The nickel content of super duplex stainless steels is only around 5%, so their pricing is far less exposed to nickel volatility than nickel alloys, which can carry 40-60% nickel. That makes super duplex stainless steels a more stable choice when nickel prices move sharply.

All metals face pricing pressure from inflation, energy costs and wages. But raw materials have proved far more volatile, and of all the materials used in stainless steels and nickel alloys, nickel has the greatest effect on short-term pricing.

Graphite electrode surcharge

Steel mills using electric arc furnaces - the default process for stainless steel and nickel alloys - introduced a graphite electrode surcharge in recent years. Once a basic consumable, graphite supply tightened through 2017 and 2018. China, one of the largest producers, cut output by up to 30% over local environmental concerns, and anticipated demand for lithium-ion battery production fuelled price speculation.

To protect supply for local steelmakers, China and India imposed 20% export tariffs. European mills responded with an additional surcharge of up to EUR 30/t, or EUR 0.03/kg.

Nickel price volatility

Historically, nickel has traded anywhere between $8,000 and $55,000 per tonne. The spike to historic highs in 2006/7 helped encourage further uptake of super duplex stainless steels: the cost gap between super duplex and nickel alloys was much wider, and month-to-month volatility made project pricing risky.

Prices have been far more stable over the last 10 years, but recent increases still bite. In June the London Metal Exchange nickel price was $12,000/t; by August it had surged to $16,000/t. Market watchers suggested the fundamentals had not changed much and linked the surge to speculation, though Indonesia - a major producer - had threatened to halt exports from 2022 to support future battery production.

For an alloy with a high nickel content of around 60% such as Alloy 718 (Inconel 718, N07718, 2.4668) or Alloy 625 (Inconel 625, N06625, 2.4856), that means a price increase of several pounds per kilogramme. For less rich nickel alloys such as Alloy 825 (Incoloy 825, N08825, 2.4858), where nickel is around 40%, the increase is smaller.

How super duplex helps

For super duplex stainless steels such as Ferralium® 255 (F61, 1.4507), SAF2507 (F53, S32750, 1.4410) and SAF32760 (F55, 1.4501), with a modest nickel content of around 5%, price increases can be measured in pennies rather than pounds.

Nickel prices can be hedged to stabilise a contract or large project, but this adds cost and reduces delivery flexibility. We see customers taking several approaches to limit price increases and volatility:

  • Exploring whether Alloy 718 can be switched for Alloy 925, which offers similar strength at lower alloy content.
  • Reviewing whether super duplex stainless steels can replace nickel alloys. Super duplex grades offer excellent corrosion performance and strength but a narrower operating temperature range - generally not above 250degC, whereas Incoloy 825 can be used up to 540degC. Super duplex impact toughness also falls off at very low temperatures, whereas for nickel alloys any decline is more gradual.
  • Exploiting the higher strength of Ferralium® 255 - a minimum yield strength above 85ksi, against above 80ksi for S32750 and S32760. As alloy prices rise, that 6-7% benefit becomes even more worthwhile.

We carry an extensive stock of duplex, super duplex and nickel alloys, offering competitive spot prices and advice on managing purchasing to limit price risk.