Temperature dependence of the strength of fine- and ultrafine-grained materials

✍ Scribed by J.H. Schneibel; M. Heilmaier; W. Blum; G. Hasemann; T. Shanmugasundaram

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 939 KB
• Volume: 59
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2010.10.062

✦ Synopsis

The yield stress of oxide dispersion-strengthened (ODS) PM2000 steel and nanocluster-strengthened (NCS) 14YWT steel was measured as a function of temperature for grain sizes from 0.2 lm to 1. In combination with data from the literature, it was found that the indirect strengthening (i.e., the Hall-Petch strengthening) for small grain sizes was often greater than the direct strengthening (i.e., the Orowan strengthening due to the dispersoids). The yield stress dropped significantly at a transition temperature near 500 °C even though the grain size remained constant. For small grain sizes, a large fraction of this drop was attributed to a decrease in grain size strengthening. Three published models describing this effect were compared with the experimental data. The observed transition temperatures were consistent with two of them. The strength-temperature curves for PM2000 with different grain sizes tended to intersect, whereas those for 14YWT did not. Because of this feature, the description of the strength-temperature dependence of 14YWT could be narrowed down to a single model. It is concluded that ODS and NCS materials are well suited to examining the temperature dependence of grain size strengthening.