Main Features

MMC Superalloy has developed MC Alloy as nitric hydrofluoric acid resistant material. This alloy is highly resistant to acid mixtures such as ones that contain hydrofluoric acids, sulfuric acids, phosphoric acids, and oxidizing acids. Also, it shows outstanding qualities as a heat-resistant material, and shows superior resistance to oxidation and high temperature corrosion (sulfur-attack-and vanadium-attack-resistant). MC Alloy is a unique and an innovative alloy which is a material that is resistant to both corrosion and heat.

Weldability

MC Alloy has the same weldability as austenite stainless steel, and it can be easily welded by a method that seals using inert gases such as TIG, MIG or plasma-arc. Since it has less hot water flow compared to stainless steel, the opening end should be wide.

Available Product Forms

Various shapes, such as flat-rolled plates, forgings, welding wire, wire, welded pipes and tubes, seamless pipes and tubes can be manufactured.

Corrosion Resistance on weld zone

Corrosion resistance to weld zone
As shown in the figure1, this alloy shows high corrosion resistance, as its corrosion rate to 3% hydrofluoric acid +17% nitric acid at 60°C is 1/1000 of stainless steel and 1/100 of MA276.
As shown in Table 2, MC Alloy has excellent corrosion resistance to 50% sulfuric acid at 80°C.

Table 1 Change in the corrosion rate for the 3% HF+17%HNO3 solution at 60°C Alloy Corrosion rate (mm/year) MC Alloy 0.042 MA 20Nb 5.15 MA 276 6.5 SUS 304 46.0

Table 2 Corrosion rate of each material for 50% sulfuric acid at 80°C Alloy Corrosion rate (mm/year) MC Alloy 0.004 MA 22 0.41 MA 625 1.3

Oxidation resistance of MC Alloy

Oxidation resistance of MC Alloy
Oxidizing tests were conducted every 20 hours repeatedly in the atomosphere. As a result, MC Alloy showed superior oxidation resistance than SCH-13, as shown in Figure 2. In addition, when the process of heating the alloy up to 1150°C for 24 hours in the atmospheric and then cooling it down to room temperature was repeated, it was revealed that MC alloy lost lesser weight than others, as shown in Figure 3 demonstrating its superior qualities.

Fig.2 Reduction in quantity every 20 hours in 1000°C atmosphere.

Fig.3 Reduction in quantity every 24 hours in 1150°C atmosphere.

Simulation test of MC Alloy in low quality heavy oil combustion gas atmosphere (85% Na2SO4+15%NaCl)

Metal loss(mg/cm2)

Retention temperature and time	MC Alloy	SCH-13
900°C X 20Hrs	1.2	5.6
1,000°C X 20Hrs	24.1	104.6

Sulfur-attack data of MC Alloy
Results of corrosion tests conducted in heavy oil heating furnace(950°C X 1year)

	Corrosion rate(mm/yr)	Wall thickness loss(mm)
MC Alloy	0.001	0.05
MA 600	0.042	1.5
SUS 310S	0.152	0.52