The mechanism of the improvement of heat affected zone(HAZ) toughness with nanometer precipitates is discussed in this paper.The austenite grain growth during welding process can be effectively prevented with the aid ...The mechanism of the improvement of heat affected zone(HAZ) toughness with nanometer precipitates is discussed in this paper.The austenite grain growth during welding process can be effectively prevented with the aid of the pinning effect of fine particles,so that the steel plate can be improved in large-heat input welding performance.The oxide metallurgy technology with strong deoxidizers is developed in Baosteel.Large number of nanometer precipitates are formed during deoxidation,solidification and phase transformation processes.With the pinning effect of these fine particles,after welding with large-heat input of 400 kJ/cm,the average austenite grain size is 61μm in HAZ,the average energy absorbed value is 142 J for V-notch Charpy test at - 20℃.展开更多
Submerged arc welding(SAW) and gas metal arc welding(GMAW) experiments of Nb-bearing X80 steel were conducted with high-toughness wires.The inclusions in weld metals were analyzed in terms of their types and sizes.In ...Submerged arc welding(SAW) and gas metal arc welding(GMAW) experiments of Nb-bearing X80 steel were conducted with high-toughness wires.The inclusions in weld metals were analyzed in terms of their types and sizes.In GMAW,the inclusions are primarily Ti, Ca, Si, Al, and Mg compounds with no Nb and are generally less than 0.8 μm in size, whereas, in SAW weld, the inclusions are larger, mostly approximately 2-5 μm in size, and are cored with Ca and Ti, exhibiting obvious oxidation metallurgical features.The SAW joint was hot-deformed, and Nb-bearing nano precipitates were newly found in the weld metal through transmission electron microscopy, and Nb-free core-shell inclusion was found through scanning electron microscopy.The inclusions and precipitates were dispersed in or on the boundaries of acicular ferrite, contributing to acicular ferrite nucleation and grain refinement.展开更多
文摘The mechanism of the improvement of heat affected zone(HAZ) toughness with nanometer precipitates is discussed in this paper.The austenite grain growth during welding process can be effectively prevented with the aid of the pinning effect of fine particles,so that the steel plate can be improved in large-heat input welding performance.The oxide metallurgy technology with strong deoxidizers is developed in Baosteel.Large number of nanometer precipitates are formed during deoxidation,solidification and phase transformation processes.With the pinning effect of these fine particles,after welding with large-heat input of 400 kJ/cm,the average austenite grain size is 61μm in HAZ,the average energy absorbed value is 142 J for V-notch Charpy test at - 20℃.
文摘Submerged arc welding(SAW) and gas metal arc welding(GMAW) experiments of Nb-bearing X80 steel were conducted with high-toughness wires.The inclusions in weld metals were analyzed in terms of their types and sizes.In GMAW,the inclusions are primarily Ti, Ca, Si, Al, and Mg compounds with no Nb and are generally less than 0.8 μm in size, whereas, in SAW weld, the inclusions are larger, mostly approximately 2-5 μm in size, and are cored with Ca and Ti, exhibiting obvious oxidation metallurgical features.The SAW joint was hot-deformed, and Nb-bearing nano precipitates were newly found in the weld metal through transmission electron microscopy, and Nb-free core-shell inclusion was found through scanning electron microscopy.The inclusions and precipitates were dispersed in or on the boundaries of acicular ferrite, contributing to acicular ferrite nucleation and grain refinement.
