US4294631A
Expired / Lapsed
US
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Surface corrosion inhibition of zirconium alloys by laser surface β-quenching
Assignee: General Electric Co
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Filing: 1978-12-22
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Granted: 1981-10-13
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Expires: 1998-12-22
Abstract
Abstract A laser beam is scanned over the surface of a structure comprising zirconium alloy in overlapping passes to form a barrier layer of corrosion resistant β-quenched zirconium alloy at the treated surface.
Inventors
- 👤 Thomas R. Anthony
- 👤 Harvey E. Cline
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:15
CPC Classifications
C; C22; C22F; C22F3/00; C22F1/00; C22F1/16; C22F1/18; C22F1/186
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
127 words
A method for improving the corrosion resistance of a body of a zirconium alloy to high pressure and high temperature steam including the process steps of (a) heating substantially isothermally, without melting, by means of a scanning laser beam a surface region of said body to a temperature range for a sufficient period of time to assure nucleation and growth of the body centered cubic β grains of said zirconium alloy material; and (b) quenching said heated surface region at a rate effective to form thereby a metallurgical microstructure in said surface region consisting of β-quenched zirconium alloy material, said surface region encompassing thereby a core of zirconium alloy material, said core having a metallurgical structure selected to maximize the physical and mechanical properties of the body.
Claim 2
Independent Claim
127 words
A method for improving the corrosion resistance of a body of a zirconium alloy to high pressure and high temperature steam including the process steps of (a) heating substantially isothermally, without melting, by means of a scanning laser beam a surface region of said body to a temperature range for a sufficient period of time to assure nucleation and growth of the body centered cubic β grains of said zirconium alloy material; and (b) quenching said heated surface region at a rate effective to form thereby a metallurgical microstructure in said surface region consisting of β-quenched zirconium alloy material, said surface region encompassing thereby a core of zirconium alloy material, said core having a metallurgical structure selected to maximize the physical and mechanical properties of the body.
Claim 3
Dependent Claim
40 words
The method of claim 1 wherein said heating of said surface region extends to a predetermined depth forming thereby a heated zone, said laser beam being scanned in a series of passes continuously over said surface region of said body.
Claim 4
Dependent Claim
116 words
The method of claim 2 wherein scanning of said surface region by said laser beam is performed at a velocity within the range defined by: ##EQU3## wherein δ is the radius of said heated zone, V G is the β grain growth velocity, τ N is the nucleation time for the β phase, and L is the β grain size; and V.sub.min ≧[(2D.sub.T /T.sub.B)(-∂T/∂t).sub.min ]1/2 wherein D T is the thermal diffusion constant of the zirconium alloy being β-quenched, T B is the temperature of the α to α+β phase boundary in the zirconium alloy, and (-∂T/∂t) min is the minimum quench rate that allows the formation of the β-quenched metallurgical microstructure of the zirconium alloy.
Claim 5
Dependent Claim
41 words
The method of claim 2 wherein said heating of said surface region is performed by holding said body of said zirconium alloy stationary and moving said laser beam in an XY direction to effect thereby said scanning of said laser beam.
Claim 6
Dependent Claim
41 words
The method of claim 2 including the additional process step of arranging said series of passes to be mutually adjacent passes and overlapping said mutually adjacent passes a predetermined amount to insure complete treatment of said surface region by laser scanning.
Claim 7
Dependent Claim
32 words
The method of claim 1 wherein said zirconium alloy is Zircaloy-2 having the following composition by element and weight percent ______________________________________
Sn 1.2-1.7
Fe 0.07-0.20
Cr 0.05-0.15
Ni 0.03-0.08
Zr Balance
______________________________________
Claim 8
Dependent Claim
30 words
The method of claim 1 wherein said zirconium alloy is Zircaloy-4 having the following composition by element and weight percent ______________________________________
Sn 1.2-1.7
Fe 0.18-0.24
Cr 0.07-0.13
Zr Balance
______________________________________
Claim 9
Dependent Claim
44 words
The method of claim 1 wherein said zirconium alloy has the following composition by element and weight percent ______________________________________
Nb 15
X 0-1
Zr Balance
______________________________________ wherein X is a transition metal selected from the group consisting of Fe, Ni, Cr, V and Ta.
Claim 10
Dependent Claim
45 words
The method of claim 2 wherein said heating of said surface region is performed by holding said laser beam stationary, and moving said body of said zirconium alloy beneath said laser beam in an XY direction to effect thereby said scanning of said laser beam.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1984-10-12 | 1985-04-13 | 1985-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-10-12 | 1989-04-13 | 1989-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-10-12 | 1993-04-13 | 1993-10-13 | $7700.00 | Window Closed / Lapsed |