<\/p>\n

Gi\u1edbi thi\u1ec7u Th\u00e9p \u0111\u01b0\u1ee3c l\u00e0m ngu\u1ed9i b\u1eb1ng c\u00e1ch nung n\u00f3ng th\u00e9p \u0111\u1ebfn nhi\u1ec7t \u0111\u1ed9 cao h\u01a1n nhi\u1ec7t \u0111\u1ed9 t\u1edbi h\u1ea1n Ac3 (th\u00e9p hypo-eutectoid) ho\u1eb7c Ac1 (th\u00e9p hypereutectoid), gi\u1eef n\u00f3 trong m\u1ed9t kho\u1ea3ng th\u1eddi gian \u0111\u1ec3 austenit h\u00f3a to\u00e0n b\u1ed9 ho\u1eb7c m\u1ed9t ph\u1ea7n, sau \u0111\u00f3 \u0111\u01b0\u1ee3c l\u00e0m ngu\u1ed9i \u1edf nhi\u1ec7t \u0111\u1ed9 nhi\u1ec7t \u0111\u1ed9 l\u1edbn h\u01a1n t\u1ed1c \u0111\u1ed9 l\u00e0m ngu\u1ed9i t\u1edbi h\u1ea1n L\u00e0m l\u1ea1nh nhanh xu\u1ed1ng d\u01b0\u1edbi Ms (ho\u1eb7c Ms g\u1ea7n \u0111\u1eb3ng nhi\u1ec7t) qu\u00e1 tr\u00ecnh x\u1eed l\u00fd nhi\u1ec7t martensitic (ho\u1eb7c bainite). X\u1eed l\u00fd dung d\u1ecbch c\u00e1c v\u1eadt li\u1ec7u nh\u01b0 h\u1ee3p kim nh\u00f4m, h\u1ee3p kim \u0111\u1ed3ng, h\u1ee3p kim titan, k\u00ednh c\u01b0\u1eddng l\u1ef1c, v.v., ho\u1eb7c c\u00e1c qu\u00e1 tr\u00ecnh x\u1eed l\u00fd nhi\u1ec7t v\u1edbi l\u00e0m l\u1ea1nh nhanh c\u0169ng th\u01b0\u1eddng \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 qu\u00e1 tr\u00ecnh t\u00f4i. L\u00e0m ngu\u1ed9i l\u00e0 m\u1ed9t qu\u00e1 tr\u00ecnh x\u1eed l\u00fd nhi\u1ec7t ph\u1ed5 bi\u1ebfn, ch\u1ee7 y\u1ebfu \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 t\u0103ng \u0111\u1ed9 c\u1ee9ng c\u1ee7a v\u1eadt li\u1ec7u. Th\u00f4ng th\u01b0\u1eddng t\u1eeb m\u00f4i tr\u01b0\u1eddng l\u00e0m ngu\u1ed9i, c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c chia th\u00e0nh l\u00e0m ngu\u1ed9i b\u1eb1ng n\u01b0\u1edbc, l\u00e0m ngu\u1ed9i d\u1ea7u, l\u00e0m ngu\u1ed9i h\u1eefu c\u01a1. V\u1edbi s\u1ef1 ph\u00e1t tri\u1ec3n c\u1ee7a khoa h\u1ecdc v\u00e0 c\u00f4ng ngh\u1ec7, m\u1ed9t s\u1ed1 quy tr\u00ecnh d\u1eadp t\u1eaft m\u1edbi \u0111\u00e3 xu\u1ea5t hi\u1ec7n.1 Ph\u01b0\u01a1ng ph\u00e1p d\u1eadp t\u1eaft l\u00e0m m\u00e1t b\u1eb1ng kh\u00f4ng kh\u00ed \u00e1p su\u1ea5t cao C\u00e1c ph\u00f4i trong d\u00f2ng kh\u00ed tr\u01a1 m\u1ea1nh \u0111\u01b0\u1ee3c l\u00e0m m\u00e1t nhanh ch\u00f3ng v\u00e0 \u0111\u1ed3ng \u0111\u1ec1u, \u0111\u1ec3 ng\u0103n ch\u1eb7n qu\u00e1 tr\u00ecnh oxy h\u00f3a b\u1ec1 m\u1eb7t, tr\u00e1nh n\u1ee9t, gi\u1ea3m bi\u1ebfn d\u1ea1ng, \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o r\u1eb1ng \u0111\u1ed9 c\u1ee9ng c\u1ea7n thi\u1ebft, ch\u1ee7 y\u1ebfu \u0111\u1ec3 l\u00e0m ngu\u1ed9i th\u00e9p c\u00f4ng c\u1ee5. C\u00f4ng ngh\u1ec7 n\u00e0y g\u1ea7n \u0111\u00e2y \u0111\u00e3 ph\u00e1t tri\u1ec3n nhanh ch\u00f3ng v\u00e0 ph\u1ea1m vi \u1ee9ng d\u1ee5ng c\u0169ng \u0111\u00e3 \u0111\u01b0\u1ee3c m\u1edf r\u1ed9ng \u0111\u00e1ng k\u1ec3. Hi\u1ec7n t\u1ea1i, c\u00f4ng ngh\u1ec7 l\u00e0m ngu\u1ed9i kh\u00ed ch\u00e2n kh\u00f4ng \u0111\u00e3 ph\u00e1t tri\u1ec3n nhanh ch\u00f3ng v\u00e0 l\u00e0m m\u00e1t kh\u00ed t\u1ed1c \u0111\u1ed9 d\u00f2ng ch\u1ea3y cao \u00e1p su\u1ea5t \u00e2m (<1 \u00d7 105 Pa), sau \u0111\u00f3 l\u00e0 l\u00e0m m\u00e1t kh\u00ed v\u00e0 \u00e1p su\u1ea5t cao (1 \u00d7 105 ~ 4 \u00d7 105 Pa) 10 \u00d7 105 Pa) kh\u00f4ng kh\u00ed -l\u00e0m m\u00e1t, l\u00e0m m\u00e1t b\u1eb1ng kh\u00f4ng kh\u00ed \u00e1p su\u1ea5t c\u1ef1c cao (10 \u00d7 105 ~ 20 \u00d7 105 Pa) v\u00e0 c\u00e1c c\u00f4ng ngh\u1ec7 m\u1edbi kh\u00e1c kh\u00f4ng ch\u1ec9 gi\u00fap t\u0103ng c\u01b0\u1eddng \u0111\u00e1ng k\u1ec3 kh\u1ea3 n\u0103ng l\u00e0m ngu\u1ed9i