{"id":1957,"date":"2026-04-28T12:34:14","date_gmt":"2026-04-28T05:34:14","guid":{"rendered":"https:\/\/inoxcuongthinh.com\/vi-sao-inox-304-van-bi-ri-nguyen-nhan-va-cach-xu-ly-dut-diem\/"},"modified":"2026-04-28T12:34:14","modified_gmt":"2026-04-28T05:34:14","slug":"vi-sao-inox-304-van-bi-ri-nguyen-nhan-va-cach-xu-ly-dut-diem","status":"publish","type":"post","link":"https:\/\/inoxcuongthinh.com\/vi-sao-inox-304-van-bi-ri-nguyen-nhan-va-cach-xu-ly-dut-diem\/","title":{"rendered":"V\u00ec sao inox 304 v\u1eabn b\u1ecb r\u1ec9? Nguy\u00ean nh\u00e2n v\u00e0 c\u00e1ch x\u1eed l\u00fd d\u1ee9t \u0111i\u1ec3m"},"content":{"rendered":"<div class=\"custom-toc\">\n<h3>N\u1ed9i dung ch\u00ednh<\/h3>\n<ul>\n<li><a href=\"#toc-0-co-che-khong-gi-cua-304-va-vi-sao-van-ri\">C\u01a1 ch\u1ebf \u201ckh\u00f4ng g\u1ec9\u201d c\u1ee7a 304 v\u00e0 v\u00ec sao v\u1eabn r\u1ec9<\/a><\/li>\n<li><a href=\"#toc-1-phan-biet-cac-dang-ri-thuong-gap\">Ph\u00e2n bi\u1ec7t c\u00e1c d\u1ea1ng \u201cr\u1ec9\u201d th\u01b0\u1eddng g\u1eb7p<\/a><\/li>\n<li><a href=\"#toc-2-nguyen-nhan-cot-loi-khien-304-ri-trong-dieu-kien-v\">Nguy\u00ean nh\u00e2n c\u1ed1t l\u00f5i khi\u1ebfn 304 r\u1ec9 trong \u0111i\u1ec1u ki\u1ec7n Vi\u1ec7t Nam<\/a><\/li>\n<li><a href=\"#toc-3-chan-doan-nhanh-ri-that-hay-o-be-mat\">Ch\u1ea9n \u0111o\u00e1n nhanh: r\u1ec9 th\u1eadt hay \u1ed1 b\u1ec1 m\u1eb7t?<\/a><\/li>\n<li><a href=\"#toc-4-quy-trinh-xu-ly-triet-de-theo-muc-do-hu-hai\">Quy tr\u00ecnh x\u1eed l\u00fd tri\u1ec7t \u0111\u1ec3 theo m\u1ee9c \u0111\u1ed9 h\u01b0 h\u1ea1i<\/a><\/li>\n<li><a href=\"#toc-5-phong-ngua-dai-han-vat-lieu-thiet-ke-thi-cong-bao-\">Ph\u00f2ng ng\u1eeba d\u00e0i h\u1ea1n: v\u1eadt li\u1ec7u, thi\u1ebft k\u1ebf, thi c\u00f4ng, b\u1ea3o tr\u00ec<\/a><\/li>\n<li><a href=\"#toc-6-hieu-lam-pho-bien-can-loai-bo\">Hi\u1ec3u l\u1ea7m ph\u1ed5 bi\u1ebfn c\u1ea7n lo\u1ea1i b\u1ecf<\/a><\/li>\n<li><a href=\"#toc-7-meo-thuc-te-cho-xuong-va-cong-truong\">M\u1eb9o th\u1ef1c t\u1ebf cho x\u01b0\u1edfng v\u00e0 c\u00f4ng tr\u01b0\u1eddng<\/a><\/li>\n<li><a href=\"#toc-8-nguon-tham-khao-ky-thuat\">Ngu\u1ed3n tham kh\u1ea3o k\u1ef9 thu\u1eadt<\/a><\/li>\n<li><a href=\"#toc-9-khi-nao-nen-nang-cap-vat-lieu\">Khi n\u00e0o n\u00ean n\u00e2ng c\u1ea5p v\u1eadt li\u1ec7u?<\/a><\/li>\n<li><a href=\"#toc-10-ket-luan-304-ri-khong-phai-do-inox-gia-ma-do-dieu-\">K\u1ebft lu\u1eadn: 304 r\u1ec9 kh\u00f4ng ph\u1ea3i do \u201cinox gi\u1ea3\u201d, m\u00e0 do \u0111i\u1ec1u ki\u1ec7n v\u00e0 x\u1eed l\u00fd<\/a><\/li>\n<\/ul>\n<\/div>\n<p>Inox 304 n\u1ed5i ti\u1ebfng b\u1ec1n g\u1ec9, nh\u01b0ng th\u1ef1c t\u1ebf nhi\u1ec1u c\u00f4ng tr\u00ecnh v\u00e0 x\u01b0\u1edfng v\u1eabn g\u1eb7p hi\u1ec7n t\u01b0\u1ee3ng \u1ed1 v\u00e0ng n\u00e2u, r\u1ed7 pitting ho\u1eb7c r\u1ec9 \u0111\u1ecf sau m\u1ed9t th\u1eddi gian s\u1eed d\u1ee5ng. \u0110\u00e2y l\u00e0 ch\u1ee7 \u0111\u1ec1 then ch\u1ed1t c\u1ee7a b\u1ea3o d\u01b0\u1ee1ng \u2013 v\u1ec7 sinh \u2013 ph\u1ee5c h\u1ed3i s\u1ea3n ph\u1ea9m inox. B\u00e0i vi\u1ebft \u0111i th\u1eb3ng v\u00e0o b\u1ea3n ch\u1ea5t v\u00ec sao 304 v\u1eabn r\u1ec9, c\u00e1ch ch\u1ea9n \u0111o\u00e1n nhanh nguy\u00ean nh\u00e2n v\u00e0 quy tr\u00ecnh x\u1eed l\u00fd tri\u1ec7t \u0111\u1ec3, k\u00e8m khuy\u1ebfn ngh\u1ecb ch\u1ecdn m\u00e1c th\u00e9p\/ph\u01b0\u01a1ng \u00e1n ph\u00f2ng ng\u1eeba cho m\u00f4i tr\u01b0\u1eddng Vi\u1ec7t Nam.