Mechanical Properties of High Carbon Low-Density Steels

The paper presents the possibilities of heat treatment of low-density structural steels usable for springs. Heats have been prepared with chemical compositions 0.7 wt% C and 1 wt% C, as well as 7 wt% Al and 5 wt% Al. Samples were prepared from ingots weighing approximately 50 kg. These ingots were homogenised, then forged, and hot rolled. Primary transformation temperatures and specific gravity values were determined for these alloys. For low-density steels, there usually needs to be a solution to achieve the required ductility values. At cooling rates of 50 ?/s and 100 ?/s, the kappa phase is not present. A SEM analysed the fracture surfaces for the presence of transit carbides during tempering. The martensite start temperatures ranged from 55-131 ?, depending on the chemical composition. The densities of the measured alloys were 7.08 g/cm(3) and 7.18 g/cm(3), respectively. Therefore, heat treatment variation was carried out to achieve a tensile strength of over 2500 MPa, with ductility of almost 4%. Hardnesses above 60 HRC were achieved for 1 wt% C heats using the appropriate heat treatment.

Automated summary

The paper discusses the heat treatment possibilities for low-density structural steels used in springs. Different alloy compositions were prepared, including ones with carbon and aluminum. Various tests and analyses were conducted to determine the transformation temperatures, density values, and mechanical properties of the alloys. The results showed that appropriate heat treatment can achieve high tensile strength and hardness for these steels.