Spot Weld Mechanical Properties 3 Impact Testing Mechanical

Spot Weld Mechanical Properties 3 Impact Testing

Mechanical Properties 3 Lesson Objectives When you finish this lesson you will understand: • Impact Mechanical testing techniques • Factors which effect performance in Impact tests • The importance of these test for part design Learning Activities 1. View Slides; 2. Read Notes, 3. Listen to lecture 4. Do on-line workbook Keywords Impact Test, Ductile-Brittle Transition, Tensile Shear Impact Test, Direct Tension Impact Test

Mechanical Properties of Spot Welds • Peel Tests • Chisel Test • Tensile Shear Ratios • Torsion Test • Impact Tests • Fatigue Test

Impact Testing of Tensile Shear Samples Low Temp Ductile to Brittle Temp Fine “Evaluation of a new, Dua Phase. . ” SAE Paper 780136, Fgeb 1978

Effect of Sheet Size on Impact Test Results Bibber, “Spot Weldability of Low Carbon and other Aircraft Steels”, Welding Journal, Dec 1943

Effect of Sheet Thickness on Impact Results Tensile Shear Samples Pollard, “Spot Welding Characteristics of HSLA Steel. . ”, Weldign Journal, Aug 1974

Effect of Nugget Size On Impact Test Results Comparison of Test Samples Tensile Shear Direct Tension Sawhill, “Spot Weldabiloity of High Strength Steels”, Welding Journal, Jan 1980

Effect of Weld Time (for same nugget diameter) Increased weld time may have resulted in nugget softening Unger “Behavior of Spot Welds Under Impact” Welding Journal, 1942

Effect of Hold Time Plain Carbon Steel No Effect on Tensile Shear Slight Decrease In Impact Energy For Cross Tension No Similar Data Found for Other Materials Dinsdale “A Comparison of Static and Impact Strength…” Sheet Metal Industries, Aug 1977

Effect of Chemistry 0. 1 – 0. 2 Carbon Steels 0. 2 – 0. 5 Carbon Steels Hess “Spot Welding of SAE…” Welding Journal, Oct 1943 Dinsdale “A Comparison of Static and Impact Strength…” Sheet Metal Industries, Aug 1977

Effect of Chemistry - 40 ksi HSLA different microalloy Ti free = Higher Impact Partial Nugget Failure = Higher Impact Fine “Spot Weldability of High Strength. . ” SAE Paper 790005, Feb 1979

Effect of Material Strength Increase Strength Bibber “The Spot Weldability of Low Carbon. . ” Welding Journal, Dec 1943