Microstructural evolution in weld metals was in-situ observed through utilizing a laser scanning confocal microscope at two cooling rates.The specimens with various nickel contents were adopted for the observation.In ...Microstructural evolution in weld metals was in-situ observed through utilizing a laser scanning confocal microscope at two cooling rates.The specimens with various nickel contents were adopted for the observation.In the specimen with low fraction of Ni（≤2 wt.%）,granular bainite microstructure（i.e.broad surface relief）transformation from intragranular nucleation site was in-situ observed,while,lath bainite microstructure originating from grain boundary of austenite was in-situ observed for specimens with high mass percentage of Ni（≥4 wt.%）.With increasing nickel content,the transformation temperature dropped.The prior austenite grain size was initially depressed and subsequently coarsened dramatically with the addition of Ni.The microstructure difference was ascribed to various nucleation sites and growth direction in the matrix.On account of those observations,not only the chemical component,cooling rate and microstructure were systematically correlated,but also the microstructural evolution was definite.展开更多
基金financially supported by National Natural Science Foundation of China (No.51675255)Pre-research of National Basic Research Program of China(2014CB660810)the Rose Willow Outstanding Individual Programs of Lanzhou University of Technology(J201203)
文摘Microstructural evolution in weld metals was in-situ observed through utilizing a laser scanning confocal microscope at two cooling rates.The specimens with various nickel contents were adopted for the observation.In the specimen with low fraction of Ni（≤2 wt.%）,granular bainite microstructure（i.e.broad surface relief）transformation from intragranular nucleation site was in-situ observed,while,lath bainite microstructure originating from grain boundary of austenite was in-situ observed for specimens with high mass percentage of Ni（≥4 wt.%）.With increasing nickel content,the transformation temperature dropped.The prior austenite grain size was initially depressed and subsequently coarsened dramatically with the addition of Ni.The microstructure difference was ascribed to various nucleation sites and growth direction in the matrix.On account of those observations,not only the chemical component,cooling rate and microstructure were systematically correlated,but also the microstructural evolution was definite.