ch\u00e2n kh\u00f4ng c\u1ee7a l\u00e0m m\u00e1t b\u1eb1ng kh\u00f4ng kh\u00ed m\u00e0 c\u00f2n l\u00e0m ngu\u1ed9i \u0111\u1ed9 s\u00e1ng b\u1ec1 m\u1eb7t ph\u00f4i t\u1ed1t, bi\u1ebfn d\u1ea1ng nh\u1ecf, nh\u01b0ng c\u0169ng c\u00f3 hi\u1ec7u qu\u1ea3 cao, ti\u1ebft ki\u1ec7m n\u0103ng l\u01b0\u1ee3ng, kh\u00f4ng g\u00e2y \u00f4 nhi\u1ec5m, v.v. Vi\u1ec7c s\u1eed d\u1ee5ng ph\u01b0\u01a1ng ph\u00e1p l\u00e0m ngu\u1ed9i b\u1eb1ng kh\u00ed l\u00e0m m\u00e1t b\u1eb1ng kh\u00ed \u00e1p su\u1ea5t cao ch\u00e2n kh\u00f4ng l\u00e0 qu\u00e1 tr\u00ecnh l\u00e0m ngu\u1ed9i v\u00e0 t\u00f4i luy\u1ec7n v\u1eadt li\u1ec7u, dung d\u1ecbch, qu\u00e1 tr\u00ecnh l\u00e3o h\u00f3a, cacbon h\u00f3a ion v\u00e0 th\u1ea5m cacbon c\u1ee7a th\u00e9p kh\u00f4ng g\u1ec9 v\u00e0 c\u00e1c h\u1ee3p kim \u0111\u1eb7c bi\u1ec7t, c\u0169ng nh\u01b0 qu\u00e1 tr\u00ecnh thi\u00eau k\u1ebft ch\u00e2n kh\u00f4ng, l\u00e0m m\u00e1t v\u00e0 l\u00e0m ngu\u1ed9i sau khi h\u00e0n. V\u1edbi qu\u00e1 tr\u00ecnh l\u00e0m ngu\u1ed9i b\u1eb1ng nit\u01a1 \u00e1p su\u1ea5t cao 6 \u00d7 105 Pa, t\u1ea3i ch\u1ec9 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c l\u00e0m m\u00e1t r\u1eddi, th\u00e9p t\u1ed1c \u0111\u1ed9 cao (W6Mo5Cr4V2) c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c l\u00e0m c\u1ee9ng \u0111\u1ebfn 70 ~ 100 mm, th\u00e9p ch\u1ebft gia c\u00f4ng h\u1ee3p kim cao l\u00ean \u0111\u1ebfn 25 ~ 100 mm, v\u00e0ng l\u1ea1nh th\u00e9p khu\u00f4n l\u00e0m vi\u1ec7c (ch\u1eb3ng h\u1ea1n nh\u01b0 Cr12) l\u00ean \u0111\u1ebfn 80 ~ 100 mm. Khi \u0111\u01b0\u1ee3c l\u00e0m ngu\u1ed9i b\u1eb1ng nit\u01a1 \u00e1p su\u1ea5t cao 10 \u00d7 10 5 Pa, t\u1ea3i \u0111\u01b0\u1ee3c l\u00e0m m\u00e1t c\u00f3 th\u1ec3 r\u1ea5t m\u1ea1nh, l\u00e0m t\u0103ng m\u1eadt \u0111\u1ed9 t\u1ea3i kho\u1ea3ng 30% l\u00ean 40% so v\u1edbi l\u00e0m m\u00e1t b\u1eb1ng 6 \u00d7 10 5 Pa. Khi \u0111\u01b0\u1ee3c l\u00e0m ngu\u1ed9i b\u1eb1ng nit\u01a1 c\u1ef1c cao 20 \u00d7 10 5 Pa. nit\u01a1 \u00e1p su\u1ea5t ho\u1eb7c h\u1ed7n h\u1ee3p helium v\u00e0 nit\u01a1, c\u00e1c t\u1ea3i \u0111\u01b0\u1ee3c l\u00e0m m\u00e1t s\u1ebd d\u00e0y \u0111\u1eb7c v\u00e0 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c b\u00f3 l\u1ea1i v\u1edbi nhau. M\u1eadt \u0111\u1ed9 l\u00e0m m\u00e1t b\u1eb1ng nit\u01a1 6 \u00d7 105 Pa 80% \u0111\u1ebfn 150%, c\u00f3 th\u1ec3 l\u00e0m m\u00e1t t\u1ea5t c\u1ea3 th\u00e9p t\u1ed1c \u0111\u1ed9 cao, th\u00e9p h\u1ee3p kim cao, th\u00e9p c\u00f4ng c\u1ee5 gia c\u00f4ng n\u00f3ng v\u00e0 th\u00e9p crom Cr13% v\u00e0 nhi\u1ec1u lo\u1ea1i th\u00e9p t\u00f4i d\u1ea7u h\u1ee3p kim h\u01a1n, ch\u1eb3ng h\u1ea1n nh\u01b0 th\u00e9p 9Mn2V k\u00edch th\u01b0\u1edbc l\u1edbn h\u01a1n. L\u00f2 t\u00f4i hai bu\u1ed3ng l\u00e0m m\u00e1t b\u1eb1ng kh\u00f4ng kh\u00ed v\u1edbi c\u00e1c bu\u1ed3ng l\u00e0m m\u00e1t ri\u00eang bi\u1ec7t c\u00f3 kh\u1ea3 n\u0103ng l\u00e0m m\u00e1t t\u1ed1t h\u01a1n so v\u1edbi c\u00e1c lo\u1ea1i l\u00f2 m\u1ed9t bu\u1ed3ng c\u00f9ng lo\u1ea1i. L\u00f2 \u0111\u00f4i bu\u1ed3ng l\u00e0m m\u00e1t b\u1eb1ng nit\u01a1 2 \u00d7 105 Pa c\u00f3 hi\u1ec7u qu\u1ea3 l\u00e0m m\u00e1t t\u01b0\u01a1ng t\u1ef1 nh\u01b0 l\u00f2 bu\u1ed3ng \u0111\u01a1n 4 \u00d7 105 Pa. Tuy nhi\u00ean, chi ph\u00ed v\u1eadn h\u00e0nh, chi ph\u00ed b\u1ea3o tr\u00ec th\u1ea5p. Khi ng\u00e0nh c\u00f4ng nghi\u1ec7p v\u1eadt li\u1ec7u c\u01a1 b\u1ea3n c\u1ee7a Trung Qu\u1ed1c (than ch\u00ec, molypden, v.v.) v\u00e0 c\u00e1c th\u00e0nh