CRYOGENIC NON DESTRUCTIVE TESTING (NDT) AND MATERIAL TREATMENT
First Claim
1. A method for detecting a defect in a manufactured item comprising:
- determining a first metric representing at least one characteristic of the manufactured item at first temperature;
cooling the manufactured item to a cryogenic temperature;
determining a second metric representing the at least one characteristic of the manufacture item at a second temperature subsequent to the cryogenic cooling the at least one characteristic;
comparing the first metric with the second metric; and
,detecting the defect based upon the comparison.
1 Assignment
0 Petitions
Accused Products
Abstract
A non-destructive test using cryogenic temperatures is capable of detecting defects in materials that result from residual stress from manufacturing and from retained austenite. The subject materials or parts that are subjected to cryogenic temperatures approaching and below˜−300° F., −184° C., 89° K, thereby causing permanent deformations or characteristic changes in the material if excessive residual stress, retained austenite or discontinuities exist. To determine the extent of changes, a first metric of the subject material is determined, the material is then subjected to cryogenic cooling thereby triggering any deformation or characteristic changes. Subsequent to the cryogenic cooling, the subject material may be returned to a second temperature whereby a second metric representing based on the same characteristic of the subject material is determined The comparison of the first and second metrics reveals the deformation or change resultant from the defect. In addition characteristic changes in the subject material during cryogenic cooling may be use to detect the phase transition of the retained austenite to martensite.
-
Citations
48 Claims
-
1. A method for detecting a defect in a manufactured item comprising:
-
determining a first metric representing at least one characteristic of the manufactured item at first temperature; cooling the manufactured item to a cryogenic temperature; determining a second metric representing the at least one characteristic of the manufacture item at a second temperature subsequent to the cryogenic cooling the at least one characteristic; comparing the first metric with the second metric; and
,detecting the defect based upon the comparison. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
-
-
27. A method for detecting unconverted austenite in steel obtaining a specimen of heat treated steel;
-
determining a first metric representing at least one characteristics of the specimen at a first temperature; cooling the specimen to a cryogenic temperature; determining a second metric representing the at least one characteristic of the specimen at a second temperature subsequent to the cryogenic cooling; comparing the first metric with the second metric; and
, detecting the unconverted austenite based upon the comparison. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 47)
-
-
39. A method for correcting defects in a milled item;
-
milling a item to predetermined specifications; deforming the milled item by cooling the milled item to a predetermined cryogenic temperature and heating the milled item to a first temperature; detecting the deformation; and
,re-milling the milled item in response to the deformation. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 48)
-
Specification