Age Strengthening of Gray Cast Iron Phase III

Technical Report · Thu Jun 26 04:00:00 EDT 2003

DOI:https://doi.org/10.2172/812004· OSTI ID:812004

Richards, Von L ^[1]; Nicola, Wayne

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1. University of Missouri-Rolla Metallurgical Engineering Dept

The primary objective of this research is to identify the age strengthening mechanism in gray and ductile cast iron, and to quantify the parameters that control it. It is also to contribute to a new predictive model for gray and ductile iron strength and hardness. This work shows that age strengthening occurs on a sigmoidal-logarithmic scale in gray and ductile cast irons, to a statistically significant extent. This is similar to Avrami-Johnson-Mehl kinetics for phase transformations in metals. It occurs in both cupola-melted iron and induction melted iron. However, it does not happen in all compositions. We have developed some understanding of the process. Data suggests that nitrogen and nitride-forming trace elements have a significant role in the process, but that is yet not fully characterized. Also, the time dependence of the bulk hardness and strength increase, the nano-scale precipitation evidence from neutron scattering, differential scanning calorimetry results and matrix micro-hardness increase in ferrite all indicate that age strengthening occurs by a precipitation or pre-precipitate cluster formation mechanism.

• Research Organization: University of Missouri-Rolla (US)
• Sponsoring Organization: (US)
• DOE Contract Number: FC07-00ID13851
• OSTI ID: 812004
• Report Number(s): DOE/ID/13851
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGE HARDENING
CAST IRON
HARDNESS
KINETICS
PHASE TRANSFORMATIONS
PRECIPITATION
TIME DEPENDENCE