What is the difference between discontinuities and defects?
By Lily Fisher •
The difference between defects and discontinuities. All welding defects are developed discontinuities. If a discontinuity renders a weld incompetent or lowers its quality, it would be classified as a defect. Defects make the product risky to use or substandard.
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Similarly, what determines if a discontinuity is acceptable?
Welding Discontinuities Evaluation of the discontinuity will determine if the discontinuity is a defect or an acceptable condition: Undercut - A groove melted into the base metal adjacent to the weld toe or weld root and left unfilled by weld metal.
Similarly, what are the types of welding defects? Weldings defects are classified into the following types: Incorrect profile, Crater, Cracks, Spatter and surface porosity, Incomplete filled groove, Distortion, Blowholes, and internal porosity, Cracks, Inclusions, Lack of fusion, Incomplete fusion.
Likewise, what is a discontinuity in welding?
Technically, a welding discontinuity is the lack of a mechanical, physical or metallurgical harmony in the weld. This could be manifested in terms of. Varied porosity. Incomplete fusion or joint penetration. Unacceptable profiles.
What are the common discontinuities form in welding?
Some weld profile discontinuities are undercut, overlap, insufficient throat, and excessive convexity. Undercut. Undercut is defined as a groove melted into the base metal adjacent the weld toe, or weld root, and left unfilled by weld metal. The term undercutdescribes two specific conditions.
Related Question AnswersWhat discontinuity is generally considered to be the most severe?
Porosity is considered to be the most critical discontinuity.What is the defect?
In other words, a defect is an error in coding or logic that causes a program to malfunction or to produce incorrect/unexpected results. A program that contains a large number of bugs is said to be buggy. Reports detailing bugs in software are known as bug reports. ( See Defect Report)How can welding defects be prevented?
Following are six key ways to prevent weld failures.- Use low hydrogen filler metals when possible.
- Take care with fit-up and joint design.
- Pre- and post-weld materials correctly.
- Properly match filler metal and base material strengths.
- Implement proper filler metal storage and handling procedures.
What causes undercutting in welding?
An undercut typically happens when the main material and the weld metal do not fuse properly during a welding procedure. In other words, it happens when you fail to fill the corrugated area with the weld metal. When this welding defect occurs, a weak source is prone to cracking.How do you prevent undercut in welding?
To eliminate undercut, reduce current and slow travel speed, or simply reduce size until you have a puddle size you can handle. Then change the electrode angle so the arc force holds the metal in the corners. Use a uniform travel speed and avoid excessive weaving.What is excessive weld reinforcement?
Excessive Reinforcement – This is a weld that is too big or has too much convexity (too much build up). Usually caused by low travel speeds or incorrect procedures. Excessive reinforcement does not add strength to the weld.What would a small notch at the root welds leading edge in a fillet weld mean?
A small notch at the root weld's leading edge in a fillet weld means that the root is not fused together, i.e., at the leading edge, a complete fusion of the weld root has not taken place indicating an incomplete welding processWhat is weld reinforcement Why is it done?
Welding reinforcement offers advantages over conventional tying. Welds provide rigid connections that do not work loose during handling of the reinforcement or placing of the concrete. They are particularly advantageous for pre-assembled reinforcement cages, such as for piles, diaphragm walls, columns and beams.What are the welding symbols?
Most blueprints for a welding project heavily peppered with them. The skeleton of a welding symbol has an arrow, a leader line (attached to the arrow), a horizontal reference line, a tail, and a weld symbol (not to be confused with welding symbol, which refers to the whole thing.What causes underfill in welding?
UNDERFILL: When the weld metal surface remains below the adjacent surface of the base metal then it is called as an underfill. Underfill is an undersized welding. 5. LACK OF PENETRATION: When the weld metal doesn't completely penetrate the joint, then it is called as Lack of Penetration of Incomplete Penetration.How do you check for welding defects?
Visual Inspection During Welding- Check electrodes for size, type and storage (low hydrogen electrodes are kept in a stabilizing oven)
- Watch root pass for susceptibility to cracking.
- Inspect each weld pass. Look for undercut and required contour.
- Check for craters that need to be filled.
- Check weld sequence and size.
What is root concavity in welding?
Root concavity is caused by shrinkage of the weld pool in the through-thickness direction of the weld. Melting of the root pass by the second pass can also produce root concavity.What are the causes of welding defects?
Weld defects are often caused by improper technique or parameters, such as poor shielding gas coverage or incorrect travel speeds.Other causes of porosity include:
- Dirty base material.
- Excessive gun angle.
- Extending the wire too far from the nozzle.
- Wet or contaminated shielding gas cylinders.
What are the 5 basic types of welding joints?
Five types of welded joints are butt joint, corner joint, lap joint, tee-joint and edge joint.- Butt joint: In Butt welded type, the parts lie in the same plane and are joined at their edges.
- Corner joint:
- Lap joint:
- Tee-joint:
- Edge joint:
