Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7971606 | Materials Science and Engineering: A | 2018 | 43 Pages |
Abstract
Hot compression tests were performed on K107 cold-work tool steel at various temperatures in range of 800-1200â¯Â°C and strain rates of 0.001-1â¯sâ1. The microstructural evolutions including dynamic precipitation (DP) of carbide particles and dynamic recrystallization (DRX) mechanism were investigated by optical and FESEM-EBSD observations. The peak strain of flow curves showed uncommon increase within the temperature range of 900-1100â¯Â°C and strain rates of 0.001-0.01â¯sâ1. Optical microscopy observations and image analysis quantifications showed that the uncommon behavior is associated with the formation of fine carbides by DP. At 1100â¯Â°C, the rate of DP reaches a maximum and then decreases at higher temperatures. Microstructural observations implied that DP could retard DRX at 900-1100â¯Â°C and strain rates of 0.001-0.01â¯sâ1. The discontinuous DRX (DDRX) only appeared at 800â¯Â°C as the formation of grain boundary nucleation. At temperature range of 900-1100â¯Â°C, intensive DP on the grain boundaries could avoid DDRX. The continuous DRX (CDRX) was found as the major mechanism of dynamic softening at 900-1100â¯Â°C. It was found that the subgrain growth and progressive rotation lead to the transformation of sub-boundaries into high angle grain boundaries and propel CDRX.
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Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
S. Zangeneh Najafi, A. Momeni, H.R. Jafarian,