What are the possible failures in welded joints?
The defects which may fail a weld joint during service if left in a component undetected are the following: creaks, lack of penetration, lack of fusion, porosity etc. Among these defects, the linear ones such as the lack of penetration, lack of side wall fusions etc. and particularly the cracks are more harmful.
What are the design considerations of welding?
The general principles in the design of welded assemblies are as follows:
- Select the material with high weldability.
- Use of a minimum number of welds.
- Do not shape the parts based on casting or forging.
- Use standard components.
- Avoid straps, laps, and stiffeners.
- Select the proper location of the weld.
What is the greatest problem associated in fillet welded joints?
One of the greatest problems associated with fillet welded joints is achieving the correct weld size in relation to the required leg lengths or throat thickness ( Fig. 4).
Why are welded joints weak?
Fatigue of welded joints can occur when poorly made or highly stressed welded joints are subjected to cyclic loading. Under cyclic loading these defects can grow a fatigue crack, causing the assembly to fail even if these cyclic stresses are low and smaller than the base material and weld filler material yield stress.
What are the different types of failure of a bolted joint?
5 Mechanism Failures
- The bolt preload being insufficient to resist the applied forces.
- Thread stripping of the internal or external threads.
- Fatigue failure of the bolt.
- The bolt being directly overloaded by the applied force.
- Excessive bearing stress under the nut face, bolt head or within the joint itself.
How is weld strength calculated?
To measure the strength of the weld, there is a calculation using the total area of the weld by the strength it took to break that weld. Consistency in the size of the weld or the tube does not matter. The formula takes the width of a weld sample and measures by the height of the weld.
What are the main factors affecting the welding design?
Selection of Joint Design: 7 Factors | Welding
- Factor # 1. Edge Distance:
- Factor # 2. Overlap:
- Factor # 3. Fit-Up:
- Factor # 4. Accessibility:
- Factor # 5. Electrode Marking or Indentation:
- Factor # 6. Welding Sections of Unequal Thicknesses:
- Factor # 7. Weld Strength:
How do you increase fatigue strength of welded joints?
Fillet welded joints may be treated with a variety of techniques to increase the fatigue strength with respect to failure at the weld toe. The most common technique is weld toe grinding, preferably with a grinding burr rather than a disc.
Is a weld the weakest point?
Customer designed his part out of 303 stainless steel, the weld is indeed going to be weaker than the parent material and will be a failure point. However, that same part made from annealed 304L may actually be stronger at the weld.
What do you need to know about welding joint design?
For covers and decorative items, it usually suffices to specify “corners must be filled or smooth,” or alternately, to reference a paint or other finishing specification, which simply may designate “no openings.” Similarly, chassis design merely requires specifying weld location, leaving the welding method up to the supplier.
How to calculate the weld strength of a joint?
The shape of the welded joint, in the above example, is rectangular in shape with two sides as Y and Z respectively. Step-4: Calculate design strength (Pw): The design weld strength for the material can be calculated using the eq.2 as:
When to use intermittent fillet welds in welding?
Intermittent fillet welds may be used to carry calculated stress. 2.14.3 Corner and T-Joint Reinforcement. If fillet welds are used to reinforce groove welds in corner and T-joints, the fillet weld size shall not be less than 25% of the thickness of the thinner part joined, but need not be greater than 3/8 in.
Which is the shortest distance from joint root to fillet weld?
The effective throat of a combination partial joint penetration groove weld and a fillet weld shall be the shortest distance from the joint root to the weld face of the diagrammatic weld minus 1/8 in. (3 mm) for any groove detail requiring such deduction (see Figure 3.3 and Annex I).