602

Mainly used for joining similar materials, offering excellent creep and oxidation resistance up to around 1200 °C, thanks to the addition of aluminum. It demonstrates exceptional fatigue resistance in both HCF (high cycle fatigue) and LCF (low cycle fatigue) modes. It also possesses excellent high-temperature corrosion resistance in environments undergoing carburization and oxidation/oxychlorination, as well as in 'metal dusting' conditions. Typical applications include radiant tubes, furnace muffles, rotary and vertical furnaces, rolls and other furnace components, methanol and ammonia synthesis, hydrogen production, reformers in the chemical and petrochemical industries, as well as in exhaust systems for automobiles.

The nominal composition (wt. %) of filler metal of this classification is 63 Ni, 25 Cr, 9.5 Fe, and 2.1 Al.

High-carbon Ni-Cr-Fe alloy with a face-centered cubic microstructure.

Nickel-chromium-iron-aluminum alloy type UNS N6025 to itself and Nickel chromium-iron to steel and to other nickel base alloys.

• EN W.Nr.: 2.4633 (NiCr25FeAlY)
• UNS: N06025
• PROPRIETARY: Nicrofer 6025 HT (VDM)

Before welding or heating any nickel-based alloy, it is essential that the base metal is thoroughly cleaned. Oil, grease, paints, lubricants, marking pencils, temperature-indicating materials, thread compounds, and similar often contain sulfur or lead, which can cause cracking (embrittlement) in the base or filler metal if present during welding or heating. It is recommended to clean the weld area (on both sides) and the filler material (welding rods) with acetone. The application of a non-weaving technique is preferable to ensure low heat input (max < 1 kJ/mm) and the interpass temperature should be maintained below 120 °C. Normally, pre- or post-weld heat treatments are not required. However, to reduce the risk of stress relaxation cracking in materials exposed to operating temperatures between 600 and 725 °C, following cold work and/or repair welding, an annealing treatment can be considered.