Precipitation of Iron Carbides in Tempered Martensite

Abstract

The precipitation of carbides in 0.7 wt%-carbon steel as a function of tempering temperature has been studied through the Mössbauer effect, magnetic measurements, and x-ray observations. The magnetic behavior of the extracted precipitates is discussed. The tiny clusters obtained by extraction after the early stages of tempering (up to 250°C) show the relation of these clusters to martensitic bct cells (``Johnson clusters''). The results obtained by further stages of tempering (250–500°C) show a decrease in the relative amount of the Johnson clusters, followed by a precipitation of ferromagnetic carbides. The behavior of the internal field, the TC and θD, as a function of the tempering temperature suggests a decrease of the relative carbon content with the increasing tempering temperatures. The Fe3C is formed toward 550°C.

Correlation of the microstructure and fracture toughness of the heat-affected zones of an SA 508 steel

“…Table V shows initial hyperfine parameters of each sample, some cementites should be very fine. This requires an extra spectrum for superparamagnetic cementite, Fe 3 C(s), phase, [14][15][16][17][18] e.g., austenite (fcc-Fe), martensite (bct-Fe), ferrite (bcc-Fe), and carbides (Fe 3 C). The phase fractions were to analyze the sample where martensite and/or bainite are the constituents.…”

“…In this case, quantitative analyother analysis techniques mentioned previously. [14][15][16][17][18][19] ses are also difficult because of the microstructural In this study, phases present in the welded HAZ of an SA complexity. [7] The degree of embrittlement in the LBZ varies 508 steel were identified, and their volume fractions were quantitatively measured using Mössbauer spectroscopy.…”

Phase analysis of two steel work rolls using Mössbauer spectroscopy

“…microscopy, scanning electron microscopy (SEM), and X-Transmission Mössbauer spectra were taken using a 25 ray diffraction analysis. [9][10][11][12][13][14][15] In the present study, Mössbauer spectrothe spectra, the linewidth was kept constant at 0.35 mm/s scopic measurements were carried out on a high speed steel (a practical value based on our experience) except for the roll (HSS roll) and on a nickel-grain cast iron roll (Ni-grain very final step. Disc specimens of 10 to conduct quantitative and qualitative analyses of rolls in mm in diameter and 50 m in thickness were prepared by which many mixed phases are present.…”

“…[6] The Ni-grain roll specimens were tivity, continuous studies on developing rolls with enhanced subjected to the stress-relief treatment only at 450 ЊC for 15 properties in wear resistance, strength, fracture toughness, to 30 minutes after casting without austenitization. [7,8] II shows hyperfine parameters of each phase, [9][10][11][12][13][14] e.g., aus-Mössbauer spectroscopy is advantageous over the aforementenite (fcc-Fe), martensite (bct-Fe), ferrite (bcc-Fe), and cartioned analysis methods, because it can give qualitative and bides (Fe 3 C and Fe 5 C 2 ), with which the least-squares fitting in certain cases quantitative composition of the phases preswas performed on the measured Mössbauer spectra. [1][2][3][4] Because rolls are treatment time of the specimens was decided according to cast in large sizes and cannot go through a subsequent hot that of large commercial rolls.…”

“…The heatand thermal fatigue have been made. [9][10][11][12][13][14][15] In the present study, Mössbauer spectrothe spectra, the linewidth was kept constant at 0.35 mm/s scopic measurements were carried out on a high speed steel (a practical value based on our experience) except for the roll (HSS roll) and on a nickel-grain cast iron roll (Ni-grain very final step. deformation process, the cast structure composed of coarse After polishing and etching the roll specimens, their carbides is retained, and the matrix alone is transformed microstructures were examined by an optical microscope into tempered martensite by austenitization and tempering and SEM.…”