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Replacement of nickel by nitrogen in stainless steel X45CrNiW was carried out using 10 kg induction furnace at different nitrogen pressure. So, eq. While at time region can result from combined mechanisms.

High Nitrogen Steels : Structure, Properties, Manufacture, Applications

It was also found, the mass gain decreases by increasing the replacement of nickel by nitrogen up to certain content, by further replacement, the mass gain increase. This illustrates the role of nickel in oxidation resistance. Nickel hinders the diffusion of oxygen from outside to inside and also hinder the diffusion of chromium and iron from inside to outside.

The phases of modified stainless steels have been investigated using Scheaffler diagram, dilatometer and microstructure observations. Both partial and total replacement of nickel using 0. On the other hand, the increase of nitrogen content deteriorates the steel ductility. It can be concluded that partial and total replacement of nickel by nitrogen produce stainless steels with stable phase as well as it improves the mechanical properties of austenitic stainless steels at room temperatures.

Three steels with the same base composition were used for recent study[31], having different nickel and nitrogen contents with nickel in the range 0. The effect of soluble and insoluble nitrogen on mechanical properties of stainless steels was studied. Reference steel containing 0. One of the developed steels has 6. The results [31] showed that microstructures of the reference and the developed stainless steels were mainly austenitic phase.

It was concluded that nitrogen content has significant effect on grain refinement; insoluble nitrogen has more significant effect than soluble nitrogen on grain refinement. Partial replacement or total replacement of nickel improves yield and ultimate tensile strength.

[PDF] High Nitrogen Steels: Structure Properties Manufacture Applications (Engineering Materials)

The hardness—of tempered stainless steel after solution treatment— increases by increasing nitrogen content at temperatures of ,,andK. However, it decreases by increasing solution treatment temperature due to enlargement of grain size as soluble nitrogen increases accompanied by decrease in insoluble nitrogen nitrides with increasing solution treatment temperatures. The actual factors, which control the mechanical properties of nitrogen containing austenitic stainless steels may be summarized in the grain boundary hardening, matrix strengthening, the solid solution strengthening and the precipitation hardening.

The difference between predicted and actual strength increases by increasing insoluble nitrogen as a result of increasing the precipitation hardening. Insoluble nitrogen is more significant than soluble nitrogen on grain boundary hardening. The effect of nitrogen content of two types of stainless steels with the same base composition except in nickel and nitrogen contents on the mechanical properties was investigated[32].

Reference and high nitrogen stainless steels were produced in open air in induction furnace. The reference steel has Other alloying elements are 0. The results showed that the partial replacement of nickel by nitrogen increase both yield and ultimate tensile strength from MPa and MPa to MPa and MPa with insignificant change in elongation changed from A new modified austenitic stainless steel has been developed through partial replacement of nickel by nitrogen[33].

Nitrogen stainless steel was produced in 10kg induction furnace under nitrogen pressure, while reference one, AISI steel grade, was produced in open-induction furnace.

P - A high-nitrogen austenitic steel for application in bone surgery

Other alloying elements were 0. The microstructure of produced stainless steels was observed. The influence of grain size, soluble, and insoluble nitrogen on tensile strength and hardness was investigated. The major phase in the modified steel has a fcc structure similar to the reference one, but with finer grains and more expanded lattice. The yield strength and hardness of the nitrogen modified stainless steel were higher than that of the reference one.

On the other hand, the increase of nitrogen content decreases the steel ductility to a certain extent. On the other hand, other advanced technologies have been used to produce steels with higher nitrogen contents, such as pressurised induction furnace, pressurised electro slag remelting, powder metallurgy methods and mechanical alloying. Also, there are different techniques to surface steels and stainless steels by nitrogen such as nitriding gaseous and plasma , and laser. In their studies, they used both open air and controlled atmosphere technologies for production of several grades of steels containing nitrogen.

References 1. Schumacher, USP , August, Mattar, T. Thesis, Helwan University, Cairo, Egypt, Feichtinger H. Stein , G. Kamachi Mudali, U. Ueda, Y. Svyazhin, A.

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Duckworth W. Blickwede, D. Pickering, F. Pickering F. Korchynsky, ASM, 1, Narita, K. Nitrogen bearing stainless steels has been used in applications where a wide variety of adverse conditions, which include cavitation-erosion, erosion-corrosion, pitting and crevice corrosion, are found among others. The use of wear and corrosion resistant materials is vital in components such as industrial valves, impellers, pumps and turbines working in contact with slurry environments and submitted to cavitation damage.

