Pearlite

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

Dynamic properties for modeling and simulation of machining: effect of pearlite to austenite phase transition on flow stress in aisi 1075 steel

Abstract: The Pulse-Heated Kolsky Bar Laboratory at the National Institute of Standards and Technology (NIST) has been developed for the measurement of dynamic properties of metals. With this system, a small sample can be pre-heated from room temperature to several hundred degrees C in less than a second, prior to rapid loading in compression at strain rates up to the order of 104 per second. A major focus of this research program has been on investigating the influence of the heating rate and time at temperature on the flow stress of carbon steels, for application to the modeling and simulation of high-speed machining operations. The unique pulse heating capability of the NIST Kolsky bar system enables flow stress measurements to be obtained under conditions that differ significantly from those in which the test specimens have been pre-heated to a high temperature more slowly, because there is less time for thermally activated microstructural processes such as dislocation annealing, grain growth, and solid state p...

Detection of spring steel surface decarburization by magnetic hysteresis measurements

Abstract: Surface decarburization of steel was non-destructively and quantitatively investigated by magnetic hysteresis. Flat samples were prepared from spring steel 54SiCr6 and decarburized layers of different thickness were produced on their surfaces by annealing at 800 °C in air for 1, 4, 8 and 20 h. Three types of treatment were applied on different samples in order to remove the simultaneously appearing surface oxides. The decarburized layers were examined magnetically by hysteresis loops measurements and the results were related to their optically determined depths. The magnetic measurements showed high sensitivity with respect to free ferrite and mixed ferrite/pearlite layers detection even without removal of the oxide layer. The free ferrite layers were easily and quantitatively detected by minor loops measurements with low field amplitude.

The Magnetic Properties of the Ternary Alloys Fe-Si-C

Abstract: The variations in the magnetic properties of iron and iron-alloys, even of supposedly constant composition, has been puzzling to the users and investigators of ferro-magnetic materials ever since the introduction of such materials for electrical apparatus. The author started to investigate this problem over ten years ago at the University of Illinois, and has continued it at the Westinghouse Research Laboratory since 1916, concentrating on iron and iron-silicon alloys. While the results obtained do not eliminate 100 per cent of the difficulties, they go a long way in that direction. It has been found that carbon is largely responsible for the variations, because of the fact that amounts so small as previously to be regarded as traces?less than 0.01 per cent?remain dissolved in the iron in the solid state, even after slow cooling, and have a tremendous influence on the magnetic properties. Of much less effect is carbon precipitated as pearlite, free cementite and graphite, the effect being in the order named. If the effect of dissolved carbon be represented by 100, the effect of carbon as pearlite is 16.5, of carbon as Fe 3 C 2.25, and of carbon as graphite nearly nil. The form assumed by carbon?aside from the carbon in solution?depends largely on the silicon content, and can best be explained by referring to Fig. 29.

Direct Observations of Austenite, Bainite and Martensite Formation During Arc Welding of 1045 Steel using Time Resolved X-Ray Diffraction

Abstract: In-situ time-resolved X-ray diffraction (TRXRD) experiments were performed during stationary gas tungsten arc (GTA) welding of AISI 1045 C-Mn steel. These real-time synchrotron-based experiments tracked phase transforma- tions in the heat-affected zone of the weld under rapid heating and cooling condi- tions. The diffraction patterns were recorded at 100 ms intervals, and were later analyzed using diffraction peak pro- file analysis to determine the relative frac- tion of ferrite (α) and austenite (γ) phases in each diffraction pattern. Lattice para- meters and diffraction peak widths were also measured throughout the heating and cooling cycle of the weld, providing addi- tional information about the phases that were formed. The experimental results were coupled with temperatures calcu- lated by a thermo-fluids weld model, al- lowing the transformation kinetics of the α→γ phase transformation to be evalu- ated. During heating, complete austeniti- zation was observed in the heat-affected zone of the weld, and the kinetics of the α→γ phase transformation were modeled using a Johnson-Mehl-Avrami (JMA) ap- proach. The results from the 1045 steel weld were compared to those of a 1005 low-carbon steel from a previous study. Differences in austenitization rates of the two steels were attributed to differences in the base metal microstructures, particu- larly the relative amounts of pearlite and the extent of the allotriomorphic ferrite phase. During weld cooling, the austenite transformed to a mixture of bainite and martensite. In situ diffraction was able to distinguish between these two nonequilib- rium phases based on differences in their lattice parameters, diffraction peak widths, and their transformation rates, re- sulting in the first real-time X-ray diffrac- tion observations of bainite and marten- site formation made during welding.