To address the technical challenge of excessive TiN inclusions formed by residual Ti in 35MnB steel during preparation, which lead to excessive class D coarse-series non-metallic inclusions, three industrial trials were conducted on 200 mm × 240 mm section billets. The JMatPro thermodynamic software was used to calculate the solidus and liquidus temperatures of the molten steel, and the kinetics mechanism of TiN inclusion precipitation in the solid-liquid two-phase zone was analyzed to clarify the intrinsic relationship between the Ti-N solubility product and the inclusion precipitation behavior. Through macroscopic low-magnification and optical microscopy characterization, the steelmaking and rolling process parameters were optimized specifically, and the influence of process adjustments on the purity of molten steel, microstructure evolution, and mechanical properties was systematically investigated. The results showed that precisely controlling the Ti content within 0.025% to 0.030%, eliminating the RH refining nitrogenation process, and extending the vacuum holding time to more than 15 minutes could effectively reduce the amount and size of TiN inclusions, making the D-class coarse inclusions grade meet the strict requirement of ≤1.0 grade in the technical agreement. The control level of non-metallic inclusions and the stability of the end quenchability of the optimized test steel were significantly improved, and all core technical indicators such as chemical composition, low-magnification structure, and hot upset forging met the agreement requirements. The relevant test data and process experience provided engineering practice and theoretical reference for the precise control of inclusions and process optimization of high-strength wear-resistant MnB steel for construction machinery.

35MnB steel  /  material thermodynamic simulation  /  TiN inclusions  /  process optimization