{"id":1680,"date":"2026-02-16T00:34:33","date_gmt":"2026-02-15T17:34:33","guid":{"rendered":"https:\/\/inoxcuongthinh.com\/nut-moi-han-tren-ong-hop-inox-nguyen-nhan-cach-khac-phuc\/"},"modified":"2026-02-16T00:34:33","modified_gmt":"2026-02-15T17:34:33","slug":"nut-moi-han-tren-ong-hop-inox-nguyen-nhan-cach-khac-phuc","status":"publish","type":"post","link":"https:\/\/inoxcuongthinh.com\/nut-moi-han-tren-ong-hop-inox-nguyen-nhan-cach-khac-phuc\/","title":{"rendered":"N\u1ee9t m\u1ed1i h\u00e0n tr\u00ean \u1ed1ng, h\u1ed9p Inox: Nguy\u00ean nh\u00e2n &#038; c\u00e1ch kh\u1eafc ph\u1ee5c"},"content":{"rendered":"<div class=\"custom-toc\">\n<h3>N\u1ed9i dung ch\u00ednh<\/h3>\n<ul>\n<li><a href=\"#toc-0-nhan-dien-nhanh-cac-dang-nut-moi-han-thuong-gap\">Nh\u1eadn di\u1ec7n nhanh c\u00e1c d\u1ea1ng n\u1ee9t m\u1ed1i h\u00e0n th\u01b0\u1eddng g\u1eb7p<\/a><\/li>\n<li><a href=\"#toc-1-nguyen-nhan-goc-re-theo-vat-lieu-quy-trinh-va-thie\">Nguy\u00ean nh\u00e2n g\u1ed1c r\u1ec5 theo v\u1eadt li\u1ec7u, quy tr\u00ecnh v\u00e0 thi\u1ebft k\u1ebf<\/a><\/li>\n<li><a href=\"#toc-2-bien-phap-phong-ngua-theo-dang-nut-checklist-thuc-\">Bi\u1ec7n ph\u00e1p ph\u00f2ng ng\u1eeba theo d\u1ea1ng n\u1ee9t (Checklist th\u1ef1c h\u00e0nh)<\/a><\/li>\n<li><a href=\"#toc-3-quy-trinh-kiem-tra-va-sua-chua-nut-moi-han\">Quy tr\u00ecnh ki\u1ec3m tra v\u00e0 s\u1eeda ch\u1eefa n\u1ee9t m\u1ed1i h\u00e0n<\/a><\/li>\n<li><a href=\"#toc-4-tham-so-khuyen-nghi-nhanh-cho-onghop-pho-bien\">Tham s\u1ed1 khuy\u1ebfn ngh\u1ecb nhanh cho \u1ed1ng\/h\u1ed9p ph\u1ed5 bi\u1ebfn<\/a><\/li>\n<li><a href=\"#toc-5-tinh-huong-thuc-te-tai-xuong\">T\u00ecnh hu\u1ed1ng th\u1ef1c t\u1ebf t\u1ea1i x\u01b0\u1edfng<\/a><\/li>\n<li><a href=\"#toc-6-cau-hoi-thuong-gap\">C\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p<\/a><\/li>\n<li><a href=\"#toc-7-nguon-tham-khao-tieu-chuan-va-ky-thuat\">Ngu\u1ed3n tham kh\u1ea3o ti\u00eau chu\u1ea9n v\u00e0 k\u1ef9 thu\u1eadt<\/a><\/li>\n<\/ul>\n<\/div>\n<p>Hi\u1ec7n t\u01b0\u1ee3ng n\u1ee9t m\u1ed1i h\u00e0n tr\u00ean \u1ed1ng, h\u1ed9p inox l\u00e0 l\u1ed7i nghi\u00eam tr\u1ecdng, l\u00e0m m\u1ea5t k\u00edn kh\u00edt, gi\u1ea3m b\u1ec1n v\u00e0 r\u1ee7i ro \u0103n m\u00f2n nhanh. B\u00e0i vi\u1ebft n\u00e0y \u0111i th\u1eb3ng v\u00e0o c\u0103n nguy\u00ean c\u01a1 h\u1ecdc \u2013 luy\u1ec7n kim c\u1ee7a n\u1ee9t h\u00e0n tr\u00ean inox (\u0111\u1eb7c bi\u1ec7t nh\u00f3m 201\/304\/316 d\u00f9ng ph\u1ed5 bi\u1ebfn t\u1ea1i Vi\u1ec7t Nam) v\u00e0 cung c\u1ea5p quy tr\u00ecnh ph\u00f2ng ng\u1eeba, s\u1eeda ch\u1eefa chu\u1ea9n x\u01b0\u1edfng. Ch\u1ee7 \u0111\u1ec1 n\u1eb1m trong b\u1ee9c tranh l\u1edbn \u201cC\u1ea9m nang \u1ed0ng &#038; H\u1ed9p Inox\u201d, nh\u01b0ng n\u1ed9i dung d\u01b0\u1edbi \u0111\u00e2y \u0111\u1ed9c l\u1eadp v\u00e0 \u0111\u1ee7 \u0111\u1ec3 b\u1ea1n \u00e1p d\u1ee5ng ngay tr\u00ean d\u00e2y chuy\u1ec1n.