The high-temperature dissolution behavior of carbides during the quenching process significantly influences grain growth,mechanical properties,and secondary carbide precipitation,thereby playing a major role in the he...The high-temperature dissolution behavior of carbides during the quenching process significantly influences grain growth,mechanical properties,and secondary carbide precipitation,thereby playing a major role in the heat treatment process of die steel.This study investigated the changes in carbide type,particle size distribution,and weight percentage in DC53 steel after holding at 1060℃for 2 h,followed by oil quenching.The analysis was conducted using Thermo-Calc,DICTRA computations,and experimental methods including electron backscatter diffraction,transmission electron microscopy and laser particle size analysis.The experimental results showed that four types of carbides(M_(7)C_(3),M_(6)C,M_(23)C_(6),and MC)existed in DC53 steel before quenching.After quenching,M_(23)C_(6)carbides were almost entirely dissolved,while the other three types partially dissolved into the matrix.The volume-weighted geometric mean size of carbides(x_(geo,3))increased from 5.43 to 15.15μm,and the weight percentage decreased from 13.03%to 5.01%.Small-sized carbides(below 5μm)dissolved more readily,which primarily accounted for the reduction in carbide weight percentage during quenching.In contrast,the weight percentage of large-sized carbides(greater than 10μm)varies less.DICTRA computations indicated that M_(7)C_(3)carbides smaller than 7μm can completely dissolve into the matrix after holding at 1060℃for 2 h.The findings provide an effective reference for optimizing carbide control during the heat treatment process of DC53 steel.展开更多
This study analyzes the evolution of carbides in the tempering process of a newly developed semi-high speed steel cold forged roll with nitrogen addition using a transmission electron microscope （TEM） equipped with ...This study analyzes the evolution of carbides in the tempering process of a newly developed semi-high speed steel cold forged roll with nitrogen addition using a transmission electron microscope （TEM） equipped with an energy dispersive X-ray （EDX）. The precipitation sequence of the carbides was identified in the entire tempering process and it can be expressed as M3C→M3C ＋ M （C, N）Ⅱ→M（ C, N）Ⅱ → M7C3Ⅱ ＋ M23 C6. The secondary hardening in the tempering process was mainly due to the dispersed precipitation of fine M（ C, N）n particles. The dissolution of M3 C tempered at high temperatures induced the precipitation and coarsening of M7 C31/ and M23 C6.展开更多
基金supported by the Central Guide Local Science and Technology Development Project of Hubei Province of China(No.2023EGA008)the Wuhan Natural Science Foundation Exploration Project(Chenguang Project,2024040801020309)。
文摘The high-temperature dissolution behavior of carbides during the quenching process significantly influences grain growth,mechanical properties,and secondary carbide precipitation,thereby playing a major role in the heat treatment process of die steel.This study investigated the changes in carbide type,particle size distribution,and weight percentage in DC53 steel after holding at 1060℃for 2 h,followed by oil quenching.The analysis was conducted using Thermo-Calc,DICTRA computations,and experimental methods including electron backscatter diffraction,transmission electron microscopy and laser particle size analysis.The experimental results showed that four types of carbides(M_(7)C_(3),M_(6)C,M_(23)C_(6),and MC)existed in DC53 steel before quenching.After quenching,M_(23)C_(6)carbides were almost entirely dissolved,while the other three types partially dissolved into the matrix.The volume-weighted geometric mean size of carbides(x_(geo,3))increased from 5.43 to 15.15μm,and the weight percentage decreased from 13.03%to 5.01%.Small-sized carbides(below 5μm)dissolved more readily,which primarily accounted for the reduction in carbide weight percentage during quenching.In contrast,the weight percentage of large-sized carbides(greater than 10μm)varies less.DICTRA computations indicated that M_(7)C_(3)carbides smaller than 7μm can completely dissolve into the matrix after holding at 1060℃for 2 h.The findings provide an effective reference for optimizing carbide control during the heat treatment process of DC53 steel.
基金supported by the Baosteel Group Corporation Project (R05DSES220)
文摘This study analyzes the evolution of carbides in the tempering process of a newly developed semi-high speed steel cold forged roll with nitrogen addition using a transmission electron microscope （TEM） equipped with an energy dispersive X-ray （EDX）. The precipitation sequence of the carbides was identified in the entire tempering process and it can be expressed as M3C→M3C ＋ M （C, N）Ⅱ→M（ C, N）Ⅱ → M7C3Ⅱ ＋ M23 C6. The secondary hardening in the tempering process was mainly due to the dispersed precipitation of fine M（ C, N）n particles. The dissolution of M3 C tempered at high temperatures induced the precipitation and coarsening of M7 C31/ and M23 C6.
