{"id":183,"date":"2024-11-27T10:38:27","date_gmt":"2024-11-27T10:38:27","guid":{"rendered":"https:\/\/pwhtsolutions.net\/?p=183"},"modified":"2025-01-05T09:23:46","modified_gmt":"2025-01-05T09:23:46","slug":"p91-pwht-graf-2","status":"publish","type":"post","link":"https:\/\/pwhtsolutions.net\/cs\/p91-pwht-chart-2\/","title":{"rendered":"P91 PWHT graf"},"content":{"rendered":"

Ocel P91 je atraktivn\u00edm materi\u00e1lem pro energetick\u00e9 kotle a dal\u0161\u00ed vysokoteplotn\u00ed aplikace, proto\u017ee nab\u00edz\u00ed vynikaj\u00edc\u00ed kombinace mechanick\u00fdch vlastnost\u00ed p\u0159i vy\u0161\u0161\u00edch teplot\u00e1ch, jako je pevnost, odolnost proti te\u010den\u00ed a r\u00e1zov\u00e1 hou\u017eevnatost podle Charpyho.<\/p>\n

Ned\u00e1vn\u00e9 studie prok\u00e1zaly, \u017ee r\u016fzn\u00e9 podm\u00ednky normalizace a popou\u0161t\u011bn\u00ed (NT) svar\u016f oceli P91 mohou v\u00e9st k optim\u00e1ln\u00edm mechanick\u00fdm vlastnostem v HAZ bez nutnosti tepeln\u00e9ho zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed.<\/p>\n

Tvrdost<\/h2>\n

T\u0159\u00edda SA 335 91 je modifikovan\u00e1 vysoce chrom-molymern\u00ed martenzitick\u00e1 ocel ur\u010den\u00e1 pro zv\u00fd\u0161en\u00e9 teploty v elektr\u00e1rn\u00e1ch a pro dal\u0161\u00ed vysoce v\u00fdkonn\u00e9 aplikace, jako je sva\u0159ov\u00e1n\u00ed. Vyzna\u010duje se dobrou pevnost\u00ed v te\u010den\u00ed a hou\u017eevnatost\u00ed, jako\u017e i odolnost\u00ed proti korozi a sva\u0159itelnost\u00ed; b\u011bhem sva\u0159ov\u00e1n\u00ed nebo tepeln\u00e9ho zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT) v\u0161ak m\u016f\u017ee doj\u00edt ke sn\u00ed\u017een\u00ed jej\u00ed tvrdosti, co\u017e vede k prask\u00e1n\u00ed nebo p\u0159ed\u010dasn\u00e9mu selh\u00e1n\u00ed.<\/p>\n

Studie vlivu r\u016fzn\u00fdch sva\u0159ovac\u00edch proces\u016f, typ\u016f p\u0159\u00eddavn\u00fdch dr\u00e1t\u016f a teplot p\u0159edeh\u0159evu\/interpassu na P91 byly kdysi vz\u00e1cn\u00e9; v posledn\u00ed dob\u011b v\u0161ak st\u00e1le \u010dast\u011bji doch\u00e1z\u00ed k oprav\u00e1m potrub\u00ed P91 s nepodobn\u00fdmi svary za pou\u017eit\u00ed podobn\u00fdch sva\u0159ovac\u00edch proces\u016f a p\u0159\u00eddavn\u00e9ho kovu jako u p\u016fvodn\u00edch svar\u016f; to vy\u017eaduje, aby \u00farove\u0148 tvrdosti HAZ byla ni\u017e\u0161\u00ed ne\u017e jejich z\u00e1kladn\u00ed kov; jak toho lze dos\u00e1hnout v rozumn\u00e9m \u010dase p\u0159i PWHT, je t\u0159eba d\u00e1le zkoumat.<\/p>\n

