Important factors in stainless steel production

1-1. The decisive role of chromium in stainless steel: There is only one element that determines the properties of stainless steel, which is chromium, and each stainless steel contains a certain amount of chromium. To date, there is no chromium-free stainless steel. The fundamental reason why chromium has become the main element that determines the performance of stainless steel is that after adding chromium to steel as an alloying element, it promotes the internal contradictory movement to develop towards the aspect that is conducive to resisting corrosion damage.

This change can be explained by:

①Cr increases the electrode potential of iron-based solid solution

②Chromium absorbs electrons of iron to passivate iron

Passivation is a phenomenon in which the corrosion resistance of metals and alloys is improved due to the blocked anodic reaction. There are many theories for the passivation of metals and alloys, mainly including thin film theory, adsorption theory and electron arrangement theory.

1-2. Duality of carbon in stainless steel

Carbon is one of the main elements of industrial steel. The performance and structure of steel are largely determined by the content and distribution of carbon in steel. The effect of carbon is particularly significant in stainless steel. The influence of carbon on the structure of stainless steel is mainly manifested in two aspects. On the one hand, carbon is an element that stabilizes austenite, and the effect is large (about 30 times that of nickel), on the other hand, due to the high affinity of carbon and chromium. Large, formed with chromium—a complex series of carbides. Therefore, in terms of strength and corrosion resistance, the role of carbon in stainless steel is contradictory.