Thermal Stress: Aluminium alloys muaj cov coefficient siab ntawm thermal expansion thiab tsis tshua muaj elastic modulus. Thaum lub sij hawm welding, lawv muaj kev deformation tseem ceeb, nrog rau lub ntim ntim shrinkage ntawm kwv yees li 6%. Qhov ceev ceev txias thiab crystallization tus nqi ua rau muaj kev ntxhov siab nyob rau hauv cov vuam thiab siab rigidity txwv ntawm qhov sib koom ua ke, yooj yim ua rau muaj qhov tsis xws luag xws li tawg thiab wavy deformation.
Ablation thiab evaporation: Aluminium muaj qhov qis melting point (660 degree) thiab boiling point (2647 degree). Kev kub siab vuam ntau dhau tuaj yeem ua rau tawg tawg tau yooj yim, uas tau tshaj tawm hauv siab - zog nqaj vuam. Qee cov ntsiab lus alloying nyob rau hauv aluminium alloys muaj cov ntsiab lus boiling tsawg thiab yog yooj yim evaporated thiab hlawv tawm nyob rau hauv instantaneous kub kub. Splashing tshem tawm cov tee dej, hloov cov tshuaj muaj pes tsawg leeg ntawm thaj chaw weld thiab cuam tshuam rau kev tswj kev sib koom ua haujlwm. Vuam feem ntau siv cov xaim xaim lossis lwm yam khoom siv nrog cov ntsiab lus siab dua ntawm -boiling- cov ntsiab lus ntau dua li cov hlau hauv paus los them rau qhov no.
Khoom Inclusions: Aluminium yog tshuaj lom neeg thiab yooj yim oxidized. Thaum lub sij hawm vuam, qhov siab - melting- taw tes (kwv yees li 2050℃) Al₂O₃ txheej txheej nyob rau saum npoo, uas yog suav nrog hauv lub pas dej molten, qis - ntom molten alloy kua. Qhov no tsim cov khoom me me slag suav nrog uas nyuaj rau tshem tawm, cuam tshuam rau kev tsim cov qauv vuam, yooj yim ua rau electrochemical corrosion, thiab txo cov khoom siv kho tshuab ntawm kev sib koom ua ke. Lub Al₂O₃ tseem npog lub pas dej ua ke thiab zawj, cuam tshuam rau vuam.
Porosity thiab Collapse: Lub melting point ntawm aluminium alloys yog qis dua li ntawm oxides, thiab lawv yog tshuaj lom neeg. Thaum lub sij hawm vuam, cov khoom oxide zaj duab xis ua rau saum npoo ntawm lub pas dej molten vim aluminium oxidation, ua rau nws nyuaj rau kev soj ntsuam cov℃ntawm melting. Qhov no tuaj yeem ua rau muaj qhov kub thiab txias ntau dhau, ua rau loj - nplai tawg hauv tshav kub- cuam tshuam thiab ua rau cov duab thiab cov khoom ntawm cov hlau vuam puas. Nyob rau tib lub sij hawm, ib tug loj npaum li cas ntawm hydrogen roj yog yaj nyob rau hauv lub alloy kua. Tom qab vuam, raws li lub pas dej molten kub txo, cov roj solubility txo. Vim qhov ceev ceev solidification thiab tsawg ntom ntawm aluminium alloys, hydrogen pores ntawm txawv qhov ntau thiab tsawg daim ntawv thaum lub sij hawm solidification txheej txheem ntawm weld. Cov pores sib sau ua ke thiab nthuav mus rau hauv cov pores loj, txo cov yam ntxwv ntawm kev sib koom ua ke. Porosity kuj tuaj yeem tshwm sim los ntawm cov txheej txheem casting ntawm lub hauv paus hlau; Thaum lub sij hawm welding, cua sov input thiab sab hauv siab hloov ua rau cov pores uas twb muaj lawm los nthuav los yog ua ke, tsim weld pores. Vuam cov ntaub ntawv yuav tsum nruj me ntsis qhuav ua ntej siv, thiab thaum lub sij hawm welding, lub tam sim no yuav tsum tau kom tsim nyog ntxiv kom ntev lub molten pas dej ua ke lub neej lub sij hawm thiab tswj pore tsim.