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- 2. Destructive Testing Testtypes, test pieces and test objectives • Transverse tensile tests • All-weld tensile tests • Impact toughness tests • Hardness testing • Crack tip opening displacement (CTOD) testing. • Bend testing • Fracture tests Macroscopic examination • European Standards for destructive test methods
- 3. Qualitative and QuantitativeTests4.1 The following mechanical tests have units and are termed quantitative tests to measure Mechanical Properties Tensile tests (Transverse Welded Joint, All Weld Metal) Toughness testing (Charpy, Izod, CTOD) Hardness tests (Brinell, Rockwell, Vickers) The following mechanical tests have no units and are termed qualitative tests for assessing joint quality Macro testing Bend testing Fillet weld fracture testing Butt weld nick-break testing
- 4. Tensile Specimens Fracture Fillet Specimen CTODSpecimen Charpy Specimen Bend Test Specimen Mechanical Test Samples 4.1
- 5. Destructive Testing4.1 Typical Positionsfor Test Pieces Specimen Type Position •Macro + Hardness 5 •Transverse Tensile 2, 4 •Bend Tests 2, 4 •Charpy Impact Tests 3 •Additional Tests 3 WELDING PROCEDURE QUALIFICATION TESTING 2 3 4 5 top of fixed pipe
- 6. • Malleability • Ductility •Toughness • Hardness • Tensile Strength Ability of a material to withstand deformation under static compressive loading without rupture Definitions Mechanical Properties of metals are related to the amount of deformation which metals can withstand under different circumstances of force application.
- 7. • Malleability • Ductility •Toughness • Hardness • Tensile Strength Ability of a material undergo plastic deformation under static tensile loading without rupture. Measurable elongation and reduction in cross section area Definitions Mechanical Properties of metals are related to the amount of deformation which metals can withstand under different circumstances of force application.
- 8. • Malleability • Ductility •Toughness • Hardness • Tensile Strength Ability of a material to withstand bending or the application of shear stresses by impact loading without fracture. Definitions Mechanical Properties of metals are related to the amount of deformation which metals can withstand under different circumstances of force application.
- 9. • Malleability • Ductility •Toughness • Hardness • Tensile Strength Measurement of a materials surface resistance to indentation from another material by static load Definitions Mechanical Properties of metals are related to the amount of deformation which metals can withstand under different circumstances of force application.
- 10. • Malleability • Ductility •Toughness • Hardness • Tensile Strength Measurement of the maximum force required to fracture a materials bar of unit cross-sectional area in tension Definitions Mechanical Properties of metals are related to the amount of deformation which metals can withstand under different circumstances of force application.
- 11. Transverse Joint TensileTest4.2 Weld on plate Multiple cross joint specimens Weld on pipe
- 12. All-Weld Metal Tensile Specimen TransverseTensile Specimen Tensile Test 4.3
- 13. STRA (Short TransverseReduction Area) For materials that may be subject to Lamellar Tearing
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- 15. Charpy V-Notch ImpactTest4.5 Objectives: • measuring impact strength in different weld joint areas • assessing resistance toward brittle fracture Information to be supplied on the test report: • Material type • Notch type • Specimen size • Test temperature • Notch location • Impact Strength Value
- 16. - 50 0 -20 - 10 - 40 - 30 Ductile fracture Ductile/Brittle transition point 47 Joules 28 Joules Testing temperature - Degrees Centigrade Temperature range Transition range Brittle fracture Ductile / Brittle Transition Curve4.6 Three specimens are normally tested at each temperature Energy absorbed
- 17. Impact Energy Joules RoomTemperature -20oC Temperature 1. 197 Joules 2. 191 Joules 3. 186 Joules 1. 49 Joules 2. 53 Joules 3. 51 Joules Average = 191 Joules Average = 51 Joules The test results show the specimens carried out at room temperature absorb more energy than the specimens carried out at -20oC Comparison Charpy Impact Test Results 4.6
- 18. Charpy V-notch impacttest specimen4.7 Specimen dimensions according ASTM E23 ASTM: American Society of Testing Materials
- 19. Charpy V-Notch ImpactTest 4.8 Specime n Pendulu m (striker) Anvil (support)
- 20. 10 mm 8 mm 2 mm 22.5o Machined notch 100% Ductile Machined notch Largereduction in area, shear lips Fracture surface 100% bright crystalline brittle fracture Randomly torn, dull gray fracture surface Charpy Impact Test4.9 100% Brittle
- 21. Hardness Testing4.10 Definition • Measurementof resistance of a material against penetration of an indenter under a constant load • There is a direct correlation between UTS and hardness Hardness tests: • Brinell • Vickers • Rockwell
- 22. Hardness Testing 4.10 Objectives: •measuring hardness in different areas of a welded joint • assessing resistance toward brittle fracture, cold cracking and corrosion sensitivity within a H2S (Hydrogen Sulphide) environment. Information to be supplied on the test report: • material type • location of indentation • type of hardness test and load applied on the indenter • hardness value
