{"id":16,"date":"2026-06-04T18:44:57","date_gmt":"2026-06-04T16:44:57","guid":{"rendered":"https:\/\/www.matai.cz\/blog\/nerez-a2-vs-a4-faq\/"},"modified":"2026-06-26T14:57:40","modified_gmt":"2026-06-26T12:57:40","slug":"nerez-a2-vs-a4-faq","status":"publish","type":"post","link":"https:\/\/www.matai.cz\/blog\/nerez-a2-vs-a4-faq\/","title":{"rendered":"Nerez A2 vs A4 \u2014 kompletn\u00ed FAQ k nerezov\u00e9mu spojovac\u00edmu materi\u00e1lu | MATAI"},"content":{"rendered":"

Volba mezi nerezem A2 a A4 je nej\u010dast\u011bj\u0161\u00ed rozhodnut\u00ed, kter\u00e9 \u0159e\u0161\u00ed technici a n\u00e1kup\u010d\u00ed p\u0159i objedn\u00e1vce nerezov\u00e9ho spojovac\u00edho materi\u00e1lu. Ob\u011b t\u0159\u00eddy pat\u0159\u00ed mezi austenitick\u00e9 korozivzdorn\u00e9 oceli podle normy EN ISO 3506-1<\/strong>, li\u0161\u00ed se v\u0161ak chemick\u00fdm slo\u017een\u00edm a t\u00edm i odolnost\u00ed v agresivn\u00edm prost\u0159ed\u00ed. V praxi plat\u00ed jednoduch\u00e9 pravidlo: A2 pro b\u011b\u017en\u00e9 vnit\u0159n\u00ed i venkovn\u00ed pou\u017eit\u00ed, A4 v\u0161ude tam, kde hroz\u00ed kontakt s chloridy, sol\u00ed nebo chemik\u00e1liemi.<\/p>\n

V tomto p\u0159ehledu najdete odpov\u011bdi na nej\u010dast\u011bj\u0161\u00ed dotazy k rozd\u00edl\u016fm A2 a A4 \u2014 od chemie p\u0159es zna\u010den\u00ed po v\u00fdb\u011br do exteri\u00e9ru. Kompletn\u00ed sortiment najdete v kategori\u00edch \u0161roub\u016f A2<\/a> a \u0161roub\u016f A4<\/a> skladem v Praze i Ostrav\u011b.<\/p>\n

Jak\u00fd je rozd\u00edl mezi nerezem A2 a A4?<\/h3>\n

A2 i A4 jsou austenitick\u00e9 korozivzdorn\u00e9 oceli podle EN ISO 3506-1, ale li\u0161\u00ed se chemick\u00fdm slo\u017een\u00edm. A4 obsahuje nav\u00edc cca 2 % molybdenu a vy\u0161\u0161\u00ed pod\u00edl niklu, co\u017e mu d\u00e1v\u00e1 v\u00fdrazn\u011b lep\u0161\u00ed odolnost proti bodov\u00e9 korozi v chloridov\u00e9m prost\u0159ed\u00ed. A2 odpov\u00edd\u00e1 oceli 1.4301 (AISI 304), A4 oceli 1.4401 (AISI 316).<\/p>\n

Co znamen\u00e1 ozna\u010den\u00ed 1.4301 a 1.4401?<\/h3>\n

Jsou to evropsk\u00e1 materi\u00e1lov\u00e1 \u010d\u00edsla podle EN 10088. 1.4301 je ocel s cca 18 % chromu a 8\u201310 % niklu (odpov\u00edd\u00e1 A2 \/ AISI 304), zat\u00edmco 1.4401 m\u00e1 cca 16\u201318 % chromu, 10\u201314 % niklu a nav\u00edc 2\u20133 % molybdenu (odpov\u00edd\u00e1 A4 \/ AISI 316). Molybden je hlavn\u00ed rozd\u00edl, kter\u00fd odli\u0161uje ob\u011b oceli.<\/p>\n

