Freedom of design goes subsea
Imagine creating any component you want, in any geometry, with minimal risk of HISC, reduced machining and welding – in half the time of a forged or cast product. Now imagine using super-duplex stainless steel, which lets you reduce wall thickness by 30-40%. All this and you can still utilize 100% of standard properties in design calculations, according to DNV OS F-101!
HIP products give you a homogenous, fine and super-clean microstructure with ultra-high strength in all directions. This is good to know when you’re battling high pressures at sea depths of 10,000 feet (3,000 meters).
Here you can see the differences in microstructure between standard hot rolled steel (left) and cast steel (middle) compared with the density and low porosity of super-duplex stainless steel (right). The use of “hipped” powder material in our family of duplex stainless steel grades provides an improved design advantage over traditional thick-walled forged or cast infrastructure.
Avoid the risk of HISC
Even the strongest subsea components in forged or cast steel can become brittle and fracture following exposure to high stress in an disadvantageous design with coarse microstructure. Here you see a crack appearing in the microstructure of a standard duplex stainless steel.
This is caused by a coarse microstructure which, in combination with high stress and pressure, facilitates the ingress of atomic hydrogen into the metal matrix formed at the steel surface. Hydrogen diffuses much faster into the ferrite phase. HIPed products avoid this problem due to their fine microstructure (<15 μm), which is presumed to slow the transport of hydrogen and thus the risk of cracks.