The beneficial effects of nitrogen on the corrosion, erosion-corrosion and cavitation-erosion properties of stainless steels are discussed bearing in mind the distribution of nitrogen and alloying elements in the microstructure of these steels. The beneficial effect of nitrogen on localized corrosion resistance of austenitic stainless steels is reasonably well known at this time, as can be seen from the experimental results reported in literature over the last 20 years.

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Austenitic stainless steels with nitrogen contents up to 0. In duplex stainless steels the positive effect of nitrogen on pitting corrosion resistance is even more enhanced due to the higher solubility of this element in austenite, which is less resistant to this kind of localized attack than ferrite.

Effect of vanadium alloying on hydrogen embrittlement of austenitic high nitrogen steels

As nitrogen is preferentially dissolved in austenite, the pitting corrosion resistance of the whole structure is strongly improved [2]. Electrochemical tests performed in acid solutions containing chloride ions showed that the pitting potential of austenitic increases with nitrogen addition to the microstructure, as shown in Figure 1 [3]. In contrast to the numerous works regarding austenitic steels, information related to the effect of nitrogen on localized corrosion resistance of martensitic stainless steels is scarcely found in literature.

Ono et al. Toro et al. Figure 2. Figure 3. The mechanisms by which nitrogen improves the localized corrosion resistance of stainless and alloyed steels can be summarized as follows [2], [3], [6]:. The hypothesis of pH reduction due to ammonia formation is one of the most widely cited in literature. Nevertheless, some objections have been raised because the cathodic nature of this reaction would not allow to expect significant effects at higher potentials, in which pitting or crevice corrosion is usually observed [6].

On the other hand, the actual influence of nitrogen on the general corrosion resistance of stainless steels has not been clearly established so far. There are reasons to believe in a positive effect of nitrogen when in solid solution, especially if the enhancement in the metallic character of the atomic bonds due to the presence of this element is considered [7]. Nevertheless, a number of experimental results have shown that nitrogen addition to austenitic stainless steels can lead to an increase in the measured current densities in sulphuric, nitric, phosphoric and other acid solutions [8].

In austenitic stainless steels, besides the same effect on passivation, it has been reported a positive influence of nitrogen on the surface capability for regenerating the passive layer after pitting [9]. When a material is submitted to corrosion and wear conditions, their properties have to be strongly improved to prevent the negative effect of synergistic mechanisms acting on the exposed surfaces.

One of the main applications of high-nitrogen martensitic stainless is in the field of the mining and petrochemical industries, in components that work in contact with slurry environments containing chlorides. The technologies for production of nitrogen steel includes arc furnace , induction furnace, electro slag remelting, pressurized induction furnace, pressurized electroslag remelting, powder metallurgy and mechanical alloying - in addition to- the surface technologies such as gaseous solution nitriding, plasma furnaces, laser technology.

Nitrogen became promising alloying element in steel, where nitrogen alloyed different steel grades which have applications in different fields such as transportations, environment technologies, industrial plants civil engineering and equipments,…etc. Development of Production of Nitrogen Steel Nitrogen steel can be produced in open air electric arc and induction furnace, electroslag remelting , under nitrogen pressure pressurized induction furnace, pressure electroslag remelting-PESR- , by powder metallurgy and surface alloying methods.

Corresponding Author: email : a yahoo. Shumacher and others[1] produced nitrogen steels in an open air furnaces. High-nitrogen and nitrogen free commercial grades of ferroalloys and pure elements were used. After solidification, the ingots were examined for porosity and casting defects. Manganese plays an important role in stabilizing the austenitic structure of the steel and in keeping nitrogen in solid solution.

In electric arc furnace, Nb was added to fix nitrogen in steel to improve the resistance to rust as well as the resistance to the attack by acids without impairing surface appearance of the steel. In open air electro-slag refining ESR steel, the nitrogen was found to decrease. The behaviour of nitrogen in ESR depends on initial nitrogen content in consumed electrode, composition of steel to be re-melted, slag composition and consequently the physical properties of slag and re-melting rate.

It was found that in the re-melting of steels that do not contain nitride-forming elements, nitrogen content may be sharply decreased while in the case of steels contain nitride forming elements, the nitrogen content remains constant or decreases slightly[2]. This route of enhancing the N-solubility is therefore restricted to special equipment of higher cost.

Thus, it is generally used in combination with alloying to reach a nitrogen level above that feasible by alloying alone. The nitrogen content in the melt is proportional to PN 2. If it is assumed that the cost of equipment increases with nitrogen pressure, the diverging pressure exponents imply an economical pressure limit[3]. Massive nitrogen alloying of steels in pressuresed induction furnaces is effect via the gas phase.

