Tensile Strength of Heat-Treated PM Steels

摘要

In the present investigation, the tensile strength of heat-treated Fe-0.6%C-2%Cu steels, produced by powder metallurgy (PM) at two densities (namely 6.7 and 7.0 g cm~(-3)), was investigated. Tempering was carried out at high temperatures (420, 450 and 470℃) and at low temperatures (180 and 220℃). The materials tempered at high temperature displayed a ductile fracture behaviour and tensile strength was found to increase as tempering temperature was decreased. On the contrary, the materials tempered at low temperatures underwent tensile brittle fracture and tensile strength decreased as tempering temperature was decrease. This behaviour was explained by means of a simple model of the ductile and brittle fracture behaviour of PM steels. This model is also used to propose specific guidelines to obtain materials with increased tensile strength and ductile fracture behaviour.