Welding

Material Tests for Welding 201

Material Tests for Welding introduces users to the types and purposes of welding material tests. Welding materials are tested to evaluate their properties, examine for discontinuities, and ensure the project meets welding code specifications. Testing can be destructive or non-destructive. Testing can also be used to classify metals according to their carbon content.

This class includes lessons on non-destructive testing methods such as visual inspection, radiographic, ultrasonic, penetrant, and magnetic particle tests. Users will also become familiar with destructive testing methods such as the macro-etch test, fillet weld break test, guided bend test, and transverse tension test. After completing this course, users will be able to identify common material tests, the practical applications of destructive and non-destructive methods, and the advantages and disadvantages of each method.

  • Difficulty Intermediate

  • Format Online

  • Number of Lessons 22

  • Language English

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Course Outline
  • Material Properties
  • Mechanical and Physical Properties of Metal
  • Test Plates and Welding Code
  • Material Tests for Welding
  • Metal Properties and Testing Review
  • Non-destructive Tests
  • Visual Inspection
  • Visual Inspection Checklist
  • Radiographic Testing
  • Ultrasonic Inspection
  • Magnetic Particle Inspection
  • Advantages and Disadvantages of Magnetic Particle Testing
  • Penetrant Test
  • Penetrant Test Advantages and Disadvantages
  • NDT Review
  • Destructive Tests
  • Macro-etch Test: In Action
  • Fillet Weld Break Test
  • Transverse Tension and Guided Bend Tests
  • Hardness Tests
  • Spark Test and Magnetic Test
  • Final Review
Objectives
  • Define material properties.
  • Distinguish between the mechanical and physical properties of metals.
  • Describe the role of welding codes in welding operations.
  • Describe the purpose of material tests for welding.
  • Describe non-destructive tests.
  • Describe visual inspection.
  • Describe visual inspection.
  • Describe radiographic testing.
  • Describe ultrasonic inspection.
  • Describe magnetic particle inspection.
  • Distinguish between the advantages and disadvantages of magnetic particle testing.
  • Describe penetrant testing.
  • Explain the advantages and disadvantages of penetrant testing.
  • Identify destructive tests.
  • Describe macro-etch test.
  • Describe fillet weld break testing.
  • Describe transverse tension testing. Describe guided bend testing.
  • Compare hardness tests.
  • Distinguish between classification tests.
Glossary
Vocabulary Term
Definition

alignment

The arrangement of a machine's components so that they are pre-set according to design requirements. Alignment is checked during visual inspection.

American Petroleum Institute

API. A non-profit organization that regulates industrial standards for the oil and natural gas industry. American Petroleum Institute codes are used for welding operations on oil pipelines or related materials.

American Society of Mechanical Engineers

ASME. An organization that publishes technical materials and sets industrial and manufacturing standards. American Society of Mechanical Engineer's codes are used for projects involving welding high pressure piping.

American Welding Society

AWS. A professional organization that supports and promotes the welding industry and related processes. American Welding Society writes numerous welding codes.

AWS

American Welding Society. A professional organization that supports and promotes the welding industry and related processes. AWS writes numerous welding codes.

base metal

One or more metals to be welded together to form a joint. Base metal properties must be compatible with the properties of the metal that forms the joint.

brale

A conical diamond indenter used in Rockwell hardness tests. Brale indenters are used for the Rockwell-C hardness scale.

butt-welded joints

A type of groove weld that joins two parallel pieces that do not overlap. Butt-welded joints can be tested in guided bend tests and transverse tension tests.

capillary action

The ability of a substance to draw a liquid upwards against the force of gravity. Capillary action draws penetrant to the surface of a part in penetrant testing.

carbon

A common, nonmetallic element found in all types of steel. Carbon is the main hardening element in steel.

Certified Weld Inspectors

CWI. A person certified by the American Welding Society to perform visual inspections on welds. Certified Weld Inspectors must be able to identify possible welding discontinuities and defects, use measuring instruments, and monitor any repairs.

compressive strength

The ability of a material to resist forces that attempt to squeeze or crush it. Compressive strength is the amount of compressive stress that a material can withstand before fracturing.

corrosion resistance

The ability of a material to resist deterioration and chemical breakdown due to surface exposure in a particular environment. Corrosion resistance in steel can be improved by the presence of chromium.

couplant

A substance, usually an oil, that coats a test piece in ultrasonic testing. Couplants are needed to transmit sound waves during an ultrasonic test.

cross-section

The interior of a surface that is exposed by making a straight cut. Cross-sections are often subject to weld testing and inspection to ensure weld quality.

crystal quartz

A device used in ultrasonic testing that converts electrical energy into mechanical energy. The crystal quartz sends vibrations into the test piece to search for defects.

