Ni-19Cr-19Mo-1.8Ta (mass%)

  • *High-performance nickel-base alloy for the 21st century.

Aerospace & Energy Materials Dept.

Main Features

MAT21 alloy is a nickel-chromium-molybdenum-tantalum alloy with improved corrosion resistance. MAT21 alloy is a much-awaited, unprecedented alloy that is better than stainless steel, even better than the other Ni-Cr-Mo corrosion-resistant alloys which are known for their high corrosion resistance under various conditions. MAT21 has shown favorable results in the evaluation by Bayer, a German pharmaceutical manufacturer. It is now regarded as a material suitable for drug manufacturing plants.

Mechanical properties

MAT21, has high tensile strength, 1.5 to 2 times higher than austenite stainless steel, enabling thinner wall thickness design. It maintains its high impact value, needless to say at room temperature, and even at very low temperatures (-193) . High temperature steam cleaning and strong brushing pose no problem.


MAT21, like MA276, has weldability and workability that are comparable to austenite steel. Dissimilar metal welding to stainless steel is possible.

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. (Application to towers and vessels, heat exchangers, piping is also possible)


MAT21PATalloy is the first nickel-base alloy made in Japan to be registered as a material standard of the United States.


Plates Bars, Forgings Pipes and Tubes Joints
B575 B564 B619 B366
  B574 B622  


Plates Bars, Forgings Pipes and Tubes Joints
SB-575 SB-564 SB-619  
  SB-574 SB-622 -
Code Case2302

Corrosion Resistance

Corrosion rate in various boiling acids

  MAT21 MA276 MA625 SUS316
1% Hydrochloric acid 0.01 0.45 4.86 24.0
40% Sulfuric acid 0.30 1.70 1.27 Disappeared
10% Nitric acid 0.09 0.25 0.03 0.05
Method B*
0.39 1.00 - 38.2
* 23%H2SO4+1.2%HCl + 1%FeCl3+ 1%CuCl2

Results of Pitting Corrosion Testing

Results of Pitting Corrosion Testing