Ni对高强船板钢显微组织及低温韧性的影响

随着用户对高强船板钢低温韧性要求的日益提高，添加适当含量的Ni元素已成为改善其低温韧性的重要手段。研究了TMCP工艺下，高强船板钢中Ni质量分数(0.3%，0.6%，0.9%）对其显微组织及低温韧性的影响。结果表明，随着Ni含量的增加，粒状贝氏体含量增加，大角度晶界比例提高，晶界间渗碳体数量减小，其形貌特征由仿晶界形向弥散分布的岛状转变；高比例的大角度晶界将提高裂纹传播阻力，提高钢板的冲击吸收功；而沿晶界分布的渗碳体会降低晶界间结合力，恶化钢板的低温冲击韧性。为降低生产成本，同时保证高强船板钢-80 ℃条件下的低温韧性，Ni质量分数控制在0.6%较为适宜。

Effect of Ni on microstructure and low-temperature toughness of high strength ship plate steel

With the increasing demands of users on the low-temperature toughness of high strength ship plate steel,adding an appropriate content of Ni has become an important means to improve its low-temperature toughness.The effect of Ni mass fraction (0.3%,0.6%,0.9%)on the microstructure and low-temperature toughness of high strength ship plate steel was studied under TMCP technology.The results showed that with the increase of Ni content,the proportion of granular bainite and high angle grain boundaries (HAGB)increases,the number of cementite decreases,and it changes from grain boundary allotriomorphic cementite to island distribution cementite.The high proportion of HAGB will increase the resistance during crack propagation and therefore increase the impact absorbing energy of plate.The grain boundary allotriomorphic cementite will reduce the interfacial bonding force of grains and deteriorate the low-temperature impact toughness of the plate.In order to reduce the production cost and ensure the low-temperature toughness of high strength ship plate steel at -80 ℃,it is appropriate to control the content of Ni at 0.6%.