Age Strengthening of Gray Cast Iron: Nitrogen Effects and Machinability
A neutron scattering study was conducted to help determine the mechanism by which gray cast iron age strengthens. The scattering data revealed a resolved peak for the nitrogen-rich gray iron sample at 28 days. This corresponds with a particle with a diameter of 2-4 nm or an ordered array of particles with interparticle spacing of 3.7 nm. This is the same order of magnitude as GP zones. The role of free nitrogen in age strengthening was determined by plotting the change in UTS with log time versus the estimated free nitrogen in the gray iron. The age strengthening rate increases with increasing free nitrogen. A machinability study was conducted for gray irons from three foundries. The tool life was found to increase with aging. Tilt rate, surface finish deterioration rate, and power usage rate all decrease with aging.
W. M. Nicola et al., "Age Strengthening of Gray Cast Iron: Nitrogen Effects and Machinability," Transactions of the American Foundry Society, American Foundry Society (AFS), Jan 2002.
Materials Science and Engineering
Keywords and Phrases
Age Strengthening; Gray Cast Iron; Nitrogen
Article - Journal
© 2002 American Foundry Society (AFS), All rights reserved.