- 23. Vickers hardness tests: •indentation body is a square based diamond pyramid (136º included angle) • the average diagonal (d) of the impression is converted to a hardness number from a table • it is measured in HV5, HV10 or HV025 Adjustable shutters Indentation Diamond indentor Vickers Hardness Test 4.11
- 24. Vickers Hardness TestMachine4.11
- 25. • Hardened steelball of given diameter is subjected for a given time to a given load • Load divided by area of indentation gives Brinell hardness in kg/mm2 • More suitable for on site hardness testing Brinell Hardness Test 4.11 30KN Ø=10mm steel ball
- 26. Rockwell Hardness Test 1KN Ø=1.6mm steelball Rockwell B Rockwell C 1.5KN 120°Diamond Cone
- 27. Hardness Testing 4.12 HardnessTest Methods Typical Designations Vickers 240 HV10 Rockwell Rc 22 Brinell 200 BHN-W usually the hardest region 1.5 to 3mm HAZ fusion line or fusion boundary Hardness specimens can also be used for CTOD samples
- 28. Crack Tip OpeningDisplacement testing 4.12 Test is for fracture toughness Square bar machined with a notch placed in the centre. Tested below ambient temperature at a specified temperature. Load is applied at either end of the test specimen in an attempt to open a crack at the bottom of the notch Normally 3 samples
- 29. Location: Any stressconcentration area Steel Type: All steel types Susceptible Microstructure: All grain structures Test for Fracture Toughness is CTOD (Crack Tip Opening Displacement) Fatigue Fracture4.13
- 30. • Fatigue cracksoccur under cyclic stress conditions • Fracture normally occurs at a change in section, notch and weld defects i.e stress concentration area • All materials are susceptible to fatigue cracking • Fatigue cracking starts at a specific point referred to as a initiation point • The fracture surface is smooth in appearance sometimes displaying beach markings • The final mode of failure may be brittle or ductile or a combination of both Fatigue Fracture4.13
- 31. • Toe grinding,profile grinding. • The elimination of poor profiles • The elimination of partial penetration welds and weld defects • Operating conditions under the materials endurance limits • The elimination of notch effects e.g. mechanical damage cap/root undercut • The selection of the correct material for the service conditions of the component Precautions against Fatigue Cracks Fatigue Fracture
- 32. Fatigue fracture occursin structures subject to repeated application of tensile stress. Crack growth is slow (in same cases, crack may grow into an area of low stress and stop without failure). Fatigue Fracture
- 33. Initiation points /weld defects Fatigue fracture surface smooth in appearance Secondary mode of failure ductile fracture rough fibrous appearance Fatigue Fracture
- 34. Crack growth isslow It initiate from stress concentration points load is considerably below the design or yield stress level The surface is smooth The surface is bounded by a curve Bands may sometimes be seen on the smooth surface – “beachmarks”. They show the progress of the crack front from the point of origin The surface is 90° to the load Final fracture will usually take the form of gross yielding (as the maximum stress in the remaining ligament increase!) Fatigue crack need initiation + propagation periods Fatigue Fracture Fatigue fracture distinguish features:
- 35. Object of test: •To determine the soundness of the weld zone. Bend testing can also be used to give an assessment of weld zone ductility. • There are three ways to perform a bend test: Root bend Face bend Side bend Side bend tests are normally carried out on welds over 12mm in thickness Bend Tests 4.15
- 36. Bending test4.16 Types ofbend test for welds (acc. BS EN 910): Thickness of material - “t” “t” up to 12 mm “t” over 12 mm Root / face bend Side bend
- 37. Fillet Weld FractureTests 4.17 Object of test: To break open the joint through the weld to permit examination of the fracture surfaces Specimens are cut to the required length A saw cut approximately 2mm in depth is applied along the fillet welds length Fracture is usually made by striking the specimen with a single hammer blow Visual inspection for defects
- 38. Fracture should breakweld saw cut to root 2mm Notch Hammer Fillet Weld Fracture Tests4.17
- 39. This fracture indicates lackof fusion This fracture has occurred saw cut to root Fillet Weld Fracture Tests 4.17 Lack of Penetration
- 40. Nick-Break Test4.18 Object oftest: To permit evaluation of any weld defects across the fracture surface of a butt weld. • Specimens are cut transverse to the weld • A saw cut approximately 2mm in depth is applied along the welds root and cap • Fracture is usually made by striking the specimen with a single hammer blow • Visual inspection for defects
- 41. Approximately 230 mm 19mm 2 mm 2 mm Notch cut by hacksaw Weld reinforcement may or may not be removed Nick-Break Test4.18
- 42. Nick Break Test4.18 Inclusions on fracture line Lack of root penetration or fusion Alternative nick-break test specimen, notch applied all way around the specimen
- 43. We test weldsto establish minimum levels of mechanical properties, and soundness of the welded joint We divide tests into Qualitative & Quantitative methods: Qualitative: (Have no units/numbers) For assessing joint quality Macro tests Bend tests Fillet weld fracture tests Butt Nick break tests Quantitative: (Have units/numbers) To measure mechanical properties Hardness (VPN & BHN) Toughness (Joules & ft.lbs) Strength (N/mm2 & PSI, MPa) Ductility / Elongation (E%) Summary of Mechanical Testing 4.19