348 is chemically almost identical to 347 — the same 18% chromium / 9-13% nickel base, stabilized against sensitization with the same niobium addition — with one deliberate difference: tantalum is capped at 0.10% max and cobalt is restricted, on top of the normal niobium-plus-tantalum stabilization requirement. Tantalum and cobalt both have a high neutron-absorption cross-section, so in a reactor environment they generate long-lived radioactive isotopes under neutron flux. Capping them is a nuclear-service requirement, not a mechanical or corrosion-resistance one; outside of a reactor, 348 behaves essentially the same as 347.

Because of that restriction, 348 shows up almost exclusively in nuclear fuel-rod cladding, reactor internals, and other components that see sustained neutron exposure, where the niobium stabilization still protects against weld-zone intergranular corrosion but the tightened tantalum/cobalt chemistry limits activation. Outside nuclear work, specifying 347 instead is usually more practical and more readily available. Like 347, 348 is fully austenitic and non-heat-treatable — its properties come from alloy chemistry and cold work, not from a hardening heat treatment.

348 machines identically to 347 in practice — the tantalum and cobalt restrictions that separate the two grades are metallurgically minor and don't change cutting behavior. Expect the same gummy, work-hardening austenitic response as plain 304, with the same added abrasive wear from niobium carbides distributed through the matrix. Sharp, positive-rake tooling that shears cleanly rather than rubbing is the key to limiting work hardening, and a coating with good abrasion resistance offsets the niobium carbides' effect on flank wear.

Because 348 parts are frequently thin-wall nuclear cladding or precision reactor components, dimensional control and surface finish tend to matter more than raw material-removal rate. Consistent feed, sharp cutting edges, and rigid, vibration-free setups matter more here than on a heavy structural weldment — a hardened surface skin left by a light, rubbing finishing pass is just as damaging to a thin-wall tube as it is to a large forging, but there's less material to fall back on if a pass has to be repeated.

Chip control and coolant strategy follow the same rules as 347 and standard 304: expect long, stringy chips without a stainless-specific chipbreaker, and use adequate coolant to counter the alloy's low thermal conductivity.