Research Of The Effect Of Ce/Zr On The Welding Heat Affected Zone Of FH40 Ship Plate Steel

The development of oxide metallurgy technology has opened up a new path for the research and development of steel for large-line energy welding.At home and abroad,it has also reached a consensus: oxide inclusions can provide core for acicular ferrite nucleation and effectively suppress the influence of welding heat.The grain size of the area grows,but how to obtain oxide inclusions with effective size,shape and distribution is a difficult point in production.The FH40 ship plate steel was selected as the reference steel,and the experimental steel containing Ce,Zr and Ce-Zr composites was smelted to study the influence of different oxidation inclusions in the experimental ship plate steel on the as-cast microstructure,rolled structure and microstructure of the heat affected zone.The research results have important significance for the improvement and improvement of oxide metallurgy theory and the improvement of the quality of aluminum deoxidized steel.For FH40 ship plate steel,Visual-mesh software was used to model,and then the SYSWELD software is used to simulate the welding process of FH40 steel.The distribution of temperature field,the welding thermal cycle curves in different regions and the change curves of the structure composition in the welding heat affected zone are studied,which provides the basis for the subsequent Gleeble thermal simulation welding experiment.According to the chemical composition of a steel mill FH40 ship plate steel,the FH40 ship plate steel used in the composite experiment of Cr,Zr and Ce-Zr was prepared by smelting.The size,shape and oxide inclusions of the cerium,Cr,Zr and Ce-Zr composite experimental steel were investigated.The effects of Ce/Zr inclusions on the as-cast microstructure of different experimental steels were studied,and the effects of Ce/Zr oxide inclusions on the nucleation of intra-crystalline acicular ferrite(IAF)were further discussed.The results show that the experimental steel containing Ce can transform some A1-O in steel into Al-Ce-O,and the average particle size increases.In the containing Zr experimental steel,the inclusions are A1-O,Zr-O,Al-Zr-O is the main one,and the average particle size is 2.567?m.In the containing Ce-Zr composite experimental steel,part of A1-O in steel can be converted into Al-Ce-O,AlZr-O,Al-Ce-Zr-O composite inclusions,the average particle size is 2.624?m;among them,Al-Ce-O,ZrO,Al-Zr-O and Al-Ce-Zr-O can induce the formation of IAF,while A1-O can not Induced IAF production.The ingot was used as raw material.On the basis of forging,the experimental steel was rolled by TMCP process.The microstructure and mechanical properties of different experimental steels after rolling were studied,and the cerium-zirconium oxide inclusions were analyzed during the rolling process.The mechanism of action that induces the growth of IAF nucleation.The results show that the formation of IAF can be induced by Al-Ce-O,Al-Zr-O and Al-Ce-Zr-O in the composite experimental steel containing Cr,Zr and Ce-Zr under the rolling process,as in the as-cast steel.The rolled steel plate was used as the raw material,and the simulation results of SYSWELD software were used to simulate the welding of the experimental steel with Gleeble3500 welding thermal simulator.The effects of cerium-zirconium inclusions in different experimental steels on the microstructure and properties of FH40 ship plate steel welded HAZ were studied.The results show that the addition of Ce,Zr and Ce-Zr composites can refine the microstructure of the HAZ in different degrees,so that the low temperature impact toughness of the HAZ can be improved.Figure57;Table14;Reference 76...