{"id":21,"date":"2026-07-07T09:00:00","date_gmt":"2026-07-07T07:00:00","guid":{"rendered":"https:\/\/www.matai.cz\/blog\/nerez-1-4301-vs-1-4404\/"},"modified":"2026-06-26T14:58:49","modified_gmt":"2026-06-26T12:58:49","slug":"nerez-1-4301-vs-1-4404","status":"publish","type":"post","link":"https:\/\/www.matai.cz\/blog\/nerez-1-4301-vs-1-4404\/","title":{"rendered":"Nerez 1.4301 vs 1.4404 (AISI 304 vs 316L): kdy sta\u010d\u00ed A2 a kdy pot\u0159ebujete A4"},"content":{"rendered":"

P\u0159i v\u00fdb\u011bru nerezov\u00e9ho spojovac\u00edho materi\u00e1lu se nej\u010dast\u011bji rozhoduje mezi dv\u011bma austenitick\u00fdmi ocelemi: 1.4301<\/strong> (americk\u00e9 ozna\u010den\u00ed AISI 304<\/strong>) a 1.4404<\/strong> (AISI 316L<\/strong>). Ob\u011b jsou nemagnetick\u00e9 austenitick\u00e9 chrom-niklov\u00e9 oceli, ale li\u0161\u00ed se ve dvou z\u00e1sadn\u00edch bodech – v obsahu molybdenu a v obsahu uhl\u00edku. Pr\u00e1v\u011b tyto dva prvky rozhoduj\u00ed o korozn\u00ed odolnosti, sva\u0159itelnosti i o tom, zda spojovac\u00ed d\u00edl ponese ozna\u010den\u00ed A2, nebo A4. V tomto \u010dl\u00e1nku si vysv\u011btl\u00edme rozd\u00edly fakticky a prakticky, abyste pro svou aplikaci zvolili spr\u00e1vn\u00fd materi\u00e1l.<\/p>\n

Chemick\u00e9 slo\u017een\u00ed: kde je rozd\u00edl<\/h2>\n

Ob\u011b oceli vych\u00e1zej\u00ed ze stejn\u00e9ho z\u00e1kladu – p\u0159ibli\u017en\u011b 18 % chromu a 8–10 % niklu. Kl\u00ed\u010dov\u00e9 odli\u0161nosti shrnuje tabulka:<\/p>\n\n\n\n\n\n\n\n\n
Prvek<\/th>\n1.4301 (AISI 304)<\/th>\n1.4404 (AISI 316L)<\/th>\n<\/tr>\n<\/thead>\n
Chrom (Cr)<\/td>\n~ 17,5–19,5 %<\/td>\n~ 16,5–18,5 %<\/td>\n<\/tr>\n
Nikl (Ni)<\/td>\n~ 8–10,5 %<\/td>\n~ 10–13 %<\/td>\n<\/tr>\n
Molybden (Mo)<\/td>\nnen\u00ed (zbytkov\u00fd)<\/td>\n~ 2–2,5 %<\/td>\n<\/tr>\n
Uhl\u00edk (C)<\/td>\nmax. 0,07 %<\/td>\nmax. 0,03 %<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Dv\u011b v\u011bci jsou z\u00e1sadn\u00ed: 1.4404 obsahuje nav\u00edc molybden<\/strong> a m\u00e1 v\u00fdrazn\u011b ni\u017e\u0161\u00ed obsah uhl\u00edku<\/strong> (max. 0,03 % oproti max. 0,07 % u 1.4301). Ob\u011b tyto vlastnosti p\u0159\u00edmo souvisej\u00ed s t\u00edm, kde a jak materi\u00e1l obstoj\u00ed.<\/p>\n

Molybden: pro\u010d je 1.4404 odoln\u011bj\u0161\u00ed v\u016f\u010di chlorid\u016fm<\/h2>\n

