Corrosion

Unpainted Steel
NUCu steel has the lowest loss in thickness among commercial construction and weathering steels in the accelerated automotive SAE J2334 salt, wet/dry, eight-week corrosion tests performed by Bethlehem Steel Corporation as shown in Figure 1.

Painted Steel
The same set of steels shown in Figure 1 were coated with epoxy-based Carboguard 890 bridge paint from the Carboline Company and tested. The painted panels were scratched and exposed to salt-fog at 35^oC for 3 weeks (ASTM B-117 Standard). Test results are shown in Figure 2. Similarly to unpainted steels, coated and scratched NUCu steel demonstrated the best corrosion resistance of the
four steels tested.

Welding

Due to its very low carbon equivalent, pre-heating is generally not needed before welding. All welding procedures are suitable for joining NUCu 70W (ASTM A710 Grade B) steel with matching consumables. 

Welding of several different heats of NUCu 70W (ASTM A710 Grade B) steel was evaluated without pre-heat or post-heat by a submerged arc (SAW) process and also by a manual process in a construction shop environment. Matching consumables were used. No brittle heat-affected zone was formed. Depending on heat input during welding (from 35 to 120 kJ/inch), Charpy absorbed impact energy varied from 60 to 150 ft-lbs in -30 to -40^oF temperature range.

In Procedure Qualification (PQR) SAW tests without pre-heat and post-heat using Lincoln LA85 electrodes and MIL800-HPNi flux with the heat input of 60 KJ/inch the average, Charpy absorbed impact energy was 91 ft-lb at -22^oF. The requirement by the ASTM Standard A709 is 25 ft-lbs at -10^oF.

Duplicate Gapped Bead-On-Plate (G-BOP) tests using a heat input of 35 kJ/inch with low hydrogen AWS E7018 and E9018 electrodes without pre-heat did not show any cracks in the weld metal, fusion or heat-affected zone, or in the adjacent
base plates.