Age Strengthening of Gray Cast Iron: Nitrogen Effects and Machinability

Abstract

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.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Age Strengthening; Gray Cast Iron; Nitrogen

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2002 American Foundry Society (AFS), All rights reserved.

Publication Date

01 Jan 2002

Link to Full Text

Share

 
COinS