High Mechanical Strength Through Cold Working
To withstand extreme pressures in deepwater and downhole applications, the materials used must combine high strength with sufficient residual ductility. The mechanical performance of VDM Alloy 31 Plus® can be tailored to these loads through targeted cold working. Investigation results show that in the cold-worked state, the material achieves mechanical strength levels comparable to classic age-hardenable alloys like Alloy 718 and exceeds the values of Alloy 925.

An important finding from material testing: cold working does not compromise the material's excellent corrosion resistance. High resistance to localized corrosion attack is fully retained even after strain hardening.

Verified Corrosion Protection for Sour Gas and Seawater
In extensive testing procedures, the corrosion properties of VDM Alloy 31 Plus® were verified under realistic operating conditions:

• Protection Against Pitting and Crevice Corrosion: With a PREN (Pitting Resistance Equivalent Number[1]) of approx. 54, the alloy offers high resistance to localized attack in high-chloride media.
• Resistance in Sour Gas Environments: The balanced contents of nickel, chromium, and molybdenum ensure high resistance to stress corrosion cracking (SCC). In both the solution-annealed and cold-worked states, the material fully meets the stringent requirements of NACE MR0175 / ISO 15156 for downhole applications.
• No Susceptibility to Hydrogen Embrittlement: Unlike other high-strength alloys such as Alloy 725 or Alloy 718, VDM Alloy 31 Plus® shows no sensitivity to hydrogen embrittlement in either the solution-annealed or work-hardened state.
• Behavior in Seawater: In both pure and contaminated seawater, the material exhibits corrosion resistance at least comparable to Alloy 625, qualifying it for offshore cooling and injection systems, among other applications.

PREN = wt.% Cr + 3.3 wt.% * Mo + 30 wt.% * N

Good Processability and Expanded Application Fields
In the solution-annealed state, the material exhibits excellent weldability and is, for example, ideally suited as a liner material for mechanically lined pipes (MLPs).

Due to its property profile, the material covers additional demanding application areas beyond the oil and gas industry: these include the chemical process industry (e.g., handling hydrochloric acid, sulfuric acid, and phosphoric acid), geothermal heat exchangers, waste-to-energy plants, and water treatment systems.

Economic Advantages and Sustainable Manufacturing
Suitability testing for industrial use also includes economic factors. VDM Alloy 31 Plus® eliminates the need for high-cost alloying elements such as niobium, cobalt, or tungsten and reduces the required nickel content compared to many age-hardenable standard alloys.

In addition, the material offers a physical weight advantage: with a density of 8.08 g/cm³, it is lighter than Alloy 718 (8.26 g/cm³) or Alloy 625 (8.47 g/cm³), leading to a higher material yield per kilogram of purchased material.

As a so-called "lean nickel alloy," the material allows for a higher scrap ratio during manufacturing.

VDM Alloy 31 Plus® is available in various product forms, including hot- and cold-rolled sheet, strip, hot- and cold-worked bars (up to 200 mm in diameter), welding consumables, and powders for additive manufacturing processes.