<\/p>\n<h2 id=\"toc-0-nhan-dien-nhanh-cac-dang-nut-moi-han-thuong-gap\">Nh\u1eadn di\u1ec7n nhanh c\u00e1c d\u1ea1ng n\u1ee9t m\u1ed1i h\u00e0n th\u01b0\u1eddng g\u1eb7p<\/h2>\n<h3>1) N\u1ee9t n\u00f3ng (solidification cracking) \u2013 th\u01b0\u1eddng g\u1eb7p nh\u1ea5t \u1edf inox Austenit<\/h3>\n<p>&#8211; Bi\u1ec3u hi\u1ec7n: v\u1ebft n\u1ee9t d\u1ecdc t\u00e2m m\u1ed1i h\u00e0n, t\u1eeb mi\u1ec7ng h\u00e0n xu\u1ed1ng l\u00f2ng; \u0111\u00f4i khi xu\u1ea5t ph\u00e1t t\u1eeb \u201ch\u1ed1 co\u201d khi k\u1ebft th\u00fac \u0111\u01b0\u1eddng h\u00e0n. Th\u01b0\u1eddng th\u1ea5y \u1edf m\u1ed1i h\u00e0n MIG\/TIG tr\u00ean 201\/304\/316 t\u1ea5m m\u1ecfng, \u1ed1ng\/h\u1ed9p th\u00e0nh 0.8\u20132.0 mm.<br \/>\n&#8211; C\u01a1 ch\u1ebf: kim lo\u1ea1i m\u1ed1i h\u00e0n k\u1ebft tinh cu\u1ed1i gi\u00e0u t\u1ea1p ch\u1ea5t S, P t\u1ea1o eutectic n\u00f3ng ch\u1ea3y \u1edf nhi\u1ec7t \u0111\u1ed9 th\u1ea5p; n\u1ebfu m\u1ed1i h\u00e0n l\u00e0 Austenit ho\u00e0n to\u00e0n (FN\u22480) v\u00e0 m\u1ed1i gh\u00e9p b\u1ecb \u201cg\u00f2 b\u00f3\u201d cao, co ng\u00f3t k\u00e9o r\u00e1ch v\u00f9ng k\u1ebft tinh cu\u1ed1i [TWI, ASM Handbook].<br \/>\n&#8211; Y\u1ebfu t\u1ed1 l\u00e0m n\u1eb7ng: l\u01b0u hu\u1ef3nh\/phospho cao, \u0111\u01b0\u1eddng h\u00e0n qu\u00e1 r\u1ed9ng, t\u1ed1c \u0111\u1ed9 di chuy\u1ec3n cao g\u00e2y bi\u00ean \u0111\u1ed9 co l\u1edbn, d\u00e2y\/que h\u00e0n kh\u00f4ng \u0111\u1ee7 delta-ferrite.<\/p>\n<h3>2) N\u1ee9t h\u00f3a l\u1ecfng v\u00f9ng \u1ea3nh h\u01b0\u1edfng nhi\u1ec7t (HAZ liquation cracking)<\/h3>\n<p>&#8211; X\u1ea3y ra s\u00e1t bi\u00ean n\u00f3ng ch\u1ea3y kim lo\u1ea1i g\u1ed1c khi c\u00e1c pha bi\u00ean h\u1ea1t n\u00f3ng ch\u1ea3y c\u1ee5c b\u1ed9 r\u1ed3i b\u1ecb k\u00e9o r\u00e1ch.<br \/>\n&#8211; Th\u01b0\u1eddng g\u1eb7p khi h\u00e0n nhanh-n\u00f3ng v\u1edbi nhi\u1ec7t v\u00e0o cao tr\u00ean inox Austenit th\u00e0nh m\u1ecfng, ho\u1eb7c khi m\u00e9p h\u00e0n nhi\u1ec5m b\u1ea9n (Pb, Zn, S).<\/p>\n<h3>3) N\u1ee9t ngu\u1ed9i do hydro (hydrogen-assisted cold cracking)<\/h3>\n<p>&#8211; Ch\u1ee7 y\u1ebfu \u1edf inox Martensit\/Ferrit (410\/430) ho\u1eb7c li\u00ean k\u1ebft d\u1ecb v\u1eadt li\u1ec7u v\u1edbi th\u00e9p C, khi c\u00f3 hydro t\u1eeb \u1ea9m d\u1ea7u, que\/d\u00e2y \u1ea9m.<br \/>\n&#8211; Xu\u1ea5t hi\u1ec7n tr\u1ec5 v\u00e0i gi\u1edd\u201348 gi\u1edd sau h\u00e0n; v\u1ebft n\u1ee9t nh\u1ecf \u1edf HAZ\/kim lo\u1ea1i m\u1ed1i h\u00e0n, nghe \u201ct\u00e1ch\u201d khi ngu\u1ed9i nhanh [AWS D1.6].<\/p>\n<h3>4) N\u1ee9t t\u00e1i nung (reheat cracking)<\/h3>\n<p>&#8211; Xu\u1ea5t hi\u1ec7n trong chu tr\u00ecnh nung l\u1ea1i (\u0111a l\u1edbp) ho\u1eb7c sau nhi\u1ec7t luy\u1ec7n tr\u00ean th\u00e9p kh\u00f4ng g\u1ec9 c\u00f3 t\u1ed5 ch\u1ee9c nh\u1ea1y c\u1ea3m; \u00edt g\u1eb7p tr\u00ean 300-series nh\u01b0ng c\u1ea7n l\u01b0u \u00fd \u1edf Martensit khi PWHT kh\u00f4ng ph\u00f9 h\u1ee3p.