101 Questions
What does the Rockwell hardness tester measure?
Depth of penetration under load
What is the designation for Brinell hardness value?
HB
Which hardness test allows testing of welds with small indentation size and easy location of specific regions?
Vickers hardness test
What is the limitation of Brinell and Vickers tests?
Requirement to measure the size of the indentation
What is the distance requirement between each indentation in Vickers test?
No less than 25 times the indentation size
What does hardness testing assess?
A material's resistance to permanent deformation
What is the relationship between hardness and tensile strength of steel?
Hardness is related to mechanical properties and tensile strength of steel
Which scale is commonly used for testing welds in Rockwell hardness test?
Rockwell C and Rockwell B
What does the Vickers hardness number represent?
The Vickers Pyramid Number (HV)
What is the purpose of the side-bend specimen test?
To reveal internal defects in double-V-groove welds
What load range does the Vickers hardness test use?
5-100 kg load
What is the primary use of the all-weld-metal tensile test specimen?
For welding consumables classification
How is the ultimate strength of the transverse weld test specimen determined?
By dividing the maximum load reached during testing by the cross-sectional area
What is the purpose of the guided bend test?
For welder and procedure qualification
Why is a larger radius required for bending higher strength steels?
To reduce applied strain
What precaution must be taken in the preparation of bend samples?
Edges being radiused and grinding marks being parallel to the length of the specimen
What are the different types of guided bend tests?
Root-bend, face-bend, and side-bend
Why are side-bends chosen for material over 10 mm?
Due to the difficulty of performing root- and face-bends on such thickness
What does the face-bend test reveal?
Incomplete penetration or fusion
What is the diameter of the all-weld-metal tensile test specimen?
12.5 mm
What are the two commonly used tensile testing specimens?
The all-weld-metal tensile test specimen and the transverse weld test specimen
What is the cross-sectional area of the all-weld-metal tensile specimen?
122.7 mm
What is the purpose of the transverse weld test specimen?
For the qualification of welding procedures
What is the definition of quality in welding?
The degree to which inherent characteristics fulfill requirements
What is the difference between a discontinuity and a defect in welding?
A discontinuity is an interruption of the typical structure, while a defect renders a part unable to meet minimum standards
What is the purpose of nondestructive testing (NDT) in welding?
To evaluate a component without damaging it
What mechanical properties can be determined using tensile testing in welding?
Yield strength, ultimate strength, and ductility
What is the definition of stress in a material?
The intensity of internal forces resisting an external force
What happens during elastic behavior of a material?
The material returns to its original dimensions after stress is removed
What is the yield stress in welding?
The stress at which a 0.2% permanent set is observed
What do different stress-strain curves in metals indicate?
Different metals exhibit different stress-strain behaviors
What is the purpose of tensile tests in welding?
To determine mechanical properties significant in welding
What machines are used to carry out tensile tests in welding?
Special machines, mechanical, and hydraulic
Why is understanding quality, discontinuity, and testing methods crucial in welding?
To maintain welding standards and ensure the reliability of welded structures
What is the formula for calculating Vickers hardness number (HV)?
$HV = 1.854 \times \frac{P}{d^2}$
Which type of hardness test can be applied to survey the hardness of relatively small areas such as sections of welds and heat-affected zones?
Vickers hardness test
Which hardness testing method can only be used for obtaining hardness values over a relatively large area such as the face of a weld?
Brinell test
What does the Charpy impact test measure?
Toughness by recording energy absorbed when a notched specimen is broken
What units are used to measure the energy absorbed in a Charpy impact test?
Joules or foot-pounds
What type of specimen is commonly used for Charpy impact testing?
Charpy U-notch specimen
What does the transition temperature in impact testing indicate?
Temperature at which a certain energy is reached, used to compare the toughness of materials
What can lead to misleading results in impact testing?
Machining specimens from the wrong location or orienting the notch incorrectly
What is the purpose of impact tests in the classification of an electrode?
To identify the brittleness of the electrode at low temperatures
What are the two types of hardness testing methods mentioned in the text?
Micro and macro
What information do hardness traverses across a weld provide?
Information on as-welded and stress relieved conditions
What is the purpose of micro or macro hardness testing in welds?
To identify specific regions in welds
What is the significance of using a diamond or large steel ball in hardness testing?
To apply small or large loads
What can different hardness testing methods require in terms of sample thickness?
Thick or thin samples depending on the method
What is the primary use of hardness testing methods in welded structures?
To assess the brittleness of the weld
What is the mode of transfer for the welding process mentioned in the text?
Pulsed
What is the standard mentioned for the single electrode mechanized process?
CSA W47.1
What is the purpose of checking the joint preparation and fit-up in welding?
To inspect the joint preparation surfaces
Which item should be checked to ensure that all the required welds have been made?
Weld locations
What is the primary use of visual inspection after welding?
To measure the weld sizes
What is the purpose of reviewing welder qualifications?
