409L / S40903 Stainless Hlau Tube

(1) Cov khoom thiab cov theem ua kua ntawm 409L steel thaum lub sij hawm crystallization tsawg heev, tsawg dua 30 degree;
(2) Yuav luag tsis muaj theem ntawm qhov kub thiab txias. Yog li ntawd, thaum 409L steel pib crystallize tom qab pouring, cov kua theem yog supercooled vim hais tias ncaj qha kev sib cuag nrog cov nto ntawm crystallizer. Nyob rau tib lub sijhawm, qhov saum npoo ntawm crystallizer txhawb nqa cov nucleation uas tsis yog-spontaneous. Yog li ntawd, lub nucleation tus nqi ntawm cov kua theem yog siab heev, tsim Nto zoo equiaxed muaju. Qhov tsim ceev ntawm cov nplua equiaxed grain cheeb tsam ntawm qhov chaw yog ceev heev. Lub sijhawm no, titanium carbide tsis muaj sijhawm los nag vim lub sijhawm luv. Tom qab qhov zoo equiaxed grain cheeb tsam yog tsim, dav hlau cov ntaub ntawv columnar crystals, tab sis 409L steel tsis tshwm columnar muaju. Vim qhov nqaim kub ntau ntawm cov kua-khoom ob-theem cheeb tsam ntawm 409L steel, lub supercooling cheeb tsam ntawm cov muaj pes tsawg leeg thaum lub sij hawm crystallization yog me me, thiab cov columnar crystals tsis yooj yim mus rau pem hauv ntej. Nyob rau tib lub sijhawm, tom qab lub sijhawm dhau los tom qab tsim cov cheeb tsam zoo equiaxed siv lead ua, titanium thiab carbon muaj sij hawm los diffuse los tsim cov titanium carbide hais, txhawb cov uas tsis yog-spontaneous nucleation. Ob qho laj thawj saum toj no ua rau equiaxed crystals yuav tsum tau tsim nyob rau hauv cheeb tsam no es tsis txhob ntawm columnar crystals. Tsis muaj columnar siv lead ua qauv ntawm qhov hla ntu, txhua yam yog equiaxed crystals, tab sis qhov ntau thiab tsawg sib txawv. Thaum lub sij hawm pouring txheej txheem, thaum kub ntawm lub steel billet poob mus rau 1100 degree, yog hais tias cov pa roj carbon ntsiab lus siab, ib feem ntawm Cr thiab C yuav tsim carbides, ua rau ib tug chromium-depleted cheeb tsam tshwm nyob ib ncig ntawm cov carbides, thiab ib tug me me ntawm cov carbides. δ theem yuav tshwm sim. Lub sijhawm no, ob theem nrog cov khoom sib txawv tshwm sim hauv cov hlau, lossis cov ntsiab lus δ theem yog nyob nruab nrab ntawm 32% thiab 60%, uas yog thaj tsam yas ntawm lub billet. Cov ntsiab lus carbon ntawm 409L steel yog tsawg heev, thiab txawm tias delta theem tshwm, tus nqi tsawg heev. Yog li ntawd, yuav tsis muaj kev cuam tshuam loj rau kev ua haujlwm.
409L steel yuav luag tsis muaj → theem hloov los ntawm qhov kub thiab txias mus rau qhov kub tsawg, yog li cov nplej tau yooj yim loj hlob, cov qauv ntxhib ferrite tshwm, thiab lub zog tsawg. Hauv kev nruam nruam, thaum lub slab raug txiav thiab txav mus los, lub luj tshib yog qhov tshwm sim. phenomenon, cuam tshuam rau ib txwm tsim. Qhov teeb meem tseem ceeb thaum crystallizing 409L steel yog qhov txo qis hauv kev ua tau zoo los ntawm cov nplej ntxhib.