Grade distinctions
304LN and 316LN include nitrogen-related composition controls; the L designation relates to carbon requirements. The 316 family contains molybdenum and is often considered where localized corrosion is relevant, but chloride pitting and crevice corrosion still require engineering assessment. Grade 321 uses stabilization for particular service considerations.
Fabrication and surface
Control carbon-steel contamination, weld cleaning and appropriate surface restoration. The required solution-treatment condition, finish and tolerances must be tied to the product specification. A decorative polish is not proof of corrosion resistance in an immersed crevice.
Test and purchase
State the exact grade, standard edition, plate dimensions, surface condition and inspection documents. Check heat chemistry and mechanical results rather than accepting an equivalent label. Do not transfer carbon-steel density factors or hull-grade impact requirements without justification.
Information to record
- Exact product standard and edition; approved drawing or specification revision.
- Grade, dimensions, final condition and heat-to-piece traceability.
- Acceptance test, inspection document and responsible approving party.
Frequently asked questions
Is 316L immune to seawater corrosion?
No. Chlorides, temperature, stagnant conditions, crevices and surface condition affect its suitability.
Sources and reference scope
- Procurement and editorial guidance — Cross-checked against product terminology and the cited material rules
Guidance describes checks to request. It is not a claim of available stock, certificates or completed project engineering. - 钢材产品简介 — Slides 3, 5–6, 15–19
Product forms, units and grade vocabulary; not proof of current stock or class certification.