In welding, low conditions of restraint
increase the distortion but induce lesser residual stresses
reduce the distortion but induce greater residual stresses
reduce both the distortion and residual stresses
all of these
Low conditions of restraint in welding refer to situations where the welded components are allowed to move or deform more freely during the welding process. Restraint in welding is related to the degree to which the components are prevented from moving as they heat and cool during welding. The statement "reduce both the distortion and residual stresses" is the correct answer.
In welding, distortion occurs due to the non-uniform expansion and contraction of the material as it is heated and then cools down. Restraint can amplify distortion because if a component is held rigidly in place, it might deform more as it tries to expand or contract during the welding process.
Residual stresses are internal stresses that remain in a material after the applied load (in this case, the welding process) has been removed. These stresses can have a significant impact on the performance and structural integrity of the welded component. Allowing more movement or deformation during welding (low restraint) can help in reducing the buildup of residual stresses, as the material is not being constrained excessively.
So, to summarize, low conditions of restraint in welding help to reduce both distortion and residual stresses.
Deep Hole Drilling residual stress measurement technique is a
Non-destructive technique
Destructive Technique
Semi-destructive Technique
none of these
Deep Hole Drilling (DHD) is a residual stress measurement technique used to determine the residual stresses in a material or component. It is particularly suitable for measuring residual stresses at greater depths within a material. The technique involves drilling a small-diameter hole into the material and then measuring the relaxation of stress around the hole. This relaxation is related to the original residual stress distribution in the material.
Here's how the Deep Hole Drilling technique works:
1. **Drilling**: A small-diameter hole is drilled into the material using specialized equipment. The hole is often drilled perpendicular to the surface of the material.
2. **Relaxation of Stress**: As the hole is drilled, the material around the hole experiences stress relaxation due to the release of the original residual stresses. This relaxation is measurable and can be correlated to the initial stresses.
3. **Strain Measurement**: Strain gauges or other measurement techniques are used to monitor the strain relief around the hole as it is drilled. The strain measurements are used to calculate the original residual stress distribution.
4. **Data Analysis**: The strain measurements are analyzed to determine the original residual stress distribution within the material.
DHD is particularly useful for measuring residual stresses at depths that are difficult to access using other methods. It provides information about the distribution of residual stresses through the thickness of a material. This technique is commonly used in engineering and materials science to assess the integrity and performance of components, especially those subjected to manufacturing processes such as welding, heat treatment, or machining.
It's worth noting that while DHD is a valuable technique, it does have limitations and requires careful calibration and interpretation of results. Additionally, advancements in technology may have led to new developments or techniques in the field since my last knowledge update in September 2021.
Ultrasonic residual stress measurement technique is a
Non-destructive technique
Destructive Technique
Semi-destructive Technique
none of these
The Ultrasonic Residual Stress Measurement technique is generally considered a **non-destructive technique**. This method uses ultrasonic waves to assess the residual stress distribution in a material without causing permanent alterations or damage to the material itself.
Ultrasonic techniques involve sending high-frequency sound waves into a material and measuring the response of these waves as they interact with the material's internal structure. By analyzing the changes in wave propagation and reflection patterns, engineers and researchers can infer information about the material's properties, including residual stress.
It's important to note that while the ultrasonic technique itself is non-destructive, the data obtained from the measurement can be used to gain insights into the structural integrity and potential issues within the material, which could guide decisions regarding its use or further testing.
Magnitude of residual stresses is dependent on the
geometric parameters of the weld
weld order
welding parameters and the stiffness of the structure
all of these
The magnitude of residual stresses is dependent on **all of these** factors:
1. **Geometric Parameters of the Weld:** The geometry of the welded joint, including its shape, size, and configuration, can influence the distribution and magnitude of residual stresses. Different joint geometries can lead to varying stress concentrations and patterns.
2. **Weld Order:** The sequence in which welding passes are applied to a joint can affect the development of residual stresses. Welding in a specific order can introduce or alleviate certain stress patterns.
3. **Welding Parameters:** Parameters such as welding heat input, welding speed, and filler metal composition can significantly impact the thermal history of the material during welding, leading to varying levels of residual stresses.
4. **Stiffness of the Structure:** The stiffness or rigidity of the overall structure being welded can influence the degree of restraint and the resulting residual stress distribution. A more rigid structure may impose greater constraints, leading to higher residual stresses.
All these factors interact and contribute to the final magnitude and distribution of residual stresses in a welded component. Proper consideration and management of these factors are crucial for minimizing the potential negative effects of residual stresses on the structural integrity and performance of welded structures.
The type of strain not responsible for residual stress is
Plastic strain
Elastic strain
Both A and B
none of these
The type of strain **not responsible for residual stress** is **Elastic strain**.