C-scale

A scale of the Rockwell hardness test that uses a brale indenter and a 150 kilogram load to test hardness. The C-scale is the most common scale and is used for hard steels and metals.

CWI

Certified Weld Inspector. A person certified by the American Welding Society to perform visual inspections on welds. A CWI must be able to identify possible welding discontinuities and defects, use measuring instruments, and monitor any repairs.

defect

A surface or structural flaw that can cause a part to be rejected. Defects can be detected through visual inspection or other forms of non-destructive testing.

defects

A surface or structural flaw that can cause a welded part to be rejected. Weld defects can include incomplete penetration and cracks.

destructive tests

A testing method that places materials in harsh conditions that lead to product failure. Destructive tests include the guided bend test and transverse tension test.

developer

A substance that helps to draw penetrant to the surface of a part in a penetrant test. Developer makes the flaws in a part visible through capillary action.

discontinuities

An irregularity in a welded part that may or may not require a welded part to be fixed or discarded. Discontinuities can be discovered during visual inspection.

discontinuity

An irregularity in a welded part that may or may not require a welded part to be fixed or discarded. Discontinuities can be discovered through visual inspection.

ductility

The measure of a material’s ability to be drawn, stretched, or formed without fracturing. Ductility is a mechanical property.

electrical conductivity

The ability of a material to act as a medium for conveying electricity. High electrical conductivity properties are present in copper and aluminum.

electrode certifications

The process of ensuring that electrodes meet the specifications required for a project. Electrode certification requires welders to conduct hardness tests.

electromagnet

A magnet formed from electric current. An electromagnet is typically formed by wrapping wire around an iron core and electrically charging it.

electromagnetic yoke

A portable piece of equipment that establishes a magnetic field in order to detect surface and subsurface defects on a specific section of a test piece. Electromagnetic yokes are powered by alternating or direct current.

end crater

A depression on the surface of a weld bead. End craters are considered defects if they are outside of the allowances of the welding code.

file

A steel tool with a known hardness level used in a scratch hardness test. In a scratch hardness test, a file is dragged across the surface of a test piece to evaluate hardness.

file scratch test

A hardness test that indicates a material's ability to resist scratching. File scratch tests are performed with steel files.

fillet welds

A type of weld that is triangular in shape and joins two surfaces at right angles to each other in a lap joint, T-joint, or corner joint. Fillet welds cannot be tested using radiographic testing.

flatness

A tolerance that describes the allowable variability in the shape and appearance of a surface. Flatness of a welded part can be examined during visual inspection.

fluorescent

The emission of absorbed light by a substance. Fluorescent liquids used in penetrant tests require the use of a UV light in order for defects to be visible.

fluoroscopic screen

A screen, lit from behind by fluorescent lights, that displays an X-ray. Fluoroscopic screens allow for immediate viewing of an X-ray.

gamma ray

High frequency electromagnetic radiation with short wavelengths. Gamma rays have a greater depth of penetration than X-rays.

grinding wheel

A wheel-shaped abrasive tool that wears metal away from a workpiece. Grinding wheels are used in spark tests to help determine the type of metal.

groove welds

A type of weld that consists of an opening between two surfaces, which provides space to contain weld metal. Groove welds are often tested using transverse tension tests.

hardness

A material’s ability to resist penetration, indentation, and scratching. Hardness levels are tested by using indentation hardness tests.

HAZ

Heat-affected zone. The portion of the base metal that has not been melted but still has altered mechanical properties due to the heat from welding. The HAZ can contain changes in magnetic properties.

heat-affected zone

HAZ. The portion of the base metal that has not been melted but still has altered mechanical properties due to the heat from welding. The heat-affected zone can contain changes in magnetic properties.

high-carbon steel

A steel containing between 0.45% and 0.50% carbon. High-carbon steels are extremely strong and hard.

hydrochloric acid

An acidic, highly corrosive chemical compound. Hydrochloric acid is sometimes used in macro-etch tests to enhance the view of the cross-section.

incomplete fusion

A weld discontinuity in which the weld metal and base metal or adjoining weld beads are not fully fused. Incomplete fusion significantly weakens the integrity of a weld.

incomplete penetration

A weld that does not extend through the thickness of the material being joined. Incomplete penetration can be fixed if it is detected early enough in the process.

indirect magnetization

Establishing a strong magnetic field within the workpiece to search for defects. Indirect magnetization can be achieved through the use of adjustable, portable devices.

joint

The edge or point where two or more pieces of metal are joined together. Joints may contain melted base metal as well as filler metal.

joint preparation

Preparing base metals before welding. Joint preparation can involve preheating and cutting.

