Directional Properties of a Modified 5% Cr Tool Steel Ausformed by Torsion
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Report Number: AFOSR-4012
Author(s): Toth, R. G., Polakowski, N. H.
Corporate Author(s): Illinois Inst. of Tech. Dept. of Metallurgical Engineering
Date of Publication: 1962
Pages: 9
Contract: AF 49(638)308
DoD Task:
Abstract:
A modified 5% Cr tool steel (0.35% C, 5% Cr-Mo-W-V) was quenched into a hot bath at 800° to 900° F, twisted in the austenitic bay range and air cooled to produce martensite. Room-temperature torsion tests in the pretwist direction showed a nominal fracture shear stress of up to 320,000 psi compared with 245,000 after ordinary hardening. The fracture changed from brittle (45°) to the shear type after pretwisting in excess of γp = 1. Reversed torsion or axial tension on pretwisted material invariably gave brittle fractures and a lower fracture stress than quenching alone. These results are indicative of a transverse weakness of ausformed steel. On the other hand, strengthening by torsion may be useful in applications involving substantially unidirectional torsional loads.
Author(s): Toth, R. G., Polakowski, N. H.
Corporate Author(s): Illinois Inst. of Tech. Dept. of Metallurgical Engineering
Date of Publication: 1962
Pages: 9
Contract: AF 49(638)308
DoD Task:
Abstract:
A modified 5% Cr tool steel (0.35% C, 5% Cr-Mo-W-V) was quenched into a hot bath at 800° to 900° F, twisted in the austenitic bay range and air cooled to produce martensite. Room-temperature torsion tests in the pretwist direction showed a nominal fracture shear stress of up to 320,000 psi compared with 245,000 after ordinary hardening. The fracture changed from brittle (45°) to the shear type after pretwisting in excess of γp = 1. Reversed torsion or axial tension on pretwisted material invariably gave brittle fractures and a lower fracture stress than quenching alone. These results are indicative of a transverse weakness of ausformed steel. On the other hand, strengthening by torsion may be useful in applications involving substantially unidirectional torsional loads.