<\/p>\n<h3>5) N\u1ee9t mi\u1ec7ng h\u00e0n (crater crack)<\/h3>\n<p>&#8211; Do ng\u1eaft h\u1ed3 quang \u0111\u1ed9t ng\u1ed9t, \u0111\u1ec3 l\u1ea1i h\u1ed1 co ch\u01b0a \u0111\u1ed5 \u0111\u1ea7y; d\u1ec5 n\u1ee9t xuy\u00ean t\u00e2m \u2013 \u0111\u1eb7c bi\u1ec7t tr\u00ean TIG\/MIG \u1ed1ng m\u1ecfng.<\/p>\n<h3>6) N\u1ee9t ch\u00e2n\/bi\u00ean m\u1ed1i h\u00e0n do \u1ee9ng su\u1ea5t<\/h3>\n<p>&#8211; Xu\u1ea5t hi\u1ec7n \u1edf ch\u00e2n m\u1ed1i h\u00e0n (root) ho\u1eb7c bi\u00ean, khi g\u00e1 k\u1eb9p c\u1ee9ng, khe h\u1edf l\u1edbn, ho\u1eb7c chu\u1ed7i tack sai tr\u00ecnh t\u1ef1; c\u1ed9ng h\u01b0\u1edfng v\u1edbi bi\u1ebfn d\u1ea1ng t\u1ea5m\/\u1ed1ng m\u1ecfng.<\/p>\n<h3>7) N\u1ee9t do \u0103n m\u00f2n \u1ee9ng su\u1ea5t v\u00f9ng m\u1ed1i h\u00e0n (service SCC)<\/h3>\n<p>&#8211; Kh\u00f4ng ph\u1ea3i l\u1ed7i \u201cl\u00fac h\u00e0n\u201d nh\u01b0ng ph\u00e1t tri\u1ec3n sau th\u1eddi gian l\u00e0m vi\u1ec7c trong m\u00f4i tr\u01b0\u1eddng Cl- (n\u01b0\u1edbc bi\u1ec3n, h\u00f3a ch\u1ea5t). Kh\u1edfi \u0111\u1ea7u t\u1eeb khuy\u1ebft t\u1eadt nh\u1ecf \u1edf ch\u00e2n\/bi\u00ean m\u1ed1i h\u00e0n ch\u01b0a l\u00e0m s\u1ea1ch \u2013 passivation.<\/p>\n<h2 id=\"toc-1-nguyen-nhan-goc-re-theo-vat-lieu-quy-trinh-va-thie\">Nguy\u00ean nh\u00e2n g\u1ed1c r\u1ec5 theo v\u1eadt li\u1ec7u, quy tr\u00ecnh v\u00e0 thi\u1ebft k\u1ebf<\/h2>\n<h3>Th\u00e0nh ph\u1ea7n v\u1eadt li\u1ec7u v\u00e0 delta-ferrite (FN)<\/h3>\n<p>&#8211; Inox Austenit (201\/304\/316) c\u00f3 nguy c\u01a1 n\u1ee9t n\u00f3ng cao khi kim lo\u1ea1i m\u1ed1i h\u00e0n l\u00e0 Austenit ho\u00e0n to\u00e0n (FN\u22480). Khuy\u1ebfn ngh\u1ecb FN 3\u201310 trong kim lo\u1ea1i m\u1ed1i h\u00e0n \u0111\u1ec3 gi\u1ea3m n\u1ee9t n\u00f3ng; \u0111\u1ea1t \u0111\u01b0\u1ee3c b\u1eb1ng ch\u1ecdn d\u00e2y\/que c\u00f3 th\u00e0nh ph\u1ea7n ph\u00f9 h\u1ee3p (WRC-1992\/DeLong) nh\u01b0 ER308L, ER316L, ER309L [TWI, WRC-1992].<br \/>\n&#8211; T\u1ea1p ch\u1ea5t S, P cao l\u00e0m t\u0103ng nh\u1ea1y n\u1ee9t n\u00f3ng. \u01afu ti\u00ean th\u00e9p v\u00e0 d\u00e2y\/que v\u1edbi S, P \u22640.03%.<br \/>\n&#8211; Inox Martensit\/Ferrit (410\/430) nh\u1ea1y n\u1ee9t ngu\u1ed9i do t\u1ea1o martensit c\u1ee9ng; c\u1ea7n ti\u1ec1n nhi\u1ec7t v\u00e0\/ho\u1eb7c b\u00f9 Ni (filler chuy\u00ean d\u1ee5ng).<\/p>\n<h3>D\u00e2y\/que h\u00e0n v\u00e0 kh\u00ed b\u1ea3o v\u1ec7<\/h3>\n<p>&#8211; Austenit: 304 \u2192 ER308L; 316 \u2192 ER316L; 201 \u2192 th\u01b0\u1eddng d\u00f9ng ER308L; m\u1ed1i gh\u00e9p d\u1ecb v\u1eadt li\u1ec7u\/\u0111\u00f2i h\u1ecfi FN cao \u2192 ER309L.<br \/>\n&#8211; MIG: d\u00f9ng Ar + 1\u20132% O2 ho\u1eb7c Ar + 2% CO2. Tr\u00e1nh CO2 thu\u1ea7n g\u00e2y oxy h\u00f3a m\u1ea1nh, l\u1eabn t\u1ea1p, d\u1ec5 n\u1ee9t\/gi\u00f2n m\u1ed1i h\u00e0n.