Influence of a novel two-step austempering process on the strain-hardening behavior of austempered ductile cast iron (ADI)

✍ Scribed by Jianghuai Yang; Susil K. Putatunda

• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 993 KB
• Volume: 382
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2004.04.076

✦ Synopsis

An investigation was carried out to examine the influence of a novel two-step austempering process on the strain-hardening behavior of austempered ductile cast iron (ADI). Strain-hardening exponent (n value) of specimens austempered by conventional single-step austempering process as well as the novel two-step process were determined over the entire plastic deformation regions of the stress-strain curves. Optical microscopy and X-ray diffraction analysis were performed to examine mechanisms of strain-hardening behavior in ADI under monotonic (tensile) loading. Test results show that this novel two-step process has resulted in improved microstructural variables in the ADI matrix, and higher hardness, yield strength and tensile strengths, but lower ductility and strain-hardening exponent values compared to the conventional single-step austempering process. Test results also indicate that strain-hardening exponent of ADI is a function of amount and morphology of microstructural constituents and interaction intensities between carbon atoms and dislocations in the matrix.