Obsahuje nerez A4 molybden?<\/h3>\n

Ano, pr\u00e1v\u011b molybden (zhruba 2 %) je kl\u00ed\u010dov\u00fdm rozd\u00edlem oproti A2. Tento prvek z\u00e1sadn\u011b zvy\u0161uje odolnost proti bodov\u00e9 (d\u016flkov\u00e9) korozi a korozn\u00edmu prask\u00e1n\u00ed pod nap\u011bt\u00edm, zejm\u00e9na v prost\u0159ed\u00ed s chloridy. D\u00edky molybdenu je A4 vhodn\u00fd do mo\u0159sk\u00e9 vody a chemicky agresivn\u00edch provoz\u016f.<\/p>\n

Kde je nutn\u00e9 pou\u017e\u00edt A4 m\u00edsto A2?<\/h3>\n

A4 je nezbytn\u00fd v\u0161ude, kde doch\u00e1z\u00ed ke kontaktu s chloridy \u2014 v mo\u0159sk\u00e9 a brakick\u00e9 vod\u011b, na pob\u0159e\u017e\u00ed, v baz\u00e9nech a wellness s chlorovou \u00fapravou, v potravin\u00e1\u0159stv\u00ed a v chemick\u00fdch provozech. V t\u011bchto podm\u00ednk\u00e1ch by A2 podl\u00e9hal bodov\u00e9 korozi, zat\u00edmco molybden v A4 j\u00ed spolehliv\u011b odol\u00e1v\u00e1.<\/p>\n

Je nerez magnetick\u00e1?<\/h3>\n

Austenitick\u00e9 oceli A2 i A4 jsou v \u017e\u00edhan\u00e9m stavu prakticky nemagnetick\u00e9 (paramagnetick\u00e9). Po tv\u00e1\u0159en\u00ed za studena, kter\u00fdm se spojovac\u00ed materi\u00e1l b\u011b\u017en\u011b vyr\u00e1b\u00ed, v\u0161ak m\u016f\u017ee vzniknout deforma\u010dn\u011b indukovan\u00fd martenzit a \u0161roub pak slab\u011b p\u0159it\u00e1hne k magnetu. Tato slab\u00e1 magnetizace nem\u00e1 vliv na korozn\u00ed odolnost ani na kvalitu materi\u00e1lu.<\/p>\n

Jak\u00fd je cenov\u00fd rozd\u00edl mezi A2 a A4?<\/h3>\n

A4 je dra\u017e\u0161\u00ed ne\u017e A2, proto\u017ee obsahuje molybden a vy\u0161\u0161\u00ed pod\u00edl niklu \u2014 tedy n\u00e1kladn\u011bj\u0161\u00ed leguj\u00edc\u00ed prvky. Pro b\u011b\u017en\u00e9 vnit\u0159n\u00ed a nechloridov\u00e9 venkovn\u00ed aplikace proto A2 nab\u00edz\u00ed v\u00fdhodn\u011bj\u0161\u00ed pom\u011br ceny a korozn\u00ed odolnosti. A4 se vyplat\u00ed volit tam, kde to prost\u0159ed\u00ed skute\u010dn\u011b vy\u017eaduje.<\/p>\n

Co znamen\u00e1 zna\u010den\u00ed A2-70 a A4-80?<\/h3>\n

Prvn\u00ed \u010d\u00e1st (A2 nebo A4) ozna\u010duje skupinu oceli, \u010d\u00edslo za poml\u010dkou ud\u00e1v\u00e1 pevnostn\u00ed t\u0159\u00eddu \u2014 minim\u00e1ln\u00ed mez pevnosti v tahu v des\u00edtk\u00e1ch MPa. A2-70 tedy znamen\u00e1 minim\u00e1ln\u011b 700 MPa a A4-80 minim\u00e1ln\u011b 800 MPa. Vy\u0161\u0161\u00ed pevnosti se u nerezu dosahuje tv\u00e1\u0159en\u00edm za studena.<\/p>\n