P\u0159\u00eddavek p\u0159ibli\u017en\u011b 2 % molybdenu je hlavn\u00ed d\u016fvod, pro\u010d se 1.4404 (a obecn\u011b \u0159ada 316) pou\u017e\u00edv\u00e1 v n\u00e1ro\u010dn\u011bj\u0161\u00edch prost\u0159ed\u00edch. Molybden z\u00e1sadn\u011b zvy\u0161uje odolnost proti bodov\u00e9 (pitting) a \u0161t\u011brbinov\u00e9 korozi<\/strong>, zejm\u00e9na v prost\u0159ed\u00ed s chloridy – tedy u mo\u0159sk\u00e9 vody, soln\u00fdch roztok\u016f, baz\u00e9nov\u00e9 chemie nebo posypov\u00fdch sol\u00ed. Zat\u00edmco 1.4301 v takov\u00e9m prost\u0159ed\u00ed \u010dasem koroduje, 1.4404 si zachov\u00e1v\u00e1 pasivn\u00ed vrstvu v\u00fdrazn\u011b d\u00e9le. Proto se 1.4404 (a p\u0159\u00edbuzn\u00fd 1.4401) ozna\u010duje jako \u201ekyselinovzdorn\u00e1\u201c ocel.<\/p>\n

N\u00edzkouhl\u00edkov\u00e9 \u201eL\u201c proveden\u00ed a mezikrystalov\u00e1 koroze<\/h2>\n

P\u00edsmeno L<\/strong> v ozna\u010den\u00ed 316L (resp. ni\u017e\u0161\u00ed posledn\u00ed \u010d\u00edslice u 1.4404 oproti 1.4401) znamen\u00e1 Low carbon<\/em> – n\u00edzk\u00fd obsah uhl\u00edku. To m\u00e1 praktick\u00fd v\u00fdznam hlavn\u011b p\u0159i sva\u0159ov\u00e1n\u00ed. P\u0159i oh\u0159evu v teplotn\u00edm rozmez\u00ed zhruba 450–850 °C m\u016f\u017ee uhl\u00edk reagovat s chromem a tvo\u0159it na hranic\u00edch zrn karbidy chromu<\/strong>. T\u00edm se okol\u00ed hranic zrn ochud\u00ed o chrom (tzv. senzibilizace) a materi\u00e1l se stane n\u00e1chyln\u00fdm k mezikrystalov\u00e9 korozi<\/strong>.<\/p>\n

N\u00edzk\u00fd obsah uhl\u00edku u 1.4404 (max. 0,03 %) tomuto jevu prakticky zabra\u0148uje – nen\u00ed dost uhl\u00edku na to, aby se vylou\u010dilo kritick\u00e9 mno\u017estv\u00ed karbid\u016f chromu. Proto je 1.4404 odoln\u00fd v\u016f\u010di mezikrystalov\u00e9 korozi i ve sva\u0159en\u00e9m stavu a hod\u00ed se pro sva\u0159ovan\u00e9 konstrukce siln\u011bj\u0161\u00edch pr\u016f\u0159ez\u016f bez nutnosti n\u00e1sledn\u00e9ho tepeln\u00e9ho zpracov\u00e1n\u00ed.<\/p>\n

Sva\u0159ov\u00e1n\u00ed<\/h2>\n

Ob\u011b oceli maj\u00ed dobrou sva\u0159itelnost b\u011b\u017en\u00fdmi metodami (TIG, MIG\/MAG, obalen\u00e1 elektroda). Rozd\u00edl je v chov\u00e1n\u00ed po sva\u0159en\u00ed: u 1.4301<\/strong> m\u016f\u017ee u siln\u011bj\u0161\u00edch sva\u0159enc\u016f doj\u00edt k senzibilizaci a hroz\u00ed mezikrystalov\u00e1 koroze v tepeln\u011b ovlivn\u011bn\u00e9 oblasti. Tam, kde se intenzivn\u011b sva\u0159uje a kde m\u00e1 spoj n\u00e1sledn\u011b pracovat v korozn\u00edm prost\u0159ed\u00ed, je proto bezpe\u010dn\u011bj\u0161\u00ed s\u00e1hnout po n\u00edzkouhl\u00edkov\u00e9m 1.4404<\/strong>. U b\u011b\u017en\u00fdch spojovac\u00edch d\u00edl\u016f, kde se nesva\u0159uje, tento probl\u00e9m odpad\u00e1 a 1.4301 pln\u011b posta\u010d\u00ed.<\/p>\n

Vztah k ozna\u010den\u00ed A2 a A4 u spojovac\u00edho materi\u00e1lu<\/h2>\n

U \u0161roub\u016f, matic a podlo\u017eek se nepou\u017e\u00edvaj\u00ed hutn\u00ed zna\u010dky materi\u00e1lu, ale skupiny podle normy ISO 3506. Zjednodu\u0161en\u011b plat\u00ed:<\/p>\n