U n\u011bkter\u00fdch projekt\u016f elektr\u00e1ren byly b\u011bhem provozu zaznamen\u00e1ny trhliny typu IV v HAZ svaru. Tyto trhliny byly pravd\u011bpodobn\u011b d\u016fsledkem nedostate\u010dn\u00e9 PWHT. Na\u0161e \u0161et\u0159en\u00ed dosp\u011blo k z\u00e1v\u011bru, \u017ee PWHT p\u0159i teplot\u011b 750 stup\u0148\u016f C po dobu dvou hodin je ide\u00e1ln\u00ed pro sn\u00ed\u017een\u00ed tvrdosti v HAZ svaru p\u0159i zaji\u0161t\u011bn\u00ed dostate\u010dn\u00e9 mikrostruktury a p\u0159ijateln\u00e9ho rozd\u00edlu tvrdosti s v\u00fdchoz\u00edm kovem.<\/p>\n

Pevnost v tahu<\/h2>\n

Pevnost proti te\u010den\u00ed p91 ud\u00e1v\u00e1, jak velk\u00e9mu nam\u00e1h\u00e1n\u00ed materi\u00e1l odol\u00e1, ne\u017e se zdeformuje, p\u0159i\u010dem\u017e odolnost proti te\u010den\u00ed z\u00e1vis\u00ed na faktorech, jako je velikost zrn a provozn\u00ed teplota, a tak\u00e9 na chemick\u00e9m slo\u017een\u00ed, kter\u00e9 ovliv\u0148uje transforma\u010dn\u00ed teploty a dal\u0161\u00ed vlastnosti jeho slo\u017een\u00ed.<\/p>\n

Pro stanoven\u00ed meze te\u010den\u00ed kovu pou\u017e\u00edvaj\u00ed konstrukt\u00e9\u0159i pom\u011br mezi nap\u011bt\u00edm p\u0159i p\u0159etr\u017een\u00ed a jeho k\u0159ivkou nap\u011bt\u00ed-deformace, extrapolovanou a\u017e na 100 000 hodin, a vypo\u010dten\u00e9 minim\u00e1ln\u00ed rychlosti te\u010den\u00ed v tomto \u010dasov\u00e9m horizontu. Nap\u011bt\u00ed p\u0159i roztr\u017een\u00ed m\u011b\u0159\u00ed jak nap\u011bt\u00ed v koncov\u00e9m bod\u011b roztr\u017een\u00ed, tak i nap\u011bt\u00ed pot\u0159ebn\u00e9 k dosa\u017een\u00ed tohoto bodu - uv\u00e1d\u00ed se jako hodnoty nap\u011bt\u00ed i \u010dasu.<\/p>\n

Martenzitick\u00e1 \u017e\u00e1ruvzdorn\u00e1 ocel p91 (9Cr-1Mo-V-Nb) se b\u011b\u017en\u011b pou\u017e\u00edv\u00e1 v elektr\u00e1rn\u00e1ch na fosiln\u00ed paliva pro hlavice kotl\u016f a dal\u0161\u00ed sou\u010d\u00e1sti d\u00edky sv\u00e9 vynikaj\u00edc\u00ed odolnosti proti korozi vodn\u00ed parou, n\u00edzk\u00e9 tepeln\u00e9 rozta\u017enosti, vysok\u00e9 tepeln\u00e9 vodivosti a sva\u0159itelnosti; nicm\u00e9n\u011b po relativn\u011b kr\u00e1tk\u00e9 dob\u011b provozu byly zaznamen\u00e1ny poruchy sou\u010d\u00e1st\u00ed vyroben\u00fdch z tohoto kovu.<\/p>\n

K poruch\u00e1m doch\u00e1z\u00ed v d\u016fsledku sn\u00ed\u017een\u00fdch pevnostn\u00edch vlastnost\u00ed p\u0159i te\u010den\u00ed v d\u016fsledku jemnozrnn\u00fdch oblast\u00ed v tepeln\u011b ovlivn\u011bn\u00e9 z\u00f3n\u011b (HAZ).<\/p>\n