Koroduje nerez v\u016fbec?<\/h3>\n

Nerez nen\u00ed zcela nezni\u010diteln\u00fd \u2014 v agresivn\u00edm prost\u0159ed\u00ed m\u016f\u017ee korodovat, zejm\u00e9na bodovou koroz\u00ed v p\u0159\u00edtomnosti chlorid\u016f. A2 je n\u00e1chyln\u011bj\u0161\u00ed k bodov\u00e9 korozi ne\u017e A4, kter\u00fd d\u00edky molybdenu odol\u00e1v\u00e1 l\u00e9pe. Pasivn\u00ed chromov\u00e1 vrstva chr\u00e1n\u00ed povrch, ale p\u0159i jej\u00edm po\u0161kozen\u00ed nebo ve velmi agresivn\u00edm prost\u0159ed\u00ed m\u016f\u017ee i nerez napadnout koroze.<\/p>\n

Lze ve spoji m\u00edchat \u0161rouby A2 a A4?<\/h3>\n

Mezi A2 a A4 je galvanick\u00fd potenci\u00e1l velmi bl\u00edzk\u00fd, tak\u017ee riziko galvanick\u00e9 koroze p\u0159i jejich kombinaci je mal\u00e9. Z hlediska korozn\u00ed odolnosti v\u0161ak spoj ur\u010duje nejslab\u0161\u00ed \u010dl\u00e1nek \u2014 pokud je prost\u0159ed\u00ed agresivn\u00ed, pou\u017e\u00edvejte v cel\u00e9m spoji A4. Pozor naopak na kombinaci nerezu s pozinkovanou nebo uhl\u00edkovou ocel\u00ed, kde galvanick\u00e1 koroze hroz\u00ed v\u00fdrazn\u011b.<\/p>\n

Jak\u00fd je rozd\u00edl mezi AISI 304 a AISI 316?<\/h3>\n

AISI 304 odpov\u00edd\u00e1 nerezi A2 (1.4301) a AISI 316 odpov\u00edd\u00e1 nerezi A4 (1.4401). Hlavn\u00ed rozd\u00edl je p\u0159\u00eddavek cca 2 % molybdenu u 316, kter\u00fd z\u00e1sadn\u011b zlep\u0161uje odolnost proti chlorid\u016fm a mo\u0159sk\u00e9 vod\u011b. 304 je vhodn\u00fd pro b\u011b\u017en\u00e9 prost\u0159ed\u00ed, 316 pro pob\u0159e\u017en\u00ed, chemicky n\u00e1ro\u010dn\u00e9 a chloridov\u00e9 aplikace.<\/p>\n

Je A2 vhodn\u00fd do exteri\u00e9ru?<\/h3>\n

Pro v\u011bt\u0161inu venkovn\u00edch aplikac\u00ed mimo pob\u0159e\u017e\u00ed a chloridov\u00e9 prost\u0159ed\u00ed je A2 (1.4301) pln\u011b dosta\u010duj\u00edc\u00ed a nab\u00edz\u00ed v\u00fdbornou korozn\u00ed odolnost p\u0159i p\u0159\u00edzniv\u00e9 cen\u011b. V bl\u00edzkosti mo\u0159e, u baz\u00e9n\u016f nebo v prost\u0159ed\u00ed s posypovou sol\u00ed je v\u0161ak nam\u00edst\u011b s\u00e1hnout po A4 (1.4401), kter\u00fd odol\u00e1v\u00e1 bodov\u00e9 korozi v\u00fdrazn\u011b l\u00e9pe.<\/p>\n