<br \/>\n&#8211; TIG: Ar 99.99% cho m\u1eb7t tr\u00ean; purge m\u1eb7t trong b\u1eb1ng Ar ho\u1eb7c Ar+N2 (v\u1edbi Austenit) \u0111\u1ec3 h\u1ea1n ch\u1ebf \u201csugaring\u201d. Gi\u1eef O2 trong \u1ed1ng <100 ppm (t\u1ed1t nh\u1ea5t <50 ppm) tr\u01b0\u1edbc khi b\u1eaft \u0111\u1ea7u h\u00e0n \u0111\u01b0\u1eddng ch\u00e2n [Outokumpu\/ESAB].\n\n\n\n<h3>Quy tr\u00ecnh v\u00e0 th\u00f4ng s\u1ed1 h\u00e0n<\/h3>\n<p>&#8211; Nhi\u1ec7t v\u00e0o (heat input) qu\u00e1 cao \u2192 h\u1ea1t th\u00f4, HAZ h\u00f3a l\u1ecfng; qu\u00e1 th\u1ea5p nh\u01b0ng t\u1ed1c \u0111\u1ed9 cao \u2192 m\u1ed1i h\u00e0n h\u1eb9p, co r\u00fat t\u1eadp trung g\u00e2y n\u1ee9t t\u00e2m.<br \/>\n&#8211; Ki\u1ec3m so\u00e1t nhi\u1ec7t v\u00e0o Q \u2248 0.5\u20131.5 kJ\/mm cho Austenit t\u1ea5m m\u1ecfng; nhi\u1ec7t \u0111\u1ed9 gi\u1eefa l\u1edbp (interpass) <150\u00b0C v\u1edbi 300-series; Duplex <100\u2013150\u00b0C [AWS D1.6, nh\u00e0 s\u1ea3n xu\u1ea5t v\u1eadt li\u1ec7u].  \n- K\u1ebft th\u00fac h\u1ed3 quang: \u0111\u1ed5 \u0111\u1ea7y mi\u1ec7ng h\u00e0n, d\u00f9ng ch\u1ee9c n\u0103ng crater fill\/backstep \u0111\u1ec3 lo\u1ea1i tr\u1eeb h\u1ed1 co.\n\n\n\n<h3>Thi\u1ebft k\u1ebf m\u00e9p, g\u00e1 k\u1eb9p v\u00e0 \u0111i\u1ec1u ki\u1ec7n b\u1ec1 m\u1eb7t<\/h3>\n<p>&#8211; M\u00e9p c\u1eaft s\u1ea1ch, kh\u00f4; lo\u1ea1i b\u1ecf d\u1ea7u, s\u01a1n, m\u1ea1 k\u1ebdm, b\u1ee5i m\u00e0i (Fe\/Zn\/Pb) \u2013 c\u00e1c kim lo\u1ea1i l\u1ea1 c\u00f3 th\u1ec3 g\u00e2y \u201cgi\u00f2n kim lo\u1ea1i l\u1ecfng\u201d v\u00e0 n\u1ee9t bi\u00ean h\u1ea1t \u1edf nhi\u1ec7t cao.<br \/>\n&#8211; Khe h\u1edf v\u00e0 b\u00f9 d\u00e0y h\u1ee3p l\u00fd cho \u1ed1ng\/h\u1ed9p m\u1ecfng: root gap 0.5\u20131.0 mm; tr\u00e1nh k\u1eb9p c\u1ee9ng to\u00e0n b\u1ed9 chi\u1ec1u d\u00e0i \u2013 d\u00f9ng tack gi\u00e3n c\u00e1ch v\u00e0 m\u1ed1i h\u00e0n \u0111\u1ed1i x\u1ee9ng \u0111\u1ec3 gi\u1ea3m \u1ee9ng su\u1ea5t.<br \/>\n&#8211; Kh\u00f4ng \u201cve\u201d qu\u00e1 r\u1ed9ng tr\u00ean v\u1eadt m\u1ecfng; \u01b0u ti\u00ean \u0111\u01b0\u1eddng h\u00e0n h\u1eb9p (stringer), nhi\u1ec1u l\u1edbp m\u1ea3nh.<\/p>\n<h2 id=\"toc-2-bien-phap-phong-ngua-theo-dang-nut-checklist-thuc-\">Bi\u1ec7n ph\u00e1p ph\u00f2ng ng\u1eeba theo d\u1ea1ng n\u1ee9t (Checklist th\u1ef1c h\u00e0nh)<\/h2>\n<h3>Ng\u1eeba n\u1ee9t n\u00f3ng (Austenit 201\/304\/316)<\/h3>\n<p>&#8211; Ch\u1ecdn filler c\u00f3 FN 3\u201310 (ER308L\/316L; c\u1ea7n t\u0103ng FN d\u00f9ng ER309L).<br \/>\n&#8211; Ki\u1ec3m so\u00e1t nhi\u1ec7t v\u00e0o 0.5\u20131.5 kJ\/mm; m\u1ed1i h\u00e0n h\u1eb9p, nhi\u1ec1u l\u1edbp m\u1ea3nh; h\u1ea1n ch\u1ebf \u201cweave\u201d r\u1ed9ng.<br \/>\n&#8211; Gi\u1ea3m g\u00f2 b\u00f3: chia pass \u0111\u1ed1i x\u1ee9ng, tack ng\u1eaft qu\u00e3ng 150\u2013250 mm, backstep.