Dab tsi yog Qhov Quantitative Thermal Stress (MPa) Tsim nyob rau hauv 2.5 mm Thick Titanium Heater Phab Ntsa Thaum Lub Caij Nyoog ntawm 95℃txog 20℃Dej?

Tus txheej txheem engineers txhawj xeeb txog kev puas tsuaj rau thermal poob siab rau tuab -walled titanium rhaub (2.5 hli) tom qab quenching los ntawm 95℃mus rau 20℃dej tuaj yeem txiav txim siab qhov ntau ntawm thermal stress tsim nyob rau hauv phab ntsa los ntawm thermal stress equation rau ib tug ceev ceev txias raj. Qhov siab tshaj plaws thermal stress (σ th ) tshwm sim nyob rau sab hauv (xav tias ceev txias los ntawm sab nraud) thiab muab los ntawm: σ th=E × × T Δ 1 − vf ( ) Qhov twg E yog elastic modulus (110 GPa), yog coefficient ntawm thermal expansion (8.6 × {{9} ν) / degree), T (7 Δ yog qhov sib piv ntawm qhov kub thiab txias) (0.34) thiab f() yog ib qho geometry yam nyob ntawm tus lej Biot (txias tus nqi). Rau lub tuab-walled raj (t=2.5 mm, OD=25} mm) quenched hauv dej (h=1,000-5,000 W/m²K, Biot tooj> 10) f( ) ≈ 1.0 (ua tiav thermal shock). Lub laij lej thermal stress yog σ_th=(110 × 10 9 × 8.6 × 10 6 × 75) / (1 − 0.34)=(110e9 × 6.45e-4) / 0.66=(71 × 10 6}) / 0.66=(71 × 10 6}) / Qhov kev ntxhov siab no nyob ib puag ncig 39 feem pua ​​​​ntawm cov khoom muaj zog (275 MPa) thiab 54 feem pua ​​​​ntawm qhov siab tshaj plaws tensile zog (345 MPa). Thermal qaug zog tawg tuaj yeem tshwm sim los ntawm kev rov ua dua thermal shocks (100-1,000 cycles) ntawm kev ntxhov siab hauv qab lub zog tawm los.

Mechanism ntawm kev tsim cov thermal Stresses thaum quenching
Yog tias lub raj kub kub ntawm titanium plunged rau hauv dej txias, sab nraud qhov chaw txias thiab compresses sai heev. Sab hauv nto, tseem kub, tawm tsam qhov kev cog lus no, muab sab nraud ntawm qhov nro thiab sab hauv qhov chaw hauv compression (rau lub raj cua txias los ntawm sab nraud). Rau cov kub hloov pauv coefficients (h> 5,000 W / m²K) qhov kub sib txawv ntawm phab ntsa tuab tuaj yeem yog 30-50℃rau phab ntsa 2.5 hli thaum thawj ob peb feeb ntawm quenching. Qhov kev ntxhov siab thermal muaj feem xyuam rau qhov ntsuas kub tam sim no thoob plaws phab ntsa, thiab nws yog qhov siab tshaj plaws ntawm 0.3-0.5 $\\times$ $\\Delta T_{tag nrho}$. Qhov ntsuas 108 MPa yog qhov siab tshaj plaws thaum lub sijhawm quench. Yog hais tias lub zog tawm los dhau lawm, cov yas deformation tshwm sim thiab cov residual tensile stresses tam sim no tom qab txias, ua rau muaj kev nyuaj siab corrosion cracking.