Jak pozn\u00e1m A2 od A4?<\/h3>\n

Vizu\u00e1ln\u011b jsou A2 a A4 prakticky nerozeznateln\u00e9, proto se spol\u00e9h\u00e1 na zna\u010den\u00ed na hlav\u011b \u0161roubu \u2014 ra\u017eba \u201eA2-70″ nebo \u201eA4-80″ spolu s logem v\u00fdrobce. Spolehliv\u00e9 rozli\u0161en\u00ed nab\u00edz\u00ed jen materi\u00e1lov\u00fd atest nebo laboratorn\u00ed anal\u00fdza chemick\u00e9ho slo\u017een\u00ed (p\u0159\u00edtomnost molybdenu). Doporu\u010dujeme proto skladovat A2 a A4 odd\u011blen\u011b a \u0159\u00eddit se zna\u010den\u00edm a doklady.<\/p>\n","protected":false},"excerpt":{"rendered":"

Rozd\u00edl mezi nerezem A2 (1.4301\/304) a A4 (1.4401\/316), molybden, korozn\u00ed odolnost, magnetizmus, zna\u010den\u00ed A2-70\/A4-80 a kdy zvolit kterou t\u0159\u00eddu.<\/p>\n","protected":false},"author":1,"featured_media":614,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_matai_meta_desc":"Rozd\u00edl mezi nerezem A2 (1.4301\/304) a A4 (1.4401\/316), molybden, korozn\u00ed odolnost, magnetizmus, zna\u010den\u00ed A2-70\/A4-80 a kdy zvolit kterou t\u0159\u00eddu.","_matai_faq":"[{\"q\": \"Jak\u00fd je rozd\u00edl mezi nerezem A2 a A4?\", \"a\": \"A2 i A4 jsou austenitick\u00e9 korozivzdorn\u00e9 oceli podle EN ISO 3506-1, ale li\u0161\u00ed se chemick\u00fdm slo\u017een\u00edm. A4 obsahuje nav\u00edc cca 2 % molybdenu a vy\u0161\u0161\u00ed pod\u00edl niklu, co\u017e mu d\u00e1v\u00e1 v\u00fdrazn\u011b lep\u0161\u00ed odolnost proti bodov\u00e9 korozi v chloridov\u00e9m prost\u0159ed\u00ed. A2 odpov\u00edd\u00e1 oceli 1.4301 (AISI 304), A4 oceli 1.4401 (AISI 316).\"}, {\"q\": \"Co znamen\u00e1 ozna\u010den\u00ed 1.4301 a 1.4401?\", \"a\": \"Jsou to evropsk\u00e1 materi\u00e1lov\u00e1 \u010d\u00edsla podle EN 10088. 1.4301 je ocel s cca 18 % chromu a 8\u201310 % niklu (odpov\u00edd\u00e1 A2 \/ AISI 304), zat\u00edmco 1.4401 m\u00e1 cca 16\u201318 % chromu, 10\u201314 % niklu a nav\u00edc 2\u20133 % molybdenu (odpov\u00edd\u00e1 A4 \/ AISI 316). Molybden je hlavn\u00ed rozd\u00edl, kter\u00fd odli\u0161uje ob\u011b oceli.\"}, {\"q\": \"Obsahuje nerez A4 molybden?\", \"a\": \"Ano, pr\u00e1v\u011b molybden (zhruba 2 %) je kl\u00ed\u010dov\u00fdm rozd\u00edlem oproti A2. Tento prvek z\u00e1sadn\u011b zvy\u0161uje odolnost proti bodov\u00e9 (d\u016flkov\u00e9) korozi a korozn\u00edmu prask\u00e1n\u00ed pod nap\u011bt\u00edm, zejm\u00e9na v prost\u0159ed\u00ed s chloridy. D\u00edky molybdenu je A4 vhodn\u00fd do mo\u0159sk\u00e9 vody a chemicky agresivn\u00edch provoz\u016f.\"}, {\"q\": \"Kde je nutn\u00e9 pou\u017e\u00edt A4 m\u00edsto A2?