{"id":18965,"date":"2022-10-10T12:36:04","date_gmt":"2022-10-10T09:36:04","guid":{"rendered":"https:\/\/fractory.com\/?p=18965"},"modified":"2024-01-26T13:27:48","modified_gmt":"2024-01-26T11:27:48","slug":"welding-defects-types-causes-prevention","status":"publish","type":"post","link":"https:\/\/fractory.com\/welding-defects-types-causes-prevention\/","title":{"rendered":"Welding Defects – Types, Causes, Prevention"},"content":{"rendered":"
Welding defects are imperfections that occur during different welding processes<\/a>. There are various reasons why welding defects occur during an operation.<\/p>\n Welding services<\/a> are mainly used in the manufacturing industry for joining metals in constructing buildings, bridges, automobiles, aircraft, pipes, and many other objects. However, welding is not a perfect process as numerous types of welding defects can occur internally or externally in the welded metal.<\/p>\n Let’s explore some of the more common weld defects, their causes, and remedies.<\/p>\n A weld defect results from a poor weld, weakening the joint. It is defined as the point beyond the acceptable tolerance in the welding process.<\/p>\n Imperfections may arise dimensionally, wherein the result is not up to standard. They may also take place in the form of discontinuity or in material properties<\/a>. Common causes of welding defects come from incorrect welding patterns, material selection, skill, or machine settings, including welding speed, current, and voltage.<\/p>\n When a welded metal has a welding defect present, there are multiple options for resolving the issue. In some cases, the metal can be repaired, but at other times the metal itself has melted and the welding procedure needs to be restarted.<\/p>\n Weld irregularities occur for a variety of reasons and it results in different welding defects. They can be classified into two major categories: internal welding defects<\/strong> and external welding defects.<\/strong><\/p>\n External welding defects refer to discontinuities in the weld metal that are noticeable to the naked eye.<\/p>\n <\/p>\n Cracks are the worst welding defect since they can rapidly progress to larger ones, which inevitably leads to failure. Weld cracks are mainly classified depending on how they form in the weld bead.<\/p>\n Longitudinal cracks<\/strong> form parallel to the weld bead while transverse cracks<\/strong> form across the width. Crater cracks<\/strong> form at the end of the bead, where the arc concludes.<\/p>\n Welding cracks can also appear at varying temperatures:<\/p>\n Hot cracks<\/strong> form when weld joints crystallise as the parent and base metals are heated above 10000\u00b0C. The primary reasons for hot cracks is when an incorrect filler metal is used and when the workpieces undergo high heating and cooling rates in processes such as laser welding<\/a>.<\/p>\n<\/li>\n Cold cracks<\/strong> form after the cooling process of the weld metal. The weld crack may form hours or days after the metal’s cooling process.<\/p>\n<\/li>\n<\/ul>\n Using hydrogen shielding gas in welding ferrous metals<\/a>.<\/p>\n<\/li>\n Ductile base metal and the application of residual stress.<\/p>\n<\/li>\n Rigid joints that constrain the expansion and contraction of the metal.<\/p>\n<\/li>\n Use of high levels of sulphur and carbon.<\/p>\n<\/li>\n<\/ol>\n Preheating the metals and gradually cooling the weld joints.<\/p>\n<\/li>\n Maintaining acceptable weld joint gaps.<\/p>\n<\/li>\n Selection of the correct welding materials.<\/p>\n<\/li>\n<\/ol>\n <\/p>\n Porosity is the formation of holes in the weld pool resulting from gas bubbles that cannot escape. It is usually one of the common welding defects when using shielding gas, which is present in welding techniques such as TIG<\/a> and stick welding<\/a>. Absence, lack, or too much shielding gas may lead to metal contamination, which reduces the strength of the weld.<\/p>\n On the other hand, severe versions of porosity come in the form of blow holes or pits when large gas bubbles get trapped in the weld pool. Additionally, smaller gas molecules can blend with the weld metal, forming an impure compound.<\/p>\n Unclean welding surface.<\/p>\n<\/li>\n Wrong electrode selection.<\/p>\n<\/li>\n Lack or absence of shielding gas.<\/p>\n<\/li>\n Mishandled or damaged shielding gas cylinder.<\/p>\n<\/li>\n Either too low or too high welding current.<\/p>\n<\/li>\n Fast travel speed.<\/p>\n<\/li>\n<\/ol>\n Cleaning the weld surface.<\/p>\n<\/li>\n Using the correct welding electrode.<\/p>\n<\/li>\n Preheating the metals before welding.<\/p>\n<\/li>\n Proper gas flow rate setting to achieve the right amount of shielding.<\/p>\n<\/li>\n Regularly checking for moisture contamination in the shielding gas cylinder.<\/p>\n<\/li>\n Adjustment of welding current and travel speed settings.<\/p>\n<\/li>\n<\/ol>\n What Is a Weld Defect?<\/h2>\n
External Welding Defects<\/h2>\n
Cracks<\/h3>\n
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Causes<\/h4>\n
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Prevention<\/h4>\n
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Porosity<\/h3>\n
Causes<\/h4>\n
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Prevention<\/h4>\n
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