{"id":20221,"date":"2020-12-22T05:36:05","date_gmt":"2020-12-22T05:36:05","guid":{"rendered":"https:\/\/www.meetyoucarbide.com\/?p=20221"},"modified":"2020-12-22T05:36:08","modified_gmt":"2020-12-22T05:36:08","slug":"why-do-you-having-problems-frequently-when-welding-stainless-steel","status":"publish","type":"post","link":"https:\/\/www.meetyoucarbide.com\/vi\/why-do-you-having-problems-frequently-when-welding-stainless-steel\/","title":{"rendered":"T\u1ea1i sao b\u1ea1n g\u1eb7p s\u1ef1 c\u1ed1 th\u01b0\u1eddng xuy\u00ean khi h\u00e0n th\u00e9p kh\u00f4ng g\u1ec9?"},"content":{"rendered":"
\u0110\u1eb7c t\u00ednh h\u00e0n c\u1ee7a th\u00e9p kh\u00f4ng g\u1ec9 austenit: \u1ee9ng su\u1ea5t v\u00e0 bi\u1ebfn d\u1ea1ng \u0111\u00e0n h\u1ed3i v\u00e0 d\u1ebbo r\u1ea5t l\u1edbn trong qu\u00e1 tr\u00ecnh h\u00e0n, nh\u01b0ng c\u00f3 r\u1ea5t \u00edt v\u1ebft n\u1ee9t ngu\u1ed9i. M\u1ed1i h\u00e0n kh\u00f4ng c\u00f3 v\u00f9ng l\u00e0m ngu\u1ed9i v\u00e0 h\u1ea1t th\u00f4 n\u00ean \u0111\u1ed9 b\u1ec1n k\u00e9o c\u1ee7a m\u1ed1i h\u00e0n cao.<\/p>\n\n\n\n
C\u00e1c v\u1ea5n \u0111\u1ec1 ch\u00ednh c\u1ee7a h\u00e0n th\u00e9p kh\u00f4ng g\u1ec9 austenit l\u00e0: bi\u1ebfn d\u1ea1ng h\u00e0n l\u1edbn; do \u0111\u1eb7c \u0111i\u1ec3m ranh gi\u1edbi h\u1ea1t v\u00e0 \u0111\u1ed9 nh\u1ea1y c\u1ea3m v\u1edbi m\u1ed9t s\u1ed1 t\u1ea1p ch\u1ea5t vi l\u01b0\u1ee3ng (s, P), d\u1ec5 t\u1ea1o ra c\u00e1c v\u1ebft n\u1ee9t n\u00f3ng.<\/p>\n\n\n\n
N\u0103m v\u1ea5n \u0111\u1ec1 h\u00e0n ch\u00ednh v\u00e0 bi\u1ec7n ph\u00e1p x\u1eed l\u00fd th\u00e9p kh\u00f4ng g\u1ec9 austenit<\/p>\n\n\n\n
\u0102n m\u00f2n gi\u1eefa c\u00e1c h\u1ea1t: theo l\u00fd thuy\u1ebft v\u1ec1 crom k\u00e9m, khi m\u1ed1i h\u00e0n v\u00e0 v\u00f9ng ch\u1ecbu \u1ea3nh h\u01b0\u1edfng nhi\u1ec7t \u0111\u01b0\u1ee3c nung n\u00f3ng \u0111\u1ebfn v\u00f9ng nhi\u1ec7t \u0111\u1ed9 nh\u1ea1y c\u1ea3m 450 ~ 850oC, cacbua crom k\u1ebft t\u1ee7a tr\u00ean ranh gi\u1edbi h\u1ea1t, d\u1eabn \u0111\u1ebfn ranh gi\u1edbi h\u1ea1t crom k\u00e9m, kh\u00f4ng \u0111\u1ee7 \u0111\u1ec3 ch\u1ed1ng l\u1ea1i \u0103n m\u00f2n. S\u1ed1 kh\u00f4ng<\/p>\n\n\n\n
(1) C\u00f3 th\u1ec3 \u00e1p d\u1ee5ng c\u00e1c bi\u1ec7n ph\u00e1p sau \u0111\u00e2y \u0111\u1ec3 h\u1ea1n ch\u1ebf s\u1ef1 \u0103n m\u00f2n gi\u1eefa c\u00e1c h\u1ea1t c\u1ee7a m\u1ed1i h\u00e0n v\u00e0 s\u1ef1 \u0103n m\u00f2n v\u00f9ng nhi\u1ec7t \u0111\u1ed9 nh\u1ea1y c\u1ea3m tr\u00ean v\u1eadt li\u1ec7u m\u1ee5c ti\u00eau<\/p>\n\n\n\n
