Application of Nitrogen-Alloyed Martensitic Stainless Steels in the Aviation Industry

Abstract

Nitrogen in stainless martensitic steels has a beneficial influence on the mechanical as well as on the chemical properties. However the effect of nitrogen is limited due to the rather low solubility of this element. A special alloy development in combination with a pressurized melting technique lead to distinctly higher nitrogen contents. Stainless martensitic steels containing high nitrogen contents are manufactured by VSG today on an industrial scale using the PESR-process (Pressurized Electroslag Remelting). Depending on special applications these steels are available with different chemical analysis under the trade mark CRONIDUR. The basic composition of all CRONIDUR-alloys consists of about 15% Chromium, 1% Molybdenum, 0.15 to 0.35% Carbon and 0.20 to 0.40% Nitrogen. The combination of Cr + Mo + N leads to a superior corrosion resistance of these HNS-steels (HNS: High Nitrogen Steels) in comparison to similar carbon based alloys. Focused on applications with a required minimum hardness of 58 HRC, like stainless bearings or screw shafts, the C+N-content is tuned between 0.60 to 0.80% (Brand: CRONIDUR 30). Additions of max. 0.3% Vanadium and 0.1% Niobium qualifies the brand CRONIDUR 20 for enhanced temperature applications like turbine disks or blades.

Estimation of the Temperature in the Stirred Zone and Cooling Rate of Friction Stir Welding of EH46 Steel from TiN Precipitates

“…Ti usually has a strong affinity to form nitrides, oxides and even sulphides before forming carbides [23], adding elements forming nitrides (e.g. V, Ti) to steel leads to the precipitation of pure V (or Ti) nitrides and thermal stability of nitrides is higher compared to equivalent carbides [24]. It is known that pure TiN requires low amount of Ti in the steel matrix (less than 0.025wt%) and also low carbon content, otherwise other precipitates such as (Mn, Ti)S or Ti (C,N) will be more dominant precipitate depending on the composition of steel [25][26].…”

Dynamic Research of the Split-Pillar Rotation Process for Electroslag Remelting Furnace

“…So when the pillar rotates with the cross arm and electrodes, tremendous rotation torque generates. The rotation torque leads to shaking and backswing of the mechanical system, makes the rotation process to be instability and angle location control to be difficult [3], and even brings threatens to the whole ESR equipment and operators.…”

A new index to estimate the corrosion resistance of aluminium‐containing steel

“…High-nitrogen martensitic steels such as Cronidur 30 have excellent corrosion resistance and have visually no primary carbides. However, manufacturing requires expensive, pressurised electro-slag remelting [11,12] to increase the nitrogen content in the steel. [13] Case hardening with nitrogen or a solution nitriding on low carbon 13 wt% chromium steel is another way to introduce nitrogen into the steel and avoid the formation of no large primary carbide.…”