Impact of Micro-alloying Elements, Vanadium and Niobium, on the Properties of Steel Reinforcement
The trend in reinforced concrete in the modern world has been to use steel reinforcement with increased levels of strength and ductility in construction work. This necessitates the need for for improved or optimized material strength and durability. The most common approach to meet this need is the use of micro-alloying elements in steel reinforcement, such as vanadium and niobium. This paper aims to analyze and describe the effects these two elements have on the properties of steel reinforcement.
Vanadium is a metal element generally found in group V of the periodic table. In the steel industry, vanadium is a relatively inexpensive yet powerful micro-alloying element which can positively impact the strength and workability of steel reinforcement. Vanadium introduces additional strength to the steel by increasing the dissolution of carbon molecules which readily diffuses into the metal lattice. When in solution, carbon molecules that are held together form a number of chemical bonds known as carbon nanotubes. Carbon nanotubes are stronger than normal carbon molecules and are relatively difficult to break. Therefore, vanadium addition to the steel reinforcement effectively increases its tensile strength, making it more resilient and ductile.
Niobium, like vanadium, is a common element found in the fifth group of the periodic table. The primary benefit of niobium addition is the reduction of grain growth. This also significantly reduces the risk of brittle failure and improves the plasticity of steel reinforcement. In addition, niobium is known to significantly reduce the cost of processing steel, since increased grain size leads to higher energy consumption. The presence of niobium, by reducing the grain size, leads to a cost-effective solution, since the increased cost of reduction is significantly lower than that of larger grains.
Apart from the effects of the two elements separately, their combined action has been studied extensively and has been shown to produce a synergistic effect. When vanadium and niobium are added to steel at the same time, they produce a number of effects which cannot be achieved when each element is added separately. Firstly, the effect of grain refinement is significantly improved. This leads to an improved mechanical strength of the steel, due to the increased solubility of carbon within the steel matrix which is achieved due to the vanadium addition. Secondly, the tensile strength of the steel is increased due to the grain refinement and the higher levels of vanadium. Lastly, the ductility and welding properties of the steel are improved due to the presence of niobium.
To summarize, the addition of vanadium and niobium is essential to create high-performance steel reinforcement suitable for the construction of reinforced concrete structures. The combined synergistic effects of the two elements lead to an improved mechanical strength, increased tensile strength, higher ductility and welding properties of the steel. The positive impacts of these effects effectively make steel reinforcement more efficient and cost-effective in construction work.