ph\u1ea7n ph\u1ee5 tr\u1ee3 (\u0111\u1ed9ng c\u01a1) v\u00e0 c\u00e1c c\u1ea5p \u0111\u1ed9 kh\u00e1c \u0111\u01b0\u1ee3c c\u1ea3i thi\u1ec7n. Do \u0111\u00f3, \u0111\u1ec3 c\u1ea3i thi\u1ec7n vi\u1ec7c ch\u0103m s\u00f3c ch\u00e2n kh\u00f4ng \u00e1p su\u1ea5t cao m\u1ed9t bu\u1ed3ng 6 \u00d7 105 Pa trong khi duy tr\u00ec s\u1ef1 ph\u00e1t tri\u1ec3n c\u1ee7a l\u00f2 l\u00e0m ngu\u1ed9i \u00e1p su\u1ea5t bu\u1ed3ng k\u00e9p v\u00e0 l\u00e0m m\u00e1t b\u1eb1ng kh\u00f4ng kh\u00ed \u00e1p su\u1ea5t cao ph\u00f9 h\u1ee3p h\u01a1n v\u1edbi \u0111i\u1ec1u ki\u1ec7n qu\u1ed1c gia c\u1ee7a Trung Qu\u1ed1c. H\u00ecnh 1 kh\u00f4ng kh\u00ed \u00e1p su\u1ea5t cao- l\u00f2 ch\u00e2n kh\u00f4ng l\u00e0m m\u00e1t2 ph\u01b0\u01a1ng ph\u00e1p l\u00e0m ngu\u1ed9i m\u1ea1nh Ph\u01b0\u01a1ng ph\u00e1p l\u00e0m ngu\u1ed9i th\u00f4ng th\u01b0\u1eddng th\u01b0\u1eddng l\u00e0 l\u00e0m m\u00e1t b\u1eb1ng d\u1ea7u, n\u01b0\u1edbc ho\u1eb7c dung d\u1ecbch polyme, v\u00e0 quy t\u1eafc l\u00e0m ngu\u1ed9i m\u1ea1nh b\u1eb1ng n\u01b0\u1edbc ho\u1eb7c n\u01b0\u1edbc mu\u1ed1i n\u1ed3ng \u0111\u1ed9 th\u1ea5p. L\u00e0m ngu\u1ed9i m\u1ea1nh \u0111\u01b0\u1ee3c \u0111\u1eb7c tr\u01b0ng b\u1edfi kh\u1ea3 n\u0103ng l\u00e0m ngu\u1ed9i c\u1ef1c nhanh, m\u00e0 kh\u00f4ng ph\u1ea3i lo l\u1eafng v\u1ec1 s\u1ef1 bi\u1ebfn d\u1ea1ng qu\u00e1 m\u1ee9c c\u1ee7a th\u00e9p v\u00e0 n\u1ee9t. Qu\u00e1 tr\u00ecnh l\u00e0m ngu\u1ed9i th\u00f4ng th\u01b0\u1eddng \u0111\u1ebfn nhi\u1ec7t \u0111\u1ed9 l\u00e0m ngu\u1ed9i, s\u1ee9c c\u0103ng b\u1ec1 m\u1eb7t th\u00e9p ho\u1eb7c tr\u1ea1ng th\u00e1i \u1ee9ng su\u1ea5t th\u1ea5p, v\u00e0 l\u00e0m ngu\u1ed9i m\u1ea1nh \u1edf gi\u1eefa qu\u00e1 tr\u00ecnh l\u00e0m m\u00e1t, t\u00e2m ph\u00f4i v\u1eabn \u1edf tr\u1ea1ng th\u00e1i n\u00f3ng \u0111\u1ec3 ng\u1eebng l\u00e0m m\u00e1t, do \u0111\u00f3 h\u00ecnh th\u00e0nh \u1ee9ng su\u1ea5t n\u00e9n b\u1ec1 m\u1eb7t. Trong \u0111i\u1ec1u ki\u1ec7n l\u00e0m ngu\u1ed9i kh\u1eafc nghi\u1ec7t, austenite si\u00eau l\u1ea1nh tr\u00ean b\u1ec1 m\u1eb7t th\u00e9p ph\u1ea3i ch\u1ecbu \u1ee9ng su\u1ea5t n\u00e9n 1200 MPa khi t\u1ed1c \u0111\u1ed9 l\u00e0m m\u00e1t c\u1ee7a v\u00f9ng bi\u1ebfn \u0111\u1ed5i martensitic cao h\u01a1n 30 \u2103 \/ s, do \u0111\u00f3 c\u01b0\u1eddng \u0111\u1ed9 n\u0103ng su\u1ea5t c\u1ee7a th\u00e9p sau khi l\u00e0m ngu\u1ed9i \u0111\u01b0\u1ee3c t\u0103ng \u00edt nh\u1ea5t l\u00e0 25%.Nguy\u00ean l\u00fd: Th\u00e9p t\u1eeb qu\u00e1 tr\u00ecnh t\u00f4i \u1edf nhi\u1ec7t \u0111\u1ed9 austenit h\u00f3a, ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9 gi\u1eefa b\u1ec1 m\u1eb7t v\u00e0 tim s\u1ebd d\u1eabn \u0111\u1ebfn \u1ee9ng su\u1ea5t b\u00ean trong. S\u1ef1 thay \u0111\u1ed5i pha c\u1ee7a th\u1ec3 t\u00edch ri\u00eang c\u1ee7a ch\u1ea5t thay \u0111\u1ed5i pha v\u00e0 d\u1ebbo thay \u0111\u1ed5i pha c\u0169ng s\u1ebd g\u00e2y ra \u1ee9ng su\u1ea5t chuy\u1ec3n pha b\u1ed5 sung. N\u1ebfu \u1ee9ng su\u1ea5t nhi\u1ec7t v\u00e0 \u1ee9ng su\u1ea5t chuy\u1ec3n pha ch\u1ed3ng ch\u1ea5t, t\u1ee9c l\u00e0 \u1ee9ng su\u1ea5t t\u1ed5ng th\u1ec3 v\u01b0\u1ee3t qu\u00e1 c\u01b0\u1eddng \u0111\u1ed9 n\u0103ng su\u1ea5t c\u1ee7a v\u1eadt li\u1ec7u th\u00ec s\u1ebd x\u1ea3y ra bi\u1ebfn d\u1ea1ng d\u1ebbo; n\u1ebfu \u1ee9ng su\u1ea5t v\u01b0\u1ee3t qu\u00e1 \u0111\u1ed9 b\u1ec1n k\u00e9o c\u1ee7a th\u00e9p n\u00f3ng s\u1ebd h\u00ecnh th\u00e0nh v\u1ebft n\u1ee9t d\u1eadp t\u1eaft. Trong qu\u00e1 tr\u00ecnh l\u00e0m ngu\u1ed9i