<\/p>\n<h2 id=\"toc-0-co-che-khong-gi-cua-304-va-vi-sao-van-ri\">C\u01a1 ch\u1ebf \u201ckh\u00f4ng g\u1ec9\u201d c\u1ee7a 304 v\u00e0 v\u00ec sao v\u1eabn r\u1ec9<\/h2>\n<p>&#8211; Inox 304 (UNS S30400\/S30403) ch\u1ee9a kho\u1ea3ng 18% Cr v\u00e0 8% Ni. Ch\u00ednh Cr t\u1ea1o m\u00e0ng th\u1ee5 \u0111\u1ed9ng Cr2O3 c\u1ef1c m\u1ecfng (kho\u1ea3ng v\u00e0i nm) b\u00e1m tr\u00ean b\u1ec1 m\u1eb7t, t\u1ef1 t\u00e1i t\u1ea1o khi c\u00f3 oxy. M\u00e0ng n\u00e0y ng\u0103n s\u1eaft n\u1ec1n b\u1ecb oxy h\u00f3a.<br \/>\n&#8211; M\u00e0ng th\u1ee5 \u0111\u1ed9ng c\u00f3 th\u1ec3 b\u1ecb ph\u00e1 v\u1ee1 c\u1ee5c b\u1ed9 b\u1edfi: ion clo (Cl\u2212), thi\u1ebfu oxy trong khe h\u1edf\/\u0111\u1ecdng n\u01b0\u1edbc, nhi\u1ec7t \u1ea3nh h\u01b0\u1edfng m\u1ed1i h\u00e0n, t\u1ea1p nhi\u1ec5m s\u1eaft t\u1eeb th\u00e9p cacbon, ho\u1eb7c \u0103n m\u00f2n \u0111i\u1ec7n h\u00f3a khi ti\u1ebfp x\u00fac kim lo\u1ea1i kh\u00e1c. Khi \u0111\u00f3, \u0111i\u1ec3m c\u1ee5c b\u1ed9 s\u1ebd r\u1ec9 ho\u1eb7c r\u1ed7 d\u00f9 ph\u1ea7n l\u1edbn b\u1ec1 m\u1eb7t v\u1eabn \u201ckh\u00f4ng g\u1ec9\u201d.<\/p>\n<p>Ngu\u1ed3n: Nickel Institute; BSSA \u2013 British Stainless Steel Association.<\/p>\n<h2 id=\"toc-1-phan-biet-cac-dang-ri-thuong-gap\">Ph\u00e2n bi\u1ec7t c\u00e1c d\u1ea1ng \u201cr\u1ec9\u201d th\u01b0\u1eddng g\u1eb7p<\/h2>\n<p>&#8211; \u1ed0 \u201cm\u00e0u tr\u00e0\u201d (tea staining): l\u1edbp n\u00e2u v\u00e0ng tr\u00ean b\u1ec1 m\u1eb7t, th\u01b0\u1eddng \u1edf c\u00f4ng tr\u00ecnh g\u1ea7n bi\u1ec3n ho\u1eb7c b\u1ec1 m\u1eb7t No.4\/hairline. Ch\u1ee7 y\u1ebfu l\u00e0 \u0111\u1ed5i m\u00e0u b\u1ec1 m\u1eb7t do \u0111i\u1ec1u ki\u1ec7n \u1ea9m \u2013 mu\u1ed1i; \u00edt \u1ea3nh h\u01b0\u1edfng c\u01a1 t\u00ednh nh\u01b0ng l\u00e0m x\u1ea5u th\u1ea9m m\u1ef9.<br \/>\n&#8211; R\u1ec9 \u0111\u1ecf n\u00e2u loang: th\u01b0\u1eddng do t\u1ea1p nhi\u1ec5m s\u1eaft t\u1eeb m\u1ea1t th\u00e9p cacbon ho\u1eb7c d\u1ee5ng c\u1ee5 m\u00e0i chung; c\u0169ng g\u1eb7p khi ti\u1ebfp x\u00fac n\u01b0\u1edbc xi m\u0103ng ch\u1ee9a Cl\u2212.<br \/>\n&#8211; R\u1ed7 pitting\/\u0103n m\u00f2n k\u1ebd (crevice): xu\u1ea5t hi\u1ec7n l\u1ed7 li ti c\u00f3 vi\u1ec1n n\u00e2u; th\u01b0\u1eddng do clo + n\u01b0\u1edbc \u0111\u1ecdng + thi\u1ebfu oxy (m\u00e9p gh\u00e9p, gio\u0103ng, khe v\u00edt).<br \/>\n&#8211; \u0110\u1ed5i m\u00e0u xanh t\u00edm n\u00e2u quanh m\u1ed1i h\u00e0n (heat tint): \u00f4x\u00edt Cr-Ni d\u00e0y l\u00e0m ngh\u00e8o Cr \u1edf b\u1ec1 m\u1eb7t, gi\u1ea3m kh\u1ea3 n\u0103ng ch\u1ed1ng g\u1ec9; n\u1ebfu h\u00e0n kh\u00f4ng \u0111\u00fang quy tr\u00ecnh c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn nh\u1ea1y c\u1ea3m h\u00f3a (sensitization) v\u00e0 \u0103n m\u00f2n li\u00ean tinh.<br \/>\n&#8211; \u0102n m\u00f2n \u0111i\u1ec7n h\u00f3a: r\u1ec9 ph\u00e1t sinh khi 304 gh\u00e9p tr\u1ef1c ti\u1ebfp v\u1edbi th\u00e9p cacbon\/\u0111\u1ed3ng\/nh\u00f4m trong m\u00f4i tr\u01b0\u1eddng \u1ea9m, \u0111\u1eb7c bi\u1ec7t khi 304 \u0111\u00f3ng vai tr\u00f2 anode c\u1ee5c b\u1ed9.