纵向变厚度EH40钢板的组织和性能

Microstructure and Properties of Longitudinally Profiled EH40 Steel Plate

采用拉伸、冲击、硬度、OM和TEM等方法研究纵向变厚度EH40钢板的组织和性能。结果表明,由于EH40钢板的薄端和厚端的制备工艺过程不同,其纵向的组织和性能呈现多样化;随着钢板厚度的增加屈服强度由534 MPa降低至489 MPa,抗拉强度由599 MPa降低至569 MPa。在-60℃进行冲击实验时,钢板薄端的冲击吸收能量大于200 J,而厚端的冲击吸收能量出现波动。钢板厚端的晶粒尺寸比薄端的粗大,贝氏体的含量低。在30 mm和40 mm位置全厚度都有贝氏体组织,厚度为8 mm时50 mm位置的贝氏体组织全部消失。薄端和厚端的析出相均为(Nb,Ti)C,但是薄端析出相的数量多、尺寸小,厚端析出相的数量少、尺寸大。

The microstructure and mechanical properties of the longitudinally profiled EH40 steel plate with the specification of(30~50) mm×2600 mm×3000 mm were investigated by means of tensile test, impact test, hardness test, optical microscope and TEM. Results show that the microstructure and mechanical properties of the longitudinally profiled steel plate is diverse due to the experienced different processes of the thin end and thick end. As the thickness of the steel plate increases the yield strength decreases from 534 MPa to 489 MPa, while the tensile strength decreases from 599 MPa to 569 MPa.When the impact temperature is-60 oC, the absorb energy is over 200 J for the thin end of steel plate,while the absorb energy fluctuates for the thick end. The grains of the thick end with lower bainite content are larger than those of the thin end. There is Bainite within the full cross section for where with the plates of 30 mm and 40 mm in thickness. However, all the bainite disappeared for where with the plates of 8 mm and 50 mm in thickness. The precipitated phases of both the thin ends and thick ends are(Nb, Ti)C. For the plate at the thin ends, there exists large amount of precipitated phases with small particle size, whereas small amount of precipitated phases with large size for that at the thick ends.