and hence reduction in cost. The primary objective of this present research work is to develop the HSLA steels. The powder mix of High Strength Low Alloy Steel (HSLA) steels prepared from the elemental powders such as nickel, manganese, chromium, and molybdenum. Three different compositions of AISI 4340 steel powders were mixed in a potmill, and a universal testing machine prepared the cylindrical green compacts at a pressure level of 560MPa. The green compacts sintered in two different sintering atmospheres such as argon and hydrogen. Sintering in hydrogen environment was carried out by passing 250 ml hydrogen per minute. The dew point of hydrogen is -40ºC. After sintering, the sintered samples are cooled at the rate of 45 to 50oC per minute. Density measurements, mechanical properties evaluation and wear resistance properties were studied in the sintered HSLA steels. HSLA P/M steels specimens sintered in hydrogen atmosphere have exhibited better-sintered density (19% improvement in green density), reaching 96-97% theoretical density. However, argon atmosphere sintered steels exhibited a minimum density of 6.533 g/cc (82% theoretical density), which is approximately 5% density increase from its green condition. Lower aspect ratio 0.50 preforms have shown better densification characteristics than newline