<br \/>\n&#8211; \u0110\u1ea3m b\u1ea3o purge m\u1eb7t trong \u1ed1ng\/h\u1ed9p, O2 <100 ppm; b\u1ecbt k\u00edn \u0111\u1ea7u \u1ed1ng b\u1eb1ng \u0111\u0129a cao su + l\u1ed7 x\u1ea3; x\u1ea3 kh\u00ed 3\u20135 l\u1ea7n th\u1ec3 t\u00edch tr\u01b0\u1edbc khi \u0111\u00e1nh l\u1eeda.  \n- L\u00e0m s\u1ea1ch tuy\u1ec7t \u0111\u1ed1i m\u00e9p h\u00e0n: t\u1ea9y d\u1ea7u, s\u01a1n, keo; kh\u00f4ng h\u00e0n g\u1ea7n chi ti\u1ebft m\u1ea1 k\u1ebdm.\n\n\n\n<h3>Ng\u1eeba n\u1ee9t HAZ h\u00f3a l\u1ecfng<\/h3>\n<p>&#8211; Tr\u00e1nh nhi\u1ec7t v\u00e0o \u0111\u1ed9t bi\u1ebfn; gi\u1ea3m c\u01b0\u1eddng \u0111\u1ed9, t\u0103ng t\u1ed1c \u0111\u1ed9 v\u1eeba ph\u1ea3i; kh\u00f4ng \u201cd\u1ed3n nhi\u1ec7t\u201d t\u1ea1i \u0111i\u1ec3m d\u1eebng\/\u0111\u1ed5i h\u01b0\u1edbng.<br \/>\n&#8211; M\u00e9p kim lo\u1ea1i g\u1ed1c c\u00e0ng s\u1ea1ch c\u00e0ng t\u1ed1t; tr\u00e1nh S, P cao; ch\u1ecdn th\u00e9p\/d\u00e2y h\u00e0n low-S\/low-P.<\/p>\n<h3>Ng\u1eeba n\u1ee9t ngu\u1ed9i do hydro (Martensit 410\/430 v\u00e0 li\u00ean k\u1ebft d\u1ecb v\u1eadt li\u1ec7u)<\/h3>\n<p>&#8211; Ti\u1ec1n nhi\u1ec7t 150\u2013300\u00b0C (410: 200\u2013300\u00b0C), gi\u1eef nhi\u1ec7t gi\u1eefa l\u1edbp \u1ed5n \u0111\u1ecbnh; l\u00e0m kh\u00f4 ph\u00f4i, que\/d\u00e2y; che gi\u00f3\/\u1ea9m.<br \/>\n&#8211; Ch\u1ecdn filler c\u00f3 Ni \u0111\u1ec3 h\u1ea1 \u0111\u1ed9 c\u1ee9ng (E410NiMo\/ER410NiMo) ho\u1eb7c d\u00f9ng \u201cl\u1edbp \u0111\u1ec7m\u201d 309L tr\u01b0\u1edbc r\u1ed3i \u0111\u1eafp b\u1eb1ng v\u1eadt li\u1ec7u t\u01b0\u01a1ng \u1ee9ng.<br \/>\n&#8211; PWHT\/ram 600\u2013700\u00b0C khi ti\u00eau chu\u1ea9n cho ph\u00e9p \u0111\u1ec3 kh\u1eed hydro v\u00e0 gi\u1ea3m \u1ee9ng su\u1ea5t.<\/p>\n<h3>Ng\u1eeba n\u1ee9t mi\u1ec7ng h\u00e0n v\u00e0 n\u1ee9t do \u1ee9ng su\u1ea5t<\/h3>\n<p>&#8211; S\u1eed d\u1ee5ng ch\u1ee9c n\u0103ng crater fill, tr\u1ec5 kh\u00ed; cu\u1ed1i \u0111\u01b0\u1eddng h\u00e0n ch\u1ea1y l\u00f9i 2\u20133 mm \u0111\u1ec3 \u0111\u1ed5 \u0111\u1ea7y h\u1ed1 co.<br \/>\n&#8211; Tr\u00ecnh t\u1ef1 h\u00e0n \u0111\u1ed1i x\u1ee9ng, chia \u0111o\u1ea1n; ki\u1ec3m so\u00e1t \u0111\u1ed9 th\u1eb3ng \u1ed1ng\/h\u1ed9p b\u1eb1ng \u0111\u1ed3 g\u00e1 b\u00f9 co.<br \/>\n&#8211; Kh\u00f4ng \u0111\u1ec3 khe h\u1edf qu\u00e1 l\u1edbn; n\u1ebfu b\u1eaft bu\u1ed9c, t\u0103ng backing\/purge v\u00e0 \u0111i\u1ec1u ch\u1ec9nh tham s\u1ed1.<\/p>\n<h3>Ho\u00e0n thi\u1ec7n sau h\u00e0n \u0111\u1ec3 gi\u1ea3m kh\u1edfi ph\u00e1t n\u1ee9t<\/h3>\n<p>&#8211; M\u00e0i m\u00e9p s\u1eafc, lo\u1ea1i \u201cunder\/overcut\u201d; t\u1ea9y m\u00e0u nhi\u1ec7t (pickling) v\u00e0 th\u1ee5 \u0111\u1ed9ng h\u00f3a (passivation) v\u00f9ng h\u00e0n \u0111\u1ec3 gi\u1ea3m khuy\u1ebft t\u1eadt vi m\u00f4, ng\u0103n SCC trong ph\u1ee5c v\u1ee5.