Pearlite

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

Effect of hot rolling reduction on microstructure, texture and ductility of strip-cast grain-oriented silicon steel with different solidification structures

Abstract: Grain-oriented silicon steel as-cast strips with the average ferrite grain sizes of 161 μm and 367 μm were produced by twin-roll strip casting. Then the as-cast strips were reheated and hot rolled with different reductions of 5–50%. The microstructure and texture evolution were investigated by optical microscopy, X-ray diffraction, and electron backscattered diffraction methods. The elongations of the hot rolled strips were examined by the tensile tests and the fracture surfaces were observed by scanning electron microscope. It was found that the microstructure of both as-cast strips consisted of ferrite and martensite. The microstructure of all the hot rolled strips was composed of ferrite and pearlite and it was gradually refined with increasing hot rolling reduction in spite of different initial solidification structures. The hot rolled fine-grained strips showed much finer microstructure at the same hot rolling reduction and thus gave rise to higher elongations. A total reduction of more than 30% was required for the fine-grained strips to achieve relatively good ductility, while that for the coarse-grained strips was as high as 50%. With increasing hot rolling reduction, α and γ fibre textures were gradually enhanced at the expense of initial {001}〈0vw〉 fibre texture in all the hot rolled strips. Relatively strong Goss texture only evolved in the 50% hot rolled strips in spite of the different initial solidification structures, though the 50% hot rolled coarse-grained strip showed much stronger Goss texture.

On the Eutectoid Reaction in a Quaternary Fe-C-Mn-Al Alloy: Austenite → Ferrite + Kappa-Carbide + M 23 C 6 Carbide

Abstract: Lamellae of ferrite, kappa-carbide, and M23C6 carbide are involved in a eutectoid reaction of an Fe-C-Mn-Al alloy after isothermal holding at temperatures below 923 K (650 °C). These lamellar phases are product phases from the decomposition of austenite during the eutectoid reaction of the quaternary alloy, i.e., austenite → ferrite + kappa-carbide + M23C6 carbide. Since the Al concentration in the steel is higher than that of the eutectoid composition, proeutectoid ferrite and kappa-carbide appear in the austenite prior to the eutectoid reaction to reduce the Al content of the retained austenite. The retained austenite decomposes into ferrite, kappa-carbide, and M23C6 carbide during the eutectoid reaction.

Deformation of cementation

Abstract: Extraction replicas of cementite plates taken from deformed pearlite have shown that cementite is able to deform plastically before fracture of the specimen occurs. The tendency for suitably oriented plates of cementite to fracture and the observed rapid increase in dislocation density with strain are tentatively explained in terms of a dislocation locking mechanism based on ½〈111〉 partial dislocations in the cementite.

Steel material having high ductility and high strength and process for production thereof

Abstract: A process for the production of a steel material comprising rolling a steel material having a structure mainly comprising ferrite or ferrite plus pearlite or ferrite plus cementite at a percentage reduction of area of at least 20 % in a ferrite recrystallization temperature region to achieve such characteristics as a crystal particle diameter of not greater than 3 νm, preferably not greater than 1 νm, an elongation of at least 20 %, a value of tensile strength (TS: MPa) x elongation (El: %) of at least 10,000 or a percent ductile fracture of at least 95 %, preferably 100 %, in an actual pipe Charpy impact test at -100 °C. Particularly, this process yields a steel material containing 0.05 to 0.30 wt.% of C, 0.01 to 3.0 wt.% of Si, 0.01 to 2.0 wt.% of Mn and 0.001 to 0.10 wt.% of Al and having a structure comprising ferrite alone or ferrite and a second phase, wherein the ferrite particle diameter is not greater than 3 νm and the areal ratio of the second phase is not greater than 30 %. An untreated steel pipe having the composition described above is heated to (Acl + 50 °C) to 400 °C and subjected to stretch reduction at a cumulative diameter reduction ratio of at least 20 % in a rolling temperature range of (Acl + 50 °C) to 400 °C. In this case, the rolling process preferably contains at least one rolling pass having a diameter reduction ratio of at least 6 % in the stretch reduction. When the contents of C, Si, Mn and other alloy elements are kept at low levels and stretch reduction is carried out in the temperature range described above, a steel pipe having high ductility and strength and improved toughness and stress corrosion crack resistance can be manufactured and the resulting pipe can be used as a line pipe. The fatigue resistance can be improved, too.