c\u01b0\u1eddng \u0111\u1ed9 cao, \u1ee9ng su\u1ea5t d\u01b0 do \u0111\u1ed9 d\u1ebbo thay \u0111\u1ed5i pha g\u00e2y ra v\u00e0 \u1ee9ng su\u1ea5t d\u01b0 t\u0103ng do s\u1ef1 thay \u0111\u1ed5i th\u1ec3 t\u00edch ri\u00eang c\u1ee7a qu\u00e1 tr\u00ecnh bi\u1ebfn \u0111\u1ed5i austenite-martensite. Trong qu\u00e1 tr\u00ecnh l\u00e0m m\u00e1t c\u01b0\u1eddng \u0111\u1ed9 cao, b\u1ec1 m\u1eb7t ph\u00f4i ngay l\u1eadp t\u1ee9c \u0111\u01b0\u1ee3c l\u00e0m m\u00e1t \u0111\u1ebfn nhi\u1ec7t \u0111\u1ed9 b\u1ec3, nhi\u1ec7t \u0111\u1ed9 tim h\u1ea7u nh\u01b0 kh\u00f4ng thay \u0111\u1ed5i. L\u00e0m l\u1ea1nh nhanh g\u00e2y ra \u1ee9ng su\u1ea5t k\u00e9o cao l\u00e0m co l\u1edbp b\u1ec1 m\u1eb7t v\u00e0 \u0111\u01b0\u1ee3c c\u00e2n b\u1eb1ng b\u1edfi \u1ee9ng su\u1ea5t tim. S\u1ef1 gia t\u0103ng c\u1ee7a gradient nhi\u1ec7t \u0111\u1ed9 l\u00e0m t\u0103ng \u1ee9ng su\u1ea5t k\u00e9o do qu\u00e1 tr\u00ecnh bi\u1ebfn \u0111\u1ed5i mactenxit ban \u0111\u1ea7u g\u00e2y ra, trong khi s\u1ef1 gia t\u0103ng nhi\u1ec7t \u0111\u1ed9 b\u1eaft \u0111\u1ea7u bi\u1ebfn \u0111\u1ed5i mactenxit Ms s\u1ebd l\u00e0m cho l\u1edbp b\u1ec1 m\u1eb7t gi\u00e3n n\u1edf do t\u00ednh d\u1ebbo chuy\u1ec3n pha, \u1ee9ng su\u1ea5t k\u00e9o b\u1ec1 m\u1eb7t s\u1ebd gi\u1ea3m v\u00e0 bi\u1ebfn \u0111\u1ed5i \u0111\u00e1ng k\u1ec3 th\u00e0nh \u1ee9ng su\u1ea5t n\u00e9n, \u1ee8ng su\u1ea5t n\u00e9n b\u1ec1 m\u1eb7t t\u1ef7 l\u1ec7 v\u1edbi l\u01b0\u1ee3ng mactenxit b\u1ec1 m\u1eb7t sinh ra. \u1ee8ng su\u1ea5t n\u00e9n b\u1ec1 m\u1eb7t n\u00e0y x\u00e1c \u0111\u1ecbnh li\u1ec7u tim c\u00f3 tr\u1ea3i qua qu\u00e1 tr\u00ecnh bi\u1ebfn \u0111\u1ed5i martensitic trong \u0111i\u1ec1u ki\u1ec7n n\u00e9n hay khi l\u00e0m m\u00e1t th\u00eam, s\u1ebd \u0111\u1ea3o ng\u01b0\u1ee3c \u1ee9ng su\u1ea5t k\u00e9o b\u1ec1 m\u1eb7t. N\u1ebfu s\u1ef1 bi\u1ebfn \u0111\u1ed5i mactenxit c\u1ee7a s\u1ef1 gi\u00e3n n\u1edf th\u1ec3 t\u00edch tim \u0111\u1ee7 l\u1edbn, v\u00e0 mactenxit b\u1ec1 m\u1eb7t r\u1ea5t c\u1ee9ng v\u00e0 gi\u00f2n, n\u00f3 s\u1ebd l\u00e0m cho l\u1edbp b\u1ec1 m\u1eb7t b\u1ecb v\u1ee1 do \u1ee9ng su\u1ea5t \u0111\u1ea3o chi\u1ec1u. \u0110\u1ec3 \u0111\u1ea1t \u0111\u01b0\u1ee3c \u0111i\u1ec1u n\u00e0y, b\u1ec1 m\u1eb7t th\u00e9p ph\u1ea3i xu\u1ea5t hi\u1ec7n \u1ee9ng su\u1ea5t n\u00e9n v\u00e0 qu\u00e1 tr\u00ecnh bi\u1ebfn \u0111\u1ed5i martensitic \u1edf tim ph\u1ea3i x\u1ea3y ra c\u00e0ng mu\u1ed9n c\u00e0ng t\u1ed1t. Th\u1eed nghi\u1ec7m t\u00f4i luy\u1ec7n m\u1ea1nh v\u00e0 hi\u1ec7u su\u1ea5t t\u00f4i luy\u1ec7n th\u00e9p: Ph\u01b0\u01a1ng ph\u00e1p t\u00f4i luy\u1ec7n m\u1ea1nh c\u00f3 \u01b0u \u0111i\u1ec3m l\u00e0 h\u00ecnh th\u00e0nh \u1ee9ng su\u1ea5t n\u00e9n tr\u00ean b\u1ec1 m\u1eb7t, gi\u1ea3m nguy c\u01a1 n\u1ee9t v\u00e0 c\u1ea3i thi\u1ec7n \u0111\u1ed9 c\u1ee9ng v\u00e0 s\u1ee9c m\u1ea1nh. S\u1ef1 h\u00ecnh th\u00e0nh b\u1ec1 m\u1eb7t c\u1ee7a martensite 100%, th\u00e9p s\u1ebd c\u00f3 l\u1edbp c\u1ee9ng l\u1edbn nh\u1ea5t, n\u00f3 c\u00f3 th\u1ec3 thay th\u1ebf th\u00e9p cacbon \u0111\u1eaft ti\u1ec1n h\u01a1n, t\u00f4i m\u1ea1nh c\u0169ng c\u00f3 th\u1ec3 th\u00fac \u0111\u1ea9y c\u00e1c t\u00ednh ch\u1ea5t c\u01a1 h\u1ecdc \u0111\u1ed3ng nh\u1ea5t c\u1ee7a th\u00e9p v\u00e0 t\u1ea1o ra \u0111\u1ed9 bi\u1ebfn d\u1ea1ng nh\u1ecf nh\u1ea5t c\u1ee7a ph\u00f4i. C\u00e1c b\u1ed9 ph\u1eadn sau khi l\u00e0m ngu\u1ed9i, tu\u1ed5i th\u1ecd c\u1ee7a d\u1ecbch v\u1ee5 d\u01b0\u1edbi t\u1ea3i tr\u1ecdng xen k\u1ebd