F40级船板低温韧性机理

Low-temperature toughness characteristics of F40 hull structure steel

通过OM、SEM、TEM、EBSD等手段研究了F40级船板的组织特征以及组织结构对低温韧性的影响,并探讨了低温韧性的机理.结果表明:基体组织为针状铁素体+准多边形铁素体的复合组织,该复合组织具有较高的强度和优异的低温韧性;两种组织之间的界面以及针状铁素体条束之间的界面均为大角晶界,能够对裂纹的扩展起到有效的阻碍作用,增加裂纹扩展功,使得F40级船板具有良好的低温韧性,-80℃的冲击功都可以达到138J以上.

The microstructure characteristics of F40 type hull structure steel and the effect of microstructure on its low-temperature toughness were studied by OM, SEM, TEM, and EBSD. The mechanism of low-temperature toughness was also analyzed. It is shown that the micro-alloyed steel possesses high strength and excellent low-temperature toughness due to a mixed microstructure of acicular ferrite and quasi-polygonal ferrite. The grain boundaries between the two microstructures and the grain boundaries between acicular ferrites are the large boundary, which is pronounced to inhibit cleavage crack propagation and improve the crack propagation energy. The mixed microstructure shows the capability to attain such an excellent low-temperature toughness that the Charpy-V impact energy can reach 138 J at -80℃.