Microstructure Development for Brittle Fracture Control in Nb Microalloyed Line Pipe Steel  

作　　者：Subramanian Laurie Collins Jitendra Patel 

机构地区：[1]Department of Mat.Sci.and Engg.,McMaster University,Hamilton,Canada [2]Research Department,Evraz Inc.NA,Regina,SK,Canada [3]International Metallurgy Ltd,Nottingham,U.K.

出　　处：《Journal of Iron and Steel Research International》2011年第S1期831-835,共5页

基　　金：CBMM,Brazil;Chinese Government scholarship;Evraz Inc NA,Regina;NSERC,Canada

摘　　要：EBSD characterization of density and dispersion of high angle boundaries was carried out in niobium microalloyed steels of HTP base chemistry with 0.09 wt % Nb,which were thermo-mechanically processed under laboratory conditions.Similar studies were carried out in higher grade (X-100 and above) line pipe steels with different chemistries,which were processed under simulation of industrial rolling conditions.The twin objectives are (i) to understand the effect of chemistry and processing parameters on the density and dispersion of high angle boundaries,and (ii) to correlate the microstructure and density of high angle boundaries with strength and fracture properties.The present studies confirm that refinement of austenite grain size prior to pancaking,large strain accumulation in austenite conditioning,alloy design with high hardenability and high cooling rates are essential to control high density and uniformity of dispersion of high angle boundaries in the final microstructure in order to achieve high strength,toughness,low DBTT and consistently 100% ductile shear in DWTT in thermo-mechanically rolled higher grade line pipe steels.EBSD characterization of density and dispersion of high angle boundaries was carried out in niobium microalloyed steels of HTP base chemistry with 0.09 wt % Nb,which were thermo-mechanically processed under laboratory conditions.Similar studies were carried out in higher grade (X-100 and above) line pipe steels with different chemistries,which were processed under simulation of industrial rolling conditions.The twin objectives are (i) to understand the effect of chemistry and processing parameters on the density and dispersion of high angle boundaries,and (ii) to correlate the microstructure and density of high angle boundaries with strength and fracture properties.The present studies confirm that refinement of austenite grain size prior to pancaking,large strain accumulation in austenite conditioning,alloy design with high hardenability and high cooling rates are essential to control high density and uniformity of dispersion of high angle boundaries in the final microstructure in order to achieve high strength,toughness,low DBTT and consistently 100% ductile shear in DWTT in thermo-mechanically rolled higher grade line pipe steels.

关 键 词：line pipe steel brittle fracture EBSD DBTT high angle boundaries MICROALLOYING NIOBIUM 

分 类 号：TG142.4[一般工业技术—材料科学与工程]