How Can I Tell a Good Weld from a Bad Weld?

September 11, 2017 6:31 pm Published by Leave your thoughts

There’s a lot more to welding than just melting two pieces of metal together. Welding is actually a complicated process, and different methods are used on different types of metal. At NW Metal Fabricators Inc., we offer a variety of welding services, from arc welding to TIG welding in Umatilla County, OR. We can tell you that the one thing all welding should have in common is quality and strength. If you have a bad weld, the integrity of the entire product is compromised, which can result in serious safety risks.

Signs of a bad weld will look different depending on the type of weld you’re looking at. It’s important to be able to identify a bad weld before it becomes a safety risk, but doing that can be difficult if you don’t know what to look for. Below are a few examples of different types of welds, and signs you should watch out for to identify a bad weld.

MIG welding

This is the most common form of welding. An electric arc is formed between a consumable wire electrode and the piece of metal being worked on. The heat resulting from this process causes the metal to melt and join together.

Signs of a bad weld:

  • Welding line is too thin
  • Lack of discoloration of the parent metal
  • Cracks down the middle of the bead
  • A lack of uniformity in the welding line

TIG welding

This welding process also uses an arc, but in this case a non-consumable tungsten electrode is used to produce the weld. This process is most often used when a high quality weld is needed without sacrificing the look of the finish.

Signs of a bad weld:

  • Porosity
  • Undercutting
  • Burnout
  • Tungsten inclusion
  • No filler metal used
  • A wide, flat bead without a distinct bead pattern

Stick welding

Stick welding uses an electric arc with an alternating or direct electric current between the electrode and the metals to be joined. The metal and the electrode melt together to create a weld pool. When the weld pool cools, it forms the joint.

Signs of a bad weld:

  • Cracking
  • Visible lack of fusion
  • Spatter
  • Undercutting

Oxy welding

This welding process mixes oxygen and acetylene gas to create a flame that is hot enough to melt metals (including steel) and weld them together.

Signs of a bad weld:

  • Excessive grain growth
  • Presence of “hard” spots
  • Underside of weld has insufficient penetration
  • Porosity
  • Cracking
  • Excessive globules of metal
  • Incomplete fusion
  • Oversized or undersized welding line
  • Overlapping
  • Undercutting

Spotting a bad weld can be difficult, but not if you know what to look for. At NW Metal Fabricators Inc., we offer services from arc welding to TIG welding in Umatilla County, OR. If you need a welding job done or spot a bad weld that needs to be redone, we’re the team you’ll want to work with. To learn more about our services or to schedule a welding job, give us a call today!

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