Fasahar walda ta Laser, saboda yawan kuzarinsa, ƙarancin shigar zafi da halayen rashin hulɗa, ya zama ɗaya daga cikin manyan hanyoyin da ake amfani da su a masana'antar zamani. Duk da haka, matsaloli kamar iskar shaka, porosity da ƙonewar abubuwa da suka faru sakamakon taɓawar wurin narkakken ruwa tare da yanayi yayin walda suna takaita halayen injiniya da rayuwar aikin dinkin walda. A matsayin babban hanyar sarrafa yanayin walda, zaɓin nau'in, yawan kwarara da yanayin iskar gas mai kariya yana buƙatar a haɗa shi da halayen kayan (kamar aikin sinadarai, ƙarfin wutar lantarki) da kauri na farantin.
Nau'ikan iskar gas masu kariya
Babban aikin iskar gas mai kariya yana cikin ware iskar oxygen, daidaita yanayin wurin narkakken najasa, da kuma inganta ingancin haɗin makamashi. Dangane da halayen sinadarai, ana iya rarraba iskar gas mai kariya zuwa iskar gas mara aiki (argon, helium) da iskar gas mai aiki (nitrogen, carbon dioxide). Iskar gas mara aiki suna da kwanciyar hankali mai yawa kuma suna iya hana iskar oxygen na wurin narkakken najasa yadda ya kamata, amma bambance-bambancen da ke tsakaninsu a cikin halayen jiki na zafi suna shafar tasirin walda sosai. Misali, argon (Ar) yana da yawan yawa (1.784 kg/m³) kuma yana iya samar da rufin da ya dace, amma ƙarancin wutar lantarki mai zafi (0.0177 W/m·K) yana haifar da sanyaya a hankali na wurin narkakken najasa da kuma shiga cikin walda mara zurfi. Sabanin haka, helium (He) yana da yawan wutar lantarki mai zafi sau takwas (0.1513 W/m·K) fiye da argon kuma yana iya hanzarta sanyaya wurin narkakken najasa da kuma ƙara shigar walda, amma ƙarancin yawansa (0.1785 kg/m³) yana sa ya zama mai sauƙin fita, yana buƙatar ƙarin kwarara don kiyaye tasirin kariya. Iskar gas mai aiki kamar nitrogen (N₂) na iya ƙara ƙarfin walda ta hanyar ƙarfafa maganin a wasu yanayi, amma amfani da shi fiye da kima na iya haifar da porosity ko hazo na matakan karyewa. Misali, lokacin walda ƙarfe mai duplex, yaduwar nitrogen a cikin tafkin narke na iya kawo cikas ga daidaiton matakin ferrite/austenite, wanda ke haifar da raguwar juriya ga tsatsa.
Hoto na 1. Walda ta Laser ta bakin karfe 304L (sama): Kariyar iskar gas ta Ar; (ƙasa): Kariyar iskar gas ta N2
Daga mahangar tsarin aiki, ƙarfin ionization na helium (24.6 eV) mai yawa zai iya danne tasirin kariyar plasma da haɓaka shaƙar makamashin laser, ta haka yana ƙara zurfin shiga. A halin yanzu, ƙarancin kuzarin ionization na argon (15.8 eV) yana da saurin samar da gajimare na plasma, wanda ke buƙatar cire hankali ko daidaita bugun jini don rage tsangwama. Bugu da ƙari, amsawar sinadarai tsakanin iskar gas mai aiki da wurin narkewa (kamar nitrogen da ke amsawa da Cr a cikin ƙarfe) na iya canza tsarin walda, kuma zaɓi mai kyau bisa ga halayen abu ya zama dole.
Misalan aikace-aikacen kayan aiki:
• Karfe: A cikin walda mai siriri (<3 mm), argon zai iya tabbatar da kammala saman, tare da kauri mai kauri na oxide na 0.5 μm kawai don dinkin walda na ƙarfe mai ƙarancin carbon 1.5 mm; ga faranti masu kauri (>10 mm), ana buƙatar ƙara ƙaramin adadin helium (He) don ƙara zurfin shiga.
