There are many different types of welding tests to determine the strength and integrity of welded pieces and materials. Many welded tools are also important safety materials, such as truck axles. Ensuring a high-quality item through the proper testing of strength and integrity helps in maintaining safe and functional products that many people use each day.
One of the most frequently used weld tests is the bend test because you can quickly perform it with simple tools. It tests the skill of the welder and the integrity of his welds. The theory of the bend test is that two pieces of metal welded together at the top should withstand a certain amount of bending and pressure before the item fractures or breaks. There are many different versions of the bend test such as the guided bend test that uses a jig, the free bend and back bend test.
Nick Break Test
A nick break test requires breaking a weld joint to examine the fractured pieces. By examining the interior of the pieces, defects such as porosity, degree of fusion and gas pockets are visible. To perform this test, the welding test piece of a welded butt joint is put between two supports with applied pressure. A quick blow from a hammer or a press causes the piece to fracture. You can then examine the test piece for defects such as gas pockets and slag inclusions.
Nondestructive Weld Testing
Unlike other weld test types, nondestructive weld testing does not destroy the projects it tests. The American Society for Nondestructive Testing websites states that nondestructive testing investigates the material integrity of the test object. Nondestructive weld testing encompasses a large range of scientific techniques to test the weld, material strength and integrity. By not destroying the test pieces, this type of weld testing can save welding companies both money and time. Some of the welding tests used with nondestructive testing are radiography, sonograms, visual tests, liquid penetrant inspection and magnetic particle testing.
Acid Etch Test
The acid etch weld test determines the actual soundness of a weld by cutting a cross section of a welded joint. The cut test piece is put into an etching solution such as nitric acid or iodine and potassium iodide. This acid will react with the welding material and will visually show the boundary between the base metal and the weld metal. This will cause any imperfections in the weld such as gas pockets to appear.