Ce对DH36船板钢显微组织和力学性能的影响

Effect of Ce on Microstructure and Mechanical Properties of DH36 Ship Plate Steel

为探究稀土Ce对DH36船板钢显微组织和力学性能的影响,采用真空感应炉熔炼不同Ce含量的DH36船板钢,利用场发射扫描电镜、显微硬度计、冲击试验机、电子万能试验机等设备研究了Ce对DH36船板钢组织、硬度、冲击性能、拉伸性能的影响。结果显示:在DH36船板钢中加入Ce使铁素体和珠光体组织细化。含0.009%Ce的试验钢综合力学性能最好,硬度增幅最大,相比未加Ce的试验钢提升15.6%;抗拉强度由未添加Ce的581.97 MPa提升到643.80 MPa,提升10.6%;冲击功由未添加Ce的162.8 J提升到174.5 J,提升7.2%。加入稀土Ce后,试验钢的拉伸断口和冲击断口形貌得到改善,韧窝数量增多,断口表面的夹杂物类型发生改变,由大尺寸不规则夹杂物变成了小尺寸类球状稀土夹杂物,降低了有害夹杂物引起的应力集中,使断口表面的裂纹源明显减少。

To investigate the effects of rare earth Ce on the microstructure and mechanical properties of DH36 ship plate steel,the DH36 ship plate steels with different Ce contents were smelted in a vacuum induction furnace.The effects of Ce on the microstructure,hardness,impact properties,and tensile properties of DH36 ship plate steel were studied using field emission scanning electron microscope,microhardness tester,impact testing machine,and electro-mechanical universal testing machine.The results show that the addition of Ce to the DH36 ship plate steel refines the structure of ferrite and pearlite.The test steel containing 0.009% Ce exhibits the best comprehensive mechanical properties,with the largest increase in its hardness,which is 15.6% higher than the Ce-free test steel.The tensile strength is increased from 581.97 MPa to 643.80 MPa,which is 10.6% higher.And the impact energy is increased from 162.8 J to 174.5 J,7.2% higher.After adding rare earth Ce,the morphology of the tensile and impact fracture of the test steel is improved,and the number of ductile dimples also increases.The type of inclusions on the fracture surface changes from large-sized irregular inclusions to small-sized spherical rare earth inclusions,reducing the stress concentration caused by harmful inclusions and significantly decreasing the number of crack sources on the fracture surface.