Metallurgical Performance

Vistar Technology and competitive edge
Vistar is classified as a super austenitic stainless steel.  With its high strength, excellent fracture toughness and exceptional corrosion resistance it is further classified as a high performance corrosion resistant alloy, HP-CRA.  Vistar is made from readily available, commodity materials: iron, chromium and nickel etc., but its extraordinary properties are actually achieved by the insertion of the non-metallic elemental bonds of 0.75% nitrogen and .003% boron into its structure in the course of the patented melting process.  These give it its unique tight, interlocking and stable atomic structure, and thence its extraordinary properties.
The material has been awarded US and European patents (for its chemical composition and manufacturing process), a UNS designation (indicating a novel composition), and special approval by NACE (recognising its exceptional corrosion resistance).  Significantly it has also obtained approval for use from a number of Blue Chip end users including Statoil, BP, Shell and more recently Exxon Mobil.

Vistar’s Competitive Position
Vistar and its competing HR-CRAs constitute a range of metals and alloys that are known for their strength, ductility, and corrosion resistance. This class of metals consists of stainless steels, nickel-based alloys, and more exotic metals such as titanium and tantalum.
The combination of a material’s properties defines its potential applications. While the properties of strength, ductility and corrosion resistance are key, there are many other characteristics to consider, such as density, strength- to-weight ratio, high temperature creep resistance and thermal conductivity. Based on its combination of material properties, Vistar competes predominantly with nickel-based alloys, high-performance stainless steels, and titanium in non-heat-resistance applications. The following comparisons are examples of the differentiation of Vistar from its main competitors:

CAST STRENGTH COMPARISON
VISTAR® has very high tensile strength as-cast, comparable to duplex and super duplex stainless steels and superior to competitive nickel-based alloys.

WROUGHT STRENGTH COMPARISON
VISTAR has excellent tensile strength properties in wrought form, differentiated from competitive corrosion resistant alloys.

Ductility and fracture toughness comparison
Vistar has good ductility and fracture toughness.  It retains excellent fracture toughness at cryogenic temperatures.
5.1.1.1 Low temperature performance

Corrosion resistance comparison
VISTAR has excellent corrosion resistance.  It is cathodic relative to titanium in aqueous galvanic potential. It is also comparable to the most corrosion resistant nickel alloys.

Corrosion Resistance Comparison
Vistar has excellent resistance to pitting, crevice corrosion and stress-corrosion cracking. In the ASTM G28 and G48 tests, its performance is superior to duplex and super-duplex stainless steels, and comparable to nickel alloys.

 
In summary
Compared to its competitors Vistar offers exceptional performance in applications requiring high strength in aggressively corrosive environments.  And it offers this improved performance while being less richly alloyed than these competitors. Advantage is therefore available both to the user in better performance and longer life and to the producer in lower raw material cost.

Life Cycle Cost Benefit
In addition to the above advantages Vistar’s significant life cycle cost savings must also be factored into any commercial equation. The life cycle inventory (LCI), as defined by the International Stainless Steel Forum, namely the total lifetime cost of a product in a given environment over a given life cycle period has yet to be conducted for a Vistar item.  However it is clear that the LCI for Vistar should show further advantage as against competing alloys based on, among others:

  • exceptional life cycle duration; similar to or longer than titanium depending on environment and measurably longer than other HP-CRAs,
  • similar production costs to steel and nickel HP-CRAs but lower costs than titanium,
  • lower fabrication and installation costs than other HP-CRAs (good weldability),
  • lower other installation and maintenance costs (no creep, less spalling, erosion, crevicing and cracking),
  • superior mass-strength-lifespan ratio: being stronger, smaller amounts of Vistar can be used for the same or longer lifespan (comparable to or better than Ti),
  • no additional material costs during lifetime, and, probably the biggest economy of all
  • minimal lost production costs.

Whilst evidence is anecdotal at this stage, components made from Vistar are now being opened up for inspection after periods of service in various exceptionally hostile applications.  So far none has failed and some have already been in place for 6 times, and more, longer than parts made of other HP-CRAs.
Using guidelines such as “EFC32” produced by the European Federation of Corrosion, for the oil and gas industries, the management team will carry out further research and analysis during Phase 1, in order to quantify the full inventory of Vistar’s life cycle benefits, and ensure that an appropriate portion of such benefits is reflected in a premium to be applied once market acceptance has been confirmed.

Proprietary Technology and Intellectual Property Rights
Trevor Machin was awarded title of the US patent 6,632,395 81 dated October 14 2003 and The Village Partnership was awarded title of the European Patent 1147328 dated January 28th 2004.