Fig. 37 Fully reversed torsional fatigue results for the SAE 1050M shafts. Source: Ref 43 More

Fig. 44 Fully reversed torsional fatigue data for SAE 1040 test shafts. Source: Ref 43 More

Fig. 45 Fully reversed torsional fatigue data for SAE 1541 test shafts. Source: Ref 43 More

Fig. 46 Torsional fatigue life versus tempering temperature for several different shafts. Source: Ref 18 More

Fig. 9 Torsional fatigue life versus total case depth (at ±407 MPa, or 59 ksi). Q&T, quenched and tempered More

Fig. 10 Torsional fatigue life versus effective case depth (at ±407 MPa, or 59 ksi). Q&T, quenched and tempered More

Fig. 11 Full-float torsional fatigue of 1038 steel with ultimate torsion strength of 1359 MPa (1214–1566) and torsional yield strength (by Johnson elastic limit method) of 710 MPa (676–800). Effective case depth was 14% (11–28), with total case depth of 25% (16–33) and core hardness of 9 HRC More

Fig. 12 Full-float torsional fatigue of 1541 steel with ultimate torsion strength of 1497 MPa (1207–1862) and torsional yield strength (by Johnson elastic limit method) of 966 MPa (710–1269). Effective case depth was 22% (15–33), with total case depth of 33% (17–50) and core hardness of 19 HRC More

Fig. 165 Torsional fatigue fracture in an 86-mm (3 3 8 -in.) diam keyed tapered shaft of 1030 steel, commonly termed a “peeling” type of fracture. A loose nut had reduced the frictional force on the tapered portion of the shaft, transferring the torsional load to the key. The fatigue More

Fig. 196 Surface of a bending-plus-torsional-fatigue fracture in an experimental 89-mm (3 1 2 -in.) diam tractor axle of AISI 1041 steel that had been induction hardened. Fracture occurred after 1212 h on an endurance-test track. Note beach marks fanning out from the fatigue-crack More

Fig. 197 Surface of a torsional-fatigue fracture in an induction-hardened AISI 1041 steel experimental tractor axle same as in Fig. 196 . Hardness in the hardened zone was 50 HRC at 11 to 12 mm ( 7 16 to 15 32 in.) beneath the axle surface at the crack origin. This axle More

Fig. 216 Surface of a torsional-fatigue fracture in an AISI 1045 steel crankshaft induction hardened to 55 HRC. The crack originated at the edge of an oil hole. Although it is not clearly evident in this view, the crack grew at a 45° angle to the axis of the crankshaft because of tensile More

Fig. 278 Torsional fatigue fracture in an 8-mm ( 5 16 -in.) diam torsion bar of AISI 1070 steel that was quenched and tempered to a hardness of 45 HRC. Cracking occurred along both longitudinal and transverse shear planes. 5.6× More

Fig. 375 Reversed torsional fatigue fracture of splined shaft due to overtempering. The SAE 4150 part was oil quenched and tempered to 34 HRC throughout—a hardness too soft for the application. Note the “starry” pattern characteristic of multiple fatigue cracks. 3.5× (D. Roche and H.H More

Fig. 481 Surface of a torsional-fatigue fracture in the cylindrical portion of a 35-mm (1 3 8 -in) diam torsion-bar spring of AISI 50B60 steel heat treated to a hardness of 53 HRC. The fatigue crack originated in a very small (0.38 mm, or 0.015 in. long) facet (labeled “Origin More

Fig. 515 Surface of torsional-fatigue fracture in a splined shaft of AISI 8620 steel that was carburized and case hardened. Multiple fatigue cracks evidently formed at the roots of the splines and then joined to penetrate much of the case before final fast fracture occurred. 2× More

Fig. 7 4340 steel rotor shaft that failed by torsional fatigue. (a) Shear groove designed to protect gear mechanism from sudden overload. Dimensions are in inches. (b) Star-shaped pattern on a fracture surface of the shaft. (c) Longitudinal and transverse shear cracks on the surface More

Fig. 15 Stress fields and corresponding torsional-fatigue cracks. (a) and (b) Shaft with keyway. (c) Shaft with splines More

Fig. 17 Torsional fatigue failure of boron-containing alloy steel helical spring. Fatigue initiated at an abraded area marked by arrows. The material in compression coil springs is subjected to unidirectional torsion, so fatigue propagates on a single helical surface. Source: Ref 4 More

Fig. 19 Surface of a torsional-fatigue fracture in an induction-hardened 1041 (1541) steel shaft. The shaft fractured after 450 hours of endurance testing. 1 1 4 × More