Elastic strain refers to the reversible deformation that occurs in a material when a load is applied but is removed before the material exceeds its elastic limit. Elastic deformation does not result in permanent changes to the material's shape or structure. Residual stresses, on the other hand, are caused by irreversible plastic deformation or the permanent change in shape that occurs when a material is subjected to external forces beyond its elastic limit.
So, the correct answer is **Elastic strain**.
The development of residual stresses in weld joint is due to:
Heat treatment operations
Unevenly distributed non-elastic strain
Non-uniform heating and cooling
All of the above
The development of residual stresses in a weld joint is due to **all of the above** factors:
1. **Heat Treatment Operations:** Certain heat treatment operations can introduce or modify residual stresses in a weld joint. Heat treatment processes involve controlled heating and cooling cycles, which can cause changes in the material's microstructure and induce residual stresses.
2. **Unevenly Distributed Non-Elastic Strain:** Non-elastic or plastic strain that arises from the welding process, as well as from the mechanical interaction between the base metal and the weld filler material, can lead to the development of residual stresses. This strain is not completely relieved during the cooling phase, resulting in residual stresses.
3. **Non-Uniform Heating and Cooling:** Welding involves localized heating and subsequent cooling, and these temperature gradients can cause non-uniform expansion and contraction within the material. The resulting non-uniformity in thermal stress distribution contributes to the development of residual stresses.
All of these factors can interact to create a complex pattern of residual stresses in a weld joint, and understanding and managing them are crucial to ensuring the structural integrity and performance of welded components.
In most of the structural material, vicinity of weld zone which type of stress develops?
Tensile residual stress
Compressive residual stress
Bending and tensile residual stress
Bending and compressive residual stress
In most structural materials, particularly in the vicinity of a weld zone, **tensile residual stresses** tend to develop. This is because the welding process involves localized heating and subsequent cooling, which can lead to non-uniform expansion and contraction of the material. As the material cools and solidifies, it can contract more in some areas than others, resulting in regions of higher tensile residual stresses.
These tensile residual stresses near the weld zone can be detrimental to the structural integrity of the welded component, as they can contribute to cracking, distortion, and reduced fatigue life. Therefore, it's common practice to implement techniques like preheating, post-weld heat treatment, or specific welding sequences to manage and mitigate the development of excessive tensile residual stresses.
Among this what is the non-destructive stress relaxation techniques?
Neutron diffraction
Gunnert drilling
Rosenthal Norton sectioning
Brittle coat method
Among the options provided, the **neutron diffraction** technique is a non-destructive stress relaxation technique. Neutron diffraction is a powerful method used to measure residual stresses in materials without causing damage to the specimen.
Neutron diffraction involves directing a beam of neutrons at a material and analyzing how the neutrons interact with the crystal lattice of the material. By measuring the shifts in diffraction patterns, scientists can determine the lattice spacing, which is influenced by the residual stresses within the material. This technique provides valuable information about the distribution and magnitude of residual stresses in a non-destructive manner.
The other techniques mentioned—Gunnert drilling, Rosenthal Norton sectioning, and the brittle coat method—are not generally non-destructive stress relaxation techniques. They involve altering or damaging the material in some way to analyze residual stresses, making them either semi-destructive or destructive techniques.
In a butt welded joint how longitudinal (𝜎𝑙) and transverse residual stresses (𝜎𝑡) varies according to each other?
𝜎𝑙 > 𝜎𝑡
𝜎𝑙 < 𝜎t
𝜎𝑙 = 𝜎𝑡
None of these
In a typical butt welded joint, the relationship between longitudinal (σ𝑙) and transverse (σ𝑡) residual stresses is generally:
**𝜎𝑙 > 𝜎𝑡**
In a butt welded joint, the longitudinal residual stress (parallel to the weld direction) tends to be higher than the transverse residual stress (perpendicular to the weld direction). This is because the welding process involves localized heating and cooling, which results in non-uniform expansion and contraction of the material. The longitudinal residual stress is influenced by the differential cooling rates along the weld direction, leading to higher tensile stresses in that direction.
Transverse residual stresses, while still present, are typically lower than the longitudinal stresses. This relationship is due to the thermal and mechanical effects of the welding process, and it has implications for the structural integrity and behavior of the welded component.
Which of the following is incorrect for residual stresses?
Results in weld cracking
Results in brittle fracture
Affect the fatigue strength
Increase the creep strength
The following statement is incorrect for residual stresses:
**Results in brittle fracture**
Residual stresses can indeed affect the material's properties and behavior, but they generally do not directly result in brittle fracture. Residual stresses can impact factors like fatigue strength, corrosion resistance, and distortion, but they are not a primary cause of brittle fracture. Brittle fracture is typically associated with material properties, such as low ductility, high stress concentrations, and the presence of flaws, rather than solely being caused by residual stresses.