Anealing uye kudzima uye kuchembera ndiwo akakosha ekupisa emhando dzealuminium alloys. Annealing inzira yekunyorovesa, chinangwa chekugadzira yunifomu yealloy uye yakagadzikana mukugadzirwa uye chimiro, kubvisa kuoma kwebasa, uye kudzorera plastiki yealloy. Kudzima uye kuchembera ndiko kusimbisa kupisa kurapwa, chinangwa chekuvandudza simba reiyo alloy, uye inonyanya kushandiswa kune aruminiyamu alloys anogona kusimbiswa nekupisa kurapwa.
1 Annealing
Zvinoenderana nezvinodiwa zvakasiyana zvekugadzira, aluminium alloy annealing yakakamurwa kuita akati wandei mafomu: ingot homogenization annealing, billet annealing, yepakati annealing uye kupera chigadzirwa annealing.
1.1 Ingot homogenization annealing
Pasi pemamiriro ekukurumidza kudonhedza uye kusaenzana kwekristallisation, iyo ingot inofanirwa kuve isina kuenzana kuumbwa uye chimiro, uye zvakare kuve nekunetseka kukuru kwemukati. Kuti uchinje mamiriro aya uye uvandudze kupisa kwekushanda kweingot, homogenization annealing inowanzodiwa.
Kuti ukudziridze kupararira kweatomu, tembiricha yepamusoro inofanirwa kusarudzirwa homogenization annealing, asi haifanirwe kudarika yakaderera melting point eutectic melting point yealloy. Kazhinji, iyo homogenization annealing tembiricha iri 5 ~ 40 ℃ yakadzikira pane inonyungudika, uye nguva yekunyungudutsa kazhinji iri pakati pe12 ~ 24h.
1.2 Billet annealing
Billet annealing inoreva kuvharirwa pamberi pekutanga kutonhora deformation panguva yekumanikidza kugadzirisa. Chinangwa ndechekuita kuti billet iwane chimiro chakaenzana uye ive nepamusoro pepurasitiki deformation simba. Semuyenzaniso, tembiricha yekupera kweiyo inopisa-yakakungurutswa aruminiyamu alloy slab ndeye 280 ~ 330 ℃. Mushure mekukurumidza kutonhora pakupisa kwekamuri, basa rekuomesa chiitiko hachigone kubviswa zvachose. Kunyanya, kune kupisa-yakagadziriswa yakasimbiswa aruminiyamu alloys, mushure mekukurumidza kutonhora, iyo recrystallization maitiro haina kupera, uye iyo supersaturated yakasimba mhinduro haina kuparara zvachose, uye chikamu chebasa rekuomesa uye kudzima chichiri kuchengetwa. Zvakaoma kutonhora roll zvakananga pasina annealing, saka billet annealing inodiwa. Kune asina-kupisa-akagadziriswa aruminiyamu alloys, akadai seLF3, annealing tembiricha i370 ~ 470 ℃, uye kutonhora kwemhepo kunoitwa mushure mekudziya kwe1.5 ~ 2.5h. Iyo billet uye annealing tembiricha inoshandiswa kutonhora-inodhonzwa chubhu kugadzirisa inofanirwa kunge yakakwira zvakafanira, uye tembiricha yekumusoro inogona kusarudzwa. Kune aruminiyamu alloys anogona kusimbiswa nekupisa kupisa, seLY11 uye LY12, iyo billet annealing tembiricha i390 ~ 450 ℃, inochengetwa patembiricha iyi kwe1 ~ 3h, yozotonhodzwa muchoto kusvika pazasi 270 ℃ pamwero usingapfuure 30 ℃ / h nechoto kunze kwemhepo.
1.3 Kuiswa kwepakati
Intermediate annealing inoreva annealing pakati peinotonhora deformation maitiro, chinangwa chekubvisa kuoma kwebasa kufambisa kuenderera kutonhora deformation. Kazhinji, mushure mekunge zvinhu zvave zvavharwa, zvichave zvakaoma kuenderera mberi nechando kushanda pasina kuvharirwa kwepakati mushure mekuita 45 ~ 85% inotonhora deformation.
