What is the effect of high Si content on 51CrV4 steel

Silicon element (Si) is an important agent of reducing and deoxidizer in the process of smelting 51CrV4 steel: for many materials in carbon steel, it contains less than 0.5% Si, which is generally due to the reduction of Si in the process of the steel brought in by agents and deoxidizers.

Si element can be dissolved in ferrite and austenite to improve the hardness and strength of 51CrV4 steel, compared with manganese, nickel, chromium, tungsten, molybdenum, vanadium and other elements, its effect is second only to phosphorus. But when the silicon content of 51CrV4 steel exceeds 3%, the plasticity and toughness of 51CrV4 steel will be significantly reduced. Silicon can improve the elastic limit, yield strength and yield ratio (σs/σb), and fatigue strength and fatigue ratio (σ-1/σb) of 51CrV4 steel. This is the reason why silicon or silicon-manganese steel can be used as spring steel.