Hot-deformation induced static recrystallization and nano-MX precipitation in a low activation martensitic steel

The static recrystallization and MX precipitation of a low activation martensitic (LAM) steel processed by different com pression tem peratures were studied. The result shows that at an identical duration of 200 s, the static recrystallization degree of steel decreases continuously from 96% to 62% and 25 % with decreasing compression temperature from 1050 degrees C to 950 degrees C and 850 degrees C, respectively. Analysis shows that, with the decrease of compression temperature, the reduced recrystallization rate is mainly due to the decrease of temperature and the increase of nano precipitation content. After solution treatment, the sizes of grains, subgrains and the MX carbides decrease in the LAM steel with the decrease of compression temperature. After 1050 degrees C compression, the average size of grains, subgrains and MX carbides are 7 mu m, 220 nm and 15 nm, respectively. However, in the 850 degrees C case, the corresponding size significantly decreases to 4.5 mu m, 175 nm and 10 nm, respectively, which is mainly due to the lower recrystallization degree and the increase of nano precipitation content in the steel after compression. With the decrease of the compression temperature from 1050 degrees C to 950 degrees C and 850 degrees C, the hardness of LAM steel after solid solution treatment increases from 4.0 GPa to 4.2 GPa and 4.5 GPa, mainly resulting from the refinement of grains, subgrains and MX carbides. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study found that decreasing compression temperature leads to a decrease in static recrystallization degree, as well as a reduction in the sizes of grains, subgrains and MX carbides in low activation martensitic steel. This also results in an increase in hardness, mainly due to the decrease in temperature and the increase in nano precipitation content.