To ensure that welders only weld joints for which they are qualified
What should be monitored, if required, during welding?
Preheat and interpass temperatures
What is the purpose of measuring fillet weld sizes?
To ensure they are correct
What is the purpose of ensuring that electrodes are stored and handled correctly?
To maintain their quality and performance
What is the purpose of checking for the presence of moisture, scale, slag, oil, grease, paint, etc. on the joint surface?
To ensure the quality of the joint surface
What is the purpose of identifying the weld size requirements?
To ensure they are correct
What is the primary use of visual inspection during welding?
To verify the welding process being used
What is the purpose of the nick-break test in weld inspection?
To reveal internal weld discontinuities
Where are the impact specimens located for a 20 mm thick test plate?
Mid-thickness
What is the basis for all weld examination methods?
Visual inspection
What is the purpose of the fillet weld break test?
To evaluate the general quality of the weld
What does the nick-break test evaluate in a region of the welded joint?
Entire surface area
What is examined when macroscopic examination is performed?
Cross-section of the finished weld
When should visual inspection be performed in the welding process?
Before, during, and after welding
What is the purpose of testing the heat-affected zone in weld inspection?
Can be troublesome due to its narrow width and slope
What is the purpose of the macroscopic examination in weld inspection?
To examine the cross-section of the finished weld
What is the purpose of the fillet weld break test in weld inspection?
To evaluate the general quality of the weld
What is the purpose of the nick-break test in weld inspection?
To reveal internal weld discontinuities
What is the basis for all weld examination methods?
Visual inspection
What tools are used for traditional visual inspection of weld surface discontinuities?
Good lighting, magnifiers, rulers, micrometers and optical comparators
What are examples of nondestructive examination methods mentioned in the text?
Witnessing the root pass and subsequent backgouging, radiographic inspection
Why is visual inspection commonly used in production?
Perceived to require relatively little training and equipment
What are the main tools used to facilitate visual inspection?
Commercial gauges, good lighting, magnifiers
What type of discontinuities can the AC yoke be used to detect?
Linear discontinuities parallel to the direction of the weld
Why is the use of prods prohibited by certain codes in magnetic particle inspection?
Chance of causing arc strikes
Which materials cannot be examined using magnetic particle inspection?
Aluminum, brass, bronze, and austenitic stainless steels
What is the primary purpose of radiographic inspection (RT) in welds?
Detect subsurface volumetric discontinuities
What is the difference between X-radiography and gamma radiography?
The type of radiation used
What is the danger associated with ionizing radiation used in radiography?
It is dangerous and cannot be felt, seen, smelled, or tasted
What determines the appearance of light or dark shadows on the radiographic film?
Differences in the amount of radiation passing through the weld
What is the primary use of the dry powder method in radiographic inspection?
More sensitive to subsurface discontinuities
What is the primary use of the wet fluorescent method in radiographic inspection?
Locating smaller discontinuities
What is the main limitation of radiography in the inspection of welds?
Material thickness and density must show up on the film image
What is the primary purpose of establishing a safe zone and posting warning signs during radiography?
To prevent exposure to ionizing radiation
What is the significance of evaluating the shape, density, and location of the images created by voids and inclusions on radiographic film?
Interpreting the radiographic film
What does liquid penetrant inspection measure in welding?
Undercut and excess groove weld height
What is the purpose of magnetic particle inspection in welding?
To detect fine cracking that comes to the surface
What is the difference between visible dye and fluorescent dye penetrant?
Fluorescent dye penetrant requires ultraviolet light for viewing, while visible dye does not
What is the main limitation of magnetic particle inspection?
Limited in detecting isolated indications such as porosity
What is the primary use of fluorescent penetrant testing?
To detect leaks in welded joints in tanks and containers
What is the purpose of applying a developer in liquid penetrant inspection?
To improve the visibility of indications
What is the main advantage of liquid penetrant inspection in welding?
Simple, inexpensive, and does not require complex equipment
How is the magnetic field induced in magnetic particle inspection?
By placing the part inside a coil to produce a longitudinal field
When is direct current used in magnetic particle inspection?
To detect linear discontinuities near the surface
What is the purpose of the ultraviolet or black light in fluorescent penetrant testing?
To improve the visibility of indications
Which type of penetrant testing is effective for detecting leaks in welded joints in tanks and containers?
Fluorescent dye penetrant
What is the main advantage of magnetic particle inspection over liquid penetrant inspection?
Ability to detect isolated indications such as porosity
Study Notes
Quality Control and Inspection Methods in Welding
- Quality is defined as the degree to which inherent characteristics fulfill requirements, with the concept of meeting needs, requirements, and expectations being a common element.
- A weld's quality is defined as its ability to perform reliably throughout its intended service life, and is influenced by workmanship, which depends on the skill of the welder and the experience of the supervisor.
- Discontinuity refers to an interruption of the typical structure of a material, while a defect is a discontinuity that renders a part unable to meet minimum acceptance standards or specifications.
