Claims
- 1. Machining the surface of a nickel-base superalloy workpiece by the process which comprises:
- removing workpiece material using a thermal-effect process which causes melting and vaporization of metal, thereby leaving on the workpiece surface a recast layer; and
- contacting the surface from which material is removed with an etchant comprised by volume percent of 40-60 HNO.sub.3, 5-20 HCl, balance H.sub.2 O, at least 0.016 moles/liter CuSO.sub.4 and 0.008-0.025 moles/liter FeCl.sub.3, thereby chemically dissolving the recast layer without substantially removing other workpiece surface material.
- 2. The process of claim 1 wherein the thermal-effect process is one utilizing beam energy, such as from a laser or electron beam.
- 3. The process of claim 1 wherein the thermal-effect process is one utilizing an electric discharge.
- 4. The process of claim 2 wherein the removal of material produces holes in the workpiece.
- 5. The process of claim 1 wherein the etchant is maintained at 40.degree.-80.degree. C. and which further comprises sensing the completion of removal of the recast layer from a substantial diminution in the evolution of gas at the workpiece.
- 6. The process of claim 1 wherein the molar ratio of FeCl.sub.3 and CuSO.sub.4 is maintained at 1:2.
- 7. The process of claim 1 wherein the etchant consists by volume percent of about 50 HNO.sub.3, 10 HCl, 40 H.sub.2 O, with 1.3 g/l FeCl.sub.3 and 2.6 g/l CuSO.sub.4.
- 8. The process of claims 1 or 7 where in the superalloy is based on the alloy consisting by weight percent of 10Co, 9Cr, 2Ti, 5Al, 12W, 1Cb, 0.15C, 0.015B, 0.05Zr, balance Ni.
BACKGROUND
This is a continuation-in-part of Ser. No. 192,668 filed Oct. 1, 1980, now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3866398 |
Vernon et al. |
Feb 1975 |
|
4239954 |
Howard et al. |
Dec 1980 |
|
4353780 |
Fishter et al. |
Oct 1982 |
|
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
192668 |
Oct 1980 |
|