Iyo process system yepakati annealing yakangofanana neye billet annealing. Zvinoenderana nezvinodiwa zvekutonhora deformation degree, yepakati annealing inogona kukamurwa kuita marudzi matatu: annealing yakakwana (total deformation ε≈60 ~ 70%), nyore annealing (ε≤50%) uye zvishoma annealing (ε≈30 ~ 40%). Iwo maviri ekutanga annealing masisitimu akafanana nebillet annealing, uye yekupedzisira inodziiswa pa 320 ~ 350 ℃ kwe 1.5 ~ 2h uyezve mweya watonhodzwa.
1.4. Yakapera chigadzirwa annealing
Yakapedzwa chigadzirwa annealing ndiyo yekupedzisira kupisa kupisa iyo inopa izvo zvinhu zvimwe zvesangano uye zvemuchina zvivakwa zvinoenderana nezvinodiwa zvechigadzirwa tekinoroji mamiriro.
Yakapedzwa chigadzirwa annealing inogona kukamurwa kuita yakanyanya tembiricha annealing (kugadzirwa kwezvakapfava zvigadzirwa) uye yakaderera tembiricha annealing (kugadzirwa kwehafu-yakaoma zvigadzirwa munzvimbo dzakasiyana). Yepamusoro tembiricha annealing inofanirwa kuve nechokwadi chekuti yakazara recrystallization chimiro uye yakanaka plasticity inogona kuwanikwa. Pasi pemamiriro ekuvimbisa kuti zvinhu zvinowana chimiro chakanaka nekushanda, nguva yekubata haifaniri kunge yakareba. Kune aruminiyamu alloys anogona kusimbiswa nekupisa kurapwa, kuitira kudzivirira kutonhora kwemhepo kudzima mhedzisiro, chiyero chekutonhora chinofanira kunyatsodzorwa.
Kudzikira tembiricha annealing kunosanganisira kuzorora kwekushushikana uye kupfava zvishoma, izvo zvinonyanya kushandiswa kune yakachena aruminiyamu uye isiri-yekupisa kurapwa inosimbisa aruminiyamu alloys. Kugadzira yakaderera tembiricha annealing system ibasa rakaoma kwazvo, iro risingangoda kufunga tembiricha yekumisa uye kubata nguva, asi inodawo kufunga nezve pesvedzero yetsvina, alloying degree, kutonhora deformation, yepakati annealing tembiricha uye inopisa deformation tembiricha. Kugadzira yakaderera tembiricha annealing system, zvinodikanwa kuyera shanduko yekuchinja pakati peannealing tembiricha uye michina zvivakwa, uye wozoona iyo annealing tembiricha renji zvinoenderana nemaitiro ekuita anotsanangurwa mumamiriro ehunyanzvi.
2 Kudzima
Kudzimwa kwealuminium alloy kunonziwo kugadzirisa kwekugadzirisa, ndiko kunyungudutsa zvinhu zvakawanda zvinosanganiswa musimbi sechikamu chechipiri kupinda mugadziro yakasimba sezvinobvira kuburikidza nekupisa kwepamusoro-tembiricha, kuteverwa nekukurumidza kutonhora kudzivirira kunaya kwechikamu chechipiri, nokudaro kuwana supersaturated aluminium-based α solid solution, iyo yakanyatsogadzirirwa kurapwa kunotevera.
Mhedzisiro yekuwana supersaturated α yakasimba mhinduro ndeyokuti kunyunguduka kwechikamu chechipiri mu alloy mualuminium kunofanira kuwedzera zvakanyanya nekuwedzera kwekushisa, kana zvisina kudaro, chinangwa chekugadzirisa chigadziro chakasimba hachigone kuwanikwa. Mazhinji alloying zvinhu mualuminium anogona kugadzira eutectic chikamu dhizaini ine hunhu uhu. Tichitora Al-Cu alloy semuenzaniso, tembiricha ye eutectic i548 ℃, uye tembiricha yekunyungudika kwemhangura mualuminium isingasviki 0.1%. Kana yapiswa kusvika 548 ℃, solubility yayo inowedzera kusvika 5.6%. Naizvozvo, Al-Cu alloys ine isingasviki 5.6% mhangura inopinda α imwe chikamu nharaunda mushure mekupisa kwekupisa kudarika mutsara wayo we solvus, ndiko kuti, chikamu chechipiri CuAl2 yakanyungudika zvachose mumatrix, uye imwechete supersaturated α yakasimba mhinduro inogona kuwanikwa mushure mekudzima.
