Effect of Cerium on the Behavior of Primary Carbides in Cast H13 Steels

Characteristics of carbides, such as their shape, size, type, and structure, significantly affect the plasticity and toughness of D2 cold‐work die steel. The effect of variations in the cooling rate on characteristics of carbides during solidification of D2 cold‐work die steel is investigated. Characteristics of carbides solidified at various cooling rates are quantified by scanning electron microscopy, energy‐dispersive spectroscopy, and X‐ray diffraction. The quantity of M7C3 carbides increases, but their size and the layer spacing decrease as the cooling rate increases in the range of 0.3–4 °C s−1. The types of carbide are not affected by the cooling rate. The main type is M7C3, with small amounts of M23C6 and MC. The carbides mostly comprise hexagonal hollow bars. There are a few lamellar and curved bar structures. The formation mechanism of hexagonal hollow bar carbides is clarified. The growth of hexagonal hollow bar M7C3 carbides is primarily affected by the chromium content and temperature gradient. Carbides form planar shapes together with nucleation masses and subsequently grow within a lateral envelope of helical dislocations. The interior cavity of M7C3 bar carbides shrinks and becomes filled with austenite as the cooling rate increases, which results in thin hexagonal hollow bar carbides.

Section: Introductionmentioning

confidence: 99%

Effect of Cooling Rates on the Characteristics of Carbides during Solidification of D2 Cold‐Work Die Steel

Liu

2022

“…The serious macrosegregation was the result of solidification and the area of serious macrosegregation was the residual liquid‐phase zone in the solidification process, that is, the final solidification zone. [ 34 ] Figure 12 shows the schematic diagram of the final solidification zone which was indicated by the blue oval. The residual liquid‐phase zone in the center of the continuous casting slab at the end of solidification contained a high concentration of elements C and Mn due to their macrosegregation behavior.…”

Section: Discussionmentioning

confidence: 99%

Cause Analysis of Low Tensile Plasticity in Normal Direction for Hot‐Rolled Thick Plate of HSLA Steel

Shen

Cheng

Zhang³

et al. 2023

Self Cite

“…Then, three samples were electrolyzed by nonaqueous solution electrolysis method (electrolyte composition [volume fraction]: 1% tetramethylammonium chloride, 10% acetylacetone, and 89% anhydrous methanol; voltage: 20 V; electrolysis time: 5À10 s) to expose the inclusions. [29] The distribution of rare earth inclusions in the solidification structure was observed by a scanning electron microscope (SEM) (FEI Quanta-250; FEI Co., Hillsboro, OR, USA), energy-dispersive spectrometer (EDS) (XFlash 5030; Bruker, Berlin, Germany), and electron probe microanalyzer (EPMA) (EPMA-1720 H; Shimadzu Co., Kyoto, Japan). Finally, the morphology, type, size, and number of inclusions were observed and counted by SEM, EDS, and an automatic inclusion analysis system (EVO18-INCA, Carl Zeiss AG, Oberkochen, Germany).…”

Section: Methodsmentioning

confidence: 99%

Refinement of Solidification Structure of H13 Steel by Rare Earth Sulfide

Bao

Cheng

Huang

et al. 2021

Self Cite

To improve the solidification structure of H13 steel, rare earth sulfide (Ce−S) is used as the nucleation core of δ‐ferrite or γ‐austenite to refine the original austenite grain. The relationship between rare earth inclusions and grain refinement is discussed in terms of the type, distribution, size, number, and formation characteristic of rare earth inclusions. The results show that to form a large amount of Ce−S (> 35 mm−2) and inhibit the formation of rare earth oxide (Ce−O), rare earth oxysulfide (Ce−O−S), and MnS, the content of O, S, and Ce must be strictly controlled. Most Ce−S in the solidification structure is located in the original austenite grain interior, indicating that Ce−S can act as the nucleation core of δ‐ferrite or γ‐austenite. The most effective size of Ce−S as nucleation core is 1−2 μm, followed by 2−3 μm, and the Ce−S with the size larger than 3 μm has the least effect. The original austenite grain size is related to the number density of Ce−S, and the higher the number density of Ce−S, the smaller the grain size. The precipitation size of Ce−S during solidification is mostly 1−3 μm, and these Ce−S can act as the nucleation core more effectively.