Most modern X80 pipeline steels achieve their high strength by having high-Mn levels, i.e. 1 .5%-2.0wt%, this level also leads to local segregation in the slab and to a heterogeneous microstructure in the final hot band product. The lack of microstructural uniformity along with the presence of M-A constituents often results in a deterioration of the low temperature toughness. This paper reports on the transformation characteristics of M-A constituents in three Nb-microalloyed steels with low-Mn additions continuously cooled after TMP simulations of a HSM process. Martensite/Austenite (M-A) constituents were observed in polygonal ferrite, non- polygonal ferrite and acicular ferrite. Martensite/Austenite constituents usually appeared inside the ferrite grains, along grain boundaries or mixed with acicular ferrite or pearlite. It was also observed that the volume fraction of M-A constituents increased with Mn content andJor decreasing the coiling temperature. The effect of M-A on the low temperature toughness behavior of the steels will also be reported.
Transformation characteristics of M-A constituents in Nb-Ti microalloyed, low-Mn steel and their effect on mechanical properties
Merkmale der Phasenumwandlung der Gefügebestandteile Martensit und Austenit und ihr Einfluss auf die mechanischen Eigenschaften eines mikrolegierten Stahls mit geringem Mangangehalt
MS&T, Materials Science and Technology, 2008 ; 1337-1347
2008
11 Seiten, 17 Quellen
Conference paper
English
Austenit , Bruchzähigkeit , ferritischer Stahl , Hochfestigkeit , kontinuierliche Abkühlungskurve , Korngrenze , Kühlung , Martensit , mikrolegierter Stahl , Niedrigtemperatur , niobstabilisierter Stahl , Niobzusatz , Phasenzusammensetzung , Pipeline , Rohrstahl , Stahlrohr , Titanzusatz , Warmband , Zähfestigkeit
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