{"id":203,"date":"2024-12-12T14:22:35","date_gmt":"2024-12-12T14:22:35","guid":{"rendered":"https:\/\/pwhtsolutions.net\/?p=203"},"modified":"2024-12-12T14:22:36","modified_gmt":"2024-12-12T14:22:36","slug":"vyznam-tepelneho-zpracovani-po-svarovani","status":"publish","type":"post","link":"https:\/\/pwhtsolutions.net\/cs\/the-importance-of-post-weld-heat-treatment\/","title":{"rendered":"V\u00fdznam tepeln\u00e9ho zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed"},"content":{"rendered":"

Sva\u0159ov\u00e1n\u00ed zanech\u00e1v\u00e1 zbytkov\u00e1 nap\u011bt\u00ed, kter\u00e1 mohou naru\u0161it vlastnosti materi\u00e1lu. Ke sn\u00ed\u017een\u00ed t\u011bchto nap\u011bt\u00ed a obnoven\u00ed p\u016fvodn\u00edch vlastnost\u00ed materi\u00e1lu m\u016f\u017ee b\u00fdt zapot\u0159eb\u00ed tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT).<\/p>\n

PWHT vyu\u017e\u00edv\u00e1 \u0159\u00edzen\u00fd profil n\u00e1b\u011bhu a nam\u00e1\u010den\u00ed p\u0159i teplot\u00e1ch ni\u017e\u0161\u00edch ne\u017e je po\u010d\u00e1te\u010dn\u00ed teplota transformace materi\u00e1lu k op\u011btovn\u00e9mu oh\u0159evu sva\u0159ovan\u00e9ho materi\u00e1lu v oblasti zn\u00e1m\u00e9 jako vyh\u0159\u00edvan\u00e1 z\u00f3na nebo p\u00e1smo regulace gradientu, kter\u00e9 obklopuje nevyh\u0159\u00edvanou \u010d\u00e1st vy\u017eaduj\u00edc\u00ed tepelnou izolaci, aby bylo dosa\u017eeno p\u0159ijateln\u00e9ho teplotn\u00edho gradientu.<\/p>\n

\u00daleva od stresu<\/h2>\n

Tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT) je d\u016fle\u017eitou sou\u010d\u00e1st\u00ed procesu sva\u0159ov\u00e1n\u00ed. Slou\u017e\u00ed ke sn\u00ed\u017een\u00ed zbytkov\u00fdch nap\u011bt\u00ed ve sva\u0159ovan\u00fdch materi\u00e1lech a ke zv\u00fd\u0161en\u00ed mechanick\u00fdch vlastnost\u00ed a odolnosti proti korozi. Krom\u011b toho m\u016f\u017ee PWHT pomoci zabr\u00e1nit vzniku korozn\u00edch trhlin v ur\u010dit\u00fdch slitin\u00e1ch oceli; pokud se v\u0161ak provede nespr\u00e1vn\u011b, m\u016f\u017ee m\u00edt za n\u00e1sledek vady v hotov\u00e9m v\u00fdrobku.<\/p>\n

Zbytkov\u00e1 nap\u011bt\u00ed vznikaj\u00ed ve sva\u0159ovan\u00fdch konstrukc\u00edch, kdy\u017e lok\u00e1ln\u00ed oh\u0159ev a ochlazov\u00e1n\u00ed zp\u016fsob\u00ed, \u017ee se kovy rozp\u00ednaj\u00ed a smr\u0161\u0165uj\u00ed r\u016fznou rychlost\u00ed, co\u017e vede k deformaci, k\u0159ehk\u00e9mu lomu, sn\u00ed\u017een\u00ed mechanick\u00fdch vlastnost\u00ed nebo jejich kombinaci. Tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (nebo uvoln\u011bn\u00ed nap\u011bt\u00ed) pom\u00e1h\u00e1 zm\u00edrnit tyto \u00fa\u010dinky zah\u0159\u00e1t\u00edm cel\u00e9 konstrukce na ni\u017e\u0161\u00ed kritickou teplotu p\u0159etvo\u0159en\u00ed po p\u0159im\u011b\u0159en\u011b dlouhou dobu - to z\u00e1vis\u00ed na typu materi\u00e1lu\/slo\u017een\u00ed\/po\u017eadavc\u00edch na teplotu a tak\u00e9 na dob\u011b nam\u00e1\u010den\u00ed p\u0159i \u0161pi\u010dkov\u00fdch teplot\u00e1ch.<\/p>\n

Tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed nejen sni\u017euje zbytkov\u00e9 nap\u011bt\u00ed, ale m\u016f\u017ee tak\u00e9 zm\u011bk\u010dit sva\u0159ovan\u00e9 konstrukce, aby se sn\u00e1ze obr\u00e1b\u011bly a sn\u00ed\u017eily se n\u00e1klady s nimi spojen\u00e9. Krom\u011b toho tento proces pom\u00e1h\u00e1 zpevnit a prodlou\u017eit \u017eivotnost sva\u0159ovan\u00fdch konstrukc\u00ed, co\u017e je d\u016fle\u017eit\u00fd aspekt p\u0159i pr\u016fmyslov\u00fdch aplikac\u00edch a konstrukci za\u0159\u00edzen\u00ed.<\/p>\n

Odolnost proti korozi<\/h2>\n

Ropn\u00e9, plynov\u00e9, petrochemick\u00e9 a jadern\u00e9 aplikace, kde jsou za\u0159\u00edzen\u00ed vystavena drsn\u00fdm podm\u00ednk\u00e1m, vy\u017eaduj\u00ed maxim\u00e1ln\u00ed odolnost proti korozi; k tomu je t\u0159eba \u00fasp\u011b\u0161n\u011b prov\u00e9st tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT), aby se sn\u00ed\u017eila zbytkov\u00e1 nap\u011bt\u00ed a zlep\u0161ily metalurgick\u00e9 vlastnosti materi\u00e1lu.<\/p>\n

Sva\u0159ov\u00e1n\u00ed je ned\u00edlnou sou\u010d\u00e1st\u00ed v\u00fdroby a \u00fadr\u017eby tlakov\u00fdch n\u00e1dob, potrub\u00ed a dal\u0161\u00edch konstrukc\u00ed v r\u016fzn\u00fdch pr\u016fmyslov\u00fdch odv\u011btv\u00edch. P\u0159i nespr\u00e1vn\u00e9m proveden\u00ed v\u0161ak m\u016f\u017ee doj\u00edt k po\u0161kozen\u00ed za\u0159\u00edzen\u00ed vytvo\u0159en\u00edm ne\u017e\u00e1douc\u00edch nap\u011bt\u00ed, kter\u00e1 se s\u010d\u00edtaj\u00ed s nam\u00e1h\u00e1n\u00edm p\u0159i zat\u00ed\u017een\u00ed a p\u0159ekra\u010duj\u00ed konstruk\u010dn\u00ed limity materi\u00e1l\u016f, co\u017e vede k selh\u00e1n\u00ed svaru a zv\u00fd\u0161en\u00e9 n\u00e1chylnosti k prask\u00e1n\u00ed vyvolan\u00e9mu vod\u00edkem. PWHT nab\u00edz\u00ed \u00fa\u010dinn\u00e9 \u0159e\u0161en\u00ed, jak tyto probl\u00e9my \u0159e\u0161it a z\u00e1rove\u0148 zv\u00fd\u0161it pevnost a odolnost svar\u016f.<\/p>\n

PWHT zahrnuje oh\u0159ev materi\u00e1lu pod kritickou teplotu p\u0159em\u011bny a jeho udr\u017eov\u00e1n\u00ed po stanovenou dobu, aby do\u0161lo k metalurgick\u00fdm zm\u011bn\u00e1m a sn\u00ed\u017een\u00ed zbytkov\u00fdch nap\u011bt\u00ed, kter\u00e9 n\u00e1sledn\u011b zajist\u00ed p\u0159esn\u011bj\u0161\u00ed struktury svar\u016f, lep\u0161\u00ed ta\u017enost a sn\u00ed\u017een\u00ed rizika k\u0159ehk\u00e9ho lomu.<\/p>\n