Knoop test

A microhardness test that uses a small pyramid-shaped diamond indenter and relatively light loads between 10 grams and 1 kilogram. A Knoop hardness test lasts for about 10-15 seconds.

laps

A discontinuity in the base metal that can form during the steel production process. Laps result in small gaps in the steel.

low-alloy steels

A steel containing small amounts of intentionally added materials that change the properties of the metal. Low-alloy steel is strongly magnetic.

magnetic field

A force of attraction that surrounds magnets and current-carrying conductors. A magnetic field is used to help identify defects in magnetic particle inspection.

magnetic particle inspection

A type of non-destructive test that locates discontinuities on a weldment by using magnetic powder and magnetic forces. Magnetic particle inspections use magnetic fields and electric currents to examine a weldment.

magnetic particle tests

A non-destructive test that uses a magnetic powder or liquid to identify defects in a part. In magnetic particle tests, the magnetic powder will cluster around a surface defect.

magnetic tests

A simple test used to determine the type of metal being used by holding a magnet to the workpiece and observing the reaction. Magnetic tests are not as definitive as chemical analysis.

magnetism

The power of attraction and repulsion between materials. Magnetism most often occurs between metals.

mechanical properties

A characteristic that describes how a material reacts when subjected to a force that attempts to stretch, compress, bend, dent, scratch, or break it. Mechanical properties can be tested with destructive testing methods.

methanol

A poisonous liquid alcohol that can be used as a solvent during a macro-etch test. Methanol will help the test piece to dry faster in a macro-etch test.

microhardness test

A type of hardness test designed to test very small or brittle materials. Microhardness tests, also known as microindentation tests, involve very light loads.

NDT

Non-destructive tests. A testing method used to evaluate the specific properties of a material without causing damage or permanent alteration of the material. NDT methods include visual inspection and x-ray testing.

nickel

A silver-white metal that is easily manipulated. Nickel is often used in alloys.

non-destructive tests

NDT. A testing method used to evaluate the specific properties of a material without causing damage or permanent alteration of the material. Non-destructive test methods include visual inspection and x-ray testing.

overfill

Weld beads that are too large for the specifications. Overfill is costly and can cause future distortion.

penetrant test

A type of non-destructive test that uses a fluorescent liquid or dye to detect surface flaws. Penetrant tests can be used when magnetic tests cannot be used.

penetrant tests

A non-destructive test that uses a dye or a fluorescent liquid to locate defects on a material by drawing the liquid into minuscule surface openings on a part. Penetrant tests can be used where magnetic particle testing is ineffective.

physical properties

A characteristic that describes a material's volumetric, thermal, electrical, and magnetic qualities. Physical properties can be tested before, during, and after the welding process.

pinholes

A welding defect caused by a high welding temperature that results in small bubbles on a weld bead. Pinholes are another name for small porosity.

porosity

A discontinuity characterized by the appearance of tiny voids or bubbles on a weld bead, resulting from trapped gases in a material. Excessive porosity can weaken a weld and cause a part to be rejected if it is outside the code specifications.

post weld heat

Applying heat to a base metal after completing a welding process. Post weld heat reduces the residual stress introduced to a metal during welding.

precious metals

A rare, naturally occurring chemical element. Precious metals include gold and silver.

preheating

Applying heat to the base metal in order to maintain a specific temperature during the welding operation. Preheating may be necessary to avoid cracking of the weld metal and adjacent weld zones.

properties

The physical and mechanical characteristics of a material that distinguish it from other materials. Properties determine the behavior and performance of a material, including how a material will react under a heavy load or under extreme temperature changes.

prototypes

A preliminary model of a product tested to evaluate performance of a design. Prototypes generally undergo destructive testing to provide information about the potential success or failure of joint material in a specific environment.

pulse echo equipment

Ultrasonic inspection equipment that uses high frequency sound waves to detect flaws or irregularities in a part. Pulse echo equipment is often battery powered and portable.

radiation

Potentially harmful energy emitted in the form of particles or waves. Radiation is emitted during radiographic testing.

radiograph

An image produced on a sensitive screen or film by X-rays or gamma rays. Radiograph images can allow the interior of a weld to be viewed.

radiographic testing

A widely used non-destructive test that uses X-rays or gamma rays to produce a picture of the internal structure of a material. In a radiographic test, defects or irregularities in a material show up as dark spots.

