Kev ua haujlwm tawv tawv yog qhov tshwm sim ntawm cov yas deformation, kev hloov pauv mus tas li. Qhov no yog qhov txawv ntawm elastic deformation, uas yog thim rov qab. Cov ntaub ntawv feem ntau tsis tuaj yeem tsuas yog ib qho lossis lwm qhov, tab sis yog kev sib xyaw ntawm ob. Cov kev sib tham hauv qab no feem ntau siv rauhlau, tshwj xeeb tshaj yog cov hlau, uas tau kawm zoo. Ua hauj lwm hardening tshwm sim tshwj xeeb tshaj yog rau cov ntaub ntawv ductile xws li hlau. Ductility yog lub peev xwm ntawm cov khoom siv los ua cov yas deformations ua ntejtawg(piv txwv li, khoov lub pas hlau kom txog thaum nws tawg).
Covtensile xeemyog dav siv los kawm deformation mechanisms. Qhov no yog vim hais tias nyob rau hauv compression, cov ntaub ntawv feem ntau yuav ntsib qhov tsis tseem ceeb (lattice mismatch) thiab cov xwm txheej tsis tseem ceeb (buckling) ua ntej yas deformation los yog tawg. Li no cov txheej txheem nruab nrab uas tshwm sim rau cov khoom nyob rau hauv uniaxial compression ua ntej qhov xwm txheej ntawm cov yas deformation ua rau compressive test fraught nrog teeb meem.
Cov khoom siv feem ntau deforms elastically nyob rau hauv tus ntawm me mezog; cov ntaub ntawv rov qab sai sai rau nws cov qauv qub thaum lub zog deforming raug tshem tawm. Qhov tshwm sim no hu ua elastic deformation. Qhov kev coj cwj pwm no hauv cov ntaub ntawv tau piav qhia los ntawmHook's Law. Cov ntaub ntawv coj elastically kom txog thaum lub deforming quab yuam nce tshaj qhovelastic txwv, uas yog tseem hu ua yield stress. Thaum lub sij hawm ntawd, cov khoom siv tas li deformed thiab tsis rov qab mus rau nws qhov qub thaum lub zog raug tshem tawm. Qhov tshwm sim no hu ua yas deformation. Piv txwv li, yog ib tug stretches acoil caij nplooj ntoos hlavmus txog rau ib qho taw tes, nws yuav rov qab mus rau nws qhov qub, tab sis thaum nws ncav cuag qhov kev txwv elastic, nws yuav nyob twj ywm deformed thiab yuav tsis rov qab mus rau nws qhov qub.
Elastic deformation stretches cov bonds ntawm atoms deb ntawm lawv qhov sib npaug vojvoog ntawm kev sib cais, tsis siv lub zog txaus los rhuav tshem cov inter-atomic bonds. Yas deformation, ntawm qhov tod tes, tawg inter-atomic bonds, thiab yog li ntawd cuam tshuam nrog kev hloov pauv ntawm cov atoms hauv cov khoom siv.
