Rau Titanium Sheath rhaub siv los tuav 140℃hauv 50% Sodium Hydroxide Solution Nyob rau hauv 2 Bar Siab, Dab Tsi Yog Qhov Siab Tshaj Tawm Tensile Stress (MPa) hauv Tube Phab Ntsa los tiv thaiv Caustic Cracking rau 5 Xyoo?
Tso lus
Caustic cracking (kev nyuaj siab corrosion cracking) ntawm qib 2 titanium yog tshwm sim los ntawm 50% sodium hydroxide ntawm 140℃nyob rau hauv 2 bar siab. 5 xyoo max tso cai tensile kev nyuaj siab los tiv thaiv cracking yog 50 MPa. Qhov no yog raws li qhov pib ntawm kev siv zog ntawm caustic cracking. Lub hoop kev ntxhov siab tshwm sim los ntawm lub siab sab hauv yog σ=P × D / 2 t. Rau lub 25 hli OD raj nrog 1.5 hli phab ntsa lub hoop stress yog 1.7 MPa ntawm 2 bar deb tshaj qhov txwv. Tab sis residual loads los ntawm dabtsi yog khoov los yog vuam yuav ua tau ntau dua.
Mechanism ntawm Caustic Cracking hauv Ti
Titanium reacts nrog kub concentrated NaOH los tsim ib txheej ntawm sodium titanate. Cracks pib ntawm qhov tsis xws luag hauv txheej no nyob rau hauv tensile nro. Qhov tawg loj hlob intergranularly. Qhov chaw pib kev nyuaj siab rau pob txha txo qis nrog nce qhov kub thiab txias.
Quantitative threshold stress thiab nws qhov kub thiab txias dependence
Kub (degree) NaOH Conc. (%) Kev ntxhov siab rau 5-xyoo lub neej (MPa) 120 50 100 130 50 75 140 50 50 150 50 30
Phau ntawv ntawm Kev Tswj Kev Nyuaj Siab
Tau qhov twg los ntawm Stress Normal Stress (MPa) Txais tau? Kev txo qis
Sab hauv siab (2 bar, 25x1.5 mm) 1.7 Yog Tsis yog
Residual los ntawm dabtsi yog khoov (5D vojvoog) 80-120 Tsis muaj kev ntxhov siab
Vuam residual (raws li -welded) 150-250No ci thiab kev ntxhov siab
Thermal expansion stress 20-50 BorderlineFlexible Installation
Sau ntawv zoo- qhia txog Specification
Rau titanium rhaub hauv 50% NaOH ntawm 140 degree: Kev ntxhov siab txo tag nrho cov welds thiab khoov ntawm 540℃rau 30 feeb. Kev ntxhov siab hauv qab 50 MPa. Tus kws tshaj lij tswj cov kev ntxhov siab seem kom tiv thaiv kev tawg ntawm caustic.