Kudzima ndiyo inonyanya kukosha uye inonyanya kudiwa kupisa kupisa kwealuminum alloys. Chinokosha ndechokusarudza yakakodzera kupisa tembiricha yekudzimisa uye kuve nechokwadi chekudzima kutonhora kwakaringana, uye kunyatso kudzora tembiricha yechoto uye kuderedza kudzima deformation.
Nheyo yekusarudza tembiricha yekudzima ndeyekuwedzera kudzima tembiricha yekudziya zvakanyanya sezvinobvira uchive nechokwadi chekuti aruminiyamu alloy haina kupisa kana kuti zviyo zvinokura zvakanyanya, kuitira kuti iwedzere supersaturation ye α yakasimba mhinduro uye simba mushure mekuchembera kurapwa. Kazhinji, iyo aluminium alloy yekupisa choto inoda kuti tembiricha yekudzora tembiricha kuve mukati me ± 3 ℃, uye mhepo iri muchoto inomanikidzwa kutenderera kuti ive nechokwadi chekufanana kwekushisa kwechoto.
Kupisa kwealuminium alloy kunokonzerwa nekunyunguduka kwezvikamu zvakaderera-zvinonyunguduka mukati mesimbi, zvakadai sebhinary kana multi-element eutectics. Kupisa kwakanyanya hakungokonzeredzi kuderedzwa kweiyo mechanical properties, asi inewo kukanganisa kwakakomba pakupokana kwekuora kwealloy. Naizvozvo, kana imwe aruminiyamu alloy yakapisa, haigone kubviswa uye chigadzirwa chealloy chinofanira kubviswa. Iyo chaiyo yekupisa tembiricha yealuminium alloy inonyanya kutsanangurwa neiyo alloy kuumbwa uye kusachena zvirimo, uye zvakare ine chekuita neiyo alloy processing state. Iyo tembiricha yekupisa yezvigadzirwa izvo zvakapfuura epurasitiki deformation processing yakakwira kupfuura iyo yekukanda. Iyo yakakura iyo deformation processing, zviri nyore kune zvisiri-equilibrium low-melting-point zvikamu zvinyunguduke mumatrix kana ichipisa, saka tembiricha chaiyo yekupisa inowedzera.
Mwero wekutonhodza panguva yekudzima kwealuminium alloy ine simba rakakosha pakuchembera kusimbisa kugona uye kushorwa kwekupokana kwealloy. Munguva yekudzima kweLY12 uye LC4, zvinodikanwa kuve nechokwadi kuti iyo α yakasimba mhinduro haina kuora, kunyanya munzvimbo ine tembiricha ye290 ~ 420 ℃, uye yakakura zvakakwana yekutonhora inodiwa. Zvinowanzo taurwa kuti mwero wekutonhora unofanirwa kunge uri pamusoro pe50 ℃/s, uye yeLC4 alloy, inofanirwa kusvika kana kudarika 170 ℃/s.
Iyo inonyanya kushandiswa quenching medium yealuminium alloys imvura. Kugadzirwa kwemaitiro kunoratidza kuti iyo yakakura kutonhora kweyero panguva yekudzima, kunowedzera kwasara kushushikana uye kusara deformation yezvinhu zvakadzimwa kana workpiece. Naizvozvo, kune zvidiki zvekushanda zvine maumbirwo akareruka, tembiricha yemvura inogona kudzika zvishoma, kazhinji 10 ~ 30 ℃, uye haifanirwe kudarika 40 ℃. Kune maworkpieces ane maumbirwo akaomarara uye misiyano mikuru mukukora kwemadziro, kuti uderedze kudzima deformation uye kutsemuka, tembiricha yemvura dzimwe nguva inogona kuwedzera kusvika 80 ℃. Nekudaro, zvinofanirwa kutaurwa kuti sezvo tembiricha yemvura yetangi yekudzima ichiwedzera, simba uye kushora kwekushomeka kwezvinhu zvinodererawo zvinoenderana.
