摘要
Heterogeneous microstructure-induced mechanical responses in EH420 shipbuilding steel welded joint by electro-gas welding processed have been systematically studied by scanning electron microscopy,electron backscatter diffraction and mechanical testing.Comparing with the coarse-grained heat-affected zone(CGHAZ),the weld metal presents higher toughness(129.3 J vs.37.3 J)as it contains a large number of acicular ferrites with high-angle grain boundaries(frequency 79.2%)and special grain boundary∑3(frequency 55.3%).Moreover,coarse austenite grains in CGHAZ and slender martensite–austenite constituents between bainite laths may likely facilitate crack propagation.Polygonal ferrites and tempered pearlites formed at the junction of the fine-grained heat-affected zone and the intercritical heat-affected zone induced a softened zone with an average hardness of 185 HV0.5,which is the main reason for the occurrence of tensile fracture.
基金
the National Natural Science Foundation of China(Grant Nos.U20A20277,51861130361,51861145312,51850410522,5201101443,and 52011530180)
the Newton Advanced Fellowship by Royal Society(Grant No.RP12G0414)
the Royal Academy of Engineering(No.TSPC1070)
the Special Fund for Key Program of Science and Technology of Liaoning Province(Grant No.2019JH1/101000014)
the Research Fund for Central Universities(Grant Nos.N172502004 and N2025025)
the Xingliao Talents Program(Nos.XLYC1807024 and XLYC1802024)
the Regional Innovation Joint Fund of Liaoning Province(No.2020-YKLH-39)
funded in part by the National Research Foundation of South Africa(No.BRICS171211293679)。