Krom\u011b uvoln\u011bn\u00ed nap\u011bt\u00ed je PWHT nezbytn\u00e1 tak\u00e9 pro zachov\u00e1n\u00ed integrity precipita\u010dn\u011b vytvrzen\u00fdch slitin po sva\u0159ov\u00e1n\u00ed. Tyto slitiny jsou z\u00e1visl\u00e9 na precipit\u00e1tech, kter\u00e9 blokuj\u00ed dislokace v jejich krystalick\u00e9 struktu\u0159e a zvy\u0161uj\u00ed pevnost a tvrdost; sva\u0159ov\u00e1n\u00ed zp\u016fsobuje zm\u011bny t\u011bchto precipit\u00e1t\u016f, kter\u00e9 by mohly sn\u00ed\u017eit pevnost nebo tvrdost - proto prov\u00e1d\u011bn\u00ed PWHT po sva\u0159ov\u00e1n\u00ed zaji\u0161\u0165uje, \u017ee se precipit\u00e1ty vytvo\u0159\u00ed ve spr\u00e1vn\u00e9 velikosti pro maxim\u00e1ln\u00ed tvrdost a pevnost.<\/p>\n

Mechanick\u00e9 vlastnosti<\/h2>\n

Vysok\u00e9 teploty spojen\u00e9 s tepeln\u00fdm zpracov\u00e1n\u00edm PWHT mohou deformovat sou\u010d\u00e1sti, kter\u00e9 jsou tvarovan\u00e9 nebo maj\u00ed velk\u00fd pr\u016fm\u011br, co\u017e vede k deformaci. Aby se tento probl\u00e9m zm\u00edrnil, mus\u00ed b\u00fdt p\u0159edm\u011bt podroben\u00fd PWHT vhodn\u011b podep\u0159en; bu\u010f pomoc\u00ed speci\u00e1ln\u011b tvarovan\u00fdch kozl\u00edk\u016f, kter\u00e9 dokonale padnou kolem n\u011bj, nebo n\u011bkolika stejn\u00fdch kozl\u00edk\u016f um\u00edst\u011bn\u00fdch v pravideln\u00fdch intervalech kolem n\u011bj - t\u00edm se zajist\u00ed, \u017ee ka\u017ed\u00e1 oblast za\u017eije stejnou m\u00edru rozta\u017enosti\/smr\u0161t\u011bn\u00ed jako zbytek jej\u00edch sou\u010d\u00e1st\u00ed.<\/p>\n

Kontrola doby nam\u00e1\u010den\u00ed svarov\u00e9ho kovu a rychlosti ochlazov\u00e1n\u00ed je z\u00e1sadn\u00ed, aby se zabr\u00e1nilo p\u0159eh\u0159\u00e1t\u00ed, kter\u00e9 by mohlo v\u00e9st ke vzniku nov\u00fdch pnut\u00ed v materi\u00e1lu. Krom\u011b toho mohou procesy zah\u0159\u00edv\u00e1n\u00ed vyvolat v materi\u00e1lu f\u00e1zov\u00e9 zm\u011bny, kter\u00e9 zlep\u0161uj\u00ed mechanick\u00e9 vlastnosti - nap\u0159\u00edklad \u017e\u00edh\u00e1n\u00ed m\u016f\u017ee vytvo\u0159it jemn\u011bj\u0161\u00ed strukturu zrn, co\u017e vede k vy\u0161\u0161\u00ed pevnosti a hou\u017eevnatosti.<\/p>\n

Mnoh\u00e9 p\u0159edpisy a normy na\u0159izuj\u00ed tepeln\u00e9 zpracov\u00e1n\u00ed svar\u016f po sva\u0159ov\u00e1n\u00ed pr\u00e1v\u011b z tohoto d\u016fvodu, aby se sn\u00ed\u017eilo riziko poruchy v d\u016fsledku zbytkov\u00e9ho nap\u011bt\u00ed, zv\u00fd\u0161ila se \u00fanavov\u00e1 \u017eivotnost svar\u016f, sn\u00ed\u017eila se n\u00e1chylnost ke vzniku korozn\u00edch trhlin a chr\u00e1nily se p\u0159ed korozn\u00edm prask\u00e1n\u00edm pod nap\u011bt\u00edm - zejm\u00e9na u procesn\u00edch potrub\u00ed nebo tlakov\u00fdch d\u00edl\u016f, kter\u00e9 jsou v nep\u0159etr\u017eit\u00e9m provozu.<\/p>\n

