TEST METHODS FOR EVALUATING WELDED JOINTS

Prepared by theWelding Handbook Chapter Committee on Test Methods for Evaluating Welded Joints:

D. E. Williams, ChairConsulting Engineer

D. M. BeneteauCenterline (Windsor)

Limited

J. A. ClarkWestinghouse Electric

Corporation

B. H. LyonsConsultant

E. R. SampsonConsultant

R. F. WaiteConsultant

Welding Handbook Volume 1 Committee Member:

D. W. DickinsonThe Ohio State University

Contents

Introduction 240Testing for Strength 241Hardness Tests 256Bend Tests 260Fracture ToughnessTesting 261Fatigue Testing 272Corrosion Testing 277Creep and RuptureTesting 280Testing of ThermalSpray Applications 281Weldability Testing 284Conclusion 292Bibliography 292SupplementaryReading List 294

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TEST METHODS FOR EVALUATING WELDED JOINTS

INTRODUCTION

All types of welded structuresfrom steel bridges tojet componentsserve a function. Likewise, the weldedjoints in these structures and components are designedfor service-related capabilities and properties. Predict-ing service performance on the basis of laboratory test-ing presents a complex problem because weld size,configuration, and the environment as well as the typesof loading to which weldments are subjected differ fromstructure to structure. This complexity is furtherincreased because welded jointsconsisting of unaf-fected base metal, weld metal, and a heat-affected zone(HAZ)are metallurgically and chemically heteroge-neous. In turn, each of these regions is composed ofmany different metallurgical structures as well as chem-ical heterogeneities.

Testing is usually performed to ensure that weldedjoints can fulfill their intended function. The ideal test,of course, involves observing the structure in actual orsimulated service. An example of such mock-up test-ing is that done to validate new designs of momentframe and similar connections for large buildings instrong seismic areas.

1

Unfortunately, mock-up andactual service tests are expensive, time consuming, andpotentially hazardous. Therefore, standardized testsand testing procedures are performed in the laboratoryto compare a specimens results with those of metalsand structures that have performed satisfactorily in ser-vice. Standardized testing provides a bridge between the

1. American Institute for Steel Construction (AISC),

Seismic Provi-sions for Structural Steel Buildings,

Chicago: American Institute forSteel Construction.

properties assumed by designers and analysts and thoseexhibited by the actual structure.

Mechanical testing provides information on themechanical or physical properties of a small sample ofwelds or metals to infer the properties of the remainingmaterial within a lot, heat range, or welding procedure.Standardized procedures are used to sample, orient,prepare, test, and evaluate the specimens in order toprovide results that can be compared to design criteria.For example, virtually all design codes are based on aminimum tensile strength that must be achieved notonly in the base metal but also in the weldment.

When selecting a test method, the tests purpose mustbe considered and balanced against the amount of timeand the resources available. For example, tension andhardness tests both provide a measure of strength, butthe latter are simpler and more economical to perform.Hardness tests can be used to confirm that adequatestrength has been achieved in some heat-treated compo-nents. Although they can verify that a maximum heat-affected-zone hardness has not been exceeded, hardnesstests cannot adequately establish the strength of awelded joint because of the heterogeneous nature ofwelds. Regardless of the differences between test meth-ods, all testing procedures measure either a compositeaverage or a weak-link component of the property ofinterest within the area sampled. Thus, an understand-ing of the test details is necessary to interpret theresults.

When testing a welded or brazed joint, the investiga-tor must not only relate the test to the intended serviceof the actual structure but also determine whether trueproperties are measured by the limited region tested.

TEST METHODS FOR EVALUATING WELDED JOINTS

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