The use of Photomicroscopy in the Forensic Investigation of Microstructure

In this case a Spot Weld.

The following images are of Spot Weld Specimens which were encapsulated in resin, sectioned, polished and etched to reveal the microstructure of the metal, the crystalline structure of the steel sheet is obvious as are the forms the material takes due to the rate of cooling.

The dark columnar crystals in the centre have grown inwards as the molten pool of steel cooled.

The light amorphous intrusion is copper from the tips of the Spot Weld machine. This inclusion was found to be the cause of weld failure.

 


Spot Weld Microstructure © Phil Gee

 

 

Spot Weld Microstructure © Phil Gee