\", \"a\": \"A4 je nezbytn\u00fd v\u0161ude, kde doch\u00e1z\u00ed ke kontaktu s chloridy \u2014 v mo\u0159sk\u00e9 a brakick\u00e9 vod\u011b, na pob\u0159e\u017e\u00ed, v baz\u00e9nech a wellness s chlorovou \u00fapravou, v potravin\u00e1\u0159stv\u00ed a v chemick\u00fdch provozech. V t\u011bchto podm\u00ednk\u00e1ch by A2 podl\u00e9hal bodov\u00e9 korozi, zat\u00edmco molybden v A4 j\u00ed spolehliv\u011b odol\u00e1v\u00e1.\"}, {\"q\": \"Je nerez magnetick\u00e1?\", \"a\": \"Austenitick\u00e9 oceli A2 i A4 jsou v \u017e\u00edhan\u00e9m stavu prakticky nemagnetick\u00e9 (paramagnetick\u00e9). Po tv\u00e1\u0159en\u00ed za studena, kter\u00fdm se spojovac\u00ed materi\u00e1l b\u011b\u017en\u011b vyr\u00e1b\u00ed, v\u0161ak m\u016f\u017ee vzniknout deforma\u010dn\u011b indukovan\u00fd martenzit a \u0161roub pak slab\u011b p\u0159it\u00e1hne k magnetu. Tato slab\u00e1 magnetizace nem\u00e1 vliv na korozn\u00ed odolnost ani na kvalitu materi\u00e1lu.\"}, {\"q\": \"Jak\u00fd je cenov\u00fd rozd\u00edl mezi A2 a A4?\", \"a\": \"A4 je dra\u017e\u0161\u00ed ne\u017e A2, proto\u017ee obsahuje molybden a vy\u0161\u0161\u00ed pod\u00edl niklu \u2014 tedy n\u00e1kladn\u011bj\u0161\u00ed leguj\u00edc\u00ed prvky. Pro b\u011b\u017en\u00e9 vnit\u0159n\u00ed a nechloridov\u00e9 venkovn\u00ed aplikace proto A2 nab\u00edz\u00ed v\u00fdhodn\u011bj\u0161\u00ed pom\u011br ceny a korozn\u00ed odolnosti. A4 se vyplat\u00ed volit tam, kde to prost\u0159ed\u00ed skute\u010dn\u011b vy\u017eaduje.\"}, {\"q\": \"Co znamen\u00e1 zna\u010den\u00ed A2-70 a A4-80?\", \"a\": \"Prvn\u00ed \u010d\u00e1st (A2 nebo A4) ozna\u010duje skupinu oceli, \u010d\u00edslo za poml\u010dkou ud\u00e1v\u00e1 pevnostn\u00ed t\u0159\u00eddu \u2014 minim\u00e1ln\u00ed mez pevnosti v tahu v des\u00edtk\u00e1ch MPa. A2-70 tedy znamen\u00e1 minim\u00e1ln\u011b 700 MPa a A4-80 minim\u00e1ln\u011b 800 MPa. Vy\u0161\u0161\u00ed pevnosti se u nerezu dosahuje tv\u00e1\u0159en\u00edm za studena.\"}, {\"q\": \"Koroduje nerez v\u016fbec?\", \"a\": \"Nerez nen\u00ed zcela nezni\u010diteln\u00fd \u2014 v agresivn\u00edm prost\u0159ed\u00ed m\u016f\u017ee korodovat, zejm\u00e9na bodovou koroz\u00ed v p\u0159\u00edtomnosti chlorid\u016f. A2 je n\u00e1chyln\u011bj\u0161\u00ed k bodov\u00e9 korozi ne\u017e A4, kter\u00fd d\u00edky molybdenu odol\u00e1v\u00e1 l\u00e9pe. Pasivn\u00ed chromov\u00e1 vrstva chr\u00e1n\u00ed povrch, ale p\u0159i jej\u00edm po\u0161kozen\u00ed nebo ve velmi agresivn\u00edm prost\u0159ed\u00ed m\u016f\u017ee i nerez napadnout koroze.\"}, {\"q\": \"Lze ve spoji m\u00edchat \u0161rouby A2 a A4?\", \"a\": \"Mezi A2 a A4 je galvanick\u00fd potenci\u00e1l velmi bl\u00edzk\u00fd, tak\u017ee riziko galvanick\u00e9 koroze p\u0159i jejich kombinaci je mal\u00e9. Z hlediska korozn\u00ed odolnosti v\u0161ak spoj ur\u010duje nejslab\u0161\u00ed \u010dl\u00e1nek \u2014 pokud je prost\u0159ed\u00ed agresivn\u00ed, pou\u017e\u00edvejte v cel\u00e9m spoji A4. Pozor naopak na kombinaci nerezu s pozinkovanou nebo uhl\u00edkovou ocel\u00ed, kde galvanick\u00e1 koroze hroz\u00ed v\u00fdrazn\u011b.