Pearlite

About: Pearlite is a research topic. Over the lifetime, 6028 publications have been published within this topic receiving 65695 citations.

Deformation-induced phase transitions in a high-carbon steel

Abstract: The methods of Mossbauer spectroscopy, X-ray diffraction analysis, electron microscopy, magnetostructural analysis and durometry were used to examine structural and phase transitions in a high-carbon pearlitic steel of the formula Fe–1.37mass% C (U13) during cold deformation (300 K) by compression shear in Bridgman anvils. The dissolution kinetics of a cementite having different morphologies was established. A supersaturated solid solution of carbon in BCC iron, an austenite with a high carbon concentration, and metastable e - and χ -carbides were formed during dissolution of the pearlite. Strengthening of the U13 steel depended on the formation of solid solutions of carbon in iron and precipitation of dispersed metastable carbides facilitating pinning of dislocations.

Barkhausen noise from plain carbon steels: analysis of the influence of microstructure

Abstract: The characteristics of the Barkhausen noise phenomenon are investigated for various crystalline microstructures of plain steels. The measurements of the magnetic Barkhausen noise (MBN) and of the acoustic Barkhausen noise (ABN) are performed using the same magnetisation rate for different materials, specially developed to provide fully reproducible experimental conditions. The MBN fingerprints of single constituent steels (ferrite, pearlite and martensite) are first studied. Then, examples of MBN characteristics for more complex microstructures are presented. The results concerning single constituent steels are discussed in terms of shape, amplitude and position of the MBN and ABN fingerprints, taking into account two main aspects: the elementary Barkhausen events (sources), linked to the interaction of the magnetic domain microstructure with the crystalline microstructure, and the propagation of the electromagnetic waves in the material as well as its detection at the pick-up coil, both strongly influencing the frequency spectrum of the detected signal. This approach enables us to get a better understanding of the dependency of Barkhausen noise on the crystalline microstructure, which is then used to explain the characteristics of MBN observed for more complex microstructures.

Kinetics of austenite-pearlite transformation in eutectoid carbon steel

Abstract: The kinetics of the austenite-to-pearlite transformation have been measured under isothermal and continuous-cooling conditions on a eutectoid carbon (1080) steel using a diametral dilatometric technique. The isothermal transformation kinetics have been analyzed in terms of the Avrami Equation containing the two parametersn andb; the initiation of transformation was characterized by an empirically determined transformation-start time (tAv). The parametern was found to be nearly constant; and neithern norb was dependent on the cooling rate betweenTA1 and the test temperature. Continuous-cooling tests were performed with cooling rates ranging from 7.5 to 108 °C per second, and the initiation of transformation was determined. Comparison of this transformation-start time for different cooling rates with the measured slow cooling of a test coupon immersed in a salt bath indicates that, particularly at lower temperatures, the transformation in the traditional T-T-T test specimen may not be isothermal. The additivity rule was found to predict accurately the time taken, relative to tAv, to reach a given fraction of austenite transformed, even though there is some question that the isokinetic condition was met above 660 °C. However, the additivity rule does not hold for the pretransformation or incubation period, as originally proposed by Scheil, and seriously overestimates the incubation time. Application of the additivity rule to the prediction of transformation-finish time, based on transformation start at TA1, also leads to overestimates, but these are less serious. The isothermal parameters—n (T),b (T), and tAv (T)—have been used to predict continuous-cooling transformation kinetics which are in close agreement with measurements at four cooling rates ranging from 7.5 to 64 °C per second.