Improving Your Automobile

How Welders Prevent Cracks When Fabricating Automotive Parts from High Strength Steel

18 May 2016

Addison Morris

Some car enthusiasts fear that the custom parts, such as exhaust systems, that they order to be made from high strength steel will have cracks in the welded areas of constrained joints. This fear may be a result of information that they may have received that high strength steel is prone to cracking during the welding process due to its limited ductility. However, metal fabricators take several steps to prevent such cracks from developing. This article discusses some of those steps that will prevent the auto parts from cracking at the weld joints.

Careful Use of Heat

Metal fabricators preheat the high strength steel before the welding process begins. That heat is intended to make the material more flexible so that it will not crack once it is welded. For instance, the location where a pipe section of the exhaust system is to be welded onto the engine of your performance car is heated to a predetermined temperature so that the two metals will fuse without the development of lines of weakness at the weld joint. Once welding is complete, the part is slowly cooled so that the fresh weld joint contracts gradually. That gradual contraction prevents cracks from developing at the joint.

Detailed Joint Preparation

Metal fabricators also prevent cracking in high strength steel by paying special attention to the preparation of the joint before welding begins. The pieces are cleaned thoroughly so that no residues from the previous fabrication processes, such as beveling and cutting, remain on the material. Any grease and moisture is also removed. Such meticulous preparation ensures that there will be no source of air pockets that can create an opportunity for cracks to develop once welding is completed.

Careful Weld Bead Sequencing

Cracks can also be prevented from developing in high strength steel by the careful selection of a bead sequence so that any contraction at a weld point is counterbalanced by another contraction at another weld point. Think of the joint as the face of a clock. Instead of welding from the 12 O'clock position continuously until the joint has been welded all round, the fabricator may sequence the welding process into four distinct segments. For instance, he or she may place a weld bead running from the 12 O'clock position to 3 O'clock. Next, he or she will place the next bead from 6 O'clock to the 9 O'clock position. Such a sequence may balance out any forces that would have caused the steel to crack.

As you can see, metal fabricators are aware of the unique challenges of welding different materials, such as high strength steels. They take steps to ensure that those challenges are kept at bay. You should therefore have no fears that your custom automotive parts will bear welding defects once they are delivered to you.

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