Microstructural evolution and precipitation strengthening of the newly-developed 20Cr steel were investigated in present work. Three types of precipitates, including G-phase (Ni₁₆Ti₆Si₇, intermetallic silicide), Laves phase (Fe₂Ti, intermetallic compound) and carbide (TiC), were observed and their crystal structures were resolved with combined electrochemical phase extraction, X-ray diffraction and transmission electron microscopy analysis. G-phase particles were observed in the grains and Laves phase occurred at grain boundaries while carbides were present at both of the two sites. A temperature-dependency sketch map for these precipitates was also plotted to illustrate the characteristics of G-particles below 750 °C, Laves phase at 850 °C~1050 °C and carbide below 1150 °C. In particular, G-phase precipitated and had the cubic-cubic orientation with the ferritic matrix, thus showing a strong aging hardening characteristic. Nanodispersion of these G-particles greatly enhanced the yield strength, which was estimated to be up to ~1700 MPa. Finally, theoretical calculations for phase equilibria, critical radius and precipitation strengthening helped to understand the precipitation thermodynamics and strengthening mechanisms for developing high-performance steel by making use of G-phase.

在目前的工作中，对新开发的20Cr钢的组织演变和析出强化进行了研究。三种类型的沉淀物，包括G相（Ni ₁₆ Ti ₆ Si ₇，金属间硅化物），Laves相（Fe ₂观察到了钛（金属间化合物）和碳化物（TiC），并通过电化学相萃取，X射线衍射和透射电子显微镜分析对它们的晶体结构进行了解析。在晶粒中观察到G相颗粒，Laves相出现在晶界，而碳化物存在于两个部位。还绘制了这些沉淀物的温度依赖性示意图，以说明750°C以下的G粒子，850°C至1050°C的Laves相和1150°C的碳化物的特性。特别是，G相析出并且与铁素体基体具有立方-立方取向，因此显示出强的时效硬化特性。这些G粒子的纳米分散极大地提高了屈服强度，据估计屈服强度高达〜1700 MPa。最后，