c\u00f3 th\u1ec3 t\u0103ng l\u00ean theo m\u1ed9t m\u1ee9c \u0111\u1ed9 l\u1edbn. [1]H\u00ecnh 2 x\u00e1c su\u1ea5t h\u00ecnh th\u00e0nh v\u1ebft n\u1ee9t d\u1eadp t\u1eaft m\u1ea1nh v\u00e0 m\u1ed1i quan h\u1ec7 t\u1ed1c \u0111\u1ed9 l\u00e0m m\u00e1t3 ph\u01b0\u01a1ng ph\u00e1p l\u00e0m m\u00e1t h\u1ed7n h\u1ee3p n\u01b0\u1edbc-kh\u00f4ng kh\u00edB\u1eb1ng c\u00e1ch \u0111i\u1ec1u ch\u1ec9nh \u00e1p su\u1ea5t c\u1ee7a n\u01b0\u1edbc v\u00e0 kh\u00f4ng kh\u00ed v\u00e0 kho\u1ea3ng c\u00e1ch gi\u1eefa v\u00f2i phun nguy\u00ean t\u1eed v\u00e0 b\u1ec1 m\u1eb7t ph\u00f4i, kh\u1ea3 n\u0103ng l\u00e0m m\u00e1t c\u1ee7a h\u1ed7n h\u1ee3p n\u01b0\u1edbc-kh\u00f4ng kh\u00ed c\u00f3 th\u1ec3 thay \u0111\u1ed5i v\u00e0 l\u00e0m m\u00e1t c\u00f3 th\u1ec3 \u0111\u1ed3ng \u0111\u1ec1u. Th\u1ef1c ti\u1ec5n s\u1ea3n xu\u1ea5t cho th\u1ea5y r\u1eb1ng vi\u1ec7c s\u1eed d\u1ee5ng quy lu\u1eadt v\u1ec1 h\u00ecnh d\u1ea1ng c\u1ee7a c\u00e1c b\u1ed9 ph\u1eadn l\u00e0m c\u1ee9ng b\u1ec1 m\u1eb7t b\u1eb1ng th\u00e9p carbon ho\u1eb7c th\u00e9p h\u1ee3p kim ph\u1ee9c t\u1ea1p, c\u00f3 th\u1ec3 ng\u0103n ch\u1eb7n hi\u1ec7u qu\u1ea3 vi\u1ec7c t\u1ea1o ra c\u00e1c v\u1ebft n\u1ee9t l\u00e0m ngu\u1ed9i. , c\u00f3 th\u1ec3 c\u00f3 t\u00e1c d\u1ee5ng l\u00e0m c\u1ee9ng t\u1ed1t h\u01a1n, \u0111\u1ec3 l\u00e0m ngu\u1ed9i ho\u1eb7c b\u00ecnh th\u01b0\u1eddng h\u00f3a th\u00e9p. Hi\u1ec7n t\u1ea1i, c\u00f4ng ngh\u1ec7 n\u00e0y \u0111\u00e3 \u0111\u01b0\u1ee3c \u00e1p d\u1ee5ng th\u00e0nh c\u00f4ng \u0111\u1ec3 t\u00f4i gang d\u1ebbo. L\u1ea5y h\u1ee3p kim nh\u00f4m l\u00e0m v\u00ed d\u1ee5: Theo c\u00e1c th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt x\u1eed l\u00fd nhi\u1ec7t hi\u1ec7n t\u1ea1i \u0111\u1ed1i v\u1edbi r\u00e8n v\u00e0 r\u00e8n h\u1ee3p kim nh\u00f4m, nhi\u1ec7t \u0111\u1ed9 n\u01b0\u1edbc t\u00f4i th\u01b0\u1eddng \u0111\u01b0\u1ee3c ki\u1ec3m so\u00e1t d\u01b0\u1edbi 60 \u00b0 C, nhi\u1ec7t \u0111\u1ed9 n\u01b0\u1edbc t\u00f4i th\u1ea5p, t\u1ed1c \u0111\u1ed9 l\u00e0m m\u00e1t cao v\u00e0 d\u01b0 l\u01b0\u1ee3ng l\u1edbn c\u0103ng th\u1eb3ng sau khi d\u1eadp t\u1eaft x\u1ea3y ra. Trong qu\u00e1 tr\u00ecnh gia c\u00f4ng cu\u1ed1i c\u00f9ng, \u1ee9ng su\u1ea5t b\u00ean trong m\u1ea5t c\u00e2n b\u1eb1ng do h\u00ecnh d\u1ea1ng v\u00e0 k\u00edch th\u01b0\u1edbc b\u1ec1 m\u1eb7t kh\u00f4ng \u0111\u1ed3ng nh\u1ea5t, d\u1eabn \u0111\u1ebfn gi\u1ea3i ph\u00f3ng \u1ee9ng su\u1ea5t d\u01b0, d\u1eabn \u0111\u1ebfn c\u00e1c ph\u1ea7n b\u1ecb bi\u1ebfn d\u1ea1ng, u\u1ed1n cong, h\u00ecnh b\u1ea7u d\u1ee5c v\u00e0 c\u00e1c ph\u1ea7n bi\u1ebfn d\u1ea1ng kh\u00e1c c\u1ee7a b\u1ed9 ph\u1eadn gia c\u00f4ng tr\u1edf th\u00e0nh ch\u1ea5t th\u1ea3i cu\u1ed1i c\u00f9ng kh\u00f4ng th\u1ec3 ph\u1ee5c h\u1ed3i v\u1edbi t\u1ed5n th\u1ea5t nghi\u00eam tr\u1ecdng. V\u00ed d\u1ee5: c\u00e1nh qu\u1ea1t, c\u00e1nh m\u00e1y n\u00e9n v\u00e0 c\u00e1c bi\u1ebfn d\u1ea1ng r\u00e8n h\u1ee3p kim nh\u00f4m kh\u00e1c sau khi gia c\u00f4ng r\u00f5 r\u00e0ng, d\u1eabn \u0111\u1ebfn dung sai k\u00edch th\u01b0\u1edbc c\u00e1c b\u1ed9 ph\u1eadn. Nhi\u1ec7t \u0111\u1ed9 n\u01b0\u1edbc t\u00f4i t\u0103ng t\u1eeb nhi\u1ec7t \u0111\u1ed9 ph\u00f2ng (30-40 \u2103) l\u00ean nhi\u1ec7t \u0111\u1ed9 n\u01b0\u1edbc s\u00f4i (90-100 \u2103), \u1ee9ng su\u1ea5t d\u01b0 r\u00e8n trung b\u00ecnh gi\u1ea3m kho\u1ea3ng 50%. [2]H\u00ecnh 4 S\u01a1 \u0111\u1ed3 l\u00e0m ngu\u1ed9i b\u1eb1ng n\u01b0\u1edbc s\u00f4i5 Ph\u01b0\u01a1ng ph\u00e1p l\u00e0m