Evolution of Nonmetallic Inclusions with Varied Argon Stirring Condition during Vacuum Degassing Refining of a Bearing Steel

Ren

Huang

et al. 2023

The effect of cerium on inclusions and solidification structure of a low‐nickel Si–Mn‐killed stainless steel is studied using laboratory experiments. When the cerium content in steel increased from 0 to 250 ppm, modification sequence of inclusions is Si–Mn(–Al)–O and MnS → Ce–Si–Mn–O–S → Ce(–Si)–O–S → CeS and CeC2. The number density and area fraction of inclusion first decrease with the increase in the cerium content and then increase due to the formation of CeC2 inclusions when the cerium content is bigger than 150 ppm, which is precipitated in solid steel during solidification. When the cerium content increases from 0 to 250 ppm, the fraction of equiaxed grain zones of steel ingot first increases and reaches a maximum value when the cerium content is 54 ppm; then the fraction of equiaxed grain zones decreases with the increase of the cerium content. 2D lattice misfit calculations are performed and it is found that there are no heterogeneous nucleation cores in the steel without cerium during solidification. For the steel with cerium, Ce4.67Si3O13, Ce2O2S, and CeS inclusions act as heterogeneous nucleation cores, increasing the fraction of the equiaxed grain zone. Bigger effective heterogeneous nucleation cores number density leads to a larger fraction of the equiaxed grain zone.

Section: Modification Mechanism Of Cerium On Solidification Structurementioning

confidence: 99%

mentioning

confidence: 99%

Effects of Cerium Addition on Inclusions and Solidification Structure of a Low‐Nickel Si–Mn‐Killed Stainless Steel

Ren

Huang

et al. 2023

“…It was well known that the contact angle between solid oxides and the molten steel was larger than 90°, [ 45–47 ] promoting the collision and growth of solid inclusions. Cheng et al [ 48 ] calculated the coagulation coefficient of different types of inclusions and found that solid inclusions have a larger coagulation coefficient than liquid inclusions, indicating that the solid inclusion was more likely to collide and agglomerate. The morphology and elemental mapping of part Ce 2 O 3 ‐rich inclusions are shown in Figure 17 .…”

Section: Evolution Mechanism Of Nonmetallic Inclusions During Cerium ...mentioning

confidence: 99%

Transient Evolution of Nonmetallic Inclusions in a Si–Mn‐Killed Stainless Steel with Cerium Addition

Ren

et al. 2022

Self Cite

Laboratory experiments are performed to study the transient evolution of inclusions in Si–Mn‐killed stainless steels with additions of 40, 100, and 400 ppm cerium. With the increase of the cerium content in the molten steel, the evolution path of inclusions is Al2O3–SiO2–MnO–CaO → Ce2O3–Al2O3–SiO2–MnO–CaO → Ce2O3 → Ce2O3–CeS. The addition of 40 ppm cerium gradually increases the Ce2O3 content in liquid oxide inclusions. After the addition of 100 ppm cerium, inclusions first evolve to Ce2O3–Al2O3–SiO2–CaO–CeS, then to Ce2O3. The CeS is generated as a transient product then disappears. After the addition of 400 ppm cerium, liquid Al2O3–SiO2–MnO–CaO inclusions are modified to solid Ce2O3–CeS ones. The addition of 40 ppm cerium into the steel lowers the size from 1.74 to 1.53 μm. After the addition of 100 and 400 ppm cerium into the steel, the size of inclusions immediately decreases due to the formation of small Ce2O3–CeS inclusions and then increases owing to the collision of solid inclusions. A higher cerium content in the steel promotes the collision of Ce‐rich inclusions.

“…[ 1,2 ] The requirement for the well control of nonmetallic inclusions in steel is becoming higher. Inclusions could generally be controlled by the refining slag, [ 3–6 ] argon stirring, [ 7–9 ] and calcium treatment. [ 10–13 ] Calcium treatment operation could modify solid Al 2 O 3 ‐based inclusions [ 10,11,14–18 ] into liquid, which could effectively prevent the nozzle clogging.…”

Section: Introductionmentioning

confidence: 99%

Effect of Types of Calcium‐Containing Cored Wires on the Inclusion Modification by Calcium Treatment

Yang

et al. 2022

Self Cite