1, Alloying elements in stainless steel mainly play a role in the following aspects.
(1) Promote the formation and stabilization of the passive film of steel
(2) Increase the electrode potential of steel
(3) Adjust the structure of steel
(4) Reduce or eliminate the inhomogeneity of the structure in the steel and enhance the stability of the structure
(5) Balance or reduce the adverse effect of carbon on corrosion resistance
(6) Strengthen the matrix of the steel and adjust the mechanical properties of the steel
(7) Improve the performance of cold and hot processing
2,
In addition to the above stainles steel elements, some other elements are added to improve some properties of stainless steel. such as
1, adding cobalt (Co) to improve the hardness of stainless steel,
2, adding vanadium (V) to improve the thermal strength of stainless steel,
3, adding to improve the process performance.
4, Rare Earth Elements (RE) etc.
3,
we have mentioned The roles and effects of each alloying element in stainless steel. we also should point out that stainless steel is the coexistence of multiple elements. Their influence is more complicated than the individual role of each element in stainless steel. Therefore, except the role of each element itself, we should also consider the interaction and influence between them.
4,
For example, in terms of the structure of stainless steel. since carbon, nickel, manganese, nitrogen, and copper are elements that form and stabilize austenite. while chromium, molybdenum, titanium, niobium, vanadium, tungsten, and aluminum are elements that form stable ferrite . When these two types of elements coexist in stainless steel, the structure of stainless steel depends on the result of their interaction. Therefore, there are
1, single-phase ferritic stainless steels
2, austenitic stainless steels, duplex stainless steels,
3, stainless steels that can undergo phase transformation and adjust their properties by heat treatment.
For another example, in order to improve the corrosion resistance in some reducing media, by adding molybdenum element. and to maintain the austenite structure, it is necessary to increase the nickel content in the stainless steel, to balance the influence of molybdenum.
In short, in the analysis and use of stainless steel. when determining the stainless steel heat treatment specification, each alloying element and the comprehensive effect of several alloying elements, should be comprehensively and comprehensively considered.