What is undercut in a weld?
What is undercut in a weld?
5 UNDERCUTTING As shown in Figure 10-3, undercutting is a defect that appears as a groove in the parent metal directly along the edges of the weld. It is most common in lap fillet welds, but can also be encountered in fillet and butt joints.
How do I know if my weld is undercut?
Conclusion
- High Speeds of Electrode Movement.
- Excessive Heat Generated.
- Poor Welding Technique.
- Greater Arc Length.
- Wrong Electrode Size.
- Holding the Electrode at a Wrong Angle.
- Contaminated Shielding Gas.
- Incorrect Proportion of the Filler Material.
What is the cause of undercut defect in welding?
One of the most important reasons for the undercutting during welding is the use of high heat during an operation near the free edges. This causes the melting of the main metal or the previous weld metal. To avoid this, reduce the welding current, which may require a reduction in arc speed.
How much undercut is allowed?
Depth of undercut that is not more than 1/32 in. is acceptable, period! Also, undercut greater than 1/32 in. deep that does not exceed 1/16 in. deep and its accumulated length comes to 2 in. or less is also acceptable.
What is the adverse effect of an undercut?
Basically, undercut will cause local stress concentration, since the depth of under- cut reduces the cross-sectional area of base metal.
Is undercut allowed in welding?
If the weld has undercut its entire length that did not exceed 1/32 in. deep, it’s acceptable. If along that same weld at one location the undercut is 1/16 in.
What is a weld toe?
Toe– The junction of the weld face and the base metal. Leg– The distance from the joint root to the toe of the weld. Face– The exposed surface of a weld on the side from which welding was done. Theoretical Throat– The minimum distance minus any reinforcement between the joint root and the face of a fillet weld.
How much undercut is acceptable in a weld?
Undercuts must fulfil specific requirements when visual inspecting: their depth at the toe of the final bead on the outside of the pipe shall not exceed 0.8 mm or 12.5% of the pipe wall thickness, whichever is smaller. Moreover, there must not be more than 50 mm of undercutting in any continuous 300 mm length of weld.
What are the unacceptable weld profiles?
We will consider some of the discontinuities associated with weld profiles: Undercut, Overlap, Insufficient Throat, and Excessive Convexity. Undercut – This discontinuity is defined as a groove melted into the base metal adjacent to the weld toe, or weld root, and left unfilled by weld metal.