Qhov kub thiab txias hloov pauv (DBTT), nil ductility kub (NDT), lossis nil ductility hloov pauv kub ntawm cov hlau yog qhov kub ntawm lub zog tawg dhau los ntawm tus nqi predetermined (rau steels feem ntau 40 J rau tus qauv.Charpy impact test). DBTT yog ib qho tseem ceeb vim hais tias, ib zaug ib qho khoom txias hauv qab DBTT, nws muaj kev nyiam ntau dua rau kev tawg ntawm kev cuam tshuam es tsis txhob khoov lossis deforming. Piv txwv li,zawm 3pom zoo ductility ntawm chav tsev kub tab sis shatters thaum cuam tshuam ntawm sub-zero kub. DBTT yog ib qho tseem ceeb heev rau kev xaiv cov ntaub ntawv uas raug rau cov neeg kho tshuab kev nyuaj siab. Ib qho zoo sib xws phenomenon, lubiav hloov kub, tshwm sim nrog iav thiab polymers, txawm hais tias cov txheej txheem sib txawv ntawm cov khoom siv amorphous.
Hauv qee cov ntaub ntawv kev hloov pauv yog sharper dua lwm tus thiab feem ntau yuav tsum tau ib tug kub-rhiab heev deformation mechanism. Piv txwv li, hauv cov ntaub ntawv nrog alub cev-centered cubic(bcc) lattice lub DBTT yog yooj yim pom, raws li cov lus tsa suab ntawm cov ntsia hlaudislocationsNws yog qhov kub thiab txias heev vim tias qhov hloov pauv ntawm cov tub ntxhais dislocation ua ntej yuav plam yuav tsum tau ua kom thermal. Qhov no tuaj yeem ua teeb meem rau cov hlau uas muaj cov ntsiab lus ferrite siab. Qhov no famously ua rau lojhull tawg hauv Liberty nkojnyob rau hauv dej txias thaum lub sij hawmNtiaj Teb Tsov Rog II, ua rau ntau lub dab dej. DBTT kuj tuaj yeem cuam tshuam los ntawm lwm yam xws lihluav taws xob neutron, uas ua rau muaj kev nce ntxiv hauv lub cevcov kab hlau rhuavthiab ib qho kev txo qis hauv ductility thiab nce hauv DBTT.
Qhov tseeb tshaj plaws ntawm kev ntsuas DBTT ntawm cov khoom siv yog los ntawm kev kuaj pob txha. Feem ntauplaub taw tes khoov kuajntawm qhov kub thiab txias yog ua rau ntawm cov khoom ua ntej tawg ntawm cov khoom polished.
Rau kev sim ua nyob rau hauv qhov kub siab dua, kev ua haujlwm dislocation nce. Ntawm qhov kub thiab txias, dislocations tiv thaiv lub qhov tawg mus rau qhov uas qhov kev thov deformation tsis txaus rau qhov kev ntxhov siab ntawm qhov tawg-ntsiab kom ncav cuag tus nqi tseem ceeb rau kev tawg (KiC). Qhov kub ntawm qhov no tshwm sim yog qhov kub ntawm qhov hloov pauv ntawm cov ductile-brittle. Yog tias kev sim ua tiav ntawm tus nqi siab dua, yuav tsum muaj kev cuam tshuam ntau dua los tiv thaiv kev puas tsuaj, thiab qhov kub hloov pauv tau nce.
