Casting kev ntxhov siab tuaj yeem muab faib ua ob hom raws li qhov laj thawj ntawm nws qhov tshwm sim: thermal stress thiab shrinkage stress.
(1) Thermal stress
Qhov kev ntxhov siab tshwm sim los ntawm qhov tsis sib xws hauv qhov sib txawv ntawm cov castings thaum lub sij hawm solidification thiab txias yog hu ua thermal stress. Thermal stress ua rau cov phab ntsa tuab uas txias qeeb kom ncab, thaum cov phab ntsa nyias los yog cov chaw uas txias sai dua rau compress. Qhov ntau dua qhov sib txawv ntawm phab ntsa thickness ntawm cov casting, qhov ntau dua cov linear shrinkage los yog elastic modulus ntawm alloy, thiab ntau dua thermal stress. Thaum lub sij hawm Directional solidification, lub casting yog feem ntau deformation thiab kab nrib pleb vim lub thermal stress loj tshwm sim los ntawm inconsistent cua txias ceev ntawm txhua feem ntawm lub casting.
(2) Shrinkage kev ntxhov siab
Cov kev ntxhov siab tsim los ntawm sab nraud quab yuam xws li pwm, tub ntxhais, thiab riser thaum lub sij hawm solid-state shrinkage ntawm castings yog hu ua shrinkage stress Tom qab txias lub casting mus rau lub xeev elastic, shrinkage kev nyuaj siab yuav raug generated thaum lub shrinkage yog hindered. Shrinkage stress feem ntau manifested li tensile stress. Thaum qhov kev tsim tawm raug tshem tawm (xws li tom qab casting xuab zeb poob lossis tshem tawm lub rooj vag), qhov kev ntxhov siab ntawm lub ntsws kuj ploj mus, yog li kev ntxhov siab shrinkage yog ib qho kev ntxhov siab ib ntus. Tab sis ua ntej cov xuab zeb poob, yog tias qhov sib xyaw ua ke ntawm shrinkage kev nyuaj siab thiab thermal stress ntawm lub casting tshwm sim nyob rau hauv ib tug instantaneous kev nyuaj siab ntau tshaj lub tensile lub zog ntawm casting, lub casting yuav ua rau tawg.