<\/p>\n<h2 id=\"toc-3-quy-trinh-kiem-tra-va-sua-chua-nut-moi-han\">Quy tr\u00ecnh ki\u1ec3m tra v\u00e0 s\u1eeda ch\u1eefa n\u1ee9t m\u1ed1i h\u00e0n<\/h2>\n<h3>Ki\u1ec3m tra (VT\/PT\/RT\/UT)<\/h3>\n<p>&#8211; M\u1eaft th\u01b0\u1eddng (VT): soi \u0111\u00e8n, k\u00ednh l\u00fap; t\u1eadp trung \u0111\u01b0\u1eddng t\u00e2m v\u00e0 mi\u1ec7ng h\u00e0n.<br \/>\n&#8211; Th\u1ea5m m\u00e0u (PT theo ISO 3452 ho\u1eb7c ASTM E1417): ph\u00f9 h\u1ee3p \u1ed1ng\/h\u1ed9p m\u1ecfng, inox Austenit (kh\u00f4ng nhi\u1ec5m t\u1eeb).<br \/>\n&#8211; Ch\u1ee5p X\/RT ho\u1eb7c si\u00eau \u00e2m m\u1ea3ng pha (UT-PA): \u00e1p d\u1ee5ng v\u1edbi chi\u1ec1u d\u00e0y l\u1edbn h\u01a1n, m\u1ed1i h\u00e0n ch\u1ecbu \u00e1p.<br \/>\n&#8211; Ti\u00eau ch\u00ed ch\u1ea5p nh\u1eadn: ti\u00eau chu\u1ea9n AWS D1.6 v\u00e0 ISO 5817 \u0111\u1ec1u \u201ckh\u00f4ng ch\u1ea5p nh\u1eadn v\u1ebft n\u1ee9t\u201d \u1edf m\u1ecdi c\u1ea5p ch\u1ea5t l\u01b0\u1ee3ng.<\/p>\n<h3>S\u1eeda ch\u1eefa<\/h3>\n<p>&#8211; D\u1eebng h\u00e0n, \u201ckhoan ch\u1eb7n\u201d 2 \u0111\u1ea7u v\u1ebft n\u1ee9t (\u22051.5\u20132.0 mm) \u0111\u1ec3 ng\u0103n lan.<br \/>\n&#8211; M\u00e0i\/gouge h\u1ebft b\u1ec1 r\u1ed9ng\/\u0111\u1ed9 s\u00e2u v\u1ebft n\u1ee9t \u0111\u1ebfn n\u1ec1n kim lo\u1ea1i l\u00e0nh; l\u00e0m s\u1ea1ch.<br \/>\n&#8211; Ch\u1ecdn filler t\u1ed1i \u01b0u (v\u00ed d\u1ee5 n\u00e2ng FN b\u1eb1ng 309L \u0111\u1ed1i v\u1edbi Austenit), h\u00e0n l\u1edbp m\u1ea3nh, purge \u0111\u1ea7y \u0111\u1ee7.<br \/>\n&#8211; PT l\u1ea1i 100% sau s\u1eeda; n\u1ebfu l\u00e0 Martensit, c\u00e2n nh\u1eafc ram\/PWHT theo quy ph\u1ea1m.<br \/>\n&#8211; Ghi ch\u00e9p WPS\/PQR, NDT v\u00e0 nguy\u00ean nh\u00e2n g\u1ed1c \u0111\u1ec3 ng\u0103n t\u00e1i di\u1ec5n (y\u00eau c\u1ea7u theo ASME IX\/AWS D1.6).<\/p>\n<h2 id=\"toc-4-tham-so-khuyen-nghi-nhanh-cho-onghop-pho-bien\">Tham s\u1ed1 khuy\u1ebfn ngh\u1ecb nhanh cho \u1ed1ng\/h\u1ed9p ph\u1ed5 bi\u1ebfn<\/h2>\n<p>&#8211; Austenit 201\/304\/316 \u2013 TIG (DCEN):<br \/>\n  + D\u00e0y 1.0\u20131.5 mm: \u00d8 d\u00e2y 1.0\u20131.2 mm; 45\u201385 A; Ar 8\u201312 L\/min; purge Ar 5\u201310 L\/min; interpass <150\u00b0C; Q \u2248 0.5\u20131.0 kJ\/mm.  \n  + D\u00e0y 1.5\u20133.0 mm: 70\u2013120 A; c\u00f3 th\u1ec3 d\u00f9ng backing\/copper chill \u0111\u1ec3 t\u1ea3n nhi\u1ec7t.  \n- Austenit MIG:  \n  + D\u00e2y ER308L\/316L\/309L \u00d80.8\u20131.0 mm; 16\u201320 V; 70\u2013140 A; Ar + 1\u20132% O2 (ho\u1eb7c +2% CO2); l\u01b0u l\u01b0\u1ee3ng 12\u201318 L\/min; chu k\u1ef3 ng\u1eafn (short-arc) cho v\u1eadt m\u1ecfng.  \n- Martensit 410\/430:  \n  + Ti\u1ec1n nhi\u1ec7t 200\u2013300\u00b0C; filler E\/ER410NiMo ho\u1eb7c \u0111\u1ec7m 309L; c\u00f3 th\u1ec3 PWHT 650\u00b0C\/2 h n\u1ebfu ti\u00eau chu\u1ea9n cho ph\u00e9p.  \n- Duplex 2205 (n\u1ebfu c\u00f3):  \n  + Filler ER2209; interpass <100\u00b0C; Q ~ 0.5\u20132.5 kJ\/mm; purge k\u1ef9, tr\u00e1nh qu\u00e1 nhi\u1ec7t \u0111\u1ec3 gi\u1eef c\u00e2n b\u1eb1ng pha.