WELDING DEFECTS PDF
Understand the definition & cause of weld defects. • Solve the problem. • Suggest possible remedies associated with individual weld defects. Here you will learn about different types of welding defects produced during welding, its causes and remedies to remove it. This standard does not classify existing welding defects according to their origin but most important welding defects is explained in the following paragraphs.
|Language:||English, Spanish, Japanese|
|ePub File Size:||22.62 MB|
|PDF File Size:||10.66 MB|
|Distribution:||Free* [*Regsitration Required]|
Welding Defects & Prevention. Defects. Causes. Preventive Measure. Fibrous. Structures. There are columnar structures present in the fractured part of weld. In addition to brittleness, other common weld defects like cracks, porosity, lack of penetration and distortion can compromise the strength of the base metal, as. Welding Defects. Wanda S. Benton. Florence-Darlington Technical College. UNDERCUT. POROSITY. INCOMPLETE FUSION. OVERLAP. UNDERFILL.
Inclusion: This is may be in the form of slag or any other foreign material, which does not get a chance to float on the surface of the solidifying weld metal and thus gets entrapped inside the same.
Inclusion lowers the strength of the joint and makes it weaker. Causes: Too high or too low arc current Long arc and too large electrode diameter The too small included angle of the joint Insufficient chipping and cleaning of previous passes in multipass welding. Wrongly placed tack welds.
Remedies: Cleaning the weld bed surface before the next layer is deposited, by means of a wire brush. Providing sufficient shielding gases. Redesigning the joint so as to permit sufficient space for proper manipulation of the puddle of molten weld metals. Porosity and Blowholes: Porosity is a group of small voids and blowholes are comparatively bigger isolated holes or cavities.
They are mainly generated due to entrapped gases. Causes: Use of improper electrode and longer arc faster arc travel speed.
Too low and too high arc currents Due to gas entrapment during solidification of the weld Unclean job surface i. Remedies: Proper selection of electrode and filler materials.
Improve welding technique such as preheating of the weld area or an increase in the rate of heat input. Reducing welding speed to allow time for gas to escape.
What is Welding Defects – Types, Causes and Remedies?
Proper cleaning and the prevention of contaminants from entering the weld zone. Spatter: Spatter is the small metal particles which are thrown out of the arc during welding and get deposited on the base metal around the weld bead along its length.
Due to the expansion of gas bubbles entrapped in the molten globules of metal. Use of AC power to reduce arc blow.
Distortion: Distortion is the change in the shape and difference between the position of two plates before and after welding due to the temperature gradient present at various point along the joints. Slag Inclusions A little bit of slag goes a long way. Bits of flux, rust, and even tungsten can be counted as slag and can cause contamination in your welds.
Head to Chapter 13 for more on brazing and soldering. These inclusions are usually closely spaced, and they can cause a soldered joint to leak.
Porosity If you read very much of this book, you quickly figure out that porosity tiny holes in the weld can be a serious problem in your welds especially stick or mig welds. Cracks Cracks can occur just about everywhere in a weld: in the weld metal, the plate next to the weld metal, or in any other piece affected by the intense heat of welding.
Check out the example of cracking in Figure.
Here are the three major types of cracks, what causes them, and how you can prevent them. It can even happen days or weeks after a weld. You can guard against cold cracking by increasing the thickness of your first welding pass when starting a new weld. The really annoying part about crater cracks is that they can cause other cracks, and the cracking can just kind of snowball from there.
Check out an example in Figure. If you weld a piece of metal over and over, the chances of it warping are much higher. You can also cause a piece of metal to warp if you clamp the joints too tightly.
The vertical part of the Tsometimes pulls itself toward the weld joint.Adrianne Bazo. Ian Maldonado. The purpose of this training material is to tell about various welding defects and their effects to the strength of metal construction, and also how to avoid welding defects. Using improper welding sequences.
If we use the wrong electrode or if the angle of the electrode is wrong, then also the defect may form. Welding defects 9 Cracks on the welding area: In this case, failure initiates around the weld nugget from the location where hardness is minimum.
High magnification microscopic images are shown in Figs.