论文部分内容阅读
针对400 MPa级海洋工程用热轧H型钢,研究了不同终轧温度时得到的显微组织对-40℃条件下低温冲击韧性的影响。采用光学显微镜、扫描电镜以及透射电镜对两种冲击吸收能量差别较大的试样进行了显微组织观察以及晶粒度、力学性能和显微硬度测定。结果表明,正火轧制过程不同显微组织差异对海工H型钢钢的冲击韧性具有重要的影响。温度较高条件下的魏氏组织和粗大的第二相析出粒子使冲击韧性偏低。因此,采用正火轧制海工H型钢时,片层珠光体+微细铁素体为基体,同时细小均匀弥散分布的第二相粒子是提高韧性的重要保证。
Aiming at the hot-rolled H-section steel for 400 MPa marine engineering, the effect of microstructure on the low temperature impact toughness at -40 ℃ was studied. The microstructures, grain size, mechanical properties and microhardness of the two samples with large difference in impact energy absorbed by optical microscope, scanning electron microscope and transmission electron microscope were measured. The results show that the difference of microstructure during the normalizing and rolling process has an important influence on the impact toughness of H-section steel. The Wiegand structure and coarse second phase precipitated particles under the high temperature make the impact toughness low. Therefore, the use of normal-rolled H-beam offshore engineering, the lamellar pearlite + fine ferrite as the matrix, while the small uniform dispersion of the second phase particles is an important guarantee to improve toughness.