Improving printability and alleviating hot-work challenges with Osprey® HWTS 50

Today’s hot-work applications in use within general engineering are benefiting from additive manufacturing (AM). At the same time, they are facing challenges regarding the choice of material. Osprey^® HWTS 50 hot-work tool steel offers a solution, improving printability. Also, with the alloy design philosophy in HWTS 50, using computational tools as well as a leaner chemical composition, we drive the shift towards a more sustainable future. Principal Metallurgist Faraz Deirmina at Sandvik explains more.

AM is increasingly being used for the manufacturing of tools and dies with the need for intricate cooling channels that conform to the contours of the components. Hot-work applications like these are constantly facing increasing high demands in terms of the performance of additively manufactured dies, and of tool steel properties.

HWTS 50 improves the processability in Laser Powder Bed Fusion (L-PBF), lowering the susceptibility of cold cracking compared with conventional H-class hot work tool steels.

In what ways are Osprey® HWTS 50 reducing challenges in hot-work applications?

“HWTS 50 improves the processability in Laser Powder Bed Fusion (L-PBF), lowering the susceptibility of cold cracking compared with conventional H-class hot work tool steels. Moreover, the alloy design philosophy, using computational thermodynamics and a leaner chemical composition, are part of driving the shift towards a more sustainable future.”

The chemical composition of the tool steel is tailored for improved hot hardness at temperatures exceeding 600 degrees Celsius (1 112 degrees Fahrenheit). Despite lower carbon content than other hot-work tool steels, it ensures a comparable or even enhanced tempering resistance.

Also, the thermal conductivity is higher compared to medium carbon tool steels over a wide range of temperatures. High thermal conductivity is beneficial for applications running at elevated temperatures, such as die casting. It ensures fast and efficient heat dissipation, resulting in shorter cycle times and improved quality of the products.

What was the motivation behind developing Osprey® HWTS 50?

“Laser AM processing of conventional H class hot-work tool steels is challenging because they are difficult to weld. On the other hand, maraging steel alternatives possessing excellent weldability may result in a compromise from a performance viewpoint, especially in hot-work applications. In this regard HWTS 50 offers a solution.”

What application areas is Osprey® HWTS 50 suitable for?

“Typical applications include high-pressure die casting dies, injection molds, hot forming tools, and tool holders. It is primarily developed for laser-based Additive Manufacturing (AM) and is also well-suited for Hot Isostatic Pressing (HIP) and Metal Injection Molding (MIM).”

What makes Sandvik a trusted partner in hot-work applications and Additive Manufacturing?

“We use our profound knowledge in the development of new metal powder alloys, in the melting practice and in atomization parameters to manufacture and introduce cutting edge solutions within general engineering.

With 160 years of metal powder production expertise, we can offer the widest range of alloys on the market, tailored to fit every customer’s need.”

Where and how is Osprey® HWTS 50 manufactured?

“It is manufactured in Sandvik’s production sites in the UK and in Sweden. The technology we use is either induction melting under Vacuum Inert Gas Atomization (VIGA) or melting under argon prior to Inert Gas Atomization (IGA), producing a powder with a spherical morphology which provides good flow characteristics and high packing density. In addition, the powder has a low oxygen content and low impurity levels, resulting in a metallurgically clean product with enhanced mechanical performance.”

Key characteristics of Osprey® HWTS 50:

Processability: improved processability in Laser Powder Bed Fusion (L-PBF), reducing cold cracking compared to conventional hot-work tool steels.
Chemical composition: Optimized for improved hot hardness, tempering-, and thermal fatigue resistance. It features lower carbon content and modified carbide-forming elements to ensure comparable or improved tempering resistance.
Thermal conductivity: Approximately 35 W/mK at room temperature, providing excellent performance in high-temperature applications such as die casting and forging.
Hardness: Depending on tempering temperature, a hardness range of 40 to 50 HRC in combination with excellent tensile and impact properties can be achieved, ensuring the longevity and durability of molds and dies under high-stress conditions.

Application areas for Osprey® HWTS 50:

Mold making: Injection molds.
Extrusion dies: Mandrels and cores.
Hot forging: Dies and components.
Die casting tooling: Hot-gripper dies and related components.
Plastic molding: Molds and dies.
Tool holders: Various tooling applications.
Mold repair: Rebuilding die casting molds via Direct Energy Deposition (DED)