3. Kuchembera
3.1 Shanduko yesangano uye shanduko yemaitiro panguva yekukwegura
Iyo supersaturated α yakasimba mhinduro inowanikwa nekudzima chimiro chisina kugadzikana. Kana ichipisa, inoora uye inoshanduka kuita chimiro chekuenzanisa. Kutora Al-4Cu alloy semuenzaniso, chimiro chayo chekuenzanisa chinofanira kunge chiri α+CuAl2 (θ chikamu). Kana iyo imwe-phase supersaturated α yakasimba mhinduro mushure mekudzima ichidziya nekuda kwekuchembera, kana tembiricha yakakwira zvakakwana, θ chikamu chinonaya zvakananga. Zvikasadaro, ichaitwa mumatanho, ndiko kuti, mushure mematanho epakati ekuchinja, chikamu chekupedzisira chekuenzanisa CuAl2 chinogona kusvika. Mufananidzo uri pazasi unoratidza chimiro chekristaro chimiro chega rega rekunaya kwemvura panguva yekuchembera kweAl-Cu alloy. Mufananidzo a. ndiyo crystal lattice chimiro munzvimbo yakadzimwa. Panguva ino, i-single-phase α supersaturated solid solution, uye maatomu emhangura (madotsi matema) anogoverwa zvakaenzana uye zvisina tsarukano mualuminium (white dots) matrix lattice. Mufananidzo b. inoratidza chimiro chelattice padanho rekutanga rekunaya kwemvura. Maatomu emhangura anotanga kunangana mune dzimwe nzvimbo dzematrix lattice kuita nzvimbo yeGuinier-Preston, inodaidzwa kuti GP nzvimbo. Iyo GP zone idiki zvakanyanya uye disc-shaped, ine dhayamita ingangoita 5 ~ 10μm uye ukobvu hwe0.4 ~ 0.6nm. Huwandu hwenzvimbo dzeGP mumatrix yakakura zvakanyanya, uye density yekugovera inogona kusvika 10¹⁷~10¹⁸cm-³ . Iyo crystal chimiro cheGP zone ichiri yakafanana neye matrix, ese ari maviri-akatarisana ne cubic, uye inochengetedza yakabatana interface nematrix. Nekudaro, nekuti ukuru hwemaatomu emhangura idiki pane yeatomu yealuminium, kupfumiswa kwemaatomu emhangura kuchaita kuti crystal lattice iri pedyo nenharaunda iderere, izvo zvinokonzeresa kumonyoroka kwelatisi.
Schematic dhizaini yekristaro chimiro shanduko yeAl-Cu alloy panguva yekukwegura
Mufananidzo a. Yakadzimwa nyika, imwe-chikamu α yakasimba mhinduro, maatomu emhangura (madotsi matema) akagoverwa zvakaenzana;
Mufananidzo b. Muchikamu chekutanga chekukwegura, nzvimbo yeGP inoumbwa;
Mufananidzo c. Muchikamu chekupedzisira chekuchembera, chikamu cheshanduko chehafu-chakabatana chinoumbwa;
Mufananidzo d. Kuchembera kwakanyanya kwekushisa, kunaya kweiyo incoherent equilibrium phase
Iyo GP zone ndiyo yekutanga pre-precipitation chigadzirwa chinoonekwa panguva yekuchembera kwealuminium alloys. Kuwedzera nguva yekuchembera, kunyanya kuwedzera tembiricha yekuchembera, kuchaitawo mamwe epakati ekuchinja nhanho. MuAl-4Cu alloy, kune θ” uye θ' zvikamu mushure meGP zone, uye pakupedzisira chikamu chekuenzanisa CuAl2 chasvikwa. θ” uye θ' ese ari maviri matanho ekuchinja echikamu che θ, uye chimiro chekristaro ireti ine sikweya, asi retisi risingaperi rakasiyana. Saizi ye θ yakakura kupfuura iyo yeGP zone, ichiri disc-shaped, ine dhayamita ingangoita 15 ~ 40nm uye ukobvu hwe0.8 ~ 2.0nm. Iyo inoenderera mberi nekuchengetedza yakabatana interface nematrix, asi dhigirii relattice kukanganisa kwakanyanya. Kana uchichinja kubva ku θ” kuenda ku θ' chikamu, saizi yakakura kusvika 20 ~ 600nm, ukobvu i 10 ~ 15nm, uye iyo inobatana interface inoparadzwawo zvishoma, ichiita semi-inobatana interface, sezvakaratidzwa muFigure c. Chigadzirwa chekupedzisira chekunaya kwemvura ndiyo yakaenzana pachikamu θ inova iyo Culibrium chikamu θ inoparadzwa zvachose panguva yechikamu θ. isina kubatana, sezvakaratidzwa mumufananidzo d.
