Effect of Pressure on Dendrite Structure and Characteristics of Carbides during Solidification Process of H13 Die Steel Ingot

Self Cite

In this study, to clarify the evolution mechanism of dendrite structure and shrinkage porosity in 30Cr15Mo1N ingots under varying pouring rates, the changes in cooling rate, temperature gradient, secondary dendrite arm spacing (SDAS), columnar to equiaxed transition (CET), and area of shrinkage porosity with pouring rate are investigated. The cooling rate and temperature gradient calculated by using the ProCAST software increase with the pouring rate, leading to a great solidification rate. As a result, the SDAS decreases and the position of CET moves toward the center of 30Cr15Mo1N ingot. Additionally, the area proportion of shrinkage porosity increases with the increase in pouring rate. This phenomenon can be mainly due to the less overlap between columnar dendrite and higher permeability with the larger SDAS, which are conducive to the feeding of the molten steel. In addition, the delayed formation of semi‐solidified shell at the top of the ingot at low pouring rate minimizes the impact of solid contraction on the surface sink, which results in a flatter top surface of the ingot at low pouring rate.

Section: Mean Cooling Rate and Temperature Gradientmentioning

confidence: 99%

Evolution of Dendrite Structure and Shrinkage Porosity in 30Cr15Mo1N Ingot with Pouring Rate

He,

Zhu,

et al. 2024

Self Cite

“…[8,12,31] To calculate the nitrogen segregation in the 30Cr15Mo1N ingot, the Clyne-Kurz model is utilized. [32][33][34] The nitrogen content in the residual liquid phase can be determined using the following equation: [35] α…”

Section: Nitrogen Content During Solidificationmentioning

confidence: 99%

“…[ 8,12,31 ] To calculate the nitrogen segregation in the 30Cr15Mo1N ingot, the Clyne–Kurz model is utilized. [ 32–34 ] The nitrogen content in the residual liquid phase can be determined using the following equation: [ 35 ]

\alpha = \frac{0.25 \left(\lambda\right)_{2} ^{2} V}{D \left(\right. T_{L} - T_{S} \left.\right)}

\left(\lambda\right)_{2} = b \times V^{- c}

$$\Omega = \left[\right.

…”

Section: Theoretical Basis Of Bubble Nucleation and Growthmentioning

confidence: 99%

Revealing the Removal Mechanism of Vanadium Addition on Nitrogen Pores in 30Cr15Mo1N High‐Nitrogen Steel Ingot

Zhu,

Ni,

et al. 2023

Self Cite

The removal mechanism of vanadium addition on nitrogen pores in 30Cr15Mo1N ingot is systematically investigated through statistical analysis and theoretical calculation. The nitrogen solubility is obtained by the thermodynamic model, and the nitrogen content is obtained by combining the ProCAST software and the C–K model. Then, according to the formula of critical nucleation radius and growth rate of nitrogen bubbles, the variation of critical nucleation radius and growth rate of nitrogen bubbles with different vanadium contents is calculated. As the vanadium content increases, the number and mean area of nitrogen pores decrease. In comparison to the 0 V ingot, the number of nitrogen pores decreases in the 0.2 V ingot, but there is an increase in the number of large‐sized nitrogen pores (>3000 μm in diameter). When the vanadium content increases to 0.4, the nitrogen pores are completely removed. The results demonstrate that increasing vanadium content can remove nitrogen pores. Since the solidification mode remains unchanged with increasing vanadium content, increasing the vanadium content cannot remove nitrogen pores by changing the solidification mode of the 30Cr15Mo1N ingots. Therefore, increasing the vanadium content removes the nitrogen pores mainly by inhibiting the nucleation of nitrogen bubbles and promoting nitrogen bubble overflow in 30Cr15Mo1N ingots.

“…The researches on the improvement in segregation mainly focused on the optimization of the remelting parameters, [15][16][17] or applying some new ESR technologies, such as vacuum ESR [18] and pressurized ESR. [19] The addition of a modifier, such as a rare earth element, is another approach to suppress dendritic segregation. [20][21][22][23][24] Our previous study showed the improving effects of a cerium treatment on the H13 steel through the following mechanisms [24] : 1) refinement of the solidification structure, and improvement in the homogeneity of the microstructure of the forged H13 steel, 2) limitation of the growth of primary carbides, and 3) modification of the Al 2 O 3 and MnS inclusions into Ce 2 O 3 and Ce 2 O 2 S inclusions, which prevented the inclusions from becoming nucleation cores of the primary carbides to generate large complex precipitates.…”

Section: Introductionmentioning

confidence: 99%

“…The researches on the improvement in segregation mainly focused on the optimization of the remelting parameters, [ 15–17 ] or applying some new ESR technologies, such as vacuum ESR [ 18 ] and pressurized ESR. [ 19 ]…”

Section: Introductionmentioning

confidence: 99%

Industrial Trials on Preparation of Cerium‐Treated H13 Steel by Electroslag Remelting with Cerium‐Oxide Containing Slag

Wang

Chen³

et al. 2023

To realize an industrial production of a cerium‐treated electroslag remelted H13 steel, electroslag remelting (ESR) of H13 steel using a CaF2–CeO2–CaO–Al2O3 system slag combined with a Si–Ca reductant addition is studied. The influence of the Al2O3 content in the slag on the cerium treatment effect of cerium‐oxide‐containing slag is investigated to determine the appropriate slag. A 52.2 wt% CaF2–26.7 wt% CeO2–17.8 wt% CaO–3.3 wt% Al2O3 slag (RE‐Slag) is employed for the industrial ESR production of H13 steel. An H13 steel remelted by a 70 wt% CaF2–30 wt% Al2O3 slag (CA‐Slag) is used for comparison. Al2O3 can suppress the reduction of cerium oxide by changing the activities of slag components. ESR with RE‐Slag achieves a cerium treatment of H13 steel. However, an uneven distribution of Ce is obtained due to the limitation of the reductant addition method. The H13 steel remelted with RE‐Slag (RE‐Slag‐H13) has higher cleanliness, finer dendritic structures, and finer primary carbides than those of the steel remelted with CA‐Slag (CA‐Slag‐H13). Compared to the forged CA‐Slag‐H13 steel, the banded segregation of the RE‐Slag‐H13 steel is suppressed, and the impact toughness is increased by 30%.