- Inspection test methods include destructive testing, which involves destroying the completed weld to evaluate its characteristics, and nondestructive testing (NDT), where a component is evaluated without damaging it.
- Tensile testing is used to determine mechanical properties such as yield strength, ultimate strength, and ductility of materials in welding.
- Stress in a material is the intensity of internal forces resisting an external force, while strain measures the change in dimensions due to applied load.
- Elastic behavior occurs when a material returns to its original dimensions after stress is removed, while plastic deformation results in permanent strain.
- The yield stress is the stress at which a given permanent set is recorded, and it is usually defined as the stress at which a 0.2% permanent set is observed.
- Different metals exhibit different stress-strain curves, with some showing a gradual change from elastic to plastic behavior, while others show an abrupt change.
- Tensile tests involve loading a standard test specimen in tension until it fails, and can determine mechanical properties significant in welding, such as yield strength, ultimate strength, and ductility.
- Special machines, mechanical, and hydraulic, are used to carry out tensile tests, exerting the necessary force in a controlled manner.
- Understanding the concepts of quality, discontinuity, and testing methods is crucial in maintaining welding standards and ensuring the reliability of welded structures.
Hardness Testing Methods and Impact Test in Welded Structures
- Hardness testing methods include using a diamond or large steel ball and applying small or large loads
- Different methods require measuring indent or not, and may require thick or thin samples
- Micro or macro hardness testing is used, with preference for certain regions in welds and limitations on welds
- Hardness traverses across a weld provide information on as-welded and stress relieved conditions
- Impact tests are crucial in identifying materials' behavior under notches or cracks, especially in welded structures
- Charpy impact test is commonly used to measure toughness by recording energy absorbed when a notched specimen is broken
- The value of energy absorbed is measured in joules or foot-pounds
- Charpy V-notch (CVN) specimen with specific dimensions is commonly used for testing
- Steel's brittleness at low temperatures is revealed through impact tests at different temperatures
- The transition temperature, at which a certain energy is reached, is used to compare the toughness of materials
- Misleading results can occur if the impact test specimens are not machined from the right location or if the notch is oriented incorrectly
- Impact tests are required as part of the classification of an electrode, and the specimens are machined from the same test weld as the tensile specimens
Weld Inspection and Testing Methods
- The test plate is 20 mm thick and the impact specimens are located mid-thickness
- Notch is placed perpendicular to the plate surface on the centreline of the weld
- Testing the heat-affected zone can be troublesome due to its narrow width and slope
- Nick-break test is used for revealing internal weld discontinuities
- Fractured surface is examined for discontinuities such as porosity, slag inclusions, incomplete penetration, and incomplete fusion
- The nick-break test is required in codes to evaluate the entire surface area within a region of the welded joint
- The fillet weld break test is used to evaluate the general quality of the weld
- A force is applied to the back side of the welded T-joint until the fillet weld fractures
- Macroscopic examination involves cutting through the finished weld to examine its cross-section
- Visual inspection is the basis for all weld examination methods
- Visual inspection is fast, inexpensive, and is performed before, during, and after welding
- Before welding starts, weld preparations and fit-up dimensions must be verified to comply with requirements
Non-Destructive Testing Methods in Welding
- Liquid penetrant inspection measures undercut, excess groove weld height, fillet weld leg length, theoretical fillet weld throat, and permissible fillet weld tolerance for convexity and concavity.
- Liquid penetrant inspection, also known as penetrant testing, is used to locate cracks, porosity, laps, and folds that are open to the surface.
- The method involves preparing the surface, applying the penetrant, allowing it to dwell, removing excess penetrant, applying a developer, and visually examining the indication.
- Liquid penetrant inspection is simple, inexpensive, and does not typically require complex equipment.
- There are two basic types of penetrant: visible dye and fluorescent dye, with the latter requiring ultraviolet or black light for viewing.
- Fluorescent penetrant testing is effective for detecting leaks in welded joints in tanks and containers.
- Magnetic particle inspection is used to detect surface and near-surface discontinuities in ferromagnetic materials.
- The method involves inducing a magnetic field into the part and dusting it with fine, colored, iron powder, which collects at the poles created by discontinuities.
- Magnetic particle inspection is effective for detecting fine cracking that comes to the surface but limited in detecting isolated indications such as porosity.
- The magnetic field can be induced using the AC/DC yoke method or by placing the part inside a coil to produce a longitudinal field between the poles.
- Direct current is used to detect surface discontinuities and linear discontinuities near the surface, while alternating current is used for discontinuities breaking the surface of the weld.
- Both liquid penetrant inspection and magnetic particle inspection are widely used non-destructive testing methods in the welding industry.
Test your knowledge of quality control and inspection methods in welding with this quiz. Explore concepts such as weld quality, discontinuity, inspection test methods, tensile testing, stress and strain, and mechanical properties. Enhance your understanding of maintaining welding standards and ensuring the reliability of welded structures.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