Charpyho hou\u017eevnatost<\/h2>\n

Ocel P91 je ide\u00e1ln\u00ed pro dlouhodob\u00e9 pou\u017eit\u00ed v sou\u010d\u00e1stech elektr\u00e1ren, kter\u00e9 pracuj\u00ed p\u0159i vysok\u00fdch teplot\u00e1ch, v\u010detn\u011b t\u011bch, kter\u00e9 jsou vystaveny te\u010den\u00ed a tepeln\u00e9mu zat\u00ed\u017een\u00ed, vysok\u00e9 ta\u017enosti a minim\u00e1ln\u00ed tepeln\u00e9 rozta\u017enosti. Vzhledem k tomu, \u017ee jej\u00ed oxida\u010dn\u00ed odolnost kles\u00e1 pod 610 stup\u0148\u016f C, jej\u00ed pou\u017eit\u00ed pro energetiku se st\u00e1v\u00e1 omezen\u00fdm. Krom\u011b toho omezuje jeho pou\u017eit\u00ed p\u0159i dynamick\u00e9m zat\u00ed\u017een\u00ed n\u00edzk\u00e1 r\u00e1zov\u00e1 hou\u017eevnatost; pro dal\u0161\u00ed zv\u00fd\u0161en\u00ed t\u00e9to vlastnosti se doporu\u010duje tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT). Norma DIN EN 288-3 uv\u00e1d\u00ed mechanick\u00e9 zkou\u0161ky na skute\u010dn\u00fdch vzorc\u00edch HAZ svar\u016f, p\u0159i nich\u017e se \u0161\u00ed\u0159en\u00ed trhlin v ka\u017ed\u00e9 d\u00edl\u010d\u00ed z\u00f3n\u011b li\u0161\u00ed v z\u00e1vislosti na jej\u00ed mikrostruktu\u0159e a vede k rozd\u00edl\u016fm v r\u00e1zov\u00e9 energii mezi jednotliv\u00fdmi zkou\u0161kami.<\/p>\n

V\u00edcepr\u016fchodov\u00e9 obloukov\u00e9 svary v ochrann\u00e9 atmosf\u00e9\u0159e ocel\u00ed P91 a P22 vykazuj\u00ed v z\u00f3n\u00e1ch taven\u00ed svar\u016f (FGHAZ) n\u00edzkou r\u00e1zovou hou\u017eevnatost. To je zp\u016fsobeno hromad\u011bn\u00edm nezpevn\u011bn\u00e9ho martenzitu v t\u00e9to oblasti v d\u016fsledku nespr\u00e1vn\u00e9 PWHT.<\/p>\n

Studie prok\u00e1zaly vliv hladiny dif\u00fazn\u00edho vod\u00edku a d\u00e9lky PWHT na mechanick\u00e9 vlastnosti svarov\u00fdch spoj\u016f a gradient tvrdosti. Pandey a kol. zkoumali vliv tohoto faktoru na mikrostrukturu a hou\u017eevnatost u v\u00edcepr\u016fchodov\u00fdch sva\u0159enc\u016f desek P91 sva\u0159ovan\u00fdch metodou SMAW se \u010dty\u0159mi r\u016fzn\u00fdmi hladinami vod\u00edku a uk\u00e1zali, \u017ee vy\u0161\u0161\u00ed hladina difuzn\u00edho vod\u00edku a doba PWHT vedly ke zlep\u0161en\u00ed hou\u017eevnatosti, ale ke sn\u00ed\u017een\u00ed r\u00e1zov\u00e9 hou\u017eevnatosti.<\/p>\n

Odolnost proti korozi<\/h2>\n

Ocel t\u0159\u00eddy 91 je zn\u00e1m\u00e1 svou vynikaj\u00edc\u00ed odolnost\u00ed proti korozi, av\u0161ak v d\u016fsledku po\u0161kozen\u00ed martenzitem a te\u010den\u00edm m\u016f\u017ee doj\u00edt ke korozi. Tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT) m\u016f\u017ee pomoci tyto \u00fa\u010dinky zm\u00edrnit; tato metoda v\u0161ak nemus\u00ed b\u00fdt v\u017edy provediteln\u00e1 nebo n\u00e1kladov\u011b efektivn\u00ed, zejm\u00e9na p\u0159i oprav\u00e1ch v provozu.<\/p>\n

