Seamless Rolled Rings

Propulsion Shaft Coupling Ring — Seamless Rolled Ring, Alloy 4140

A seamless rolled ring for a marine propulsion shaft coupling — 4140 alloy, rolled to a heavier section than the tower-flange example above, sized for the torsional load a main propulsion shaft coupling carries in continuous service.

Induction-heated steel billet glowing orange, prepared for piercing and ring rolling

The project

A propulsion shaft coupling sees sustained torsional load in continuous service, which is exactly the load case seamless ring rolling's circumferential grain flow is best suited to — the alternative, machining the coupling from a solid forged disc or from thick plate, would leave grain flow running across the ring's cross-section rather than around it. 4140 was specified for the combination of strength after quench-and-temper heat treatment and reasonable machinability the coupling's keyway and bolt-hole finish machining required.

The ring was heat-treated to the customer’s specified hardness range after rough machining and before finish machining, per standard practice for a quenched-and-tempered alloy-steel ring where heat-treatment distortion has to be accounted for in the machining allowance.