\"}, {\"q\": \"Jak\u00fd je rozd\u00edl mezi AISI 304 a AISI 316?\", \"a\": \"AISI 304 odpov\u00edd\u00e1 nerezi A2 (1.4301) a AISI 316 odpov\u00edd\u00e1 nerezi A4 (1.4401). Hlavn\u00ed rozd\u00edl je p\u0159\u00eddavek cca 2 % molybdenu u 316, kter\u00fd z\u00e1sadn\u011b zlep\u0161uje odolnost proti chlorid\u016fm a mo\u0159sk\u00e9 vod\u011b. 304 je vhodn\u00fd pro b\u011b\u017en\u00e9 prost\u0159ed\u00ed, 316 pro pob\u0159e\u017en\u00ed, chemicky n\u00e1ro\u010dn\u00e9 a chloridov\u00e9 aplikace.\"}, {\"q\": \"Je A2 vhodn\u00fd do exteri\u00e9ru?\", \"a\": \"Pro v\u011bt\u0161inu venkovn\u00edch aplikac\u00ed mimo pob\u0159e\u017e\u00ed a chloridov\u00e9 prost\u0159ed\u00ed je A2 (1.4301) pln\u011b dosta\u010duj\u00edc\u00ed a nab\u00edz\u00ed v\u00fdbornou korozn\u00ed odolnost p\u0159i p\u0159\u00edzniv\u00e9 cen\u011b. V bl\u00edzkosti mo\u0159e, u baz\u00e9n\u016f nebo v prost\u0159ed\u00ed s posypovou sol\u00ed je v\u0161ak nam\u00edst\u011b s\u00e1hnout po A4 (1.4401), kter\u00fd odol\u00e1v\u00e1 bodov\u00e9 korozi v\u00fdrazn\u011b l\u00e9pe.\"}, {\"q\": \"Jak pozn\u00e1m A2 od A4?\", \"a\": \"Vizu\u00e1ln\u011b jsou A2 a A4 prakticky nerozeznateln\u00e9, proto se spol\u00e9h\u00e1 na zna\u010den\u00ed na hlav\u011b \u0161roubu \u2014 ra\u017eba \u201eA2-70\\\" nebo \u201eA4-80\\\" spolu s logem v\u00fdrobce. Spolehliv\u00e9 rozli\u0161en\u00ed nab\u00edz\u00ed jen materi\u00e1lov\u00fd atest nebo laboratorn\u00ed anal\u00fdza chemick\u00e9ho slo\u017een\u00ed (p\u0159\u00edtomnost molybdenu). Doporu\u010dujeme proto skladovat A2 a A4 odd\u011blen\u011b a \u0159\u00eddit se zna\u010den\u00edm a doklady.\"}]","_matai_schema_type":"Article","footnotes":""},"categories":[3],"tags":[],"class_list":["post-16","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-caste-dotazy"],"_links":{"self":[{"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/posts\/16","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/comments?post=16"}],"version-history":[{"count":1,"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/posts\/16\/revisions"}],"predecessor-version":[{"id":409,"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/posts\/16\/revisions\/409"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/media\/614"}],"wp:attachment":[{"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/media?parent=16"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/categories?post=16"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.matai.cz\/blog\/wp-json\/wp\/v2\/tags?post=16"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}