Quantification ntawm Thermal Stress raws li ib tug muaj nuj nqi ntawm phab ntsa Thickness thiab quench hnyav
Phab ntsa Thickness t (mm) Quench Medium Heat Transfer Coefficient h (W/m 2 K) Max ΔT Hla Phab Ntsa (degree) Thermal Stress (MPa) % of Yield (275 MPa) Yas Deformation Hazard
1.5 Cov dej tseem (mob) 500 15 22 8% Tsis muaj 1.5 Dej Ntshiab 2,000 30 43 16% Tsis muaj
1.5 Quench ( dej txias) 5, 000 45 65 24% Tsis muaj
2.0 Quench ( dej txias) 5, 000 55 79 29% Tsis muaj 2.5 Quench (dej txias) 5, 000 65 108 39% Tsis muaj (elastic)
3.0 Quench ( dej txias) 5, 000 75 125 45% Tsis muaj (Elastic)
2.5 Dej khov (0℃, ΔT=95℃) 10,000 85 140 51% Kaw rau yield
3.0 Dej khov (0℃) 10000 100 165 60% Yas deformation yog qhov yuav
Ib Scenario-Raws li Phau Ntawv Qhia rau Thermal Shock Management
Kev khiav hauj lwm mob & Quench hom Phab ntsa Thickness (mm) Thermal Stress (MPa) Cracking RiskRecommended Action:
Ib txwm kaw, cua txias (slow) 1.5-3.0 < 10 Tsis muaj teeb meem
Kev kaw ib txwm, dej yaug (sov) 1.5-2.0 20-40 Tsis muaj qhov lees txais
Thaum muaj xwm ceev quench (dej txias, ib - sij hawm) 2.5 108 Tsawg (ib - sij hawm) Txais. Tshaj tawm kev txheeb xyuas.
Emergency Quench (dej dej khov, ib qho xwm txheej) 2.5 140 Nruab nrab (tej zaum yuav tawm hauv zos) Tshem lub rhaub rau kev kuaj Warp check.
2.5 108 Moderate (fatigue) Increase quench temperature (warm water) Repeated thermal cycles (>100) nrog dej quench Txo qhov cua txias.
Nquag (txhua hnub) quenchingAny> 2.0> 100 Siab ( qaug zog tawg) Siv cov cua txias (tswj tus nqi) es tsis txhob quench.
Quench from high temperature (>150 degree) 2.5> 200 SevereNot qhia. Siv qeeb txias lossis lwm yam khoom siv.
Engineering mitigation ntawm quench -induced thermal stress
Thermal quenching yog yam tsis muaj kev zam rau ntawm cov tuab -cov titanium cov cua sov tab sis muaj peb qhov kev txo qis uas pab txo cov kev ntxhov siab thermal. Thawj qhov kev txo qis yog kev siv dej sov (40{19}}50℃vs. 20℃). Txo ΔT los ntawm 75℃mus rau 45℃txo cov thermal stress ntawm 108 MPa mus rau 65 MPa (40% txo), kev ntxhov siab nyob rau hauv qab yield. Qhov thib ob mitigation yog siv cov dej tseem es tsis txhob agitated dej (h{11}} W/m2K es tsis txhob 5,000) kom lub sij hawm quenching. Qhov txo cov cua sov hloov coefficient txo qhov kub ntawm gradient los ntawm phab ntsa, txo qhov siab tshaj plaws ntawm 22 MPa rau 2.5 hli phab ntsa. Qhov thib peb mitigation yog pre-txias ntawm lub rhaub cua sov ua ntej dej quenching. Cua txias ntawm 95℃mus rau 60℃(10 min) ua raws li quenching txo ΔT los ntawm 75℃mus rau 40℃thiab yog li thermal stress.

Conclusion: 2.5 mm Titanium Wall Sees 108 MPa Thermal Stress During 95 C ->20 C Kub
A 2.5 mm tuab Qib 2 titanium rhaub phab ntsa muaj kev ntxhov siab ntau ntawm 108 MPa thaum lub sijhawm quench los ntawm 95℃mus rau 20℃dej nrog lub tshav kub kis coefficient ntawm 5,000 W / m2K (dej agitated). Qhov kev ntxhov siab no yog 39% ntawm cov khoom siv zog (275 MPa) thiab 54% ntawm lub zog tensile siab tshaj plaws (345 MPa). Qhov nro tseem nyob rau hauv qhov elastic ntau yam xws li ib qho quench yuav tsis tsim cov yas deformation lossis tsis ua haujlwm sai. Rov ua dua cov cua sov (100{19}}1,000 lub voj voog) tuaj yeem ua rau cov thermal qaug zog tawg, tshwj xeeb tshaj yog ntawm welds, khawb lossis lwm yam kev ntxhov siab. Cov dej sov quenching (40-50 degree), txias txias hauv cov dej tseem thiab cua txias ua ntej quenching yog pom zoo kom txhim kho lub neej ntawm lub rhaub. Qhov twg nquag quenching yog xav tau, txo cov phab ntsa thickness mus rau 1.5-2.0 hli txo cov thermal stress rau 65-79 MPa, zoo nyob rau hauv qhov kev nyab xeeb elastic ntau yam.