热处理及NbV-N微合金化对船板钢组织性能的影响

为了获得一种良好强韧性匹配的390MPa级船板钢,通过NbV-N复合微合金化及不同热处理工艺(正火+回火、淬火+回火),对实验室钢板的室温拉伸、-40℃冲击性能及钢的微观组织、析出相等进行了分析研究。结果表明,钒、铌的添加能细化晶粒,且氮质量分数的增加使得这种细晶效果更为显著,从而使得钢的强韧性,特别是冲击韧性明显提升。相比轧态,正火+回火、淬火+回火热处理后钢的力学性能均有明显提高,特别是低温韧性有明显改善,这得益于回火过程中大量微合金碳氮化物的弥散析出及钢的有效晶粒尺寸的显著细化。

Effect of heat treatment process and NbV N microalloying on mechanical property and microstructure of grade ship plate steel

In order to obtain a 390 MPa grade ship plate steel with good strengthen and toughness matching, the NbV N composite microalloying and different heat treatment process（normalizing＋tempering or quenching＋tempering）were applied, and the room temperature tensile properties, impact properties at －40 ℃, microstructure and precipitated phase of the laboratory steel plate were analyzed. The results showed that the addition of V and Nb can effectively refine the grain size, and the increase of N mass fraction can make the fine grain effect more obvious, which can result in the increase of the strength and toughness, especially the impact toughness. Compared with the hot rolling state, the normalizing＋tempering and quenching＋tempering states could significantly improve the mechanical properties of steel, especially the low temperature toughness, which benefited from a large member of the dispersed precipitations of the microalloyed carbonitrides during tempering and the obvious refinement of the effective grain size in steel during the normalizing/quenching＋tempering process.