Pearlite

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

Ultra-fine (α+θ) Duplex Structure Formed by Cold Rolling and Annealing of Pearlite

Abstract: The ferrite (α)+cementite (θ) microduplex structure formed by heavy cold rolling and annealing of pearlite was studied in an Fe-1.4Cr-1.0C (mass%) alloy. Cold-rolled pearlite structure is inhomogeneous consisting of three components; (1) irregularly bent lamellae (IBL), (2) coarse lamellae with shear band (CLS) and (3) fine lamellae (FL) as was previously reported by the present authors. Misorientation in α is large in the IBL and near the shear band in the CLS. As rolling reduction increases, the proportion of FL increases. By annealing at 973K after heavy cold rolling, the (α+θ) microduplex structure with α and θ grain sizes less than 0.5 μm is formed. This structure consists of a coarse grain region (dα∼0.4 μm) containing high-angle α boundaries and a fine grain region (dα∼0.2 μm) with low-angle α boundaries by inheriting local orientation distribution in the deformed α structure. The coarse grain region is formed at the deformed region where local misorientation in α is large essentially by recovery under pinning by θ particles. As the annealing is prolonged, the fraction of the coarse grain region increases. The cold-rolled and annealed pearlite exhibits a wide range of strength-ductility balance.

High-voltage Lorentz electron microscopy studies of domain structures and magnetization processes in pearlitic steels

Abstract: Pearlitic steels with volume fractions of pearlite from 5 to 100% have been studied using a high-voltage electron microscope and by measuring the Barkhausen activity. The results indicate that the microstructural parameters that affect the coercivity most strongly are the volume fractions and grain sizes of ferrite and pearlite. In electron microscope studies it was observed that domain walls were particularly strongly pinned in cementite lamellae in pearlite grains. A simple model is derived from these observations, which correctly predicts the coercivity of a large number of steels.

Microstructural modifications and changes in mechanical properties during cyclic heat treatment of 0.16% carbon steel

Abstract: In this work an annealed 0.16 wt% carbon steel was subjected to cyclic heat treatment process that consisted of repeated short-duration (6 min) holding at 910 °C (above Ac 3 temperature) followed by forced air cooling. A typical microstructural development, not so common for low carbon hypoeutectoid steel, was observed. The main features involved were: (i) a substantial grain refinement (mainly at initial stage), (ii) generation of dislocations (at initial stage) and its annihilation (at later stage) and (iii) generation of grain boundary network of cementite and cementite cluster owing to divorced eutectoidal reaction. In low carbon steel, the presence of large proportion of grain boundary areas promoted grain boundary diffusion of carbon during short-duration holding. This phenomenon finally led to the generation of grain boundary cementite network and cluster through divorced eutectoidal reaction. Unlike high carbon steel, the contribution of divorced eutectoidal reaction to spheroidization was not so significant. For higher cycles (5–8 cycles) substantial presence of grain boundary cementite and cementite cluster deteriorated the strength property. However, quite a high strength (UTS = 455 MPa) was achieved for this low carbon steel with two cycles of heat treatment due to fine ferrite grain size, high dislocation density and adequate proportion of fine lamellar pearlite in the microstructure.