ngu\u1ed9i b\u1eb1ng d\u1ea7u n\u00f3ng Vi\u1ec7c s\u1eed d\u1ee5ng d\u1ea7u l\u00e0m ngu\u1ed9i n\u00f3ng \u0111\u1ec3 ph\u00f4i tr\u01b0\u1edbc khi l\u00e0m ngu\u1ed9i th\u00eam \u1edf nhi\u1ec7t \u0111\u1ed9 b\u1eb1ng ho\u1eb7c g\u1ea7n v\u1edbi nhi\u1ec7t \u0111\u1ed9 c\u1ee7a \u0111i\u1ec3m Ms \u0111\u1ec3 gi\u1ea3m thi\u1ec3u ch\u00eanh l\u1ec7ch nhi\u1ec7t \u0111\u1ed9, c\u00f3 th\u1ec3 ng\u0103n ch\u1eb7n qu\u00e1 tr\u00ecnh l\u00e0m ngu\u1ed9i m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3 s\u1ef1 bi\u1ebfn d\u1ea1ng ph\u00f4i v\u00e0 n\u1ee9t. K\u00edch th\u01b0\u1edbc nh\u1ecf c\u1ee7a th\u00e9p c\u00f4ng c\u1ee5 h\u1ee3p kim ch\u1ebft ngu\u1ed9i 160 ~ 200 \u2103 trong qu\u00e1 tr\u00ecnh l\u00e0m ngu\u1ed9i d\u1ea7u n\u00f3ng, c\u00f3 th\u1ec3 l\u00e0m gi\u1ea3m bi\u1ebfn d\u1ea1ng v\u00e0 tr\u00e1nh n\u1ee9t m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3. austenite \u0111\u01b0\u1ee3c gi\u1eef l\u1ea1i ti\u1ebfp t\u1ee5c \u0111\u01b0\u1ee3c chuy\u1ec3n th\u00e0nh martensite, m\u1ee5c \u0111\u00edch l\u00e0 c\u1ea3i thi\u1ec7n \u0111\u1ed9 c\u1ee9ng v\u00e0 kh\u1ea3 n\u0103ng ch\u1ed1ng m\u00e0i m\u00f2n c\u1ee7a th\u00e9p, c\u1ea3i thi\u1ec7n \u0111\u1ed9 \u1ed5n \u0111\u1ecbnh c\u1ea5u tr\u00fac v\u00e0 \u0111\u1ed9 \u1ed5n \u0111\u1ecbnh k\u00edch th\u01b0\u1edbc c\u1ee7a ph\u00f4i, \u0111\u1ed3ng th\u1eddi c\u1ea3i thi\u1ec7n hi\u1ec7u qu\u1ea3 tu\u1ed5i th\u1ecd c\u1ee7a d\u1ee5ng c\u1ee5. X\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh l\u00e0 nit\u01a1 l\u1ecfng nh\u01b0 m\u1ed9t ph\u01b0\u01a1ng ti\u1ec7n l\u00e0m m\u00e1t cho c\u00e1c ph\u01b0\u01a1ng ph\u00e1p x\u1eed l\u00fd v\u1eadt li\u1ec7u. C\u00f4ng ngh\u1ec7 x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh l\u1ea7n \u0111\u1ea7u ti\u00ean \u0111\u01b0\u1ee3c \u00e1p d\u1ee5ng cho c\u00e1c d\u1ee5ng c\u1ee5 m\u00e0i m\u00f2n, v\u1eadt li\u1ec7u d\u1ee5ng c\u1ee5 khu\u00f4n, sau \u0111\u00f3 \u0111\u01b0\u1ee3c m\u1edf r\u1ed9ng sang th\u00e9p h\u1ee3p kim, cacbua, v.v., s\u1eed d\u1ee5ng ph\u01b0\u01a1ng ph\u00e1p n\u00e0y c\u00f3 th\u1ec3 thay \u0111\u1ed5i c\u1ea5u tr\u00fac b\u00ean trong c\u1ee7a v\u1eadt li\u1ec7u kim lo\u1ea1i, t\u1eeb \u0111\u00f3 c\u1ea3i thi\u1ec7n t\u00ednh ch\u1ea5t c\u01a1 h\u1ecdc v\u00e0 t\u00ednh ch\u1ea5t gia c\u00f4ng, \u0111\u00f3 l\u00e0 hi\u1ec7n t\u1ea1i M\u1ed9t trong nh\u1eefng quy tr\u00ecnh c\u01b0\u1eddng l\u1ef1c m\u1edbi nh\u1ea5t. X\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh (X\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh), c\u00f2n \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 x\u1eed l\u00fd nhi\u1ec7t \u0111\u1ed9 c\u1ef1c th\u1ea5p, th\u01b0\u1eddng \u0111\u1ec1 c\u1eadp \u0111\u1ebfn v\u1eadt li\u1ec7u d\u01b0\u1edbi -130 \u2103 \u0111\u1ec3 x\u1eed l\u00fd nh\u1eb1m c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t t\u1ed5ng th\u1ec3 c\u1ee7a v\u1eadt li\u1ec7u. Ngay t\u1eeb 100 n\u0103m tr\u01b0\u1edbc, ng\u01b0\u1eddi ta \u0111\u00e3 b\u1eaft \u0111\u1ea7u x\u1eed l\u00fd l\u1ea1nh \u00e1p d\u1ee5ng cho c\u00e1c b\u1ed9 ph\u1eadn c\u1ee7a \u0111\u1ed3ng h\u1ed3, gi\u00fap c\u1ea3i thi\u1ec7n \u0111\u1ed9 b\u1ec1n, kh\u1ea3 n\u0103ng ch\u1ed1ng m\u00e0i m\u00f2n, \u1ed5n \u0111\u1ecbnh k\u00edch th\u01b0\u1edbc v\u00e0 tu\u1ed5i th\u1ecd. X\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh l\u00e0 m\u1ed9t c\u00f4ng ngh\u1ec7 m\u1edbi \u0111\u01b0\u1ee3c ph\u00e1t tri\u1ec3n