Omezen\u00ed vybaven\u00ed<\/h2>\n

PWHT zahrnuje zah\u0159\u00e1t\u00ed oceli na extr\u00e9mn\u011b vysokou teplotu a n\u00e1sledn\u00e9 pomal\u00e9 ochlazen\u00ed, co\u017e m\u016f\u017ee v\u00e9st k deformaci a pok\u0159iven\u00ed, kter\u00e9 ohro\u017euj\u00ed jej\u00ed rozm\u011brovou p\u0159esnost a struktur\u00e1ln\u00ed integritu. PWHT nav\u00edc zpo\u017e\u010fuje vznik trhlin ve svarov\u00fdch spoj\u00edch, co\u017e zt\u011b\u017euje kontrolu - zvy\u0161uje riziko \u00faniku, proto\u017ee oddaluje opravy pozd\u011bji vznikl\u00fdch trhlin.<\/p>\n

PWHT m\u016f\u017ee b\u00fdt n\u00e1kladn\u00fd proces, co\u017e vytv\u00e1\u0159\u00ed ekonomickou motivaci vyhnout se mu, kdykoli je to mo\u017en\u00e9. Oh\u0159ev a chlazen\u00ed velk\u00fdch ocelov\u00fdch sestav vy\u017eaduje \u010dasov\u011b n\u00e1ro\u010dn\u00e9 procesy, kter\u00e9 by mohly zastavit \u010dinnost v\u00fdrobn\u00ed linky; krom\u011b toho zna\u010dn\u00e1 spot\u0159eba energie p\u0159isp\u00edv\u00e1 k emis\u00edm sklen\u00edkov\u00fdch plyn\u016f a tak\u00e9 k obav\u00e1m o \u017eivotn\u00ed prost\u0159ed\u00ed; n\u011bkolik cykl\u016f PWHT b\u011bhem \u017eivotnosti jednoho tlakov\u00e9ho za\u0159\u00edzen\u00ed m\u016f\u017ee tyto negativn\u00ed dopady d\u00e1le prohloubit.<\/p>\n

Proto\u017ee PWHT m\u016f\u017ee zp\u016fsobit tepelnou deformaci v oblastech, kter\u00e9 j\u00ed nejsou vystaveny, nelze PWHT v\u017edy \u00fa\u010dinn\u011b prov\u00e1d\u011bt na tlakov\u00fdch za\u0159\u00edzen\u00edch vzhledem k jejich velikosti nebo geometrii. Tepeln\u00e9 deformace zp\u016fsoben\u00e9 PWHT nav\u00edc mohou p\u0159esunout zbytkov\u00e1 nap\u011bt\u00ed p\u0159es svarov\u00e9 \u0161vy, co\u017e \u010dasem sni\u017euje pevnost a hou\u017eevnatost - kompozitn\u00ed opravy nab\u00edzej\u00ed alternativn\u00ed metodu zpevn\u011bn\u00ed tlakov\u00fdch za\u0159\u00edzen\u00ed bez nutnosti tepeln\u00e9ho zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed.<\/p>","protected":false},"excerpt":{"rendered":"

Welding leaves residual stresses behind that can erode material properties. Post-weld heat treatment (PWHT) may be required to reduce these stresses and restore original material properties. PWHT uses a controlled ramp-soak profile at temperatures below the material’s initial transformation temperature to reheat welded material in an area known as the heated zone, or gradient control … <\/p>\n

P\u0159e\u010dt\u011bte si v\u00edce “The Importance of Post Weld Heat Treatment”<\/span><\/a><\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-203","post","type-post","status-publish","format-standard","hentry","category-pwht-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/posts\/203","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=203"}],"version-history":[{"count":1,"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/posts\/203\/revisions"}],"predecessor-version":[{"id":204,"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/posts\/203\/revisions\/204"}],"wp:attachment":[{"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/media?parent=203"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/categories?post=203"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pwhtsolutions.net\/cs\/wp-json\/wp\/v2\/tags?post=203"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}