M\u1ed9t. \u0110\u1ec3 tr\u00e1nh s\u1ef1 h\u00ecnh th\u00e0nh Cr23C6, c\u00e1c nguy\u00ean t\u1ed1 \u1ed5n \u0111\u1ecbnh nh\u01b0 Ti v\u00e0 Nb \u0111\u01b0\u1ee3c th\u00eam v\u00e0o kim lo\u1ea1i c\u01a1 b\u1ea3n \u0111\u1ec3 gi\u1ea3m h\u00e0m l\u01b0\u1ee3ng cacbon trong kim lo\u1ea1i c\u01a1 b\u1ea3n v\u00e0 m\u1ed1i h\u00e0n.<\/p>\n\n\n\n
b. C\u1ea5u tr\u00fac pha k\u00e9p c\u1ee7a austenite v\u00e0 m\u1ed9t l\u01b0\u1ee3ng nh\u1ecf ferit \u0111\u01b0\u1ee3c h\u00ecnh th\u00e0nh trong m\u1ed1i h\u00e0n. Khi c\u00f3 m\u1ed9t l\u01b0\u1ee3ng ferit nh\u1ea5t \u0111\u1ecbnh trong m\u1ed1i h\u00e0n, k\u00edch th\u01b0\u1edbc h\u1ea1t c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c tinh ch\u1ebf, di\u1ec7n t\u00edch h\u1ea1t c\u00f3 th\u1ec3 t\u0103ng l\u00ean v\u00e0 l\u01b0\u1ee3ng k\u1ebft t\u1ee7a crom cacbua tr\u00ean m\u1ed9t \u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch ranh gi\u1edbi h\u1ea1t c\u00f3 th\u1ec3 gi\u1ea3m \u0111i.<\/p>\n\n\n\n
Cr23C6 \u0111\u01b0\u1ee3c \u01b0u ti\u00ean h\u00ecnh th\u00e0nh trong ferit thay v\u00ec crom k\u00e9m \u1edf ranh gi\u1edbi h\u1ea1t austenit; ferrite gi\u1eefa austenite c\u00f3 th\u1ec3 ng\u0103n ch\u1eb7n s\u1ef1 \u0103n m\u00f2n khu\u1ebfch t\u00e1n v\u00e0o b\u00ean trong d\u1ecdc theo ranh gi\u1edbi h\u1ea1t.<\/p>\n\n\n\n
c. Ki\u1ec3m so\u00e1t th\u1eddi gian c\u01b0 tr\u00fa trong ph\u1ea1m vi nhi\u1ec7t \u0111\u1ed9 nh\u1ea1y c\u1ea3m. \u0110i\u1ec1u ch\u1ec9nh chu tr\u00ecnh nhi\u1ec7t h\u00e0n \u0111\u1ec3 r\u00fat ng\u1eafn th\u1eddi gian l\u01b0u tr\u00fa 600-1000oC c\u00e0ng nhi\u1ec1u c\u00e0ng t\u1ed1t. C\u00f3 th\u1ec3 l\u1ef1a ch\u1ecdn ph\u01b0\u01a1ng ph\u00e1p h\u00e0n c\u00f3 m\u1eadt \u0111\u1ed9 n\u0103ng l\u01b0\u1ee3ng cao (ch\u1eb3ng h\u1ea1n nh\u01b0 h\u00e0n h\u1ed3 quang argon plasma). N\u0103ng l\u01b0\u1ee3ng \u0111\u01b0\u1eddng h\u00e0n nh\u1ecf h\u01a1n. Kh\u00ed Argon \u0111\u01b0\u1ee3c c\u1ea5p v\u00e0o m\u1eb7t sau c\u1ee7a m\u1ed1i h\u00e0n ho\u1eb7c mi\u1ebfng \u0111\u1ed3ng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 t\u0103ng t\u1ed1c \u0111\u1ed9 l\u00e0m m\u00e1t c\u1ee7a m\u1ed1i h\u00e0n. S\u1ed1 l\u1ea7n \u0111\u00e1nh h\u1ed3 quang v\u00e0 d\u1eebng h\u1ed3 quang \u0111\u01b0\u1ee3c gi\u1ea3m b\u1edbt \u0111\u1ec3 tr\u00e1nh b\u1ecb nung n\u00f3ng nhi\u1ec1u l\u1ea7n. B\u1ec1 m\u1eb7t ti\u1ebfp x\u00fac gi\u1eefa v\u1eadt h\u00e0n nhi\u1ec1u l\u1edbp v\u00e0 m\u00f4i tr\u01b0\u1eddng \u0103n m\u00f2n c\u00e0ng b\u1ec1n c\u00e0ng t\u1ed1t.<\/p>\n\n\n\n