tr\u00ean c\u01a1 s\u1edf x\u1eed l\u00fd l\u1ea1nh th\u00f4ng th\u01b0\u1eddng v\u00e0o nh\u1eefng n\u0103m 1960. So v\u1edbi x\u1eed l\u00fd l\u1ea1nh th\u00f4ng th\u01b0\u1eddng, x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh c\u00f3 th\u1ec3 c\u1ea3i thi\u1ec7n h\u01a1n n\u1eefa c\u00e1c t\u00ednh ch\u1ea5t c\u01a1 h\u1ecdc v\u00e0 \u0111\u1ed9 \u1ed5n \u0111\u1ecbnh c\u1ee7a v\u1eadt li\u1ec7u, \u0111\u1ed3ng th\u1eddi c\u00f3 tri\u1ec3n v\u1ecdng \u1ee9ng d\u1ee5ng r\u1ed9ng h\u01a1n. C\u01a1 ch\u1ebf x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh: Sau khi x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh, austenite c\u00f2n l\u1ea1i trong c\u1ea5u tr\u00fac b\u00ean trong c\u1ee7a v\u1eadt li\u1ec7u kim lo\u1ea1i (ch\u1ee7 y\u1ebfu l\u00e0 khu\u00f4n v\u1eadt li\u1ec7u) \u0111\u01b0\u1ee3c chuy\u1ec3n th\u00e0nh martensite, v\u00e0 cacbua k\u1ebft t\u1ee7a c\u0169ng \u0111\u01b0\u1ee3c k\u1ebft t\u1ee7a trong martensite, do \u0111\u00f3 c\u00f3 th\u1ec3 lo\u1ea1i b\u1ecf martensite trong \u1ee9ng su\u1ea5t d\u01b0, nh\u01b0ng c\u0169ng t\u0103ng c\u01b0\u1eddng ma tr\u1eadn martensite, do \u0111\u00f3 \u0111\u1ed9 c\u1ee9ng v\u00e0 kh\u1ea3 n\u0103ng ch\u1ed1ng m\u00e0i m\u00f2n c\u1ee7a n\u00f3 c\u0169ng s\u1ebd t\u0103ng l\u00ean. S\u1edf d\u0129 \u0111\u1ed9 c\u1ee9ng t\u0103ng l\u00ean l\u00e0 do s\u1ef1 bi\u1ebfn \u0111\u1ed5i m\u1ed9t ph\u1ea7n austenit gi\u1eef l\u1ea1i th\u00e0nh mactenxit. S\u1ef1 gia t\u0103ng \u0111\u1ed9 d\u1ebbo dai l\u00e0 do s\u1ef1 ph\u00e2n t\u00e1n v\u00e0 k\u1ebft t\u1ee7a \u03b7-Fe3C nh\u1ecf. \u0110\u1ed3ng th\u1eddi, h\u00e0m l\u01b0\u1ee3ng carbon c\u1ee7a martensite gi\u1ea3m v\u00e0 \u0111\u1ed9 bi\u1ebfn d\u1ea1ng m\u1ea1ng gi\u1ea3m, C\u1ea3i thi\u1ec7n \u0111\u1ed9 d\u1ebbo. Thi\u1ebft b\u1ecb x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh ch\u1ee7 y\u1ebfu bao g\u1ed3m b\u1ec3 ch\u1ee9a nit\u01a1 l\u1ecfng, h\u1ec7 th\u1ed1ng truy\u1ec1n nit\u01a1 l\u1ecfng, h\u1ed9p l\u1ea1nh s\u00e2u v\u00e0 h\u1ec7 th\u1ed1ng \u0111i\u1ec1u khi\u1ec3n. Trong \u1ee9ng d\u1ee5ng, x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh \u0111\u01b0\u1ee3c l\u1eb7p l\u1ea1i nhi\u1ec1u l\u1ea7n. C\u00e1c quy tr\u00ecnh \u0111i\u1ec3n h\u00ecnh nh\u01b0: t\u00f4i d\u1ea7u 1120 \u2103 + -196 \u2103 \u00d7 1h (2-4) x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh s\u00e2u + \u1ee7 200 \u2103 \u00d7 2h. Sau khi x\u1eed l\u00fd t\u1ed5 ch\u1ee9c, \u0111\u00e3 c\u00f3 s\u1ef1 bi\u1ebfn \u0111\u1ed5i c\u1ee7a austenite, nh\u01b0ng c\u0169ng \u0111\u01b0\u1ee3c k\u1ebft t\u1ee7a t\u1eeb s\u1ef1 ph\u00e2n t\u00e1n martensite \u0111\u00e3 \u0111\u01b0\u1ee3c l\u00e0m ngu\u1ed9i c\u00f3 m\u1ed1i quan h\u1ec7 ch\u1eb7t ch\u1ebd cao v\u1edbi ma tr\u1eadn cacbua si\u00eau m\u1ecbn, sau khi \u1ee7 \u1edf nhi\u1ec7t \u0111\u1ed9 th\u1ea5p ti\u1ebfp theo \u1edf 200 \u2103, s\u1ef1 ph\u00e1t tri\u1ec3n c\u1ee7a cacbua si\u00eau m\u1ecbn Ph\u00e2n t\u00e1n \u03b5 cacbua , s\u1ed1 l\u01b0\u1ee3ng v\u00e0 \u0111\u1ed9 ph\u00e2n t\u00e1n t\u0103ng l\u00ean \u0111\u00e1ng k\u1ec3. Vi\u1ec7c x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh \u0111\u01b0\u1ee3c l\u1eb7p \u0111i l\u1eb7p l\u1ea1i m\u1ed9t s\u1ed1 l\u1ea7n. M\u1ed9t m\u1eb7t, c\u00e1c cacbua si\u00eau m\u1ecbn \u0111\u01b0\u1ee3c k\u1ebft t\u1ee7a t\u1eeb martensite \u0111\u01b0\u1ee3c bi\u1ebfn \u0111\u1ed5i t\u1eeb austenite \u0111\u01b0\u1ee3c gi\u1eef l\u1ea1i