This paper mainly used database technology, machine learning, thermodynamic calculation, experimental verification, etc., on integrated computational materials engineering. The interaction between different alloying elements and the strengthening effect of precipitated phases were investigated mainly for martensitic ageing steels. Modelling and parameter optimization were performed by machine learning, and the highest prediction accuracy was 98.58%. We investigated the influence of composition fluctuation on performance and correlation tests to analyze the influence of elements from multiple perspectives. Furthermore, we screened out the three-component composition process parameters with composition and performance with high contrast. Thermodynamic calculations studied the effect of alloying element content on the nano-precipitation phase, Laves phase, and austenite in the material. The heat treatment process parameters of the new steel grade were also developed based on the phase diagram. A new type of martensitic ageing steel was prepared by selected vacuum arc melting. The sample with the highest overall mechanical properties had a yield strength of 1887 MPa, a tensile strength of 1907 MPa, and a hardness of 58 HRC. The sample with the highest plasticity had an elongation of 7.8%. The machine learning process for the accelerated design of new ultra-high tensile steels was found to be generalizable and reliable.

The effect of Ti content on the microstructure and mechanical properties of 1Cr10Co6MoVNbN steel was systematically investigated by comparing a low-Ti steel (LTS, 0.0066 wt.%) with a high-Ti steel (HTS, 0.02 wt.%). Increasing the Ti content was found to markedly alter the precipitate distribution and, consequently, the creep and high-temperature tensile behavior. In HTS, the higher Ti level promoted the preferential formation of (Ti,Nb)N inclusions during solidification; EDS analyses indicated that the matrix of HTS was substantially depleted of Nb, N, Mo, and V relative to LTS, consistent with this preferential nitride formation. In the tempered state, HTS exhibited larger NbC particles that were frequently attached to (Ti,Nb)N inclusions, whereas LTS contained finer, more uniformly dispersed NbC and abundant needle-like Cr₂N precipitates within martensitic laths. These microstructural differences correlated with a substantially higher 100 h creep strain in HTS compared with LTS at 550 °C and 325 MPa, and with a 550 °C tensile strength in HTS that fell below the aerospace standard requirement. Post-creep examination further revealed void formation around (Ti,Nb)N inclusions in HTS, suggesting that these inclusions act as stress concentrators that reduce the effective load-bearing area during creep. The results indicate that strict control of Ti content is essential in Nb–N-strengthened martensitic steels to avoid excessive (Ti,Nb)N formation and the associated degradation of high-temperature mechanical performance.