Method to determine skin-layer thickness in high pressure die castings

Patent metadata

Field	Value
Publication number	US-9576352-B2
Application number	US-201414253119-A
Country	US
Kind code	B2
Filing date	Apr 15, 2014
Priority date	Apr 15, 2014
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

A quantitative metallographic method to measure skin layer thickness in high pressure die cast aluminum components. Because the faster-cooling skin layer region exhibits a higher volume fraction of eutectic phases than that of a slower-cooling inner region, measurements showing such higher eutectic phases can be used to quantify such layer thickness. An image at various thicknesses of a location of interest in a cast component sample is first obtained using an image analyzer, from which eutectic volume fractions within each of the received images may be determined. Comparisons of the determined volume fractions can be made against a known or predicted quantity for a particular alloy composition, and then correlated to the skin layer thickness via differences between the received or measured quantities and those of the known standard.

First claim

What is claimed is:

1. A method of determining skin layer thickness in a high pressure die cast component, said method comprising:
providing an image analysis system having a computer, a memory, and a camera;
receiving a plurality of images from said camera corresponding to varying depths of a location of interest in a sample of said component;
determining a eutectic volume fraction within each of said plurality of received images;
comparing said determined volume fraction against a predicted quantity; and
correlating differences in said comparison to said skin layer thickness.

2. The method of claim 1 , wherein said predicted quantity comprises particular locations on a phase diagram of a known alloy used in said component.

3. The method of claim 2 , wherein determining a eutectic volume fraction within each of said plurality of received images further comprises determining a eutectic volume fraction within each of said plurality of received images using quantifying contrasting light and dark portions of a respective one of said received images.

4. The method of claim 3 , wherein providing an image analysis system having a computer, a memory, and a camera further comprises providing an image analysis system having a computer, a memory, and a camera, and wherein said memory includes at least one algorithm for performing said comparing.

5. The method of claim 4 , wherein said determining a eutectic volume fraction is performed by said algorithm through the following calculations:
Vol % EutectiCinnerregion= BC/BD
Vol % EutectiCouterregion= AC/AE
where A represents a location on said phase diagram that corresponds to the intersection of the solvus line, solidus line and eutectic isotherm line for an outer region of the alloy used in said component, B represents a location on said phase diagram that corresponds to the intersection of the solvus line, solidus line and eutectic isotherm line for an inner layer region of the alloy used in said component, C represents an initial liquid alloy concentration of aluminum or silicon of the alloy used in said component, D represents a location on said phase diagram that corresponds to the eutectic point of an inner layer region of the alloy used in said component and E corresponds to the eutectic point of an outer layer region of the alloy used in said component.

6. The method of claim 5 , wherein said outer region corresponds to said skin layer thickness and said inner region corresponds to a layer contained within said skin layer thickness.

7. A method of determining skin layer thickness in a high pressure die cast component, said method comprising:
configuring an image analysis system to receive and store a plurality of images, each of the plurality of images corresponding to varying depths of a location of interest in a sample of said component;
determining a eutectic volume fraction within each of said plurality of images by quantifying contrasting light and dark portions; and
comparing said determined volume fraction against a predicted phase diagram quantity of a known alloy used in said component, wherein differences between said predicted quantity and said determined volume fraction are used to correlate said skin layer thickness.

8. The method of claim 7 , wherein said determining a eutectic volume fraction is performed by said algorithm using the following calculations:
Vol % EutectiCinnerregion= BC/BD
Vol % EutectiCouterregion= AC/AE
where A represents a location on said phase diagram that corresponds to the intersection of the solvus line, solidus line and eutectic isotherm line for an outer region of the alloy used in said component, B represents a location on said phase diagram that corresponds to the intersection of the solvus line, solidus line and eutectic isotherm line for an inner layer region of the alloy used in said component, C represents an initial liquid alloy concentration of aluminum or silicon of the alloy used in said component, D represents a location on said phase diagram that corresponds to the eutectic point of an inner layer region of the alloy used in said component and E corresponds to the eutectic point of an outer layer region of the alloy used in said component.

9. An article of manufacture comprising a computer memory having computer readable program code embodied therein for determining skin layer thickness in a high pressure die cast component, said computer readable program code in said article of manufacture comprising:
computer readable program code portion for causing a computer to accept data pertaining to digital information of a location of interest within a sample of said high pressure die cast component;
computer readable program code portion for causing said computer to process said digital information into a eutectic volume fraction;
computer readable program code portion for causing said computer to convert said eutectic volume fraction into a corresponding skin layer thickness through an algorithm based on at least one of an empirical relationship and a theoretical relationship; and
computer readable program code portion for causing said computer to produce an output that corresponds to said skin layer thickness.

10. The article of manufacture of claim 9 , wherein said computer readable program code portion for causing said computer to convert said eutectic volume fraction into a corresponding skin layer thickness through an algorithm based on at least one of an empirical relationship and a theoretical relationship is performed by said algorithm using the following calculations:
Vol % EutectiCinnerregion= BC/BD
Vol % EutectiCouterregion= AC/AE
where A represents a location on said phase diagram that corresponds to the intersection of the solvus line, solidus line and eutectic isotherm line for an outer region of the alloy used in said component, B represents a location on said phase diagram that corresponds to the intersection of the solvus line, solidus line and eutectic isotherm line for an inner layer region of the alloy used in said component, C represents an initial liquid alloy concentration of aluminum or silicon of the alloy used in said component, D represents a location on said phase diagram that corresponds to the eutectic point of an inner layer region of the alloy used in said component and E corresponds to the eutectic point of an outer layer region of the alloy used in said component.

11. The article of manufacture of claim 9 , wherein said computer memory is selected from the group consisting of random-access memory and read-only memory.

12. The article of manufacture of claim 9 , wherein said computer memory is configured as a computer input device.

13. The article of manufacture of claim 12 , wherein said computer input device is selected from the group consisting of flash drives, compact disks and digital video disks.

Assignees

• Gm Global Tech Operations Llc
• Gm Global Tech Operations Llc

Inventors

• Wang Qigui
• Yang Wenying
• Knight James W

Classifications

• G06T2207/30136

  Metal · CPC title

• G01N21/88

  Investigating the presence of flaws or contamination · CPC title

• G06T7/0004 Primary

  Industrial image inspection · CPC title

• G01B21/08 Primary

  for measuring thickness · CPC title

• G01N21/8422

  Investigating thin films, e.g. matrix isolation method · CPC title