A welding challenge in ship propulsion systems

Fronius Welding Challenge Winner: Duplex steel is a two-phase structure, in which steel containing ferrite formers (such as chrome, titanium or aluminum) is alloyed with steel containing austenite formers (such as nickel or manganese). The ratio is set such that it remains balanced when it cools to room temperature. This gives the material greater strength than conventional chrome-nickel steels, high ductility and deformability, and high resistance to corrosion.

Duplex steel is therefore particularly suitable for the chemical industry, but also for applications in which seawater is involved, just as it is in products from Hamilton Jet Global.The company, with headquarters in Christchurch, New Zealand, has been specializing in propulsion systems for ships and associated control systems for over 35 years.Hamilton Jet manufactures waterjets in New Zealand, and a network of distributors sells them to customers around the world. Amongst other things, the products are used in fire boats and rescue ships, fast ferries, fishing vessels and also in pleasure boats.

Hamilton Jet uses duplex stainless steel to manufacture wear rings for marine waterjet propulsion systems. The wear ring protects the aluminum impeller race from abrasion caused by ingested debris and the rotating impeller. New designs require a joint in this component to be welded. Although Hamilton have experience with keyhole plasma welding of thicker material, the welding of material only 1.5 mm thick has proved a challenge. Hamilton has clear requirements in terms of quality: The weld joints must not have any notches, distortion may only be minimal, and the joining process is not to have any negative impact on the corrosion resistance of the material.

As the senior plant and process engineer, Gary Martin is responsible for all of the necessary equipment, systems and processes being ready for the introduction of a product. It is also up to him to overcome the challenge of welding the duplex steel to the required level of quality. As one of the winners of the Welding Challenge Contests, he has Fronius by his side.

The Fronius Welding Challenge

Special materials, difficult surroundings, high demands on quality and efficiency: When welding, there are all kinds of challenges. Therefore, Fronius Perfect Welding started the Welding Challenge Contest 2017 at SCHWEISSEN & SCHNEIDEN. Around 60 participants submitted their applications, from these the jury determined the three winners. Fronius will involve the prize winners in the development of clever solutions, geared to their respective welding challenge.