<\/p>\n<h2 id=\"toc-2-nguyen-nhan-cot-loi-khien-304-ri-trong-dieu-kien-v\">Nguy\u00ean nh\u00e2n c\u1ed1t l\u00f5i khi\u1ebfn 304 r\u1ec9 trong \u0111i\u1ec1u ki\u1ec7n Vi\u1ec7t Nam<\/h2>\n<h3>1) Clo\/chloride trong m\u00f4i tr\u01b0\u1eddng<\/h3>\n<p>&#8211; Ngu\u1ed3n: s\u01b0\u01a1ng mu\u1ed1i ven bi\u1ec3n; n\u01b0\u1edbc r\u1eeda\/gi\u1eb7t c\u00f3 Javel (NaClO); h\u00f3a ch\u1ea5t h\u1ed3 b\u01a1i; mu\u1ed1i kh\u1eed b\u0103ng (\u00edt ph\u1ed5 bi\u1ebfn \u1edf VN) ho\u1eb7c b\u1ee5i \u0111\u01b0\u1eddng.<br \/>\n&#8211; H\u1eadu qu\u1ea3: pitting\/crevice, \u1ed1 m\u00e0u tr\u00e0, SCC (\u0103n m\u00f2n n\u1ee9t \u1ee9ng su\u1ea5t) \u1edf >50\u201360\u00b0C v\u1edbi \u1ee9ng su\u1ea5t k\u00e9o.<br \/>\n&#8211; Ng\u01b0\u1ee1ng tham kh\u1ea3o trong n\u01b0\u1edbc: v\u1edbi n\u01b0\u1edbc s\u1ea1ch d\u01b0\u1edbi 50\u00b0C, 304 th\u01b0\u1eddng ph\u00f9 h\u1ee3p \u0111\u1ebfn kho\u1ea3ng 200 mg\/L Cl\u2212; 316L khuy\u1ebfn ngh\u1ecb \u0111\u1ebfn 500 mg\/L; cao h\u01a1n c\u1ea7n duplex\/super austenitic. Ngu\u1ed3n: Nickel Institute.<\/p>\n<h3>2) T\u1ea1p nhi\u1ec5m s\u1eaft v\u00e0 ch\u00e9o nhi\u1ec5m t\u1eeb gia c\u00f4ng<\/h3>\n<p>&#8211; D\u00f9ng \u0111\u00e1 m\u00e0i\/nh\u00e1m \u0111\u00e3 d\u00f9ng cho th\u00e9p th\u01b0\u1eddng, tia l\u1eeda h\u00e0n th\u00e9p cacbon b\u1eafn l\u00ean inox, ho\u1eb7c k\u1ec7 ch\u1ee9a th\u00e9p chung l\u00e0m b\u1ec1 m\u1eb7t inox d\u00ednh s\u1eaft t\u1ef1 do, sau \u0111\u00f3 r\u1ec9 \u0111\u1ecf khi \u1ea9m.<br \/>\n&#8211; L\u01b0u \u00fd: len th\u00e9p (steel wool), b\u00e0n ch\u1ea3i th\u00e9p cacbon g\u00e2y x\u01b0\u1edbc + t\u1ea1p nhi\u1ec5m.<\/p>\n<h3>3) \u1ea2nh h\u01b0\u1edfng nhi\u1ec7t\/m\u1ed1i h\u00e0n<\/h3>\n<p>&#8211; Heat tint l\u00e0m gi\u1ea3m Cr b\u1ec1 m\u1eb7t; v\u00f9ng \u1ea3nh h\u01b0\u1edfng nhi\u1ec7t (HAZ) c\u00f3 th\u1ec3 nh\u1ea1y c\u1ea3m h\u00f3a 450\u2013850\u00b0C, k\u1ebft t\u1ee7a Cr23C6 \u1edf ranh gi\u1edbi h\u1ea1t l\u00e0m ngh\u00e8o Cr, t\u0103ng nguy c\u01a1 \u0103n m\u00f2n li\u00ean tinh. D\u00f9ng 304L ho\u1eb7c 321\/347 v\u00e0 h\u00e0n \u0111\u00fang WPS \u0111\u1ec3 gi\u1ea3m r\u1ee7i ro.<\/p>\n<h3>4) Thi\u1ebft k\u1ebf t\u1ea1o khe h\u1edf, \u0111\u1ecdng n\u01b0\u1edbc, thi\u1ebfu oxy<\/h3>\n<p>&#8211; M\u00e9p g\u1ea5p, khe v\u00edt, gio\u0103ng, r\u00e3nh h\u1eb9p, m\u1eb7t ph\u1eb3ng kh\u00f4ng d\u1ed1c tho\u00e1t n\u01b0\u1edbc t\u1ea1o \u201ct\u00fai\u201d mu\u1ed1i + \u1ea9m, c\u1ea3n oxy t\u00e1i th\u1ee5 \u0111\u1ed9ng h\u00f3a.<\/p>\n<h3>5) Ho\u00e0n thi\u1ec7n b\u1ec1 m\u1eb7t nh\u00e1m v\u00e0 b\u1ee5i b\u1ea9n t\u00edch t\u1ee5<\/h3>\n<p>&#8211; No.4\/hairline c\u00f3 bi\u00ean d\u1ea1ng r\u00e3nh; Ra c\u00e0ng cao c\u00e0ng d\u1ec5 gi\u1eef mu\u1ed1i\/b\u1ee5i \u2192 \u1ed1 tr\u00e0. \u0110\u1ed9 b\u00f3ng g\u01b0\u01a1ng No.8, electropolish ch\u1ed1ng \u1ed1 t\u1ed1t h\u01a1n.<\/p>\n<h3>6) \u0102n m\u00f2n \u0111i\u1ec7n h\u00f3a v\u1edbi kim lo\u1ea1i kh\u00e1c<\/h3>\n<p>&#8211; Gh\u00e9p tr\u1ef1c ti\u1ebfp v\u1edbi th\u00e9p cacbon\/\u0111\u1ed3ng\/nh\u00f4m trong m\u00f4i tr\u01b0\u1eddng \u1ea9m m\u00e0 kh\u00f4ng c\u00e1ch \u0111i\u1ec7n \u2192 304 c\u00f3 th\u1ec3 b\u1ecb anod h\u00f3a c\u1ee5c b\u1ed9. D\u00f9ng long \u0111en nh\u1ef1a, keo c\u00e1ch \u0111i\u1ec7n, s\u01a1n c\u00e1ch ly.