Cryogenic systems have played a crucial role in almost all of the finest technological achievements of mankind. Cryogenic applications demand materials with a unique combination of properties, which drastically limits the choice of materials. In most other engineering applications, because of wide tailorability of their properties and excellent combination of strength and toughness, coupled with lower cost compared with nonferrous materials, steels have become the preferred/dominant structural material for cryogenic applications. The contradictory requirement of higher strength without compromising toughness at cryogenic temperatures posed considerable challenges and led to the development of large array of steels tailored for specific applications. This review is an attempt to survey the metallurgical aspects, material selection, mechanical property evaluation, and application of various standard and nonstandard steels for cryogenic applications. This review covers the influence of low temperatures on material properties, simulative mechanical tests for property evaluation, metallurgy of steels, and application examples surveying the published literature to date. The review also analyzes the origins of low-temperature toughness, various application requirements, and the work carried out at authors’ laboratories. The issues pertaining to mechanical tests at low temperatures and status of data generation in international scenario have been critically analyzed. Physical metallurgy aspects have been highlighted in the review, and microstructure-property-processing correlations for various steels have also been covered. One of the recent advances in steels for cryogenic applications, high-entropy alloys, which are proposed as alternatives for the conventional steels, have been reviewed, and mechanical property data have been critically analyzed. The potential of additive manufactured steels for low-temperature applications has been reviewed. Finally, this review article discusses challenges in processing–mechanical properties correlation for various grades of steels for cryogenic applications. It also provides useful information for researchers working on steels for cryogenic applications with a glimpse of recent advances made in this area.

We report the epitaxial growth of europium-activated yttrium oxide $({\mathrm{Y}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}\mathrm{:Eu})$ (001) thin films on ${\mathrm{LaAlO}}_{\mathrm{3}}$ (001) using laser ablation deposition at a substrate temperature of 775 °C and 10 Hz pulse repetition rate. The orientation relationship between the films and the substrates is ${\mathrm{[110]Y}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}{\mathrm{\parallel [100]LaAlO}}_{\mathrm{3}}$ and ${\mathrm{[-110]Y}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}{\mathrm{\parallel [010]LaAlO}}_{\mathrm{3}}$ which results in a lattice mismatch of only 0.8%. Transmission electron microscopy (TEM) of the films reveals the single crystalline ${\mathrm{Y}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}\mathrm{:Eu}$ thin film to contain small pores. Scanning transmission electron microscopy (STEM) imaging of the films shows the substrate always terminates with the Al sublattice. Moreover, the STEM reveals that no precipitates of Eu had formed in the films.

The yield strength anomaly (YSA) and dynamic strain ageing (DSA) behaviour of advanced ultra-supercritical boiler grade wrought nickel-based superalloy IN 740H is studied by conducting tensile tests in temperature range 28–930°C and by employing strain rates 1 × 10⁻², 1 × 10⁻³, 1 × 10⁻⁴ and 1 × 10⁻⁵ s⁻¹ followed by extensive electron microscopic examination. Increase in yield strength accompanied by impairment of ductility indicates that YSA exists in alloy IN 740H in temperature range of 650–760°C. The electron microscopic observation confirms that YSA is due to pinning of dislocations by γ′ precipitates and shearing of γ′ precipitates in IN 740H. DSA is observed in the temperature range of 200–500°C and is predominant at 300°C. The nature of serrated plastic flow due to DSA is dependent on the temperature and strain rate.

Hot deformation studies and optimization of hot working parameters and corresponding microstructure evolution were explored in a modified AISI 321 austenitic stainless steel. Hot compression tests were carried out in the temperature range of 800°C–1,100°C and five different strain rates (0.001–10 s⁻¹). Processing maps were developed based on the results of hot compression tests, employing the principles of dynamic materials model and various domains of microstructure evolution were identified. The stable and unstable domains, as well as various domains indicating other microstructural reconstitutive mechanisms, including dynamic recrystallization (DRx), were identified with the aid of a processing map. The domain for DRx was confirmed by microstructural analysis of deformed specimens and also from the inflections in hardening curves. The processing regime for microstructural control was identified, and the results were validated by actual forging trials on a 1,000-T hydraulic forging press. The grain size of laboratory-tested hot-compressed samples and industrially forged billets exhibited excellent correlation. Constitutive equation for hot deformation was also developed for the steel based on hot compression test results.

A low temperature method $(\sim 400°\mathrm{C})$ for nitrogen incorporation in hafnia based dielectrics has been developed for future gate dielectric applications. Hf metal films were deposited on Si substrates in ammonia ambient and were subsequently oxidized under ultraviolet illumination. Using this method, an interfacial layer comprising Hf–Si–O–N bonding was formed at the hafnia-Si interface, which led to a substantial enhancement in the overall dielectric properties of the film. An equivalent oxide thickness of $11.5\mathrm{\AA }$ and leakage current densities lower than ${10}^{-4}\mathrm{A}∕{\mathrm{cm}}^2$ at a gate bias of $-1\mathrm{V}$ were achieved by this approach.