1,09%Materials for the Hydrogen Transition by Aperam Innovation Lab
The competition between the various electrolysis technologies is fully underway – and for each of them, Aperam provides the appropriate materials. Under one roof, manufacturing sites dedicated to stainless steels, nickel alloys and other specialty alloys, precision strip and tubes operate alongside closely interconnected research centres.
Continuity between industrial production and serial application is ensured by an integrated network of service centres deployed across the Group, guaranteeing a seamless transition from innovation to industrialisation and market deployment.
Hydrogen is far more than a simple energy carrier. It embodies the ambition to significantly reduce industrial emissions. The pace at which we will succeed in decarbonising our industrial economies — while preserving their competitiveness — will depend on our ability to secure hydrogen in sufficient volumes, at controlled cost and with a high level of supply security. The processes are known. Some are already proven at industrial scale (AEL). However, innovation remains strong in emerging electrolysis technologies (PEM, AEM, SOEC).
The technologies that will prevail depending on specific applications will also depend on the materials used. These materials must provide very high corrosion resistance, high electrical conductivity and excellent mechanical strength. Such demanding requirements naturally lead to stainless steels and highly alloyed nickel grades. Aperam masters both material families. This makes the energy transition a strategic priority for the Group.
A Clear Technological Direction
To structure this approach, Aperam has established an “Innovation Lab” built on two complementary R&D centres: one dedicated to stainless steels, based in Isbergues, and the other specialised in alloys, located in Imphy. These two hubs work in close coordination and generate industrial synergies, particularly in the development of precision strip and materials with surfaces optimised for the subsequent application of advanced functional coatings.
Mapping technological developments remains complex. To define the right direction in a rapidly evolving environment, Aperam relies on Dr Adolfo Kalergis Do Nascimento Viana. As Head of Market Innovation and Business Development – CCUS, New Energies & Hydrogen, he identifies the areas in which existing Aperam and Imphy solutions already meet market expectations.
Moreover, with a forward-looking perspective, he assesses the most promising material development pathways, as well as the industrial partners capable of contributing to new value chains. In this approach, he leverages synergies between the stainless, alloys and service centre activities.
In the German-speaking market, Adolfo Kalergis is supported by a key partner: Ralf Behle, Senior Business Development Manager for Imphy alloys. Drawing on his field experience, he explains: “In the field of electrolysers, we are confronted with a wide range of material requirements. These extend from ferritic stainless steel grades to pure nickel and titanium. This breadth is also reflected in the fluid exchange of knowledge and experience between Aperam’s two divisions.”
An Approach in Constant Evolution
Several hydrogen production technologies are currently available: alkaline electrolysis (AEL), proton exchange membrane electrolysis (PEM), anion exchange membrane electrolysis (AEM) and solid oxide electrolysis (SOEC). Asked which technology appears the most promising, Kalergis responds: “Directions continue to evolve. Depending on the context, attention may shift from one technology to another. Aperam adopts an open approach and offers a comprehensive portfolio of materials for each of them.”
To date, alkaline electrolysis (AEL) remains the most mature technology and, as such, the most widely deployed. In the future, however, PEM technologies may gradually gain prominence. Today, AEL and PEM together account for nearly 90% of market share, illustrating a technological landscape still largely structured around these two processes.
AEL (left) and PEM (right) remain the dominant technologies today.
For many, the principle of alkaline electrolysis recalls a classroom laboratory experiment. Water becomes conductive through the addition of an electrolyte, whether acidic or alkaline. When two electrodes are immersed and a direct current is applied, oxygen bubbles form at the anode while hydrogen bubbles appear at the cathode.
At industrial scale, this process operates with concentrated alkaline solutions at temperatures ranging from 60 to 90 °C. To withstand these highly corrosive environments, Aperam provides dedicated material solutions. For electrodes and bipolar plates, Nickel 201 alloy stands out for its high corrosion resistance combined with excellent electrical conductivity. Nickel-plated austenitic grades such as Aperam 316L, 316A, 310L and 904L, as well as the duplex grade DX2205, can also represent more cost-efficient alternatives.
For cell housings, enclosures and piping systems, standard austenitic grades such as Aperam 304 (EN 1.4301) or 316L (EN 1.4404) are particularly suitable.
