| 【文章摘要】 The effect of W on the microstructure and the mechanical properties of ultrahigh strength low alloy steels was carried out. The microstructure of 30Cr3Si2Mn2NiMoNb and 30Cr3Si2Mn2NiMoNbW steels under quenched conditions were investigated by metallographic microscope, scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM). Thermodynamic calculation was also conducted. The results showed that the addition of W made undissolved carbides more and finer, which exerted strong pinning force on migrating packet boundary and improved tensile strength significantly. M 6 C particles in 30Cr3Si2Mn2NiMoNb steel were disappeared above 1193 K, while the M 6 C particles in 30Cr3Si2Mn2NiMoNbW steel were disappeared above 1253 K, the calculation results were in agreement with the experimental. |