Zvinoenderana nemamiriro ari pamusoro, kuchembera kwekunaya kweAl-Cu alloy is αs→α+GP zone→α+θ”→α+θ'→α+θ. Danho rechimiro chekuchembera rinoenderana nekuumbwa kwealloy uye kuchembera kwacho.Kune kazhinji kanopfuura chimwe chigadzirwa chekuchembera munzvimbo imwechete.Kukwirisa tembiricha yekuchembera, padyo nechimiro.
Munguva yekuchembera, nzvimbo yeGP uye nhanho yekuchinja yakasimudzwa kubva kumatrix idiki muhukuru, yakapararira zvakanyanya, uye haisi nyore kuremara. Panguva imwecheteyo, vanokonzera kukanganisa kwelatisi mumatrix uye vanogadzira nzvimbo yekushungurudzika, iyo ine chinhu chikuru chinodzivisa pakufamba kwekuparadzanisa, nekudaro kuwedzera kupikisa kwepurasitiki deformation yealloy nekuvandudza simba rayo nekuoma. Ichi chiitiko chekuchembera chinoomesa chinonzi kunaya kwemvura. Mufananidzo uri pazasi unoratidza kuoma kwekuchinja kweAl-4Cu alloy panguva yekudzima uye kurapwa kwekuchembera nenzira yecurve. Nhanho I mumufananidzo inomiririra kuoma kwealloy mumamiriro ayo ekutanga. Nekuda kwenhoroondo dzakasiyana dzekushanda dzinopisa, kuoma kwemamiriro ekutanga kuchasiyana, kazhinji HV=30~80. Mushure mekupisa pa500 ℃ uye kudzima (danho II), maatomu ese emhangura anonyungudutswa mumatrix kuti aite imwe-phase supersaturated α solid solution ine HV=60, iyo yakaoma zvakapetwa kaviri kuomarara kweiyo annealed state (HV=30). Uyu ndiwo mugumisiro wekusimbisa mhinduro yakasimba. Mushure mekudzima, inoiswa pakamuri yekupisa, uye kuoma kweiyo alloy kunoramba kuchiwedzerwa nekuda kwekuenderera mberi kwekuumbwa kweGP zones (danho III). Uku kuchembera kuomesa mutembiricha yekamuri kunonzi kuchembera chaiko.
I-yekutanga nyika;
II-solid solution state;
III-kukwegura kwepanyama (GP zone);
IVa-regression kurapwa pa150 ~ 200 ℃ (yakagadziriswazve munzvimbo yeGP);
IVb—kuchembera chaiko (θ”+θ' phase);
V—kuwandisa (θ”+θ' chikamu)
Muchikamu chechina IV, alloy inopisa kusvika 150 ° C yekukwegura, uye kuomeswa kwemaitiro kunonyanya kuoneka kupfuura kukwegura kwepanyama. Panguva ino, chigadzirwa chekunaya ndicho chinonyanya θ” chikamu, icho chine simba guru rekusimbisa muAl-Cu alloys. Kana tembiricha yekuchembera ikawedzera kuwedzera, chikamu chemvura chinoshanduka kubva paθ” chikamu kuenda kuchikamu θ, kuomarara kunopera, uye kuoma kunoderera, kupinda muchikamu V. Chero kurapwa kwekuchembera kunoda kunzi artificial heat, uye V. chikamu ichi. Kana kuomarara kwasvika pakuomarara ukoshi hunogona kusvika musanganiswa mushure mekuchembera (kureva, nhanho IVb), kuchembera uku kunonzi peak kuchembera. Kana kukosha kwekuoma kwepamusoro kukasasvikwa, kunonzi kuchembera kana kuchembera kwekugadzira kusina kukwana. Kana iyo yepamusoro kukosha yakayambuka uye kuoma kwakaderera, kunonzi kudarika-kukwegura. Kudzikamisa kuchembera kurapwa zvakare ndekwekunyanya kuchembera. Iyo GP zone yakaumbwa panguva yekuchembera kwepanyama haina kugadzikana. Kana ichikurumidza kupisa kusvika kune tembiricha yepamusoro, senge 200 ° C, uye yakaramba ichidziya kwenguva pfupi, nzvimbo yeGP inonyungudika ichidzokera mune α yakasimba mhinduro. Kana ikakurumidza kutonhodzwa (kudzimwa) mamwe matanho ekuchinja asati aita senge θ” kana θ' kunaya kwemvura, alloy inogona kudzoserwa payanga yakadzimwa. Chiitiko ichi chinodaidzwa kuti “regression”, kunova kudonha kwekuoma kunoratidzwa nemutsara une doti padanho IVa pamufananidzo.