AEL technology is industrially proven and recognised for its robustness. The required investments remain comparatively moderate. Electrical efficiency typically ranges between 60% and 70%. It is primarily suited to large-scale, continuous operations at sites benefiting from stable power supply.
Polymer Membranes: Electrical Conductivity and Corrosion Resistance
PEM electrolysers maintain high efficiency, including under intermittent operation. They are therefore particularly well suited to variable renewable energy sources such as wind and solar power, which are characteristic of many regions in Central Europe. They are also appropriate for smaller-scale installations and decentralised configurations. Operating temperatures remain moderate, typically ranging between 50 and 80 °C. However, the process involves highly acidic environments. Bipolar plates are generally manufactured from titanium or, alternatively, from titanium-coated stainless steel.
Anion exchange membrane (AEM) technology represents a promising alternative. It combines mechanisms characteristic of alkaline electrolysis and PEM technology. Its design is compact, it does not require highly noble catalytic metals, and operating temperatures typically range between 40 and 70 °C.
AEM electrolysers also operate in aqueous environments. Conditions are most often moderately alkaline and pressures relatively low. The materials used must therefore exhibit good corrosion resistance in alkaline media. Kalergis emphasises: “Corrosion resistance and electrical conductivity are closely interconnected. Anyone who has encountered oxidised battery contacts knows that metal oxides are electrically insulating. In an electrolyser, corrosion would not only compromise operational safety, it would also hinder ionic transport and reduce electrical performance.”
For AEM electrolysis, the same materials are used as for PEM technology. The electrical efficiency of both processes is at a comparable level. However, AEM technology is still in the early stages of industrial scale-up, and long-term operational feedback remains limited.
SOEC: High Temperature and Large-Scale Production
Solid oxide electrolyser cells (SOEC) are among the most promising candidates for large-scale, continuous hydrogen production. The electrolysis process, based on ceramic membranes, requires operating temperatures ranging from 650 to 850 °C. In return, electrical efficiency reaches between 80% and 90%. Another major advantage lies in the use of steam as feedstock, enabling part of the required energy input to be supplied in the form of recovered industrial heat, further improving overall system efficiency.
While the potential is considerable, the material challenges are equally significant: creep resistance, fatigue strength, high-temperature oxidation resistance, gas diffusion and coating compatibility. Kalergis explains: “These operating temperatures are not unfamiliar territory for us. Our materials have been used for decades in high-temperature processes, particularly in the chemical industry. Long-term operational data are extensively documented and analysed within our R&D department. They support joint developments with our plant engineering customers and also serve as the foundation for new material solutions developed in close collaboration with stack manufacturers.”
SOEC technology enables the valorisation of waste heat, particularly that generated by data centres.
For interconnect plates, current collectors and end plates, the market is currently moving towards ferritic stainless steels. Several leading electrolyser manufacturers have already validated Aperam grades K41, K44M, K45 and K46. The Imphy 23SO alloy is also under consideration. It stands out for its excellent creep resistance and outstanding high-temperature oxidation performance.
Balance of Plant: A Critical Systemic Role
Beyond the electrolysers themselves, the surrounding components referred to as the Balance of Plant (BoP) — that is, the upstream and downstream installations of the core process — are equally decisive for the proper functioning of the overall system. Kalergis illustrates this complementarity with a clear comparison: “The electrolyser is the heart of the installation; the BoP forms its circulatory system.” This includes, in particular, water treatment and conditioning of the produced gas. The BoP associated with SOEC technology represents a particularly promising example. The rise of artificial intelligence opens significant potential in this area: data centres, which are essential to these applications, generate substantial amounts of waste heat that can be recovered and utilised as process heat for SOEC electrolysis. The high temperatures encountered in heat exchangers and enclosures require creep-resistant materials such as Aperam 309N and 310S, as well as the Imphy 625 alloy.
In terms of material volumes involved, hydrogen treatment and transport infrastructures far exceed the catalytic technologies themselves. Liquefaction, storage and transport of hydrogen would not be feasible without austenitic stainless steels and the iron-nickel alloy Invar® M93. Liquid hydrogen tanks and pipe-in-pipe systems require materials capable of maintaining mechanical strength and corrosion resistance at −253 °C, the boiling point of hydrogen.
