MAKE | GRADE | HARDNESS |
Hoganas | 1040 1060 | 37 to 40 HRc 58 to 62 HRc |
OMG Corp. | 72W40 75W62 402P 602P | 37 to 40HRc 60 to 63HRc 35 to 40HRc 60 to 65HRc |
And other respective grades of Nickel as well as Tungsten carbide
(A) Rockwell “C” Hardness Test for Sample Piece
A sample piece is prepared with the given base metal and specified metal powder. This piece is then machined and checked for the required surface hardness using the Rockwell “C” Hardness Tester. When the specified hardness is reached, the metal powder is then cleared for the hard facing of the jobs to be supplied to the customer.
Note : Required hardness is not possible with 0.5 mm or less coating thickness. The following table describes the hardness achievable for a given coating thickness of 0.5 mm.
POWDER | COATING THICKNESS | ROCKWELL – C |
1040 | 0.5 mm | 35 max. |
1060 | 0.5 mm | 50 to 55 |
72 W 40 | 0.5 mm | 35 max |
75 W 62 | 0.5 mm | 50 to 55 |
402P | 0.5 mm | 33 max |
602P | 0.5 mm | 50 to 55 |
The base metal is sectioned transversely to the direction of the hard-faced overlay. The microetching test is then performed on the sectioned faces. Then the sectioned faces are visually examined with X5 magnification for cracks in the base metal and or i the heat-affected zone, lack of fusion or other linear defects, which may result in weakness or brittleness. If none of the above defected is visible then the job is cleared for further process.
Process | : | Spray & Fuse Method. |
Base Metal | : | ASTM A 240 Gr. 316/316L/304/304L ASTM A 743 Gr. CF8/CF8M/CF3/CF3M. |
Hard Facing Powders | : | Grade 1040 & 1060 of Hoganas.or Grade 102P & 602P of OMG America. |
AWS Classification of Powder | : | AWS A5.13 R NI Cr -A & AWS A5.13 R Ni Cr-C. |
Base Metal Thickness | : | Min. 6mm. |
Coating Thickness | : | Min 1mm. Max. 2mm. |
A sample piece is prepared with the given base metal and specified Bare Rod. This piece is then machined and checked for the required surface hardness using the Rockwell “C” Hardness Tester. When the specified hardness is reached, the Bar Rod is then cleared for the hard facing of the jobs to be supplied to the customer.
The base metal is sectioned transversely to the direction of the Stellited overlay. The micro-etching test is then performed on the sectioned faces. Then the sectioned faces are visually examined with X5 magnification for cracks in the base metal or in the heat-affected zone, lack of fusion or other linear defects, which may result in weakness or brittleness. If none of the above defected is visible, the job is cleared for further process.
BARE RODS | COATING THICKNESS | ROCKWELL – C |
Stellite 6 | 3.00 mm | 39 – 42 |
Stellite 6 | 3.00 mm | 45 – 50 |
Stellite 6 | 3.00 mm | 50 – 55 |
And other respective grades of Cobalt Alloy.
Dye Penetration Test (D.P.T) is performed on each finished job to ensure that there is no crack or blowholes present on the hard-faced surfaces.
Acceptance Criteria : Zero porosity, blowholes and cracks.
Preheat Temp. | 200 – degree Celsius Min. |
Interpass Temp. | 300 – degree Celsius Max. |
Shielding gas | Argon |
Mixtures (Gas) | 99.5% |
Flow | 5 lit/min |
Current | D.C. |
Polarity | Positive + |
Amperage | 70 to 100 A |
Bare Rod Size | 3.16 |
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