How to avoid common defects while structural steels are laser welded?

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Just like arc welding, laser welding is also a fusion welding process on structural steels and it can contain defects. Defects such as pores, solidification cracks, and loss of toughness are more common because of improper material preparation and welding parameter selection. Defects like excessive distortion are less likely in the laser welding process. If you want to know more about the laser welding process and machines then visit the website of Headland company. We are one of the best machine and software solutions providers for industries in Australia. 

  1.    Solidification cracking: this is not an acceptable defect and happens when the welded metal is not able to sustain the strains that occur on it during the solidification process when the weld cools and solidifies. The reason for this cracking in structural steels is a mainly high level of phosphorus and /or Sulphur. Elements like Mn, C, Ni, etc can also promote the formation of primary austenite and cracking too. To avoid this type of cracking it is recommended to have a low quantity of elements such as P, C, and S and a high quantity of Mn while welding. Sometimes filler wire can also be used to minimize this process. It is important to monitor the speed and shape of welding too. Cracking also depends upon factors such as joint type, plate thickness, and fit-up, joint surface contamination as well as component restraint.  
  2. Porosity: in laser welding, porosity can also be a problem that can occur due to excessive gas and shows up as bubbles in the final output. It can be caused because of the collapse of the keyhole of laser welding if it is unstable. Even surface contamination can cause it. It can be avoided by surface cleaning, preparation, and adequate edge. Using fully killed steels or using inert gas shielding can avoid porosity. Welds of partial penetration type are more prone to get porosity as compared to fully penetrating welds. 
  3. Changes in the properties of materials: it is not a weld defect technically but the weld metal sometimes experiences high cooling rates and HAZ occurs after laser welding. This can result in the creation of low toughness, brittleness, microstructures creation in structural steels. By monitoring the levels of hardness especially while specifying the welding procedure, it can serve as a useful guide to know the minimum heat input which is acceptable. It is advisable that this should be complemented by testing the impact toughness as required such as CTOD testing. 

If you are looking for high-end machines that can minimize the chances of laser welding defects then do visit the website of Headland company at www.headland.com.au. 

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