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Recent Technological Advances: Development and Application of High-Nitrogen, High-Strength Martensitic Stainless Steel

 

Corrosion leads to a loss of precision and performance degradation in components, and can even trigger sudden, catastrophic failures. In rolling bearings, corrosion accelerates fatigue and wear, significantly reducing service life and reliability. Consequently, sectors such as aerospace, marine engineering, and medical equipment strongly advocate for the use of stainless steel bearings to ensure the operational performance and safety of critical components like lead screws and bearings. Traditional stainless bearing steels—primarily the high-carbon, high-chromium martensitic steel 440C (domestic grade 9Cr18(Mo)) and the high-temperature stainless bearing steel BG42 (Cr14Mo4)—contain large carbide particles (50–70 μm). These particles act as initiation sites for corrosion and fatigue, severely compromising corrosion and fatigue resistance. As these materials fall far short of the requirements for long-life bearings and lead screw assemblies in high-end aerospace equipment, there is an urgent need to develop and apply the domestic high-nitrogen, high-strength martensitic stainless steel 30Cr15Mo1N, which offers superior corrosion resistance and longevity.

 

Nitrogen alloying in the high-nitrogen, high-strength martensitic stainless steel 30Cr15Mo1N not only suppresses the formation of large carbide particles but also significantly enhances pitting corrosion resistance and the stability of the surface passivation film, thereby markedly improving overall corrosion and fatigue resistance. Pressurized electroslag remelting (PESR) enables nitrogen content levels exceeding 0.40% in this steel grade. By further reducing carbon content and increasing nitrogen content—as exemplified by the Cronidur30 alloy—the microstructure and carbide distribution of the bearing steel become more uniform and refined (with maximum carbonitride sizes ≤10 μm). Currently, PESR has become the mainstream production process for high-nitrogen, high-strength martensitic stainless steels. Reports indicate that 30Cr15Mo1N produced via PESR exhibits 100 times the corrosion resistance of 440C and a fatigue life more than five times that of M50 and GCr15 steels. Thanks to its high metallurgical purity and fine microstructure—along with excellent low-temperature properties, corrosion and wear resistance, and long contact fatigue life—30Cr15Mo1N has been successfully applied in high-end equipment sectors such as aerospace, medical devices, marine vessels, and high-speed precision machine tools.

 

30Cr15Mo1N, a high-nitrogen, high-strength martensitic steel, stands out as a premier material combining high hardness with superior corrosion resistance; internationally, it is already utilized in components such as ball screw assemblies and bearings for aerospace, marine, and medical applications. Unlike conventional steelmaking, the production of 30Cr15Mo1N requires introducing nitrogen at levels exceeding the solubility limit while ensuring stable, uniform control. This process entails systematic research into a range of technologies: from alloy design optimization and the smelting of master electrodes and electroslag remelting (ESR) ingots to industrial-scale hot deformation and heat treatment, as well as the manufacturing and performance validation of components like aircraft ball screw assemblies and bearings.