Kuomeswa kwezera ndiyo hwaro hwekugadzira kupisa-kunopora aluminium alloys, uye kugona kwayo kuomesa zera kunoenderana zvakananga neiyo alloy kuumbwa uye kupisa kurapwa system. Al-Si neAl-Mn mabhinari alloys haana kunaya kuomesa mhedzisiro nekuti chikamu chekuenzanisa chinonatswa zvakananga panguva yekuchembera, uye haapise-anorapa aruminiyamu alloys. Kunyangwe maAl-Mg alloys achigona kuumba nzvimbo dzeGP uye nhanho dzekuchinja β', ivo vanongove nekumwe kuoma kwemvura kuoma mune yakakwirira-magnesium alloys. Al-Cu, Al-Cu-Mg, Al-Mg-Si uye Al-Zn-Mg-Cu alloys ane simba rakasimba rekunaya kwemvura munzvimbo dzavo dzeGP uye nhanho dzekuchinja, uye pari zvino ndiwo masisitimu makuru ealloy anogona kupisa-kupisa nekusimbiswa.
3.2 Kuchembera Kwenyama
Kazhinji, aruminiyamu alloys anogona kusimbiswa nekupisa kurapwa ane echisikigo kuchembera mhedzisiro mushure mekudzima. Kusimbisa kuchembera kwepanyama kunokonzerwa neGP zone. Kuchembera kwechisikigo kunoshandiswa zvakanyanya muAl-Cu uye Al-Cu-Mg alloys. Kuchembera kwechisikigo kweAl-Zn-Mg-Cu alloys kunogara kwenguva yakareba, uye kazhinji zvinotora mwedzi yakawanda kusvika padanho rakagadzikana, saka kuchembera kwechisikigo hakushandiswi.
Kuenzaniswa nekuchembera kwekugadzira, mushure mekuchembera kwechisikigo, simba regoho reiyo alloy rakaderera, asi plastiki uye kuoma kuri nani, uye kushorwa kwehutu kwakakwira. Mamiriro ezvinhu e-super-hard aluminium yeAl-Zn-Mg-Cu system yakasiyana zvishoma. Kuramba kwecorrosion mushure mekuchembera kwekugadzira kunowanzo kuve nani pane iyo mushure mekuchembera kwepanyama.
3.3 Kuchembera kwekugadzira
Mushure mekurapa kwekuchembera kwekugadzira, aruminiyamu alloys anogona kazhinji kuwana yakanyanya goho simba (kunyanya shanduko yechikamu kusimbisa) uye nani kugadzikana kwesangano. Super-hard aluminium, forged aluminium uye cast aruminiyamu vanonyanya kuchembera. Kuchembera tembiricha uye kuchembera nguva vane inokosha pesvedzero pamusoro alloy zvinhu. Kuchembera tembiricha kazhinji pakati 120 ~ 190 ℃, uye kukwegura nguva haipfuuri 24h.
Kuwedzera kune imwe-nhanho yekuchembera yekuchembera, aruminiyamu alloys anogona zvakare kutora yakagadziridzwa yekugadzira yekuchembera system. Ndiko kuti, kupisa kunoitwa kaviri kana kupfuura pane tembiricha dzakasiyana. Semuenzaniso, LC4 alloy inogona kuve yakwegura pa115 ~ 125 ℃ ye2 ~ 4h uyezve pa160 ~ 170 ℃ ye3 ~ 5h. Kuchembera zvishoma nezvishoma hakugone kupfupisa nguva chete, asi zvakare kunatsiridza iyo microstructure yeAl-Zn-Mg uye Al-Zn-Mg-Cu alloys, uye zvakanyanya kunatsiridza kusagadzikana kwekuora kwekusagadzikana, kuneta simba uye kutsemuka kusimba pasina kunyanya kudzikisa michina zvinhu.
Nguva yekutumira: Mar-06-2025
