2.1.1 The specified
minimum tensile strength of forgings for shafts is to be selected
within the following general limits:
-
Carbon and carbon-manganese
steel 400 to 760 N/mm2. See also
Pt 5, Ch 4, 3.4 Screw shafts and tube shafts 3.4.2.
-
Alloy steel not exceeding
800 N/mm2.
2.1.2 Where it
is proposed to use alloy steel, details of the chemical composition,
heat treatment and mechanical properties are to be submitted for approval.
2.1.3 Where shafts
may experience vibratory stresses close to the permissible stresses
for transient operation, the materials are to have a specified minimum
tensile strength of 500 N/mm2 .
2.1.4 Where materials with greater specific or actual tensile strengths than the
limitations given above are used, reduced shaft dimensions or higher permissible
vibration stresses are not acceptable when derived from the formulae used inPt 5, Ch 4, 3.2 Intermediate shafts, Pt 5, Ch 4, 3.4 Screw shafts and tube shafts, Pt 5, Ch 4, 3.5 Hollow shafts and Pt 5, Ch 6, 2.5 Limiting stress in propulsion shafting
unless, for intermediate shafts only, it is verified that the materials exhibit a
similar fatigue life to conventional steels through compliance with the requirements in
Pt 5, Ch 4, 4 Approval of alloy steel used for intermediate shaft material.