\n\n\n\n<h2 id=\"toc-5-tinh-huong-thuc-te-tai-xuong\">T\u00ecnh hu\u1ed1ng th\u1ef1c t\u1ebf t\u1ea1i x\u01b0\u1edfng<\/h2>\n<p>&#8211; B\u00e0i to\u00e1n: H\u1ed9p inox 201 40\u00d740\u00d71.2 mm, h\u00e0n MIG d\u00e2y ER308L, kh\u00ed Ar+CO2 8% \u2192 xu\u1ea5t hi\u1ec7n n\u1ee9t d\u1ecdc t\u00e2m 30\u201380 mm, nh\u1ea5t l\u00e0 t\u1ea1i \u0111i\u1ec3m k\u1ebft th\u00fac.<br \/>\n&#8211; Ph\u00e2n t\u00edch: T\u1ef7 l\u1ec7 CO2 qu\u00e1 cao g\u00e2y oxy h\u00f3a m\u1ea1nh, FN m\u1ed1i h\u00e0n th\u1ea5p, \u0111\u01b0\u1eddng h\u00e0n h\u1eb9p-t\u1ed1c \u0111\u1ed9 cao \u2192 co r\u00fat t\u1eadp trung.<br \/>\n&#8211; Kh\u1eafc ph\u1ee5c: Chuy\u1ec3n kh\u00ed sang Ar+2% CO2, t\u0103ng th\u1eddi gian crater fill, chia \u0111\u01b0\u1eddng h\u00e0n ng\u1eafn \u0111\u1ed1i x\u1ee9ng, gi\u1eef interpass <120\u00b0C, th\u1eed thay 309L \u0111\u1ec3 t\u0103ng FN v\u1ec1 5\u20138 (\u0111o b\u1eb1ng ferrite scope). K\u1ebft qu\u1ea3: lo\u1ea1i b\u1ecf n\u1ee9t t\u00e2m, b\u1ec1 m\u1eb7t s\u1ea1ch, \u0111\u1ea1t PT c\u1ea5p ch\u1ea5p nh\u1eadn ISO 5817-C\/B.\n\n\n\n<h2 id=\"toc-6-cau-hoi-thuong-gap\">C\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p<\/h2>\n<p>&#8211; V\u00ec sao MIG tr\u00ean \u1ed1ng\/h\u1ed9p m\u1ecfng hay n\u1ee9t d\u1ecdc t\u00e2m? \u2192 Do solidification cracking: m\u1ed1i h\u00e0n h\u1eb9p, t\u1ed1c \u0111\u1ed9 nhanh, FN th\u1ea5p, t\u1ea1p ch\u1ea5t\/oxy h\u00f3a cao. Gi\u1ea3m b\u1eb1ng t\u0103ng FN, gi\u1ea3m CO2, d\u00f9ng stringer beads.<br \/>\n&#8211; C\u00f3 n\u00ean \u1ee7 kh\u1eed \u1ee9ng su\u1ea5t cho 304 sau h\u00e0n \u0111\u1ec3 ch\u1ed1ng n\u1ee9t? \u2192 Th\u01b0\u1eddng kh\u00f4ng. 304 kh\u00f4ng c\u1ea7n PWHT; \u1ee7 sai c\u00f3 th\u1ec3 g\u00e2y nh\u1ea1y c\u1ea3m \u0103n m\u00f2n (sensitization). T\u1eadp trung ki\u1ec3m so\u00e1t FN, nhi\u1ec7t v\u00e0o v\u00e0 purge.<br \/>\n&#8211; D\u00f9ng CO2 thu\u1ea7n \u0111\u1ec3 h\u00e0n MIG inox \u0111\u01b0\u1ee3c kh\u00f4ng? \u2192 Kh\u00f4ng khuy\u1ebfn ngh\u1ecb. CO2 cao g\u00e2y oxy h\u00f3a m\u1ea1nh, b\u1eafn t\u00f3e, nguy c\u01a1 n\u1ee9t\/gi\u00f2n; d\u00f9ng Ar + 1\u20132% O2\/CO2 theo khuy\u1ebfn c\u00e1o nh\u00e0 s\u1ea3n xu\u1ea5t.<\/p>\n<h2 id=\"toc-7-nguon-tham-khao-tieu-chuan-va-ky-thuat\">Ngu\u1ed3n tham kh\u1ea3o ti\u00eau chu\u1ea9n v\u00e0 k\u1ef9 thu\u1eadt<\/h2>\n<p>&#8211; AWS D1.6\/D1.6M \u2013 Structural Welding Code: Stainless Steel (quy \u0111\u1ecbnh ch\u1ea5p nh\u1eadn khuy\u1ebft t\u1eadt, quy t\u1eafc WPS).<br \/>\n&#8211; ASME Section IX \u2013 Welding Qualifications (PQR\/WPS, ki\u1ec3m so\u00e1t quy tr\u00ecnh).<br \/>\n&#8211; ISO 5817 \u2013 Welding \u2014 Fusion-welded joints in steel, nickel \u2026 \u2014 Quality levels for imperfections.<br \/>\n&#8211; ISO 3452 \/ ASTM E1417 \u2013 Penetrant Testing.