321 vs 347 Austenitic Stainless Steels: Titanium vs Niobium-Stabilized High-Tsuas Qib

 

Dab tsi yog lawv cov ntsiab lus tseem ceeb thiab qhov sib txawv ntawm kev ua haujlwm tseem ceeb?

321 muaj 17-19% Cr, 9-12% Ni, 0.4-0.8% Ti, nrog titanium binding carbon los tsim cov carbides ruaj khov. Nws tuav cov txheej txheem kev ncaj ncees txog li 800 degree, zoo tagnrho rau cov khoom siv hluav taws xob ua haujlwm.347 nta 17–19% Cr, 9–13% Ni, 0.7–1.0% Nb (ntxiv rau Ta), nrog niobium carbides uas tiv taus coarsening ntawm qhov kub txog li 900℃7}, ua rau nws muaj peev xwm tshem tawm qhov kub siab tshaj 1. tom qab-weld kev kho cua sov, qhov tseem ceeb tshaj li tus qauv 304 rau welded siab-kub los ua ke.

Yuav ua li cas lawv stabilization mechanisms ua nyob rau hauv huab cua kub ib puag ncig?

At >800 degree, 321's titanium carbides pib coarsen, txo cov qoob loo ciam teb lub zog thiab nkag mus rau lub sijhawm ntev. extends tivthaiv lifespan los ntawm 2-3 zaug piv rau 321.

Nyob rau hauv daim ntawv thov twg yog ib qib irreplaceable dua lwm?

Xaiv 321 rau nruab nrab siab-cov cua kub welded qhov chaw: boiler raj, automotive tso headers, thiab thermal processing fixtures khiav qis dua 800℃.Opt rau 347 rau ultra-siab-kub los yog nuclear- qib kev siv: dav hlau cav combustion chambers, satellites thiab structuring.

Tus nqi thiab kev tsim khoom lag luam yog dab tsi- tawm ntawm ob qib?

321 yog 10-15% pheej yig dua li 347 (titanium muaj ntau dua li niobium), ua rau nws txoj kev xaiv pheej yig rau tsis yog- siab heev- tshav kub siv.347 yuav tsum nruj dua vuam kub tswj kom tsis txhob niobium carbide agglomeration; 321 yog kev zam txim ntau dua rau kev fabrication.Ob lub vuam zoo nrog cov khoom sib txuam (321/347), tab sis 347 lub zog siab dua xav tau cov welds tuab dua rau kev thauj khoom -cov kabmob.

Cov kev txwv tseem ceeb thiab cov txheej txheem xaiv yog dab tsi?

321 is unsuitable for service above 800°C-its carbides will degrade, leading to creep deformation.347 is over-specified for low-temperature applications; use 321 or 304H to save cost.Prioritize 321 for moderate high-heat welded assemblies; select 347 for >800℃los yog nuclear -cov khoom tseem ceeb.