Analysis of Precipitates and Precipitation Behavior in Nb-Ti Bearing Steels

Takayama, Toru; Hinotani, Shigeharu; Ishikuro, Mikio; Kurosawa, Fumio; Yasuhara, Hisao; Gennai, Norio; Chino, Atsushi; Kutsumi, Hiroyuki; Giga, Yoshikatsu; Sukenobu, Yutaka; Uchiyama, Masao; Ishii, Megumi

doi:10.2355/tetsutohagane1955.82.2_147

Cited by 9 publications

(5 citation statements)

References 5 publications

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“…SEM and transmission electron microscopy (TEM) studies of the subscales were conducted to understand the morphology and microstructure. Previous studies showed that carbides, sulfides, nitrides and oxides in steel could be extracted by potentiostatic or galvanostatic electrolysis using a nonaqueous electrolyte 15–22. In this study, the amounts of fayalite and silica, including extracted oxides, were determined by wet analysis by inductively coupled plasma atomic emission spectrometry (ICP‐AES) using the galvanostatic electrolysis method.…”

Section: Introductionmentioning

confidence: 98%

Rapid quantitative analysis of fayalite and silica formed during decarburization of electrical steel

Jung

Park

Han

et al. 2011

Surface & Interface Analysis

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Subscales on surfaces are affected by the temperature and oxidation potential during decarburization annealing of electrical steel containing 3 wt% silicon. Knowledge of the structural and chemical properties of the surface oxide layer subscales permits the control of high-temperature oxidation processes in the electrical steel. In the present work, the oxide layers were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry, and glow discharge optical emission spectrometry (GD-OES). The main oxide compounds formed within the subscales during decarburization annealing of the electrical steel were fayalite (Fe 2 SiO 4 ) and silica (SiO 2 ). The fayalite and silica contents were quantitatively determined by wet analysis via the galvanostatic electrolysis method, and these oxide content measurements were compared with the fayalite content determined by FTIR spectrometry and the silica determined by GD-OES. The results determined by rapid methods and wet analysis showed good agreement. The present findings show that FTIR spectrometry and GD-OES measurements may be used for the rapid quantitative analysis of fayalite and silica in surface oxide layers during the manufacture of electrical steel.

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Section: Introductionmentioning

confidence: 98%

Rapid quantitative analysis of fayalite and silica formed during decarburization of electrical steel

Jung

Park

Han

et al. 2011

Surface & Interface Analysis

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“…5(a), resulting in the decrease in pinning force and the occurrence of the abnormal grain growth shown in This tendency agrees with the findings in Ti-and Nb-added steels. 12,27) According to the thermodynamic calculation, Nb(C,N) consists of 49 mol% Nb, 1 mol% Ti, 31 mol% C and 19 mol% N, whereas TiN consists of 45 mol% Ti, 5 mol% Nb, 48 mol% N and 2 mol% C. When the temperature of the forging-simulated heating was increased from 1 150°C to 1 250°C, the TiN particles are still small, but the AlN-Nb(C,N) combined particles are coarsened, resulting in a decreased pinning force and increased γ grain growth, as shown in Fig. 2.…”

Section: (B1)mentioning

confidence: 99%

Effects of Concentrations of Micro-alloying Elements and Hot-forging Temperature on Austenite Grain Structure Formed during Carburization of Case-hardening Steel

et al. 2020

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Effects of fine precipitates on the austenite (γ) grain structures were investigated in JIS SCM420-based case-hardening steels with several different concentrations of the micro-alloying elements and hot-forging temperatures. Micro-alloyed steels of 18Al (0.018 mass% Al) and 35Al-32Nb (0.035 mass% Al, 0.032 mass% Nb) were forging-simulated at 1 150°C or 1 250°C, normalized at 1 070°C, and carburized at 1 050°C. When the as-received 18Al steel was normalized and carburized without forging-simulated heating, a uniform γ grain structure was observed with the distribution of fine AlN precipitates. However, coarsening of AlN occurred when the forging-simulated temperature was 1 150°C and it caused abnormal grain growth during carburization. In 35Al-32Nb steel, the same heating did not induce the abnormal grain growth owing to the AlN-Nb(C,N) combined particles. The size of these particles increase with an increase in the forging-simulated temperature. The high forging-simulated temperature caused the dissolution of the fine precipitates, followed by reformation and coarsening of the precipitates during the subsequent cooling and the normalization heating, which resulted in a decreased pinning force and γ grain coarsening. Furthermore, TEM observations revealed that a considerable amount of Nb(C,N) particles exist near large eutectic MnS particles. Thermodynamic calculations based on the Scheil's condition showed that the formation of these Nb(C,N) particles was due to segregation during solidification. It was suggested that such local concentration of the precipitate particles in the last solidifying region leads to ununiform distribution of the pinning force that may induce the abnormal grain growth.

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“…The steels were solution treated at 950°C for 300 s to dissolve Cr nitride, and then water quenched to room temperature to avoid N precipitation. The amount of Cr nitrides in the specimen was first filtered by electrochemical method in an electrolyte of methanol with 10%-acetylaceton and 1%-tetramethylammonium chloride, 20) and then the filtered residue was quantified by ICP mass spectrometry. The amount of N as Cr nitrides after the solution treatment was ensured by the analysis as less than 2 ppm for each of the Cr contents.…”

Section: Aging and Precipitation Behaviour In Cr-n Steelsmentioning

confidence: 99%

Improvement of Anti-aging Property at Low Temperature by Cr Addition in Bake Hardenable Ultra Low Nitrogen Steels

et al. 2015

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Analysis of Precipitates and Precipitation Behavior in Nb-Ti Bearing Steels

Cited by 9 publications

References 5 publications

Rapid quantitative analysis of fayalite and silica formed during decarburization of electrical steel

Rapid quantitative analysis of fayalite and silica formed during decarburization of electrical steel

Effects of Concentrations of Micro-alloying Elements and Hot-forging Temperature on Austenite Grain Structure Formed during Carburization of Case-hardening Steel

Improvement of Anti-aging Property at Low Temperature by Cr Addition in Bake Hardenable Ultra Low Nitrogen Steels

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