Much attention is paid to ship design, navigation systems, and cargo handling techniques, but one crucial component remains largely overlooked: steel springs. These small but essential elements are pivotal in stabilising loads, mitigating the impact of powerful forces, and protecting valuable cargo from damage.

A ship in transit is never truly at rest. Even in seemingly calm waters, a vessel is constantly subjected to dynamic forces, from the powerful vibrations of its engines to the rolling and pitching caused by ocean currents. The challenge intensifies in rough seas, where acceleration, deceleration, and uneven surfaces in storage holds amplify the stress placed on cargo. Without effective shock absorption, the movement of goods can lead to shifting loads, structural strain, and, in extreme cases, significant damage.

In addition to securing cargo, steel springs play a critical role in other parts of a vessel’s infrastructure, such as in engine mounts, where they dampen vibrations and prevent excessive wear on crucial mechanical components. In suspension systems, they help maintain the stability of the ship, improving safety and efficiency. Propulsion components also rely on the unique properties of spring steel to withstand the intense forces involved in driving a vessel forward.

Material selection for steel springs

Material selection is a crucial factor in ensuring the longevity of these springs in maritime applications, and not all steels are created equal. Their composition plays a defining role in how well they perform under harsh conditions, requiring elasticity, yield strength, and resistance to mechanical fatigue to ensure that they perform reliably under continuous stress. Cyclic loading (constant compression and decompression) can lead to material fatigue, reducing the steel’s ability to return to its original shape. Additionally, temperature fluctuations cause expansion and contraction, which can weaken the structural integrity of the spring.

The consequences of spring failure in a ship can be severe. A broken or weakened spring in a cargo hold can result in cargo shifting uncontrollably, leading to potential damage, financial losses, and even safety hazards. In engine mounts, failing springs can cause excessive vibration, leading to mechanical inefficiencies and increased maintenance costs.

9RU10 is a high-performance precipitation-hardened stainless steel, specifically engineered by Alleima for demanding applications where strength, elasticity, and fatigue resistance are important. Unlike conventional spring steels, 9RU10 undergoes a specialised heat treatment ageing process that enhances the precipitation of particles within its microstructure, significantly improving its resilience under repeated stress.

According to Mikael Hansson, product specialist at Alleima: “All our spring steels are thoroughly evaluated regarding fatigue resistance through extensive testing in our advanced R&D facility. During production, we keep tight control of the mechanical properties, which are very important for the material’s fatigue resistance.”

The ability to tailor the mechanical properties of Alleima’s spring steel is another significant advantage in shipbuilding. “We can tailor-make the mechanical properties to fit the customer’s needs for individual applications,” Hansson adds. This flexibility allows shipbuilders to optimise performance, ensuring that each component, whether it be a suspension system, an engine mount, or a cargo-hold stabiliser, meets the precise demands of its function.

Looking ahead

Sustainability is becoming an increasingly important factor in materials selection across industries, and maritime engineering is no exception. In recent years, there has been a growing emphasis on using recycled materials to reduce the environmental footprint of industrial production. At Alleima, the average recycled content in all heats of 9RU10 during 2024 was 82%, and they have committed to the Science Based Targets initiative (SBTi) with short- and long-term plans to meet CO2 reduction goals by 2030 and reach net zero by 2050.

As global trade continues to expand, the demand for safe and efficient cargo transport remains as strong as ever. While steel springs may not attract the same level of attention as advanced navigation systems or state-of-the-art propulsion technology, their contribution to maritime logistics is undeniable. By ensuring load stability, minimising damage, and supporting critical ship functions, they play a quiet but essential role in keeping the world’s goods moving safely across the seas.

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