Definition: Abrupt changes in the profiles of weld bead ripples Main Causes: (1) Too low or high welding amperage or voltage (2) Inappropriate electrode manipulation (irregular, too fast, or too slow) (3) Too much moisture in coatings (SMAW) or fluxes (SAW) (4) Too much flux-burden height (SAW) Preventive Measures: (1) …
What is uneven weld ripples?
7. Irregular Weld Shape. Irregular welds include those that are too wide or too narrow, those that have an excessively convex or concave surface, and those that have coarse, irregular ripples.
How should the ripples on the weld bead appear?
Bead ripples appear along the length of the weld bead as undulations with measurable differences in height by as much as 1/8” (3 mm). Often the height of the bead ripple on a welded pipe is a function of the heat that has gone into the weld process: the higher the heat, the greater the height of the bead ripple.
What are the causes of weld defects?
Most defects encountered in welding are due to an improper welding procedure. Once the causes are determined, the operator can easily correct the problem. Defects usually encountered include incomplete penetration, incomplete fusion, undercutting, porosity, and longitudinal cracking.
What causes weld concavity?
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. … Excessively high welding speeds make the formation of root concavity more likely.
What determines if a discontinuity is acceptable?
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.
What causes warpage or distortion?
The high temperature heat involved in most welding processes is largely responsible for the distortion, warpage, and stresses that occur. … This non-uniform heating and partial restraint is the main cause of thermal distortion and warpage that occur in welding.
What is an arc and how it is generated?
An arc is generated between two conductors of electricity, cathode and anode (considering direct current, DC), when they are touched to establish the flow of current and then separated by a small distance. … An arc is a sustained electric discharge through this ionised gas column called plasma between the two electrodes.
What is the acceptable width of bead in a weld metal?
The maximum bead width should be limited to 3/8 in. (10 mm). As a minimum, one complete circumferential bead should be completed before stopping or interrupting the welding sequence. In general, welding is started on the edge to be repaired closest to the middle of the shaft and should proceed toward the shaft end.
Why do you need to determine the location of weld defects?
Answer: Explanation: Weld defects such as cracking and porosity have a great effect on the performance of the weld bead. Samples taken after the LSM process, with different manufacturing parameters, were checked to verify the occurrence of porosity and cracking.
How do you prevent welding defects?
You’ll need to remove the impurities in your metal and preheat it as required. Additionally, use the proper joint design for the material and properly cool the welded area. Be sure to weld enough sectional areas, too. Use the right amperage current and welding speed.
What are the 12 most common discontinuities in welding?
What Are Some Common Welding Discontinuities?
- Porosity. Porosity occurs when gas becomes trapped in the weld pool, forming permanent bubbles as the metal cools from a liquid state back to a solid. …
- Inclusions. …
- Inadequate Joint Penetration. …
- Incomplete Fusion. …
- Arc Strikes. …
What kind of defects should not be there in good welding?
Surface defects that impair welding quality
- Insufficient reinforcement.
- Surface cracking.
- Arc strike.
- Bead meandering (bent/misaligned bead)
- Remaining groove.