V\u00fdzkum prov\u00e1d\u011bn\u00fd v r\u00e1mci tohoto projektu se zam\u011b\u0159il na zkoum\u00e1n\u00ed metalurgick\u00e9ho chov\u00e1n\u00ed materi\u00e1l\u016f b\u011bhem sva\u0159ov\u00e1n\u00ed a tepeln\u00e9ho zpracov\u00e1n\u00ed, a to vyhodnocen\u00edm mikrostruktur vzork\u016f svar\u016f a HAZ vyroben\u00fdch po sva\u0159ov\u00e1n\u00ed; na skute\u010dn\u00fdch svarech byly pot\u00e9 provedeny mechanick\u00e9 zkou\u0161ky pro m\u011b\u0159en\u00ed hou\u017eevnatosti HAZ.<\/p>\n

Srovn\u00e1v\u00e1ny byly tak\u00e9 r\u016fzn\u00e9 sva\u0159ovac\u00ed techniky se zam\u011b\u0159en\u00edm na vliv teplot p\u0159edeh\u0159evu\/interpassu a sva\u0159ovac\u00edch proud\u016f. Jako nejvhodn\u011bj\u0161\u00ed pro v\u00fdvoj postup\u016f sva\u0159ov\u00e1n\u00ed bez PWHT se uk\u00e1zaly elektrody s pr\u016fm\u011bry odpov\u00eddaj\u00edc\u00edmi pr\u016fm\u011br\u016fm zji\u0161t\u011bn\u00fdm u t\u0159\u00eddy 91; p\u0159i pou\u017eit\u00ed kombinac\u00ed SMAW elektrod o pr\u016fm\u011brech 3,2 mm (1\/8 palce, prvn\u00ed vrstva) a 4,0 mm (5\/32 palce, druh\u00e1 vrstva) do\u0161lo k v\u00fdrazn\u00e9mu zjemn\u011bn\u00ed, zat\u00edmco popou\u0161t\u011bn\u00ed bylo v HAZ omezeno.<\/p>\n

Tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed TIG svarov\u00fdch spoj\u016f mezi ocel\u00ed P22 a ocel\u00ed t\u0159\u00eddy 91 s pou\u017eit\u00edm p\u0159\u00eddavn\u00e9ho kovu Inconel 625 je nejvhodn\u011bj\u0161\u00ed prov\u00e1d\u011bt p\u0159i teplot\u011b 750 \u00b0C po dobu 2 hodin, aby se dos\u00e1hlo optim\u00e1ln\u00edho kompromisu mezi tvrdost\u00ed rozhran\u00ed a vlastnostmi svarov\u00e9ho kovu p\u0159i zachov\u00e1n\u00ed vysok\u00fdch mechanick\u00fdch vlastnost\u00ed v \u0161irok\u00e9m teplotn\u00edm spektru.<\/p>","protected":false},"excerpt":{"rendered":"

Ocel P91 je atraktivn\u00edm materi\u00e1lem pro energetick\u00e9 kotle a dal\u0161\u00ed vysokoteplotn\u00ed aplikace, nebo\u0165 nab\u00edz\u00ed vynikaj\u00edc\u00ed kombinaci mechanick\u00fdch vlastnost\u00ed p\u0159i vy\u0161\u0161\u00edch teplot\u00e1ch, jako je pevnost, odolnost proti te\u010den\u00ed a r\u00e1zov\u00e1 hou\u017eevnatost podle Charpyho. Ned\u00e1vn\u00e9 studie prok\u00e1zaly, \u017ee r\u016fzn\u00e9 podm\u00ednky normalizace a popou\u0161t\u011bn\u00ed (NT) svar\u016f z oceli P91 mohou v\u00e9st k dosa\u017een\u00ed optim\u00e1ln\u00edch mechanick\u00fdch vlastnost\u00ed v z\u00f3n\u011b ovlivn\u011bn\u00e9 teplem (HAZ) \u2026 <\/p>\n

P\u0159e\u010dt\u011bte si v\u00edce “P91 PWHT Chart”<\/span><\/a><\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-183","post","type-post","status-publish","format-standard","hentry","category-product-related"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/posts\/183","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/comments?post=183"}],"version-history":[{"count":1,"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/posts\/183\/revisions"}],"predecessor-version":[{"id":184,"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/posts\/183\/revisions\/184"}],"wp:attachment":[{"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/media?parent=183"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/categories?post=183"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/tags?post=183"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}