The Influence of Forge Reduction Ratio on the Tensile and Impact Properties of a Low-Alloy ESR (Electroslag Remelting) Steel
Abstract:
The influence of hot forging reductions ranging from 11 as-cast condition to 201 on the tensile and notch impact properties of a low sulphur 0.002 electroslag refined AISI 4340 grade steel has been investigated. Both properties achieved with the initial forging reduction of 1.51 were higher than the as-cast condition but lower than the values obtained with forging reductions of 2.51 and greater. The maximum level of mechanical properties attained with each forging reduction was found to be dependent on the amount of duplex grain structure present in the high temperature austenitic phase. Samples containing a higher percentage of duplex grain structure were also observed to require a faster quench rate to maximize the level of mechanical property. Small forging reductions of around 1.51 were considered insufficient to ensure the uniformity of deformation necessary to achieve a fine equi-axed austenite grain structure after hot working. Because of the low sulphur content, reductions of up to 201 had little influence on the anisotropy ratio of mechanical properties, in particular reduction of area and notch impact values. Keywords Electroslag refined steels, Low alloy steels, Mechanical properties, Forging, Forge ratio.