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The massive nitrogen alloying of mainly austenitic steels in laboratory scale pressurized induction furnaces was reported on as early as and Nevertheless, this type of furnace is excellent suitable for small experimental heats of up to kg. Induction furnace working under nitrogen pressure developed to be its capacity kg. At nitrogen pressure 1. After nitriding the powder is encapsulated and hot — isostatically pressed HIP. Alternatively also a nitriding of powder during the HIP process is possible [3]. The addition of nitrogen increase hardness at the surface, improve wear resistance and corrosion resistances [].

Products and Application of Nitrogen Steel Nitrogen is promising alloying element in steel, and though the application of nitrogen — containing steels is permanently expanding the possibilities of this element however it is still used insufficiently. It wider application is restricted by the more complicated processes of its introduction in comparison with other elements and an increase of the risk of obtaining porous ingots or castings as a result of gas liberation during solidification of steel[8]. In the formable mild steels, which in cold rolled and annealed flat products contain spheroidised carbides, nitrogen has frequently been seen as an embarrassment due to its ability to segregate to dislocations and dislocation sources thereby introducing discontinuous yielding and more specifically strain ageing.

Strain ageing is detrimental for subsequent formability as it leads to stretcher strains. Due to its higher solubility, nitrogen is predominantly responsible for strain ageing compared with carbon. It can also be seen that Mn decreases strain ageing by interacting with nitrogen atoms to form Mn-N clusters which restrict long range nitrogen diffusion. Mn also lowers the nitrogen solubility. Other elements interact in this way with nitrogen, whilst others are such strong nitride formers that they result in nitrides such as AlN and TiN being precipitated, which considerably minimizes strain ageing by decreasing the dissolved nitrogen.

A new nitrogen alloying technique ‐ a way to distinctly improve the properties of austenitic steel

However some strain ageing of a formed component can be advantageous, the increased yield strength conferring denting resistance. Al treated formability mild steels which are stabilized against strain ageing do, however, show the advantage of the nitrogen content in that the precipitation of AlN results in improved deep drawability[]. In the structural C-Mn steels, nitrogen is used in conjunction with an Al treatment in order to achieve a refined ferrite grain size which, together with the increased Mn content of 1.

The high yield strength and low impact transition temperature are achieved basically through ferrite grain refinement, and nitrogen has an effect on this. But nitrogen dissolved in the ferrite also influences the strength and toughness, 0. This solid solution strengthening is relatively small, especially as the solid solubility of nitrogen in ferrite is very limited, but the embrittlement can be most market. Thus nitrogen dissolved in the ferrite must be minmised which is done in the moicroalloyed steels by the additions of V, Nb or Ti, all of which form stable nitrides.

These nitrides have the ability to grain refine the austenite and thereby the ferrite, to retard recrystallisation of the austenite by strain induced precipitation which allows the implementation of controlled rolling processes which so condition the austenite that it transforms to fine grained ferrite, and to precipitation strengthen the ferrite under appropriate processing conditions when a much greater strengthening is achieved than by simple solid solution[12].

Addition of nitrogen to microalloyed steels have been studied by Lagneborg [14] and many authors[13]. The range of nitrogen studied lies below the stoichmetric level with respect to V. Also, Lagneborg [14] studied the effect of nitrogen addition in Ti microalloyed steel.

It was found that the contents of Ti and N must be sufficiently low in absolute numbers and their ratio must be close to stoichiometric or somewhat under stoichiometric with respect to Ti in order to ensure a low precipitation temperature for TiN in the solid state during casting and therefore fine precipitates. They are present used in a wide range of products such as paper machines and other pulp and paper industry machinery, pressure vessels, pipes and heat exchangers as well as offshore application and chemical tankers.

To avoid embrittlement of the austenite [17] the N content of the steel should be kept below 0. The high nitrogen austenitic stainless steels have i high YS, UTS and ductility as well as fatigue strength and fracture toughness. The nitrogen bearing steel with 0. The beneficial of nitrogen in solid state is not to attain strength or hardness but improvement of corrosion resistance. This not only improved the behavior in service but reduced the risk of cracks in large through-hardening cross-sections during quenching.

In the polymer tooling applications the resistance to pitting corrosion was considerably raised. But decrease the ductility and especially the toughness. The finer the ferrite grain size, the lower is the impact transition temperature, and the better the toughness.