Effect of Notches on the Axial Fatigue Properties of Structural Steels

The effect of the stress concentration on the zero-to-tension axial fatigue strength of notched members of four structural steels has been studied. For each of the four steels a critical notch severity was found at which a transition in behavior takes place. When the theoretical stress concentration exceeds this critical value the fatigue strength increases instead of continuing to decrease as would normally be expected. The maximum effective stress concentration determined from these tests corresponds to a critical notch severity which is dependent on the material) the geometry of the specimen) and the cyclic conditions of stress. Microscopic examinations of the roots of the notched specimens which did not fail revealed cracking in most cases. Some of the cracks apparently were nonpropagating cracks but the test lives in most cases were insufficient to isolate such cracks positively as non-propagating. A study of other data on non-propagating cracks revealed that the laws governing their formation are not yet fully understood. However, there are indications that the increase in fatigue strength obtained above the critical notch severity is coincident with the formation of non~propagating cracks.The Engineering FoundationAmerican Iron and Steel InstituteChicago Bridge and Iron FoundationThe Welding Research Counci

Fatigue and Static Properties of Welded Joints in Low Alloy Structural Steels

Ohio River Division LaboratoriesCorps of Engineers, U.S. Army.Contract No. DA-33-eng-25

The Behavior of Stiffened Beams Under Repeated Loads

The U.S. Department of Commerce. Bureau of Public Roads.Welding Research Council Fatigue Committe

The Effect of Cooling Rate and Restraint on Weld Cracking

Chicago Bridge & Iron Compan

The Fatigue Properties of Low Alloy and Carbon Structural Steels

The Engineering FoundationChicago Bridge and Iron CompanyAmerican Iron and Steel InstituteWelding Research Council Fatigue Committe

Fatigue Behavior of Welded Thin Web Girders as Influenced by Web Distortion and Boundary Rigidity

Bureau of public roads Department of Commerce Contract No. CPR-11-420

Behavior of Welded Build-Up Beams Under Repeated Loads

The U.S. Department of Commerce. Bureau of Public Roads.Association of American RailroadsWelding Research Council Fatigue Committe

Influence of Geometry and Residual Stress on Fatigue of Welded Joints

The purpose of this investigation was to study the factors which contribute to the relatively low fatigue strength of welded joints in high strength steel subjected to low mean stress and a large number of cycles. Fatigue tests were conducted on axially loaded specimens containing a double V butt-weld. A number of test series were devised to separate the effects of geometry and residual stress. The significance of weld geometry was investigated by machining unwelded specimens to weld-like contours. Fatigue tests revealed that the geometry of the weld was extremely important at all levels of stress which were studied, If small irregularities or weld undercuts existed they could initiate premature failures. The stress concentration values of the weld reinforcement were evaluated by several methods including an equivalent shear method which is based primarily on the geometric properties of the weld reinforcement. The influence of residual stress was studied by comparing the fatigue results of as-welded, stress relieved and unwelded specimens with the same geometry. Fatigue failures tended to initiate in regions of maximum tensile transverse residual stress. Estimates of the maximum stress at the toes of a weld revealed that this stress is approximately equal to the yield stress even when the maximum nominal stress is the fatigue limit. By subjecting the edges of the weld reinforcement to lateral pressure both the notch geometry and the residual stress pattern were altered. This process resulted in an increase in the fatigue strength.National Steel Corporatio

Effect of Welding on the Axial Fatigue Properties of High Strength Structural Steels

The effect of welding on the axial fatigue properties of a quenched and tempered steel in the life range between 100,000 and 2,000,000 cycles has been investigated on a zero-to-tension and partial tension-to-tension stress cycle. Included in the studies are the effect of surface geometry and the metallurgical changes imparted by the welding. The test results indicate that the introduction of a transverse butt weld in this steel decreases the fatigue strength corresponding to 2,000,000 cycles by approximately 40 percent. On a zero-to-tension stress cycle, no significant increase has been found in the fatigue strength of welds in the quenched and tempered steel over comparable welds in ASTH A-7 or A-242 steels. The quenched and tempered steel has also been found to be more notch sensitive in fatigue and highly susceptible to even the most minor internal discontinuities. The data indicate that the superiority of the quenched and tempered steel lies in its ability to resist high mean stresses and is thus eminently suited for applications where high dead to live lead ratios are encountered.The Engineering FoundationAmerican Iron and Steel InstituteChicago Bridge and Iron FoundationThe Welding Research Counci