Topic
Bainite
About: Bainite is a research topic. Over the lifetime, 9520 publications have been published within this topic receiving 145305 citations.
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01 Feb 1972-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, tensile and compressive stress-strain curves were obtained for several types of microstructures in a variety of steels, including Widmanstatten ferrite-pearlite and ultrafine-grained martensite.
Abstract: Tensile and compressive stress-strain curves were obtained for several types of microstructures in a variety of steels. The strength-differential effect, previously found in martensitic structures, was present in lower, intermediate, and upper bainite and in Widmanstatten ferritepearlite as well as in ultrafine-grained martensite. An equiaxed ferrite-pear lite structure showed no strength differential. The strength differential in martensite increased as test temperature was decreased below room temperature. In several series of tests, the same specimen design was used in tension and in compression to eliminate possible strength variations due to variations in specimen preparation. Several theories which have been proposed for the strength-differential effect are discussed with respect to the present results, and it is shown that most of the previous suggestions are invalid.
89 citations
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TL;DR: In this paper, the effects of quenching temperature on the microstructure and mechanical properties of martensitic stainless steel grade AISI 420 have been investigated using tensile test results.
Abstract: Austenite was stabilized in the martensitic stainless steel grade AISI 420 by means of quenching and partitioning (Q&P) processing. The effects of quenching temperature on the microstructure and mechanical properties were investigated. The specimens processed at low quench temperatures (regime I) had a microstructure consisting of tempered martensite and retained austenite. At high quench temperatures (regime II), fresh martensite was present too. The highest austenite fraction of about 0.35 was obtained at the quench temperature delineating regimes I and II. The amount of carbon in retained austenite increased as the quench temperature decreased. The carbon level of austenite was, however, much lower than the carbon concentrations expected from full partitioning assumption. This was mainly due to the extensive cementite formation in the partitioning step. Stabilization of austenite by Q&P processing was found not to be purely chemical. Austenite stabilization was also assisted by locking, because of local carbon enrichment, of potential martensite nucleation sites in the austenite/martensite boundaries and in austenite defects. The importance of the latter stabilization mechanism increased at higher martensite fractions. According to the tensile test results, the Q&P processed specimen with the highest austenite fraction was not associated with the best combination of strength and ductility. The mechanical stability of austenite was found to increase with its carbon concentration being the highest at the lowest quench temperature. The thermal stability, on the other hand, was almost inversely proportional to the retained austenite fraction, being low at intermediate quench temperatures where the retained austenite fraction was high.
89 citations
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TL;DR: In this paper, an experimental setup has been designed to study the magnetic alignment of two-phase microstructure with the paramagnetic austenite grains aligned as chains or columns along the direction of the field in the matrix of ferromagnetic ferrite phase.
89 citations
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TL;DR: The morphology of martensite in widely varying series of Fe-C, Fe-Ni-C and Fe-Cr-C alloys was investigated using optical microscopy as discussed by the authors.
Abstract: The morphology of martensite in widely varying series of Fe-C, Fe-Ni-C and Fe-Cr-C alloys was investigated using optical microscopy. The effects of formation temperature and alloying elements on the martensite morphology were studied in detail. It was found that in Fe-C alloys, lath martensite forms in alloys with less than 0.8wt% carbon, butterfly martensite forms in alloys with between 0.98 and 1.42wt% carbon and lenticular martensite forms in alloys with more than 1.56wt% carbon. In Fe-Ni-C alloys, four different martensite morphologies form depending upon the formation temperature and composition, and for alloys of a fixed carbon content the martensite morphology changes from lath to butterfly to lenticular to thin plate as the formation temperature is decreased. In Fe-Cr-C alloys, lath martensite forms at high temperature, and below the lath formation temperature mainly {2 2 5}f plate martensite is formed. Based on the results obtained, the importance of the strength of austenite, and the austenite stacking fault energy to the martensite morphology was discussed.
89 citations
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TL;DR: In this article, the effect of titanium addition on the SAW weld metal microstructure of API 5L-X70 pipeline steel was investigated by means of full metallographic, longitudinal tensile, Charpy-V notch and HIC tests on the specimens cut transversely to the weld beads.
89 citations