Interaction of V, Al, and N in Microalloyed Forging Steels after Hot Deformation

Abstract:

A medium-carbon V-microalloyed steel (38MnSiVS5) with three different Al levels (0.006, 0.020, and 0.031 wt pct) was used to examine the interaction of V, Al, and N after hot deformation. A complete thermomechanical cycle was simulated in the laboratory using a Gleeble® 1500. Specimens were heated to a soaking temperature that varied from 1100 to 1250 °C for 5 or 45 min and control cooled to 1000 °C in 6 min, where they were compressed to 40 pct reduction at a strain rate of 1.0 s^-1. After compression, the specimens were control cooled to 500 °C at 0.25 °C·s^-1 and die quenched to room temperature. Additional specimens were processed without the compression step for comparison. The thermal and thermomechanically processed specimens were characterized by quantitative metallography and microhardness testing. The thermomechanically processed specimens with 0.006 wt pct Al maintained their hardness while reducing pearlite fraction by approximately 10 pct. The thermomechanical processed specimens with 0.020 and 0.031 wt pct Al showed a significant drop in microhardness and pearlite fractions, as compared to the thermal only processed specimens. The decrease in microhardness and pearlite fraction for the two higher-Al–containing alloys in both the thermal and thermomechanically processed specimens appears to follow the same linear trend, suggesting that AlN precipitation reduces the amount of N in solid solution, lowers the temperature at which V(C,N) precipitation occurs, and effectively reduces such strain-induced precipitation.

• Periodical: Advanced Materials Research (Volume 922)
• Pages: 604-609
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.922.604
• Online since: May 2014
• Authors: Lee M. Rothleutner*, Chester J. van Tyne
• Keywords: Aluminum Nitride (AlN), Deformation, Microalloy Steel, Precipitation, Vanadium Nitride

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