Thaum qhov kev ntxhov siab sab hauv hauv qhov casting tshaj qhov kev txwv lub zog ntawm cov hlau, cov kab nrib pleb tshwm sim hauv qhov casting. Cov kab nrib pleb yog qhov teeb meem loj loj uas yuav tsum tau tiv thaiv. Kev tawg tuaj yeem muab faib ua ob hom raws li qhov kub thiab txias ntawm kev tsim: kub tawg thiab txias tawg.
(1) Thermal tawg
① Cov txheej txheem thermal tawg
Nws yog feem ntau tsim thaum lub sij hawm lig solidification theem thaum cov hlau nyob rau ntawm qhov kub siab nyob ze ntawm lub solidus. Nws cov duab yog tus cwj pwm los ntawm cov kab nrib pleb luv luv, qhov dav dav, cov duab tortuous, thiab oxidized xim hauv cov kab nrib pleb. Tsis tsim nyog casting qauv, loj alloy shrinkage, tsis zoo yielding ntawm pwm (core) xuab zeb, thiab tsis tsim nyog casting txheej txheem tuaj yeem ua rau kub tawg. Cov sulfur thiab phosphorus nyob rau hauv cov hlau thiab hlau txo lawv cov toughness thiab nce lawv nyiam kub tawg.
② Tiv thaiv thermal tawg
Tsim nyog kev hloov kho ntawm alloy muaj pes tsawg leeg (kev tswj nruj ntawm leej faj thiab phosphorus cov ntsiab lus nyob rau hauv steel thiab hlau), tsim nyog tsim qauv ntawm casting, saws lub hauv paus ntsiab lus ntawm ib txhij solidification, thiab kev txhim kho cov yielding peev xwm ntawm pwm (core) xuab zeb yog tag nrho cov zoo ntsuas rau tiv thaiv kub tawg.
(2) Txias tawg
① Qhov tshwm sim ntawm qhov txias txias
Txias tawg yog cov txiaj ntsig ntawm thermal stress thiab shrinkage stress generated thaum lub casting yog txias mus rau ib tug tsawg kub thiab nyob rau hauv ib tug elastic xeev. Yog hais tias nws yog ntau tshaj lub zog ntawm lub alloy ntawm qhov kub thiab txias, qhov sib tsoo txias tshwm sim. Txias tawg yog tsim nyob rau hauv qis kub, nrog me me thiab nruam nruam kab nrib pleb uas huv si thiab tej zaum me ntsis oxidized. Castings nrog loj phab ntsa thickness sib txawv thiab complex cov duab, tshwj xeeb tshaj yog loj thiab nyias castings, yog nquag mus rau txias cracking.
② Tiv thaiv kom txhob mob khaub thuas
Txhua yam kev ntsuas los txo cov kev ntxhov siab sab hauv hauv casting lossis txo cov alloy brittleness tuaj yeem tiv thaiv kev tsim ntawm qhov txias txias. Piv txwv li, phosphorus nyob rau hauv cov hlau thiab cam khwb cia hlau tuaj yeem txo qhov cuam tshuam ntawm cov hlau alloys, ua kom brittleness, thiab yooj yim ua rau txias tawg. Yog li ntawd, kev txwv nruj yuav tsum tau ua nyob rau hauv cov hlau melting.
