M（M=Mg,Zr,Mg-Zr）添加对FH40船板钢组织与力学性能影响

摘要

In order to reveal the function of Mg, Zr and Mg-Zr micro-alloying in low carbon low micro-alloyed steel, the FH40 ship plates containing different Mg and Zr contents were refined with vacuum induction furnace and rolled with double-stick reversible rolling mill, and the characteristics of casted and rolled microstructure and mechanical properties were investigated with SEM and OM. The results show that after adding Mg or Zr, for the casted microstructure, the pearlite volume fraction is reduced, and that the acicular ferrites are nucleated. The grain size in rolled microstructure is refined by the addition of Mg and Zr, and Mg addition is better than the others. With the addition of 0.072%Mg, the grain size is reduced from 9.69 to 4.31μm. The promoting function of Mg-Zr treatment in microstructure refinement is found to increase in the sequence of Zr, Mg-Zr and Mg. Single Mg addition makes the yield strength, tensile strength, elongationand transverse impact energy (−40℃) of FH40 steel increase to 473 MPa, 605 MPa and 36.5%, 188 J respectively, increasing by 38 MPa, 70 MPa, 68 J and 8% compared with that of FH40 steel without Mg-Zr addition.%为揭示Mg，Zr及Mg-Zr在低合金钢中的微合金化效果，以FH40船板钢为研究对象，利用真空感应炉、450型双棍可逆轧机制备Mg，Zr及Mg-Zr处理工艺实验钢，采用SEM和OM等手段观察实验钢铸态和轧态组织，并对其力学性能进行系统测定。研究结果表明：Mg和Zr加入FH40船板钢中均减少铸态组织中珠光体体积分数，诱导针状铁素体组织的形核。同时Mg和Zr加入也细化钢轧态组织，且单独Mg加入的效果优于单独Zr和Mg-Zr复合加入的效果，当添加质量分数为0.072%Mg时，组织中铁素体晶粒度由基准钢的9.69μm细化至4.31μm。单独加入Mg钢的屈服强度和抗拉强度分别达到473 MPa和605 MPa，伸长率达到36.5%，−40℃冲击韧性达到188 J，与未添加Mg-Zr钢相比，屈服强度、抗拉强度、冲击韧性和伸长率分别提高38 MPa，70 MPa，68 J和8%。