Fabrication and Mechanical Properties of Lotus-type Porous Carbon Steel by Unidirectional Solidification in Nitrogen Atmosphere

Abstract

Lotus-type porous carbon steel (AISI1018) whose long cylindrical pores are aligned in one direction was fabricated by unidirectional solidification in pressurized nitrogen gas. The ingots with the porosity from 10 to 30% were fabricated under the nitrogen gas pressure of 2.5 MPa at various transference velocities from 40 to 160 μms⁻¹. Tensile strength was measured for Lotus-type porous carbon steel. Elongation was improved due to normalizing at 1200K. The yield strength does not change even in lotus steel less than 20% in porosity.
This superior property is attributed to nitrogen solid solution hardening and pore existence.