The properties of thick-sheet steels of the 0.09% C – 1.5% Mn – 0.035% Si – (0.04 – 0.09)% Nb system (steel type 09G2B) with low (up to 0.10%) additions of niobium are analyzed. The main mechanisms of the influence of microalloying on the microstructure and mechanical properties of the steels are considered, i.e., suppression of the growth of austenite grains in heating for rolling, deceleration of the processes of recrystallization of hot-deformed austenite, refinement of grains, and precipitation hardening with particles of Nb(C, N) carbonitride in cooling after the rolling. The conditions for microalloying with niobium raising the strength properties and lowering the cold shortness threshold or, on the contrary, affecting positively the impact toughness without changing the strength are determined.

分析了 0.09% C – 1.5% Mn – 0.035% Si – (0.04 – 0.09)% Nb 系（钢类型 09G2B）、铌添加量低（最高 0.10%）的厚钢板的性能。考虑了微合金化对钢的显微组织和力学性能影响的主要机制，即抑制轧制加热中奥氏体晶粒的长大，减缓热变形奥氏体再结晶过程，细化晶粒，在轧制后的冷却中用Nb(C,N)碳氮化物颗粒进行沉淀硬化。确定了用铌进行微合金化提高强度性能和降低冷脆性阈值，或者相​​反，在不改变强度的情况下对冲击韧性产生积极影响的条件。