t\u1ea1i th\u1eddi \u0111i\u1ec3m l\u00e0m l\u1ea1nh b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p \u0111\u00f4ng l\u1ea1nh tr\u01b0\u1edbc \u0111\u00f3. M\u1eb7t kh\u00e1c, c\u00e1c cacbua m\u1ecbn ti\u1ebfp t\u1ee5c \u0111\u01b0\u1ee3c k\u1ebft t\u1ee7a trong mactenxit \u0111\u00e3 t\u00f4i. Qu\u00e1 tr\u00ecnh l\u1eb7p \u0111i l\u1eb7p l\u1ea1i c\u00f3 th\u1ec3 l\u00e0m t\u0103ng c\u01b0\u1eddng \u0111\u1ed9 n\u00e9n ma tr\u1eadn, c\u01b0\u1eddng \u0111\u1ed9 n\u0103ng su\u1ea5t v\u00e0 \u0111\u1ed9 b\u1ec1n va \u0111\u1eadp, c\u1ea3i thi\u1ec7n \u0111\u1ed9 d\u1ebbo dai c\u1ee7a th\u00e9p, \u0111\u1ed3ng th\u1eddi l\u00e0m cho kh\u1ea3 n\u0103ng ch\u1ed1ng m\u00e0i m\u00f2n do va \u0111\u1eadp \u0111\u01b0\u1ee3c c\u1ea3i thi\u1ec7n \u0111\u00e1ng k\u1ec3. x\u1eed l\u00fd do \u1ee9ng su\u1ea5t nhi\u1ec7t g\u00e2y ra b\u1edfi bi\u1ebfn d\u1ea1ng qu\u00e1 m\u1ee9c, t\u1ed1c \u0111\u1ed9 l\u00e0m m\u00e1t ph\u1ea3i \u0111\u01b0\u1ee3c ki\u1ec3m so\u00e1t trong qu\u00e1 tr\u00ecnh x\u1eed l\u00fd b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p \u0111\u00f4ng l\u1ea1nh. Ngo\u00e0i ra, \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o t\u00ednh \u0111\u1ed3ng nh\u1ea5t c\u1ee7a tr\u01b0\u1eddng nhi\u1ec7t \u0111\u1ed9 b\u00ean trong thi\u1ebft b\u1ecb v\u00e0 gi\u1ea3m dao \u0111\u1ed9ng nhi\u1ec7t \u0111\u1ed9, thi\u1ebft k\u1ebf c\u1ee7a h\u1ec7 th\u1ed1ng x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh c\u1ea7n t\u00ednh \u0111\u1ebfn \u0111\u1ed9 ch\u00ednh x\u00e1c ki\u1ec3m so\u00e1t nhi\u1ec7t \u0111\u1ed9 c\u1ee7a h\u1ec7 th\u1ed1ng v\u00e0 t\u00ednh h\u1ee3p l\u00fd c\u1ee7a vi\u1ec7c b\u1ed1 tr\u00ed tr\u01b0\u1eddng d\u00f2ng ch\u1ea3y. Trong thi\u1ebft k\u1ebf h\u1ec7 th\u1ed1ng c\u0169ng n\u00ean ch\u00fa \u00fd \u0111\u00e1p \u1ee9ng ti\u00eau th\u1ee5 \u00edt n\u0103ng l\u01b0\u1ee3ng, hi\u1ec7u qu\u1ea3 cao, v\u1eadn h\u00e0nh d\u1ec5 d\u00e0ng v\u00e0 c\u00e1c y\u00eau c\u1ea7u kh\u00e1c. \u0110\u00e2y l\u00e0 xu h\u01b0\u1edbng ph\u00e1t tri\u1ec3n hi\u1ec7n nay c\u1ee7a h\u1ec7 th\u1ed1ng x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh. Ngo\u00e0i ra, m\u1ed9t s\u1ed1 h\u1ec7 th\u1ed1ng l\u00e0m l\u1ea1nh \u0111ang ph\u00e1t tri\u1ec3n c\u00f3 nhi\u1ec7t \u0111\u1ed9 l\u00e0m l\u1ea1nh k\u00e9o d\u00e0i t\u1eeb nhi\u1ec7t \u0111\u1ed9 ph\u00f2ng \u0111\u1ebfn nhi\u1ec7t \u0111\u1ed9 th\u1ea5p c\u0169ng \u0111\u01b0\u1ee3c d\u1ef1 ki\u1ebfn s\u1ebd ph\u00e1t tri\u1ec3n th\u00e0nh h\u1ec7 th\u1ed1ng x\u1eed l\u00fd \u0111\u00f4ng l\u1ea1nh kh\u00f4ng ch\u1ee9a ch\u1ea5t l\u1ecfng v\u1edbi vi\u1ec7c gi\u1ea3m nhi\u1ec7t \u0111\u1ed9 t\u1ed1i thi\u1ec3u v\u00e0 c\u1ea3i thi\u1ec7n hi\u1ec7u qu\u1ea3 l\u00e0m l\u1ea1nh. [3]T\u00e0i li\u1ec7u tham kh\u1ea3o:[1]\u6a0a\u4e1c\u9ece.\u5f3a\u70c8\u6dec\u706b\u2014\u2014\u4e00\u79cd\u65b0\u7684\u5f3a\u5316\u94a2\u7684\u70ed\u5904\u7406\u65b9\u6cd5[J].\u70ed\u5904\u7406, 2005, 20(4): 1-3[2]\u5b8b\u5fae, \u90dd\u51ac\u6885, \u738b\u6210\u6c5f.\u6cb8\u6c34\u6dec\u706b\u5bf9\u94dd\u5408\u91d1\u953b\u4ef6\u7ec4\u7ec7\u4e0e\u673a\u68b0\u6027\u80fd\u7684\u5f71\u54cd[J].\u94dd\u52a0\u5de5, 2002, 25(2): 1-3[3]\u590f\u96e8\u4eae, \u91d1\u6ed4, \u6c64\u73c2.\u6df1\u51b7\u5904\u7406\u5de5\u827a\u53ca\u8bbe\u5907\u7684\u53d1\u5c55\u73b0\u72b6\u548c\u5c55\u671b[J].\u4f4e\u6e29\u4e0e\u7279\u6c14, 2007, 25(1): 1-3
\nNgu\u1ed3n: Meeyou cacbua<\/p>\n

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