<\/p>\n<h3>7) H\u00f3a ch\u1ea5t kh\u00f4ng ph\u00f9 h\u1ee3p<\/h3>\n<p>&#8211; Acid HCl, ch\u1ea5t t\u1ea9y c\u00f3 clo ho\u1ea1t t\u00ednh (Javel\/NaClO), ch\u1ea5t t\u1ea9y xi m\u0103ng ch\u1ee9a chloride, ho\u1eb7c h\u01a1i HCl t\u1eeb v\u1ec7 sinh g\u1ea1ch men c\u00f3 th\u1ec3 ph\u00e1 m\u00e0ng th\u1ee5 \u0111\u1ed9ng.<\/p>\n<p>Ngu\u1ed3n tham kh\u1ea3o: BSSA; Nickel Institute \u201cCleaning and Descaling Stainless Steels\u201d; ASTM A380\/A967.<\/p>\n<h2 id=\"toc-3-chan-doan-nhanh-ri-that-hay-o-be-mat\">Ch\u1ea9n \u0111o\u00e1n nhanh: r\u1ec9 th\u1eadt hay \u1ed1 b\u1ec1 m\u1eb7t?<\/h2>\n<p>&#8211; Quan s\u00e1t:<br \/>\n  &#8211; \u1ed0 v\u00e0ng n\u00e2u \u0111\u1ec1u, kh\u00f4ng s\u1ea7n: nhi\u1ec1u kh\u1ea3 n\u0103ng tea staining\/\u00f4x\u00edt b\u1ea9n.<br \/>\n  &#8211; \u0110\u1ed1m n\u00e2u c\u00f3 t\u00e2m l\u1ed7 nh\u1ecf, nh\u00e1m: pitting. Ki\u1ec3m tra k\u1ef9 trong khe.<br \/>\n  &#8211; V\u00f2ng \u0111\u1ed5i m\u00e0u quanh m\u1ed1i h\u00e0n: heat tint\/\u00f4x\u00edt h\u00e0n.<br \/>\n&#8211; Ki\u1ec3m tra t\u1eeb t\u00ednh: 304 c\u00f3 th\u1ec3 h\u01a1i h\u00fat nam ch\u00e2m do bi\u1ebfn c\u1ee9ng ngu\u1ed9i \u2013 kh\u00f4ng ph\u1ea3i ti\u00eau ch\u00ed x\u00e1c th\u1ef1c m\u00e1c. \u0110\u1eebng d\u00f9ng nam ch\u00e2m \u0111\u1ec3 \u201ck\u1ebft t\u1ed9i\u201d.<br \/>\n&#8211; Ki\u1ec3m tra t\u1ea1p nhi\u1ec5m s\u1eaft: nh\u1ecf v\u00e0i gi\u1ecdt dung d\u1ecbch Ferroxyl (n\u1ebfu c\u00f3) s\u1ebd hi\u1ec7n xanh khi c\u00f3 s\u1eaft t\u1ef1 do; ho\u1eb7c th\u1eed t\u1ea9y nh\u1eb9 b\u1eb1ng acid citric: n\u1ebfu s\u1ea1ch r\u1ec9 ngay, nghi nhi\u1ec5m s\u1eaft b\u1ec1 m\u1eb7t.<br \/>\n&#8211; X\u00e1c th\u1ef1c m\u00e1c th\u00e9p khi nghi ng\u1edd: y\u00eau c\u1ea7u MTR\/COC, PMI b\u1eb1ng XRF. 201\/430 th\u01b0\u1eddng r\u1ec9 nhanh h\u01a1n trong m\u00f4i tr\u01b0\u1eddng ch\u1ee9a clo.<\/p>\n<h2 id=\"toc-4-quy-trinh-xu-ly-triet-de-theo-muc-do-hu-hai\">Quy tr\u00ecnh x\u1eed l\u00fd tri\u1ec7t \u0111\u1ec3 theo m\u1ee9c \u0111\u1ed9 h\u01b0 h\u1ea1i<\/h2>\n<p>Tu\u00e2n th\u1ee7 an to\u00e0n h\u00f3a ch\u1ea5t, g\u0103ng\/\u0111\u1ed3 b\u1ea3o h\u1ed9, th\u00f4ng gi\u00f3 t\u1ed1t. Th\u1eed tr\u01b0\u1edbc tr\u00ean v\u00f9ng nh\u1ecf k\u00edn \u0111\u00e1o.<\/p>\n<h3>A) \u1ed0 nh\u1eb9\/tea staining, kh\u00f4ng c\u00f3 r\u1ed7<\/h3>\n<p>&#8211; B\u01b0\u1edbc 1: R\u1eeda b\u1eb1ng n\u01b0\u1edbc s\u1ea1ch + x\u00e0 ph\u00f2ng trung t\u00ednh, kh\u0103n m\u1ec1m, tr\u00e1ng k\u1ef9, lau kh\u00f4.<br \/>\n&#8211; B\u01b0\u1edbc 2: Kh\u1eed \u00f4x\u00edt nh\u1eb9 v\u00e0 t\u00e1i th\u1ee5 \u0111\u1ed9ng:<br \/>\n  &#8211; D\u00f9ng dung d\u1ecbch acid citric 4\u201310% \u1edf 25\u201360\u00b0C, ng\u00e2m\/lau 20\u201360 ph\u00fat; tr\u00e1ng n\u01b0\u1edbc DI n\u1ebfu c\u00f3; s\u1ea5y kh\u00f4. Tu\u00e2n theo ASTM A967 (citric passivation).<br \/>\n  &#8211; Tr\u00e1nh ch\u1ea5t t\u1ea9y ch\u1ee9a clo (NaClO), HCl.<br \/>\n&#8211; B\u01b0\u1edbc 3: Ho\u00e0n thi\u1ec7n b\u1ec1 m\u1eb7t (t\u00f9y m\u00f4i tr\u01b0\u1eddng):<br \/>\n  &#8211; \u0110\u00e1nh b\u00f3ng m\u1ecbn h\u01a1n (gi\u1ea3m Ra), ho\u1eb7c electropolish \u0111\u1ec3 n\u00e2ng kh\u1ea3 n\u0103ng ch\u1ed1ng \u1ed1.