<br \/>\n&#8211; TWI (The Welding Institute): Solidification cracking in austenitic stainless steels; Liquation cracking in HAZ.<br \/>\n&#8211; ASM Handbook, Vol. 6 \u2013 Welding, Brazing, and Soldering.<br \/>\n&#8211; Outokumpu\/ESAB\/Lincoln Electric \u2013 H\u01b0\u1edbng d\u1eabn h\u00e0n inox (kh\u00ed b\u1ea3o v\u1ec7, tham s\u1ed1, FN\/WRC-1992).<\/p>\n<p>K\u1ebft lu\u1eadn: N\u1ee9t m\u1ed1i h\u00e0n tr\u00ean \u1ed1ng, h\u1ed9p inox \u0111a ph\u1ea7n b\u1eaft ngu\u1ed3n t\u1eeb ba \u0111i\u1ec3m c\u1ed1t l\u00f5i: th\u00e0nh ph\u1ea7n\/ferrite c\u1ee7a kim lo\u1ea1i m\u1ed1i h\u00e0n, m\u1ee9c g\u00f2 b\u00f3 \u2013 nhi\u1ec7t v\u00e0o, v\u00e0 v\u1ec7 sinh\/purge. Ki\u1ec3m so\u00e1t FN 3\u201310 cho Austenit, ch\u1ecdn kh\u00ed b\u1ea3o v\u1ec7 \u0111\u00fang (Ar + 1\u20132% O2\/CO2), gi\u1eef O2 trong \u1ed1ng <100 ppm, thao t\u00e1c crater fill v\u00e0 tr\u00ecnh t\u1ef1 h\u00e0n \u0111\u1ed1i x\u1ee9ng l\u00e0 \u201cb\u1ed9 t\u1ee9\u201d ph\u00f2ng n\u1ee9t hi\u1ec7u qu\u1ea3. V\u1edbi Martensit, ti\u1ec1n nhi\u1ec7t v\u00e0\/ho\u1eb7c PWHT l\u00e0 b\u1eaft bu\u1ed9c. \u00c1p d\u1ee5ng \u0111\u00fang checklist tr\u00ean, b\u1ea1n s\u1ebd lo\u1ea1i b\u1ecf n\u1ee9t t\u1eeb g\u1ed1c, n\u00e2ng ch\u1ea5t l\u01b0\u1ee3ng m\u1ed1i h\u00e0n v\u00e0 tu\u1ed5i th\u1ecd h\u1ec7 th\u1ed1ng.\n\nC\u1ea7n t\u01b0 v\u1ea5n tham s\u1ed1 theo m\u00e1c inox, chi\u1ec1u d\u00e0y v\u00e0 quy chu\u1ea9n d\u1ef1 \u00e1n? Li\u00ean h\u1ec7 Inox C\u01b0\u1eddng Th\u1ecbnh \u0111\u1ec3 \u0111\u01b0\u1ee3c h\u1ed7 tr\u1ee3 k\u1ef9 thu\u1eadt v\u00e0 b\u00e1o gi\u00e1 t\u1ed1t nh\u1ea5t. Hotline: 0343.417.281. Email: inoxcongnghiep.cuongthinh@gmail.com\n<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Ph\u00e2n t\u00edch 7 d\u1ea1ng n\u1ee9t m\u1ed1i h\u00e0n tr\u00ean \u1ed1ng, h\u1ed9p inox v\u00e0 c\u00e1ch ph\u00f2ng ng\u1eeba, s\u1eeda ch\u1eefa theo AWS\/ASME: ch\u1ecdn v\u1eadt li\u1ec7u, tham s\u1ed1 h\u00e0n, ki\u1ec3m so\u00e1t FN, purge v\u00e0 NDT.<\/p>\n","protected":false},"author":7,"featured_media":1028,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[23],"tags":[],"class_list":["post-1680","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tin-tuc"],"acf":[],"_links":{"self":[{"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/posts\/1680","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/comments?post=1680"}],"version-history":[{"count":0,"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/posts\/1680\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/media\/1028"}],"wp:attachment":[{"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/media?parent=1680"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/categories?post=1680"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/tags?post=1680"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}