The main constraints common to hydrogen applications relate, on the one hand, to material permeability and, on the other, to hydrogen-induced embrittlement. Stress corrosion cracking represents a particularly insidious degradation mechanism: failure may occur without clearly visible warning signs. In this field, safety is paramount. Susceptibility to stress corrosion cracking is closely linked to alloy composition. The selection of the appropriate material is therefore decisive, particularly when corrosive environments, extreme temperatures and cyclic loading are combined. In this context, the Aperam Innovation Lab stands as a reference partner for designers and plant engineering companies.
Carbon Capture: A Lever for Industrial Transition
On the path towards the hydrogen transition, green hydrogen still faces significant obstacles: high production costs, technical challenges related to industrial scale-up, insufficient storage and transport infrastructure, and political uncertainty. In this context, hydrogen production from natural gas is expected to remain, in the short to medium term, an industrial reality — combined with carbon capture, in the form commonly referred to as “blue” hydrogen. Unlike “grey” hydrogen, where carbon from natural gas is converted into CO₂ and released into the atmosphere, “blue” hydrogen relies on capturing the carbon dioxide. It is either stored in deep geological formations, often beneath the seabed (carbon capture and storage, CCS), or utilised as a chemical feedstock (carbon capture and utilisation, CCU).
CO₂ capture represents a structuring step towards carbon neutrality.
Three main technologies currently dominate. The first is pre-combustion, which captures CO₂ before fuel combustion. The second is post-combustion, in which CO₂ is extracted from flue gases after combustion. Finally, oxyfuel combustion involves injecting oxygen during combustion to increase CO₂ concentration and facilitate its separation. At present, the majority of CCS and CCU solutions rely on post-combustion processes. However, oxyfuel combustion is attracting growing interest.
For this application, Aperam’s portfolio offers a comprehensive range of corrosion-resistant materials, starting with standard grades such as Aperam 304, 316A and 316L. In environments with high chloride content and increased mechanical loads, duplex grades — notably DX2205 — become particularly suitable. In the most highly stressed areas, nickel-based alloys from the Imphy range provide an additional safety margin. Pending the large-scale deployment of green hydrogen produced from renewable energy sources, CCS and CCU technologies represent pragmatic solutions to advance the hydrogen transition in a technically reliable and economically viable manner.
Material Synergies and Industrial Capabilities
The materials portfolio of the Aperam Group covers the full spectrum of electrolysis technologies, as well as Balance of Plant components, hydrogen liquefaction and carbon capture. Ferritic grades from the KARA® range, notably K41, K44M and K45, are well established in electrolysis applications due to their strong high-temperature properties, low coefficient of thermal expansion and high electrical conductivity. In this market, the austenitic stainless steel offering extends from Aperam 304M and 316L to grade 316A, up to 309N, 310S and the super-austenitic 904L. Applications subject to high mechanical and corrosive stresses tend to favour duplex grades such as DX2205. The portfolio is complemented by Imphy alloys including INVAR® M93, Nickel 625, 825 and 201.
The available product forms range from precision strip to heavy plate. Stainless steel is also supplied in flat bars and tubes, while the alloy portfolio is available in a wide variety of flat and long products. The Group has extensive expertise in coatings and functional surfaces. The Aperam Innovation Lab places its testing capabilities and material expertise at the service of developments carried out in close collaboration with customers. In partnership with them, new designs and thinner components are developed using advanced forming techniques, while maintaining — and in some cases enhancing — durability and performance.
Installations dedicated to CO₂ emissions reduction should themselves be designed using low-carbon materials. Standard stainless steel grades are also available in versions containing up to 98% recycled content — under the Aperam infinite™ range. Processors can rely on Aperam Recycling (formerly ELG) to valorise their production scrap, thereby contributing to the effective closing of the material loop. Plant engineering companies and component manufacturers benefit, within the Aperam Group, from an integrated infrastructure of service centres offering extensive stock availability and responsive logistics, including for short lead-time requirements. The e-aperam online platform allows customers to check product availability and place orders at any time.
Processors active in hydrogen technologies — or seeking to position themselves in component manufacturing — will find dedicated contacts within Aperam. As a hydrogen applications expert, Kalergis explains: “Aperam Innovation Lab brings together 150 specialists. Customers and partners seeking material advice or technical and scientific support can contact me directly, or reach out to Ralf Behle, in order to mobilise our R&D network on topics related to hydrogen electrolysis and carbon capture.”
Expertise creates value. Aperam puts it at the service of its customers.
Article published in FocusRostrei Magazine– February 2026