<\/p>\n<h3>B) R\u1ec9 do t\u1ea1p nhi\u1ec5m s\u1eaft b\u00e1m b\u1ec1 m\u1eb7t<\/h3>\n<p>&#8211; B\u01b0\u1edbc 1: C\u1ea1o\/c\u1ecd c\u01a1 h\u1ecdc b\u1eb1ng pad s\u1ee3i t\u1ed5ng h\u1ee3p (kh\u00f4ng d\u00f9ng len th\u00e9p). H\u00fat b\u1ee5i s\u1ea1ch.<br \/>\n&#8211; B\u01b0\u1edbc 2: Th\u1ee5 \u0111\u1ed9ng h\u00f3a b\u1eb1ng citric\/nitric:<br \/>\n  &#8211; Nitric 10\u201320% \u1edf 20\u201350\u00b0C, 20\u201330 ph\u00fat; sau \u0111\u00f3 r\u1eeda s\u1ea1ch, trung h\u00f2a. Tham kh\u1ea3o ASTM A967 lo\u1ea1i 2\/4. L\u01b0u \u00fd an to\u00e0n khi d\u00f9ng HNO3.<br \/>\n&#8211; B\u01b0\u1edbc 3: Ki\u1ec3m tra l\u1ea1i sau 48\u201372h. N\u1ebfu t\u00e1i r\u1ec9, l\u1eb7p l\u1ea1i v\u00e0 ki\u1ec3m so\u00e1t ngu\u1ed3n nhi\u1ec5m trong x\u01b0\u1edfng.<\/p>\n<h3>C) Heat tint\/m\u1ed1i h\u00e0n \u0111\u1ed5i m\u00e0u; HAZ nghi nh\u1ea1y c\u1ea3m h\u00f3a<\/h3>\n<p>&#8211; B\u01b0\u1edbc 1: T\u1ea9y pickling \u0111\u1ec3 lo\u1ea1i \u00f4x\u00edt h\u00e0n:<br \/>\n  &#8211; D\u00f9ng gel\/paste pickling g\u1ed1c h\u1ed7n h\u1ee3p HNO3 + HF theo TDS nh\u00e0 s\u1ea3n xu\u1ea5t; th\u1eddi gian th\u01b0\u1eddng 10\u201360 ph\u00fat t\u00f9y m\u1ee9c \u00f4x\u00edt; tuy\u1ec7t \u0111\u1ed1i PPE, che ch\u1eafn, trung h\u00f2a\/ph\u00e2n lo\u1ea1i r\u00e1c th\u1ea3i acid \u0111\u00fang quy \u0111\u1ecbnh.<br \/>\n  &#8211; Thay ch\u1ecdn: m\u00e0i b\u1eb1ng flap non-woven ri\u00eang cho inox + electropolish.<br \/>\n&#8211; B\u01b0\u1edbc 2: R\u1eeda \u00e1p l\u1ef1c n\u01b0\u1edbc s\u1ea1ch, trung h\u00f2a, s\u1ea5y. Sau pickling n\u00ean passivation (citric\/nitric).<br \/>\n&#8211; B\u01b0\u1edbc 3: V\u1edbi c\u1ea5u ki\u1ec7n m\u1edbi: d\u00f9ng 304L\/321, kh\u00ed b\u1ea3o v\u1ec7 (back purging), h\u00e0n chu\u1ea9n WPS \u0111\u1ec3 h\u1ea1n ch\u1ebf heat tint v\u00e0 nh\u1ea1y c\u1ea3m h\u00f3a. Ngu\u1ed3n: ASTM A380; BSSA.<\/p>\n<h3>D) Pitting\/crevice \u0111\u00e3 h\u00ecnh th\u00e0nh<\/h3>\n<p>&#8211; B\u01b0\u1edbc 1: L\u00e0m s\u1ea1ch c\u01a1 h\u1ecdc v\u00f9ng r\u1ed7 \u0111\u1ebfn khi s\u00e1ng kim lo\u1ea1i, lo\u1ea1i mu\u1ed1i trong l\u1ed7 (b\u00e0n ch\u1ea3i nylon, si\u00eau \u00e2m n\u1ebfu c\u00f3).<br \/>\n&#8211; B\u01b0\u1edbc 2: Pickling c\u1ee5c b\u1ed9 r\u1ed3i passivation.<br \/>\n&#8211; B\u01b0\u1edbc 3: N\u1ebfu r\u1ed7 s\u00e2u \u1ea3nh h\u01b0\u1edfng \u0111\u1ed9 d\u00e0y\/\u00e1p l\u1ef1c: h\u00e0n \u0111\u1eafp \u2013 gia c\u00f4ng l\u1ea1i ho\u1eb7c thay chi ti\u1ebft. C\u00e2n nh\u1eafc chuy\u1ec3n v\u1eadt li\u1ec7u l\u00ean 316L\/duplex n\u1ebfu m\u00f4i tr\u01b0\u1eddng gi\u00e0u clo.<\/p>\n<h3>E) Sau l\u00e0m s\u1ea1ch: ki\u1ec3m so\u00e1t t\u00e1i b\u1ea9n v\u00e0 b\u1ea3o v\u1ec7<\/h3>\n<p>&#8211; Tr\u00e1ng n\u01b0\u1edbc deion\/RO \u0111\u1ec3 gi\u1ea3m v\u1ec7t mu\u1ed1i; lau kh\u00f4.<br \/>\n&#8211; \u1ee8ng d\u1ee5ng ki\u1ebfn tr\u00fac c\u00f3 th\u1ec3 d\u00f9ng l\u1edbp ph\u1ee7 b\u1ea3o v\u1ec7 trong su\u1ed1t (fluoropolymer\/silane) ph\u00f9 h\u1ee3p inox \u0111\u1ec3 gi\u1ea3m b\u00e1m b\u1ea9n; kh\u00f4ng d\u00f9ng cho b\u1ec1 m\u1eb7t ti\u1ebfp x\u00fac th\u1ef1c ph\u1ea9m n\u1ebfu kh\u00f4ng c\u00f3 ch\u1ee9ng nh\u1eadn ph\u00f9 h\u1ee3p.