CWI Destructive Testing and Properties Questions and Answers

Question 1

Which of the following destructive tests is specifically designed to evaluate the notch toughness of a material, particularly its susceptibility to brittle fracture at various temperatures?

Accepted Answer

Charpy V-Notch Test

Answer

The Charpy V-Notch (CVN) test measures the amount of energy a standardized notched specimen absorbs during fracture from a pendulum strike. This absorbed energy is a direct measure of the material's notch toughness, which is critical for assessing its resistance to brittle fracture, often across a range of temperatures.

Question 2

A Procedure Qualification Record (PQR) for a groove weld on a 1-inch thick plate specifies side bend tests instead of root and face bend tests. What is the primary reason for this requirement?

Accepted Answer

The material thickness is too great for a meaningful root or face bend test.

Answer

Welding codes such as AWS D1.1 and ASME Section IX require side bend tests for thicker materials (typically 3/8" or 10mm and greater). On thick sections, a root or face bend would place extreme strain on the outer fibers, making a valid test of weld soundness difficult. A side bend tests the entire weld cross-section for ductility and discontinuities.

Question 3

A CWI performs a macroetch test on a cross-section of a fillet weld as part of a procedure qualification. Which of the following observations would be a primary focus of this examination?

Accepted Answer

The weld's profile, including depth of fusion and leg size.

Answer

A macroetch test involves polishing and etching a weld cross-section to reveal its metallurgical structure at a macroscopic level. It is used to evaluate the overall weld profile, depth of penetration, fusion to the root, leg sizes, and the presence of large discontinuities like porosity, lack of fusion, or cracks.

Question 4

During a transverse tensile test of a welded specimen, which of the following properties is NOT directly determined from the test data?

Accepted Answer

Impact Strength

Answer

A transverse tensile test measures a material's response to a slow, static pulling force, which is used to determine its ultimate tensile strength, yield strength, ductility (elongation and reduction of area), and the fracture location (weld metal, HAZ, or base metal). Impact strength, which is a measure of toughness under a high strain rate, is determined by a dynamic test like the Charpy V-Notch test, not a tensile test.

Question 5

A welder's performance qualification test requires a nick-break test on a groove weld. What is the primary objective of this specific destructive test?

Accepted Answer

To reveal the internal soundness and fusion of the weld metal.

Answer

The nick-break test involves cutting notches into the weld and then fracturing the specimen along the weld line. This exposes the internal fracture surface, allowing for a visual examination of the weld's internal quality. It is specifically used to check for discontinuities such as slag inclusions, porosity, and lack of fusion.

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CWI Destructive Testing and Properties Questions and Answers