There are many metals that have excellent weldability. As a result you can weld them using an array of different techniques to create various products. However, you need to be careful of defects. One thing in particular to be careful of is shrinkage. This could cause big problems, including deformation and distortion. The best thing to do is invest in NDT testing, including dye penetrant, to make sure there are no concerns.
Why does shrinkage happen?
The thing you need to keep in mind here is that welding processes involve heat to form strong bonds. But, this will result in a heat affected zone (HAZ). Here there will be some level of thermal expansion. When the metal cools following the welding, it will contract and shrink back to normal. This can cause tensile stress that could result in flaws.
What flaws can occur?
The expansion and contraction of the metal can cause two different types of shrinkage; longitudinal and transverse. The first will run parallel to the weld and heat affected zone. The latter run perpendicular to the weld and HAZ.
In addition, there may be non-uniform contraction in some cases. This occurs because of the thickness of the metal. What happens here is there can be angular distortion as well as the two shrinkages.
Other problems can include bowing and dishing, buckling, and twisting. All of them will cause problems with the final products, potentially making them unstable.
Dye penetrant non-destructive testing
At Format NDT Ltd we understand how much of an issue weld shrinkage and any subsequent distortion can cause. We work to help clients get a clearer idea of the degree of both. To do this we can use a number of different non-destructive testing methods. With them we can look at surface and subsurface flaws to make sure there are no critical defects.
Of the range of options we offer, dye penetrant testing is particularly useful here. It is established as a reliable method that can provide lots of useful info. More importantly, you can combine it with other types of NDT to look at surface and internal defects.
So, if you need to test any welds, please contact us. Our team are experts with years of experience and the best training. We can provide accurate results and useful insights.