<\/p>\n<h2 id=\"toc-5-phong-ngua-dai-han-vat-lieu-thiet-ke-thi-cong-bao-\">Ph\u00f2ng ng\u1eeba d\u00e0i h\u1ea1n: v\u1eadt li\u1ec7u, thi\u1ebft k\u1ebf, thi c\u00f4ng, b\u1ea3o tr\u00ec<\/h2>\n<h3>1) Ch\u1ecdn m\u00e1c th\u00e9p \u0111\u00fang m\u00f4i tr\u01b0\u1eddng<\/h3>\n<p>&#8211; Khu v\u1ef1c n\u1ed9i \u0111\u1ecba\/kh\u00f4ng clo, nhi\u1ec7t \u0111\u1ed9 th\u01b0\u1eddng: 304\/304L \u0111\u1ee7 d\u00f9ng.<br \/>\n&#8211; Ven bi\u1ec3n \u22645 km, c\u00f4ng tr\u00ecnh ngo\u00e0i tr\u1eddi, r\u1eeda kh\u00f4ng th\u01b0\u1eddng xuy\u00ean: \u01b0u ti\u00ean 316L (2\u20132.5% Mo, PREN ~23\u201324, ch\u1ed1ng pitting t\u1ed1t h\u01a1n 304 PREN ~18).<br \/>\n&#8211; H\u1ed3 b\u01a1i, spa, m\u00f4i tr\u01b0\u1eddng chloride >200 mg\/L, >50\u201360\u00b0C, ho\u1eb7c phun s\u01b0\u01a1ng mu\u1ed1i m\u1ea1nh: 316L t\u1ed1i thi\u1ec3u; c\u00e2n nh\u1eafc duplex 2205, 904L ho\u1eb7c si\u00eau austenitic n\u1ebfu kh\u1eafc nghi\u1ec7t. Tham kh\u1ea3o PREN = %Cr + 3.3\u00d7%Mo + 16\u00d7%N. Ngu\u1ed3n: IMOA\/Nickel Institute.<\/p>\n<h3>2) Ho\u00e0n thi\u1ec7n b\u1ec1 m\u1eb7t v\u00e0 thi\u1ebft k\u1ebf<\/h3>\n<p>&#8211; \u01afu ti\u00ean b\u1ec1 m\u1eb7t m\u1ecbn: No.2B, BA, No.8, ho\u1eb7c electropolish cho v\u00f9ng bi\u1ec3n\/\u0111\u00f4 th\u1ecb b\u1ea9n; Ra \u22640.5 \u00b5m gi\u00fap gi\u1ea3m \u1ed1.<br \/>\n&#8211; Thi\u1ebft k\u1ebf tho\u00e1t n\u01b0\u1edbc, tr\u00e1nh b\u1eaby n\u01b0\u1edbc\/khe h\u1edf; h\u00e0n k\u00edn thay v\u00ec b\u1eaft v\u00edt n\u01a1i d\u1ec5 \u0111\u1ecdng; tho\u00e1ng kh\u00ed cho ph\u00e9p t\u00e1i th\u1ee5 \u0111\u1ed9ng h\u00f3a.<br \/>\n&#8211; C\u00e1ch \u0111i\u1ec7n khi gh\u00e9p kim lo\u1ea1i kh\u00e1c: long \u0111en\/\u0111\u1ec7m nh\u1ef1a, sealant trung t\u00ednh.<\/p>\n<h3>3) Thi c\u00f4ng \u2013 gia c\u00f4ng \u0111\u00fang c\u00e1ch<\/h3>\n<p>&#8211; D\u00f9ng d\u1ee5ng c\u1ee5, \u0111\u00e1 m\u00e0i, b\u00e0n ch\u1ea3i \u201cdedicated\u201d cho inox; kh\u00f4ng d\u00f9ng chung v\u1edbi th\u00e9p th\u01b0\u1eddng.<br \/>\n&#8211; Che ch\u1eafn khi h\u00e0n\/c\u1eaft th\u00e9p cacbon g\u1ea7n khu v\u1ef1c inox.<br \/>\n&#8211; Sau gia c\u00f4ng: pickling + passivation theo ASTM A380\/A967, \u0111\u1eb7c bi\u1ec7t v\u00f9ng h\u00e0n.<\/p>\n<h3>4) B\u1ea3o tr\u00ec \u0111\u1ecbnh k\u1ef3 theo m\u00f4i tr\u01b0\u1eddng<\/h3>\n<p>&#8211; Khu v\u1ef1c \u0111\u00f4 th\u1ecb n\u1ed9i \u0111\u1ecba (nh\u01b0 H\u00e0 N\u1ed9i): r\u1eeda n\u01b0\u1edbc s\u1ea1ch + x\u00e0 ph\u00f2ng trung t\u00ednh m\u1ed7i 1\u20133 th\u00e1ng; lau kh\u00f4.<br \/>\n&#8211; Ven bi\u1ec3n, g\u1ea7n \u0111\u01b0\u1eddng l\u1edbn\/nhi\u1ec5m mu\u1ed1i: r\u1eeda h\u00e0ng tu\u1ea7n ho\u1eb7c hai tu\u1ea7n\/l\u1ea7n \u0111\u1ec3 h\u1ea1n ch\u1ebf t\u00edch mu\u1ed1i. Ngu\u1ed3n: Nickel Institute; BSSA \u201cTea staining\u201d.<br \/>\n&#8211; Tuy\u1ec7t \u0111\u1ed1i tr\u00e1nh: HCl, Javel\/NaClO, ch\u1ea5t t\u1ea9y ch\u1ee9a halogen; tr\u00e1nh len th\u00e9p. N\u1ebfu l\u1ee1 d\u00f9ng, r\u1eeda x\u1ed1i th\u1eadt k\u1ef9 ngay.