d. Sau khi h\u00e0n, n\u00ean x\u1eed l\u00fd dung d\u1ecbch r\u1eafn ho\u1eb7c \u1ee7 \u1ed5n \u0111\u1ecbnh (850-900oC) sau khi b\u1ea3o qu\u1ea3n nhi\u1ec7t v\u00e0 l\u00e0m m\u00e1t kh\u00f4ng kh\u00ed \u0111\u1ec3 k\u1ebft t\u1ee7a ho\u00e0n to\u00e0n cacbua v\u00e0 t\u0103ng t\u1ed1c \u0111\u1ed9 khu\u1ebfch t\u00e1n crom.<\/p>\n\n\n\n
(2) V\u00ec l\u00fd do n\u00e0y, c\u00f3 th\u1ec3 th\u1ef1c hi\u1ec7n c\u00e1c bi\u1ec7n ph\u00e1p ph\u00f2ng ng\u1eeba sau:<\/p>\n\n\n\n
Do kh\u1ea3 n\u0103ng khu\u1ebfch t\u00e1n m\u1ea1nh c\u1ee7a carbon n\u00ean n\u00f3 s\u1ebd ph\u00e2n t\u00e1ch \u1edf ranh gi\u1edbi h\u1ea1t v\u00e0 h\u00ecnh th\u00e0nh tr\u1ea1ng th\u00e1i si\u00eau b\u00e3o h\u00f2a trong qu\u00e1 tr\u00ecnh l\u00e0m l\u1ea1nh, trong khi Ti v\u00e0 Nb s\u1ebd t\u1ed3n t\u1ea1i trong tinh th\u1ec3 do kh\u1ea3 n\u0103ng khu\u1ebfch t\u00e1n th\u1ea5p. Khi m\u1ed1i h\u00e0n \u0111\u01b0\u1ee3c nung n\u00f3ng l\u1ea1i \u1edf kho\u1ea3ng nhi\u1ec7t \u0111\u1ed9 nh\u1ea1y c\u1ea3m, cacbon si\u00eau b\u00e3o h\u00f2a s\u1ebd k\u1ebft t\u1ee7a d\u01b0\u1edbi d\u1ea1ng Cr23C6.<\/p>\n\n\n\n
M\u1ed9t. Gi\u1ea3m h\u00e0m l\u01b0\u1ee3ng cacbon. \u0110\u1ed1i v\u1edbi th\u00e9p kh\u00f4ng g\u1ec9 c\u00f3 ch\u1ee9a y\u1ebfu t\u1ed1 \u1ed5n \u0111\u1ecbnh th\u00ec h\u00e0m l\u01b0\u1ee3ng cacbon kh\u00f4ng \u0111\u01b0\u1ee3c v\u01b0\u1ee3t qu\u00e1 0,06%.<\/p>\n\n\n\n
b. Adopt reasonable welding process. In order to reduce the residence time of overheated zone at high temperature, a smaller welding line energy should be selected to avoid “medium temperature sensitization” effect in the welding process.<\/p>\n\n\n\n
Trong tr\u01b0\u1eddng h\u1ee3p h\u00e0n hai m\u1eb7t, m\u1ed1i h\u00e0n ti\u1ebfp x\u00fac v\u1edbi m\u00f4i tr\u01b0\u1eddng \u0103n m\u00f2n ph\u1ea3i \u0111\u01b0\u1ee3c h\u00e0n cu\u1ed1i c\u00f9ng (\u0111\u00e2y l\u00e0 l\u00fd do t\u1ea1i sao vi\u1ec7c h\u00e0n b\u00ean trong \u1ed1ng h\u00e0n th\u00e0nh d\u00e0y \u0111\u01b0\u1eddng k\u00ednh l\u1edbn \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n sau khi h\u00e0n b\u00ean ngo\u00e0i). N\u1ebfu kh\u00f4ng th\u1ec3 th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c th\u00ec ph\u1ea3i \u0111i\u1ec1u ch\u1ec9nh th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt h\u00e0n v\u00e0 h\u00ecnh d\u1ea1ng m\u1ed1i h\u00e0n \u0111\u1ec3 tr\u00e1nh v\u00f9ng qu\u00e1 n\u00f3ng ti\u1ebfp x\u00fac v\u1edbi m\u00f4i tr\u01b0\u1eddng \u0103n m\u00f2n kh\u00f4ng b\u1ecb nh\u1ea1y c\u1ea3m tr\u1edf l\u1ea1i.<\/p>\n\n\n\n
c. X\u1eed l\u00fd nhi\u1ec7t sau h\u00e0n. Sau khi h\u00e0n ph\u1ea3i ti\u1ebfn h\u00e0nh x\u1eed l\u00fd b\u1eb1ng dung d\u1ecbch r\u1eafn ho\u1eb7c \u1ed5n \u0111\u1ecbnh.<\/strong><\/p>\n\n\n\n