Sanicro®625 is an extremely versatile nickel-chromium-molybdenum-niobium alloy, suitable for use in severely corrosive environments requiring high strength materials. Mainly suited for wet corrosion environments. Service temperatures ranging from cryogenic to 593°C (1100°F).
This grade is characterized by:
- Extremely good resistance to chloride-induced stress corrosion cracking
- Excellent corrosion resistance in widely varying acidic
and chloride containing environments
- Excellent resistance to general corrosion, pitting, and crevice corrosion
- Excellent resistance to corrosion in environments containing hydrogen sulfide
- Very high and even strength the recommended service temperatures
- Very good welding properties
- Good machining and fabrication properties
ASTM: UNS N06625 Grade 1
EN Number: 2.4856
ASTM B 446 (Grade 1), ASME SB-446 (Grade 1)
NACE MR0175/ISO15156, NACE MR0103/ISO17945
Approved by the American Society of Mechanical Engineers (ASME) for use in accordance with ASME Boiler and Pressure Vessel Code, Section I, Section III Div. 1 classes 1 and 3, Section VIII div.1.
Chemical composition (nominal)
Pitting Resistance Equivalent Number, (PRE) >48.
Examples of applications for Sanicro 625
Pollution control equipment
Refuse-derived fuel plants
Solar power plants
Oil & Gas / Refinery
Well construction and service
Gas lift equipment
Wellheads and Christmas trees
Phosphoric acid production
Offshore piping systems
Seawater coolant in industries
Sanicro®625 offers excellent resistance to both reducing, oxidizing, and in mixed corrosive environments. The resistance to marine corrosion / sea water is particularly good.
Sanicro®625 is stabilized against intergranular attack by the niobium content,
and the extra low carbon content. The resistance to IGC is tested acc. to ASTM G-28 Method A (Streicher test). Criteria: Max. 3mm / year.
Stress Corrosion Cracking
The nickel content of Sanicro®625 is at 62 % which promotes an excellent resistance to stress corrosion cracking induced by both chlorides and alkalis.
This makes it virtually immune to chloride-induced SCC, and the resistance to cracking in the presence of H2S and chlorides is very high. According to NACE MR 0175 / ISO 15156-3 it is acceptable for use in the oil and gas industry with no environmental limits in respect of partial pressures of H2S or elemental sulfur.
Pitting and crevice corrosion
Sanicro®625 have an extraordinary resistance to pitting and crevice corrosion in seawater at a variety of temperatures. With PRE number ≥48, Sanicro®625 is one of the grades which is least susceptible to these types of corrosion.
Forms of supply
Diameters and finished condition
Sanicro®625 is stocked in imperial dimensions.
Diameter range: 76.2mm-228.6mm (3”-9”)
Delivery condition: Soft annealed, peel-turned and ground to final finish.
Bars are delivered in random lengths of 3-6.9 m, depending on diameter.
Straightness, metric units
Height of arch, 2 mm/m
Tolerances, metric units
Diameter tolerances: -0 / +0.79 mm
Surface finish: Ra, max. 3µm
The Sanicro®625 stock program bars are delivered in soft annealed and quenched condition. Annealing at min. 910°C (1670°F) followed by quenching in water.
Min. values at room temperature:
|Dimension||Proof strength Rp0.2||Tensile strength Rm||Elongation A5|
|D≤101.9mm||415 MPa / 60 ksi||830 / 120 ksi||30%|
|D>101.9mm||345 MPa / 50 ksi||760 / 110 ksi||30%|
|-60°C Min. values||Longitudinal||Transversal (D>60mm)|
Hardness in the delivery condition is max. 35 HRC.
Density, at 20°C: 8.4 g/cm3, 0.31 lb/in3
|Temperature, °C||W/(m °C)||Temperature, °F||Btu/(ft h°F)|
Specific heat capacity
|Temperature, °C||J/(kg °C)||Temperature, °F||Btu/(lb °F)|
Thermal expansion, mean values in temperature ranges (x10-6)
|Temperature, C||Per °C||Temperature, °F||Per °F|
|Temperature, °C||µΩm||Temperature, °F||µΩin.|
Modulus of elasticity (x103) (annealed condition)
|Temperature, °C||MPa||Temperature, °F||ksi|
Modulus of elasticity (x103) (solution annealed condition)
|Temperature, °C||MPa||Temperature, °F||ksi|
The weldability of Sanicro® 625 is good. Suitable methods of fusion welding are manual metal-arc welding (MMA/SMAW) and gas-shielded arc welding, with the TIG/GTAW method as first choice.
For Sanicro® 625, heat-input of <1.2 kJ/mm and interpass temperature of <100°C (210°F) are recommended. A string bead welding technique should be used.
Recommended filler metals
TIG/GTAW or MIG/GMAW welding:
ISO 18274 S Ni 6625/AWS A5.14 ERNiCrMo-3 (e.g. Exaton Ni60)
ISO 14172 E Ni 6625/AWS A5.11 ENiCrMo-3 (e.g. Exaton Ni60)
Materials in this group of alloys (N06625) are challenging to machine.
This is due to a number of properties, leading to high cutting forces,
severe wear and poor chip control.Dedicated cutting tools and strategies to be used.For details on tool geometries, tool grades and cutting data, the tool supplier should be able to support.