<\/p>\n<h2 id=\"toc-6-hieu-lam-pho-bien-can-loai-bo\">Hi\u1ec3u l\u1ea7m ph\u1ed5 bi\u1ebfn c\u1ea7n lo\u1ea1i b\u1ecf<\/h2>\n<p>&#8211; \u201c304 kh\u00f4ng bao gi\u1edd r\u1ec9\u201d: sai. 304 ch\u1ed1ng g\u1ec9 nh\u1edd m\u00e0ng th\u1ee5 \u0111\u1ed9ng v\u00e0 \u0111i\u1ec1u ki\u1ec7n m\u00f4i tr\u01b0\u1eddng; clo, t\u1ea1p nhi\u1ec5m, thi\u1ebft k\u1ebf k\u00e9m v\u1eabn khi\u1ebfn r\u1ec9 c\u1ee5c b\u1ed9.<br \/>\n&#8211; \u201cD\u00f9ng nam ch\u00e2m \u0111\u1ec3 ph\u00e2n bi\u1ec7t 304\u201d: kh\u00f4ng \u0111\u00e1ng tin. 304 c\u00f3 th\u1ec3 nhi\u1ec5m t\u1eeb nh\u1eb9 do bi\u1ebfn d\u1ea1ng ngu\u1ed9i; c\u1ea7n PMI\/XRF ho\u1eb7c ch\u1ee9ng ch\u1ec9 MTR.<br \/>\n&#8211; \u201cT\u1ea9y g\u1ec9 b\u1eb1ng axit HCl\/Javel r\u1ea5t nhanh\u201d: \u0111\u00fang l\u00e0 \u201cnhanh\u201d nh\u01b0ng s\u1ebd ph\u00e1 m\u00e0ng th\u1ee5 \u0111\u1ed9ng, \u0111\u1ec3 l\u1ea1i clo\/ion Cl\u2212 g\u00e2y pitting v\u1ec1 sau.<\/p>\n<h2 id=\"toc-7-meo-thuc-te-cho-xuong-va-cong-truong\">M\u1eb9o th\u1ef1c t\u1ebf cho x\u01b0\u1edfng v\u00e0 c\u00f4ng tr\u01b0\u1eddng<\/h2>\n<p>&#8211; D\u00e1n nh\u00e3n \u201cch\u1ec9 cho inox\u201d tr\u00ean \u0111\u00e1 m\u00e0i, ch\u1ed5i, pad; l\u01b0u kho inox t\u00e1ch bi\u1ec7t th\u00e9p th\u01b0\u1eddng.<br \/>\n&#8211; L\u1eafp \u0111\u1eb7t xong r\u1eeda s\u1ea1ch, b\u00f3c m\u00e0ng PE b\u1ea3o v\u1ec7 s\u1edbm r\u1ed3i v\u1ec7 sinh l\u1ea7n \u0111\u1ea7u; m\u00e0ng PE \u0111\u1ec3 l\u00e2u ngo\u00e0i tr\u1eddi c\u00f3 th\u1ec3 gi\u1eef \u1ea9m\/mu\u1ed1i g\u00e2y \u1ed1.<br \/>\n&#8211; V\u1edbi lan can, m\u1eb7t d\u1ef1ng g\u1ea7n bi\u1ec3n: ch\u1ecdn 316L, b\u1ec1 m\u1eb7t No.8 ho\u1eb7c electropolish; l\u1ecbch r\u1eeda n\u01b0\u1edbc ng\u1ecdt h\u1eb1ng tu\u1ea7n trong 3 th\u00e1ng \u0111\u1ea7u, sau \u0111\u00f3 2 tu\u1ea7n\/l\u1ea7n.<br \/>\n&#8211; \u0110\u01b0\u1eddng \u1ed1ng\/h\u1ec7 th\u1ef1c ph\u1ea9m: tr\u00e1nh clo kh\u1eed tr\u00f9ng \u0111\u1eadm \u0111\u1eb7c ti\u1ebfp x\u00fac l\u00e2u; ki\u1ec3m so\u00e1t n\u1ed3ng \u0111\u1ed9 Cl\u2212, nhi\u1ec7t \u0111\u1ed9; r\u1eeda n\u01b0\u1edbc s\u1ea1ch sau CIP.<\/p>\n<h2 id=\"toc-8-nguon-tham-khao-ky-thuat\">Ngu\u1ed3n tham kh\u1ea3o k\u1ef9 thu\u1eadt<\/h2>\n<p>&#8211; ASTM A380\/A380M \u2013 Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts.<br \/>\n&#8211; ASTM A967\/A967M \u2013 Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts.<br \/>\n&#8211; Nickel Institute: \u201cCleaning and Descaling Stainless Steels\u201d; \u201cStainless Steels in Architecture: Minimising Tea Staining\u201d; \u201cGuidelines for Selection of Stainless Steel for Service in Water\u201d.<br \/>\n&#8211; BSSA (British Stainless Steel Association): \u201cWhy does stainless steel rust?\u201d; \u201cTea Staining \u2013 Causes and Remedies\u201d.<br \/>\n&#8211; IMOA (International Molybdenum Association): \u201cPractical Guidelines for the Fabrication of Stainless Steels\u201d.<\/p>\n<h2 id=\"toc-9-khi-nao-nen-nang-cap-vat-lieu\">Khi n\u00e0o n\u00ean n\u00e2ng c\u1ea5p v\u1eadt li\u1ec7u?<\/h2>\n<p>&#8211; D\u1ea5u hi\u1ec7u: pitting t\u00e1i di\u1ec5n d\u00f9 \u0111\u00e3 passivation v\u00e0 b\u1ea3o tr\u00ec \u0111\u00fang; v\u1ecb tr\u00ed nh\u1eadn s\u01b0\u01a1ng mu\u1ed1i tr\u1ef1c di\u1ec7n; nhi\u1ec7t >50\u201360\u00b0C v\u1edbi clo; c\u1ea5u ki\u1ec7n quan tr\u1ecdng an to\u00e0n.