Technical Resources

Alloy 22 Round Bar, Waterjet Cut Plate and Sheet for Synthetic Diamond Processing Tools

NeoNickel supplied alloy 22 in various sizes, thicknesses and forms to suit the tools maker’s requirements.  It was crucial the right grade of alloy was used in this application due to the fact that each tube section held up to 10,000 carats of diamonds! You wouldn’t want these parts to corrode resulting in big holes that allow these diamonds to fall off!

Alloy 22 plates and alloy 22 sheets were water-jet cut to make several porous compartments. The water-jet cutting option was preferred so that the material would not contain cutting side effects from other cutting methods i.e. heat affected zone or uneven edges. The alloy 22 round bars were fabricated into other fittings and components of the tool including fasteners, lids and stems.

In the process of producing synthetic diamonds, molten salt bath and hydrofluoric acid are used to remove rocks and other contaminants from diamond surfaces. Molten salt bath (NaCl) and hydrofluoric acid (HF) are very corrosive media. Therefore alloy 22 was selected in this particular application.

Alloy 22 is a fully austenitic, nickel-chromium-molybdenum-tungsten alloy with excellent corrosion resistance. The high chromium content provides good resistance to oxidizing conditions while the molybdenum and tungsten give good resistance to reducing media. Moreover, alloy 22 provides exceptional resistance to pitting, crevice corrosion, general corrosion and stress corrosion cracking.

 

 

Critical pitting temperatures (CPT) & Critical crevice temperatures (CCT)

In oxidizing NaCl-HCl solution

4% NaCl + 0.1% Fe2(SO4)3 + 0.01M HCl

24 hour exposure test

Pitting test in oxidizing acidic chloride environment

11% H2SO4 + 1.2%HCl +1%FeCl3 + 1% CuCl2

Alloy

 

Temperature °C

CPT

Temperature °C

CCT

Temperature °C

CPT

C22

150

102

120

C276

150

50

110

C4

140

50

90

625

90

50

75

G-30

70

40

 

Al-6XN®

70

45

254 SMo®

60

40

Ferralium®

50

35

904L

45

20

317

35

15

316

20