Dynamic and quasi-static compression of porous carbon steel S30C and S45C with directional pores

作者：Song Y H; Tane M^*; Nakajima H

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2012, 534: 504-513.

DOI：10.1016/j.msea.2011.11.099

• Mechanical characterization
• Cellular materials
• Ferrous alloy
• Plasticity

Dynamic and quasi-static compressive deformation of as-cast and normalized porous S30C and S45C carbon steels with unidirectional cylindrical pores was investigated to evaluate the effect of matrix brittleness on the appearance of a plateau stress region where deformation proceeds with almost no stress increase. Dynamic compression tests were carried out at room (298 K) and cryogenic (77 K) temperatures using the split Hopkinson pressure bar method, and quasi-static compression tests were carried out at room temperature using universal testing machine. Compression perpendicular to the orientation of the pores does not generate a plateau stress region, regardless of the matrix brittleness, which depends on the strain rate, temperature, carbon content, and heat-treatment conditions. Localized deformation and crack formation originating from a high concentration of stress around the pores during perpendicular compression promote densification in the early stage of the stress-strain curves, thereby precluding the appearance of the plateau stress region. On the other hand, a plateau stress region appears during compression parallel to the orientation of the pores. The appearance of the plateau stress region is, however, limited when rapid crack propagation and large work hardening are suppressed by the ductility of the matrix and the formation of deformation bands, which originate from the intermediate brittleness of the matrix metal and anisotropic pores. The appearance of the plateau stress region confers a high-energy absorption capacity on the as-cast porous carbon steel S45C, with an absorbed energy value of 86.8 +/- 1.6 kJ kg(-1), which is ten times higher than that of aluminum foams with isotropic pores. The energy absorption efficiency reaches 85.9 +/- 6.8%, which is almost the same as that of the aluminum foams.

• 出版日期2012-2-1