<br \/>\n&#8211; Khuy\u1ebfn ngh\u1ecb: chuy\u1ec3n 304 \u2192 316L; n\u1ebfu v\u1eabn kh\u00f4ng \u1ed5n, \u0111\u00e1nh gi\u00e1 duplex 2205 ho\u1eb7c h\u1ee3p kim Mo cao. C\u00e2n \u0111\u1ed1i t\u1ed5ng chi ph\u00ed v\u00f2ng \u0111\u1eddi (LCC) v\u1edbi r\u1ee7i ro ng\u1eebng m\u00e1y\/s\u1eeda ch\u1eefa.<\/p>\n<h2 id=\"toc-10-ket-luan-304-ri-khong-phai-do-inox-gia-ma-do-dieu-\">K\u1ebft lu\u1eadn: 304 r\u1ec9 kh\u00f4ng ph\u1ea3i do \u201cinox gi\u1ea3\u201d, m\u00e0 do \u0111i\u1ec1u ki\u1ec7n v\u00e0 x\u1eed l\u00fd<\/h2>\n<p>&#8211; Inox 304 c\u00f3 th\u1ec3 r\u1ec9 c\u1ee5c b\u1ed9 khi m\u00e0ng th\u1ee5 \u0111\u1ed9ng b\u1ecb ph\u00e1 b\u1edfi clo, t\u1ea1p nhi\u1ec5m s\u1eaft, \u1ea3nh h\u01b0\u1edfng h\u00e0n, khe h\u1edf\/\u0111\u1ecdng n\u01b0\u1edbc ho\u1eb7c \u0103n m\u00f2n \u0111i\u1ec7n h\u00f3a.<br \/>\n&#8211; X\u1eed l\u00fd tri\u1ec7t \u0111\u1ec3 g\u1ed3m: l\u00e0m s\u1ea1ch \u0111\u00fang c\u00e1ch, pickling v\u00f9ng \u00f4x\u00edt\/heat tint, th\u1ee5 \u0111\u1ed9ng h\u00f3a theo ASTM A967, s\u1eeda b\u1ec1 m\u1eb7t v\u00e0 thi\u1ebft k\u1ebf \u0111\u1ec3 n\u01b0\u1edbc tho\u00e1t \u2013 c\u00f3 oxy t\u00e1i th\u1ee5 \u0111\u1ed9ng.<br \/>\n&#8211; Ph\u00f2ng ng\u1eeba hi\u1ec7u qu\u1ea3 b\u1eb1ng: ch\u1ecdn \u0111\u00fang m\u00e1c th\u00e9p (304L\/316L\/duplex theo m\u00f4i tr\u01b0\u1eddng), ho\u00e0n thi\u1ec7n b\u1ec1 m\u1eb7t m\u1ecbn, thi c\u00f4ng tr\u00e1nh nhi\u1ec5m s\u1eaft, v\u00e0 l\u1eadp l\u1ecbch v\u1ec7 sinh b\u1eb1ng n\u01b0\u1edbc s\u1ea1ch \u0111\u1ecbnh k\u1ef3.<br \/>\n&#8211; L\u00e0m \u0111\u00fang ngay t\u1eeb \u0111\u1ea7u gi\u00fap k\u00e9o d\u00e0i tu\u1ed5i th\u1ecd, gi\u1eef th\u1ea9m m\u1ef9 v\u00e0 gi\u1ea3m chi ph\u00ed v\u00f2ng \u0111\u1eddi c\u00f4ng tr\u00ecnh\/thi\u1ebft b\u1ecb inox.<\/p>\n<p>C\u1ea7n t\u01b0 v\u1ea5n ch\u1ecdn m\u00e1c th\u00e9p, x\u1eed l\u00fd r\u1ec9 t\u1ea1i c\u00f4ng tr\u00ecnh, ho\u1eb7c nh\u1eadn b\u00e1o gi\u00e1 t\u1ed1t nh\u1ea5t t\u1ea1i H\u00e0 N\u1ed9i? Li\u00ean h\u1ec7 Inox C\u01b0\u1eddng Th\u1ecbnh \u2013 Hotline: 0343.417.281. Email: inoxcongnghiep.cuongthinh@gmail.com<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Inox 304 v\u1eabn c\u00f3 th\u1ec3 r\u1ec9 do clo, t\u1ea1p nhi\u1ec5m s\u1eaft, m\u1ed1i h\u00e0n\u2026 B\u00e0i vi\u1ebft ch\u1ec9 r\u00f5 nguy\u00ean nh\u00e2n, quy tr\u00ecnh t\u1ea9y\/pickling\u2013th\u1ee5 \u0111\u1ed9ng h\u00f3a, ph\u00f2ng ng\u1eeba v\u00e0 ch\u1ecdn m\u00e1c th\u00e9p ph\u00f9 h\u1ee3p.<\/p>\n","protected":false},"author":7,"featured_media":1049,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[23],"tags":[],"class_list":["post-1957","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\/1957","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=1957"}],"version-history":[{"count":0,"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/posts\/1957\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/media\/1049"}],"wp:attachment":[{"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/media?parent=1957"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/categories?post=1957"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/inoxcuongthinh.com\/inct\/wp\/v2\/tags?post=1957"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}