On measurement of retained austenite in multiphase TRIP steels — results of blind round robin test involving six different techniques (original) (raw)
Related papers
Materials Science and Engineering: A, 2001
The accurate determination of the volume fraction of retained austenite is of great importance for the optimization of transformation induced plasticity (TRIP) steels. In this work, two aluminium-containing TRIP steels are studied by means of magnetization and X-ray diffraction (XRD) measurements. By fitting the field dependence of the approach to saturation in the magnetization curves, the saturation magnetization is determined, which is linearly related to the volume fraction of retained austenite. Moreover, information with respect to the microstructure can be obtained from the fitting parameters and the demagnetizing factor for the magnetization curve. The volume fractions obtained from the magnetization measurements are compared with data from XRD measurements. A discussion of the data suggests that magnetization measurements lead to more reliable results and a more sensitive detection of the retained austenite than XRD measurements.
Influence of surface preparation method on retained austenite quantification
Materials Today Communications, 2020
Phase identification and quantification in multiphase steels has been a major challenge due to the preparation effects and the specificities of the analysis technique. This work aimed to identify and quantify the retained austenite fraction in 15XX class steel, in addition to verifying the best metallographic preparation methodology. X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) methods were used to identify and quantify retained austenite. It was possible to observe the difference between the methods of analysis adopted and to conclude that the XRD quantification results are less affected by surface preparation. Under the conditions reported in this study, electrolytic polishing was found to be the best methodology of surface preparation for EBSD.
Magnetic measurement of retained austenite in sintered steels – benefits and limitations
Powder Metallurgy, 2018
Measuring the magnetic saturation to quantify the retained austenite is a common method, but it is based on a relative calculation. Thus the reference, which ideally should be the same material but without retained austenite, is of extreme importance. This work focuses especially on obtaining the saturation of the reference material by using different models and applying them for determining the retained austenite content of sintered alloy steels. To verify these calculations, additional measurements of the phase fractions by X-ray diffraction were done. As a result, the contents of retained austenite vary significantly when calculating them from the saturation data using different models. Furthermore, the agreement of the results of the magnetic method and those of the X-ray measurement is not quite satisfactory. Especially when using simple approximations (reference = magnetic saturation of plain iron) the differences are very pronounced. However, it is shown that using the presented models results in markedly better agreement between the results of both methods (magnetic and Xray diffraction) than using plain iron as a reference.
Materials Science and Engineering: A, 2015
A method involving the decomposition of the X-ray diffraction (XRD) peaks for the single wavelengths Kα 1 and Kα 2 was used to quantify the amount of retained austenite at levels lower than 5% in lowcarbon high-manganese steels. By applying this method, it was possible to use the two main peaks of austenite (γ) and the two main peaks of ferrite (α) in the calculations, despite the partial overlapping of the (111)γ and (110)α peaks. The diffraction peaks were modeled with the Pearson VII equation using a nonlinear least-squares optimization technique. This allowed the integrated intensities of the XRD peaks to be calculated using only the Kα 1 side. The method was used to measure the levels of retained austenite in samples of a metal-inert gas steel welding rod cooled at the rates of 10 1C/s and 1.6 1C/s. The accuracy of the method was determined by performing six measurements in different directions in both the longitudinal and the transverse section of the 1.6 1C/s sample.
This research compares the difference in determining the austenite amount in SKD 11 tool steel using the micrographic method as opposed to the X-ray diffraction method. Calculating the amount of retained austenite in tool steel using X-ray diffraction analysis requires first taking off the primary carbide content. By etching the SKD11 specimen using Beraha's CdS reagent, the retained austenite, martensite and carbide are shown as white, red and blue regions in the microstructure, respectively. With quantitative metallography, the retained austenite can be distinguished as separate micro-constituents and properly counted. However, the calculated values are lower than those acquired from the X-ray diffraction. It is more accurate to evaluate the amount of retained austenite with carbide by X-ray diffraction analysis.
Site-specific atomic-scale characterisation of retained austenite in a strip cast TRIP steel
Acta Materialia, 2017
Knowledge of carbon content in retained austenite (RA) with different neighbouring phases is essential to understand the chemical stability of RA, which is useful for microstructure tuning of transformation-induced plasticity (TRIP) steels. The present study investigates different morphologies and chemical compositions of RA by correlating electron backscattering diffraction, transmission electron microscopy and atom probe tomography. The effect of neighbouring phases, such as polygonal ferrite, bainitic ferrite lath, ferrite in granular bainite and carbides, on the carbon content in the RA is investigated. The results reveal that the film RA morphology does not always have a higher carbon content than the blocky RA; as coarse RA sometimes displays a higher carbon content than the fine RA films or islands depending on the neighbouring phases. The diffusion of carbon and manganese between austenite and ferrite in bainitic ferrite/granular bainite has been explained according to either diffusionless and/or diffusional mechanism of bainitic ferrite formation followed by tempering.
Eff ect of Sample Preparation Method on Volume Fraction of Retained Austenite
2016
Transformation Induced Plasticity (TRIP) steels are mostly used due to high mechanical properties in automotive industry. Especially the mechanical properties of these steels are related to the volume fraction of retained austenite. Therefore, accurate detection of the retained austenite amount is important. In this study, Electron Backscatter Diffraction (EBSD) and color etching methods were performed to measure retained austenite (RA) and phase characterization. Also sample preparation is another important issue for EBSD analyses. Therefore electro polishing and metallographic specimen preparation were carried out and results were compared with each other. The effect of sample preparation method on the volume fraction of the retained austenite was analyzed.
Experimental Analysis of the Austenitic Phase in Steels by the Application of X-Ray Diffractometry
Technological Engineering
Uniform austenite remaining in the microstructure of the martensitic transformation is called the residual austenite. It is undesirable structure in components, due to its slow decay causes dimensional instability in these components and reducing the hardness. There is a change in volume and it generate internal stress which often appear as cracks. The residual austenite is highly undesirable component in the molded parts, as well as the production of gears and bearing components. The article deals with quantification of residual austenite in steels by using the Average peak method by X-ray diffraction. This method applies four separate peaks to determine the amount of austenite.
international journal of iron and steel society of iran, 2016
Transformation induced plasticity (TRIP) steels have a vast application in automotive industry because of theirhigh strength, high ductility and hence excellent energy absorption capacity. These characteristics of TRIPsteels are due to the existence of retained austenite in their microstructures in the ambient temperature, whichtransforms to the martensite phase during deformation. The microstructure of TRIP steel contains various phasesand in the past-published studies mainly the volume fraction of retained austenite was investigated and thereis not a quantitative comprehensive investigation about all phases in the microstructure of this steel. The maingoal in this study is a comprehensive qualitative and quantitative investigation in various phases of TRIP steelmicrostructure. Therefore, a TRIP steel with chemical composition of 0.2C+ 1.43Si+ 1.58Mn was produced andits complicated microstructure which contained ferrite, bainite, martensite and retained austenite was investigatedus...