Rockwell hardness test

A hardness test that measures the degree of penetration into a material caused by a ball or diamond brale indenter applied under a maximum load of 150 kilograms for a duration of 10 seconds. Rockwell hardness tests use different scales for different groups of materials.

root penetration

The depth of penetration of the filler metal into the root of a welded joint. Incomplete root penetration weakens the joint.

shear strength

A material’s ability to resist forces that attempt to cause its internal structure to slide against itself and separate. Shear strength is the amount of shear stress that a material can withstand before fracturing.

slag inclusion

Flux that has melted into the weld and become embedded in the molten metal. Slag inclusions are typically classified as defects.

solvent wash

A substance used in commercial liquid penetrant testing to clean foreign matter from a part. Solvent wash may be required in some commercial dye penetrants.

sound waves

Vibrations at very high frequencies. Sound waves used in ultrasonic testing are beyond the range of normal human hearing.

spark tests

A method of determining metal type by holding the metal to a grinding wheel and observing the sparks emitted. Spark tests are generally only used for ferrous metals and cannot replace chemical analysis.

square

A metal tool consisting of two straight edges set at right angles to each other. Squares are used in visual inspection to check the accuracy of right angles or as a guide for drawing lines on a material.

stainless steels

A type of steel that contains more than 11% chromium and exhibits excellent hardness and corrosion resistance. Stainless steel can be welded with many different welding processes.

static loads

An external force that is applied and held in a fixed position for a specific amount of time. Static loads are an important component of standardized hardness tests.

straight edge

A flat, rectangular hand tool with inches or meters that can be used to draw straight lines, determine the straightness of a line, or take measurements. A straight edge is used in visual inspection.

straightness

A tolerance that describes the allowable variability in the shape and appearance of a line. Straightness in a welded part can be examined during visual inspection.

strength

The ability of a material to resist forces that attempt to break or deform it. Specific types of strength include tensile strength, yield strength, and compressive strength.

tensile failure

When a material breaks or fails while being stretched or pulled. Tensile failure can occur in a metal with high hardness properties in the heat-affected zone.

tensile strength

The ability of a material to resist forces that attempt to pull apart or stretch it. Tensile strength is the amount of tensile stress that a material can withstand before fracturing.

test plates

A weld sample made according to the welding code that is used to test or prove a welding procedure, material properties, and welder qualifications. Test plates, also called sample coupons, are welded according to the welding code for a project.

test specimens

A portion of the test plate that undergoes material testing and inspection. Results from test specimens are recorded on a welding procedure qualification record.

thermal conductivity

A physical property that indicates how well heat energy transfers through a material. High thermal conductivity properties are present in steel alloys, copper, and aluminum.

tolerances

An acceptable deviation from a desired dimension that still meets part specifications. Tolerances indicate the allowable difference between a physical feature and its intended design.

transverse

A line that is perpendicular to the workpiece or weldment. In a fillet weld break test, a load is applied transverse to the welded side.

ultrasonic

A frequency above the range of human hearing. Ultrasonic frequencies are used in non-destructive ultrasonic inspection of welds.

ultrasonic inspection

A non-destructive examination that uses ultrasonic waves to detect internal flaws. In ultrasonic inspections, a discontinuity or density change in a piece will act as a reflector for high frequency vibrations.

ultrasonic probe

The device that produces the sound waves used in ultrasonic inspection. Ultrasonic probes have a crystal quartz tip.

ultrasonic tests

A non-destructive testing method in which a high frequency sound wave is sent through a part. In an ultrasonic test, signal changes typically indicate flaws or defects in the material.

ultraviolet light

UV light. Light that is invisible to the naked eye because it consists of very short wavelengths. Ultraviolet light is necessary in order to view the results from a fluorescent penetrant test.

undercutting

A welding defect that weakens the weld and appears as a groove in the base metal along the edge of the weld. Undercutting is not easily detected through visual inspection but can be detected through radiographic testing.

underwelding

A weld bead that is smaller than what the specifications require. Underwelding can be detected and corrected during visual inspection.

universal testing machine

A materials testing machine used for evaluating the tensile and compressive strength of materials. Universal testing machines can perform many standard destructive tests, including transverse tension and guided bend tests.

UV light

Ultraviolet light. Light that is invisible to the naked eye because it consists of very short wavelengths. UV light is necessary in order to view smaller defects in a magnetic particle test.

