Met 705

DEPARTMENT OF TECHNICAL EDUCATION ANDHRA PRADESH Name Designation Branch Institute Year/Semester Subject Subject Code Major Topic Duration Sub Topic Teaching Aids

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B.Srinivas Senior Lecturer Metallurgical Engg; J.N. Govt. Polytechnic, Hyderabad VII Semester Metal joining Techniques MET- 705 Inspection and testing of welds 50 Mins. Destructive testing of welds. PPTs, Animations, Diagrams MET705.74

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OBJECTIVES On completion of this period, you would be able to know : • Purpose of destructive testing of welds. • Types of destructive testing of welds • Salient features of destructive testing of welds.

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RECAP Visual inspection : • Visually examining the weld for surface defects

Nondestructive evaluation : • Uses various methods that do not damage the specimen

Destructive testing : • Methods in which the weld is destroyed during the test or to prepare the specimen MET705.74

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Destructive testing of welds • Destructive tests are used to measure mechanical properties and evaluate weld quality that are vital to the satisfactory performance of the welded joint in service. • Destructive testing use a weld joint in a conventional testing method, such as a tensile test or shear test. • Also carried out on samples representative of the weld joint under review often made specially for test purpose.

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Destructive testing of welds Types of tests : • Tensile test • Bend test • Impact test • Nick break test • Hardness test.

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Destructive testing of welds Tensile test : • Applied to samples representative of the welded joint. • Types of tensile tests carried out to evaluate a weldment • All weld metal test • Longitudinal butt weld test • Transverse butt weld

test

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Destructive testing of welds Types of tensile tests : All weld metal test :

• Axis of the test bar is parallel to the axis of the weld. • Entire bar consists of deposited weld metal.

Longitudinal butt weld test :

• Direction of loading is parallel to the weld axis. • Gauge cross section contains weld, HAZ and base metal.

Transverse butt weld test :

• Specimen is cut at right angle to the weld direction.

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Destructive testing of welds Tensile test (weld) specimens

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Destructive testing of welds Bend test: • The Quality of the weld in terms of ductility of weld metal and HAZ. • Opening of defects particularly Lack of sidewall fusion, root fusion and penetration of welded joint are checked.

Types of tests : • Free bend test • Guided bend test • Controlled bend test MET705.74

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Destructive testing of welds Bend test : Further classified as : • Transverse bend test • Longitudinal bend test • Side bend test

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Destructive testing of welds The Bend test

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Destructive testing of welds The Bend test

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Destructive testing of welds Impact test : • To study the behavior of welded structures under dynamic loading. • The notch may be placed with its root in the weld, the fusion boundary or the HAZ. • Mostly charpy specimens with U-notch or V-notch of proper dimensions are used. MET705.74

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Destructive testing of welds Nick break test : • Involves breaking the weld joint to examine the fractured surfaces for internal defects such as • Gas pockets • Slag inclusions • Porosity • Also determines weld ductility and the degree of fusion. MET705.74

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Destructive testing of welds Nick break test Test procedure : • A 20 mm wide strip is cut at right angle to the weld axis • Make a saw cut down the centerline of the weld 3 to 6 mm deep. • The specimen is then placed upright on two supports and force is applied on the weld either by a press or by a hammer until fracture occurs. • Visual examination of fractured surfaces is carried out to find defects. MET705.74

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Destructive testing of welds Nick break test

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Destructive testing of welds Hardness test : • Provide information about the metallurgical changes caused by welding. • Indicate whether the correct welding technique and pre and post heat treatments have been carried out. • Indentations are made in the specific areas of interest, including the weld centre line, face or root regions of the deposit, the HAZ and the base metal. MET705.74

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SUMMARY

• Purpose of destructive testing of welds. • Types of destructive testing of welds • Salient features of destructive testing of welds.

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QUIZ 1) Axis of the test bar in All weld metal test is a) parallel to the axis of the weld b) perpendicular to the axis of the weld c) none of the above

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Frequently asked questions 1) State the purpose of destructive testing of welds. 2) List the types of destructive testing of welds 3) State the salient features of any three destructive testing of welds.

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Thank you

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