Prediction of Ac&lt;sub&gt;3&lt;/sub&gt; and Martensite Start Temperatures by a Data-driven Model Selection Approach

Kim, Hoheok; Inoue, Junya; Okada, Masato; Nagata, Kenji

doi:10.2355/isijinternational.isijint-2017-212

Cited by 29 publications

(12 citation statements)

References 15 publications

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“…In the current work, while 18CrNiMo7–6 contains more Ni (1.54 wt%) and less Mn (0.7 wt%), that is, austenite formers, 20MnCr5 contains more Mn (1.17 wt%) and less Ni (0.13 wt%). The effect of Mn on the A c3 temperature of steel is comparable to that of Ni . Thus, to some extent, the different contents of Mn and Ni in two steel grades balance out, at least as far as A c3 is concerned.…”

Section: Resultsmentioning

confidence: 85%

Study of Structural Inheritance of Austenite in Nb‐Microalloyed 18CrNiMo7–6 Steel

Sharma

Bleck

2018

steel research int.

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Structural inheritance (SI) is a phenomenon in which the newly formed austenite retains the prior austenite grain size, shape, and orientation of the previous martensitic, bainitic, or even tempered martensitic microstructure. The present work studies SI in 18CrNiMo7-6 steel with 0.08 wt% Nb and compares it with that in a similar but non-microalloyed steel, 20MnCr5. While a coarse prior austenite grain size (PAGS) and a martensitic, bainitic, or tempered martensitic microstructure are found to be the pre-requisites for the manifestation of SI, heating rate, tempering, and steel composition equally influence its occurrence. The larger the PAGS, the easier is the production of SI. SI occurs with the greatest ease in a martensitic microstructure. Tempering is found to retard SI. The ease of occurrence of SI is this: as-quenched martensite>bainite>tempered martensite. The effect of heating rate is non-monotonic, in that, SI is more likely on very slow (0.05 C s À1 ) or very fast heating (50 C s À1 ; 100 C s À1 ) compared with intermediate heating rates (0.5 C s À1 ; 5 C s À1 ). Nb increases the tendency for SI, but a steel without Nb can also exhibit SI.

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Section: Resultsmentioning

confidence: 85%

Study of Structural Inheritance of Austenite in Nb‐Microalloyed 18CrNiMo7–6 Steel

Sharma

Bleck

2018

steel research int.

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“…Before the isothermal treatments, samples were normalized by austenitizing at 870 • C for 60 min followed by air cooling. Using the empirical formulas available in the literature [26][27][28][29][30][31], the martensite formation start (Ms) temperature for the chemical composition given in Table 1 was calculated approximately as 336 ± 12 • C. The heat treatment conditions applied to the RHA samples are summarized in Table 2 and graphically shown in Figure 3. Before the isothermal treatments, samples were normalized by austenitizing at 870 °C for 60 min followed by air cooling.…”

Section: Methodsmentioning

confidence: 99%

A Comparison of the Ballistic Performances of Various Microstructures in MIL-A-12560 Armor Steel

Konca

2020

Metals

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Due to their advantageous properties, there is a growing interest in developing armor steels containing fully or partially bainitic microstructures. In this study, bainitic and martensitic microstructures were obtained in rolled homogeneous armor (RHA) steel samples and their ballistic protection performances were investigated. RHA (MIL-A-12560) steel samples were subjected to isothermal heat treatments at three different temperatures, where one temperature (360 °C) was above the martensite formation start (Ms) temperature of 336 °C while the other two (320 °C and 270 °C) were below. For the assessment of the ballistic protection performance, the kinetic energy losses of the 12.7 mm bullets fired at the test samples were determined. The promising nature of the bainite microstructure was confirmed as the sample isothermally treated at 360 °C provided approximately 10% higher ballistic protection as compared to the regular RHA sample of tempered martensite microstructure. However, the ballistic performances of the isothermally treated samples decreased as the treatment temperature went below the Ms temperature. Following the ballistic tests, hardness measurements, impact tests at −40 °C, and macro- and microstructural examinations of the samples were performed. No correlation was found between the hardness and impact energies of the samples and their ballistic performances.

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“…As an application of ES-LiR, we will show an example dealing with an estimated formula for the start point of the martensitic transformation (Ms point) of steel. 20) It is known that the Ms point of steel strongly depends on the concentration of alloying elements such as carbon, and many estimated formulas have been proposed over the years. 2123) An example is the following: 23) Ms ¼ 512 À 453C þ 15Cr À 16:9Ni À 9:5Mo þ 217C 2 À 71:5CMn À 67:6CCr…”

Section: Variable Selection In Multiple Regression Analysismentioning

confidence: 99%

Development of Data-Driven System in Materials Integration

et al. 2020

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A Data-driven analysis system developed in the first-term SIP "Structural Material for Innovation" is briefly explained using several practical applications. The developed system is composed of two major systems: the data-driven prediction system and the 3D/4D analysis system. In the data-driven prediction system, the two methods in data science, that is, data assimilation and sparse modeling, are applied to optimize model parameters for the physical and phenomenological models developed in other MI systems, such as the structure and performance prediction and microstructure prediction modules, using experimental and numerical databases. Whereas, in the 3D/4D analysis system, it is demonstrated that the microstructural database can be efficiently utilized to predict mechanical properties, as well as to extract detailed geometrical information concerning the constituent microstructures.

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Prediction of Ac<sub>3</sub> and Martensite Start Temperatures by a Data-driven Model Selection Approach

Cited by 29 publications

References 15 publications

Study of Structural Inheritance of Austenite in Nb‐Microalloyed 18CrNiMo7–6 Steel

Study of Structural Inheritance of Austenite in Nb‐Microalloyed 18CrNiMo7–6 Steel

A Comparison of the Ballistic Performances of Various Microstructures in MIL-A-12560 Armor Steel

Development of Data-Driven System in Materials Integration

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