Vickers test

A hardness test that forces a pyramid-shaped diamond against a material for a standard dwell time of 10-15 seconds and at a maximum load of 120 kilograms to create an indentation. In a Vickers hardness test, the size of the indentation determines the hardness value.

video frequency

The frequency of a signal conveying images and pulses. Frequency is typically measured in Hertz (Hz) or cycles per second.

visual testing

VT. An assessment that requires an inspector to closely examine a welded part for surface flaws or defects. Visual testing is also known as visual inspection.

weld bead

Welded filler metal that runs along a joint. Weld bead inspection can reveal defects that may affect the performance of the weld.

weld procedure analyses

The outcome of a test or procedure that is performed in order to evaluate the fabrication process. Weld procedure analyses can be conducted by performing destructive tests.

welding code

A standard used to govern welding processes and to ensure safe welding practices and high-quality welded products. Many welding codes are written by the American Welding Society.

welding performance qualification test

A test administered to a welder to determine the welder's capacity to perform a specific welding application or position. Welding performance qualification tests are specific to a WPS.

welding procedure qualification record

A written record of the results of a weld that has undergone material testing and inspection. Welding procedure qualification records are specific to a WPS.

welding procedure specification

WPS. A written document that contains all the necessary and specific information regarding the application of a welding project. Welding procedure specifications must be approved and tested before they can be used.

weldment

A welded joint. Weldments are tested for defects and discontinuities.

weld-size gage

A metal tool that measures a part feature or weld bead to determine whether or not the feature is within a specified limit or tolerance. A weld-size gage is one of the main tools used in visual inspection.

WPS

Welding procedure specification. A written document that contains all the necessary and specific information regarding the application of a welding project. A WPS must be approved and tested before it can be used.

X-ray

An electromagnetic wave with a high frequency and low wavelength used in radiographic testing. X-rays are used to view the interior of solid objects during radiographic testing.

X-ray tests

A non-destructive testing method that uses electromagnetic waves to detect flaws in a material. X-ray tests are used to view the insides of solid objects.

yield strength

The ability of a material to tolerate gradual, progressive force without permanent deformation. Yield strength is the amount of force a material can withstand before fracturing.

zinc

A bluish-white metal that is corrosion resistant and has a relatively low melting point. Aluminum-zinc alloys generally have poor weldability.

dwell time

The amount of time during a hardness test that an indenter under a load is pressed into a test material. Dwell time helps to ensure accurate hardness readings.

dwell time

The amount of time elapsed while a liquid or a dye penetrant absorbs into the part surface and seeps into defects. Dwell time depends on a number of different variables, including the type of metal and the application.

ferrous metals

A metal in which iron is the main ingredient. Ferrous metals can undergo magnetic particle testing because they have high magnetic properties.

ferrous metals

A metal that contains iron. Ferrous metals can be classified using a spark test.

fillet weld break test

A destructive test that involves breaking one side of a fillet weld sample. Fillet weld break tests can provide useful weld quality information to the inspector.

fillet weld break test

A destructive test that involves breaking one side of a fillet weld test piece. In a fillet weld break test, an increasing load is applied to the unwelded side of a fillet weld until the weld fails.

guided bend test

A destructive test that bends a weld to evaluate ductility and strength. In guided bend tests, a sample piece is subjected to a three-point bend.

guided bend test

A destructive test that bends a weld to evaluate ductility and strength. In guided bend tests, a sample piece undergoes a three-point bend.

hardness tests

A test that determines how a material responds to external forces that attempt to scratch, penetrate, or indent it. Most hardness tests involve indenting a material sample and determining a hardness value based on the size of the indentation.

hardness tests

Tests that determine how a material responds to external forces that attempt to scratch, penetrate, or indent it. Most hardness tests involve indenting a sample and determining a hardness value based on the size of the indentation.

macro-etch test

A destructive test that involves polishing and etching a small cross-section of a welded joint using a mildly acidic mixture. Macro-etch tests enable examination of the internal structure of a weld.

macro-etch test

A destructive test that involves polishing and etching small cross-sections of a welded joint using a mildly acidic mixture. Macro-etch tests enable examination of the internal structure of the weld.

transverse tension test

A destructive test that pulls a weldment until it breaks. Transverse tension tests are generally required as part of mechanical testing for groove welds.

transverse tension test

A destructive test that pulls a weldment until it breaks. Tranverse tension tests are generally required as part of mechanical testing for groove welds.

undercut

A welding defect that weakens the weld and appears as a groove in the base metal along the edge of the weld. Undercut can cause a part to fail visual inspection.

undercut

A welding defect that weakens the weld and appears as a groove in the base metal along the edge of the weld. Undercut is a defect that can severely weaken a weld.