Strain Measurement at Welded Steel
A laser extensometer P-100 has been used to measure strain at a welded specimen. The locally resolved strain analysis and the high resolution of 0.25 µm of the laser extensometer are the basis to observe the strain distribution in the various areas around the welding zone showing significant difference. 
The material of the specimen was steel. After heat treatment, two pieces were welded to the center of the specimen. The size of the main piece was about 10 x 80 x 400 mm. The specimen was equipped with white markers on both sides of the welding section. The positions of the markers were chosen to be as close as possible to the built-up material. 
The specimen was placed in the grips of the tensile testor with the left hand side in the lower grips. During testing the specimen showed some necking on both sides of the welding area. It was finally breaking in the right hand side near the upper grip. The figure below shows the strain distribution along the marking of the specimen. In the center there is a section with very low strain. This is the strain across the melting zone. The areas to the left and the right show the strain along the sections of the markers. It is clearly seen, that the material near the welding zone experiences lower strain than the more distant areas. Very close to the welded area, the section of the heat affected zone shows a small local maximum. 
Strain Distribution
The figures below show the strain distribution on the left and right hand side of the specimen. 
Local Strains in Left Hand Side of Specimen
Local Strains in Right Hand Side of Specimen
|