• Bakin Karfe: Kariyar Argon na iya hana asarar sinadaran Cr, tare da abun ciki na Cr na 18.2% a cikin dinkin walda na bakin karfe 304 mai kauri mm 3 wanda ke kusantowa da kashi 18.5% na karfen tushe; ga bakin karfe duplex, ana buƙatar cakuda Ar-N₂ (N₂ ≤ 5%) don daidaita rabon. Bincike ya nuna cewa lokacin amfani da cakuda Ar-2% N₂ don bakin karfe duplex 2205 mai kauri mm 8, rabon ferrite/austenite yana da karko a 48:52, tare da ƙarfin tauri na 780 MPa, wanda ya fi kariyar argon tsantsa (720 MPa).
• Gilashin aluminum: Faranti mai siriri (<3 mm): Yawan hasken ƙarfe na aluminum yana haifar da ƙarancin yawan shan makamashi, kuma helium, tare da ƙarfin ionization mai yawa (24.6 eV), zai iya daidaita plasma. Bincike ya nuna cewa lokacin da gilashin aluminum mai kauri mm 2 na 6061 ya sami kariya daga helium, zurfin shigarsa ya kai mm 1.8, yana ƙaruwa da kashi 25% idan aka kwatanta da argon, kuma ƙimar porosity ya ƙasa da 1%. Ga faranti masu kauri (>5 mm): Faranti masu kauri na aluminum suna buƙatar shigar da makamashi mai yawa, kuma cakuda helium-argon (He:Ar = 3:1) zai iya daidaita zurfin shigarsa da farashi. Misali, lokacin walda faranti 5083 masu kauri mm 8, zurfin shigarsa ya kai mm 6.2 a ƙarƙashin kariyar iskar gas mai gauraya, yana ƙaruwa da kashi 35% idan aka kwatanta da iskar argon mai tsarki, kuma farashin walda ya ragu da kashi 20%.
Lura: Rubutun asali ya ƙunshi wasu kurakurai da rashin daidaito. Fassarar da aka bayar ta dogara ne akan sigar rubutun da aka gyara kuma mai ma'ana.
Tasirin kwararar iskar argon
Yawan kwararar iskar argon yana shafar ikon rufe iskar gas da kuma yanayin ruwa na tafkin narkewar ruwa. Idan yawan kwararar ruwa bai isa ba, layin iskar gas ba zai iya ware iska gaba daya ba, kuma gefen tafkin narkewar ruwa yana da saurin oxidation da samuwar ramukan iskar gas; lokacin da yawan kwararar ruwa ya yi yawa, yana iya haifar da rudani, wanda zai iya wanke saman tafkin narkewar ruwa kuma ya haifar da raguwar walda ko fashewa. Dangane da adadin injinan ruwa na Reynolds (Re = ρvD/μ), karuwar yawan kwararar ruwa zai kara saurin kwararar iskar gas. Lokacin da Re > 2300, kwararar laminar ta koma kwararar ruwa mai rikitarwa, wanda zai lalata kwanciyar hankalin tafkin narkewar ruwa. Saboda haka, ana buƙatar yin nazari kan tantance mahimmancin yawan kwararar ruwa ta hanyar gwaje-gwaje ko kwaikwayon lambobi (kamar CFD).
Hoto na 2. Tasirin Saurin Guduwar Iskar Gas daban-daban akan Dinkin Walda
Ya kamata a daidaita inganta kwararar ruwa tare da haɗakar thermal conductivity da kauri farantin:
• Ga ƙarfe da bakin ƙarfe: Ga faranti na ƙarfe masu siriri (1-2 mm), yawan kwararar ya fi dacewa L10-15/min. Ga faranti masu kauri (>6 mm), ya kamata a ƙara shi zuwa L18-22/min don rage iskar shaka a wutsiya. Misali, lokacin da yawan kwararar bakin ƙarfe mai kauri mm 6 mai 316L ya kai L20/min, daidaiton taurin HAZ zai inganta da kashi 30%.
• Ga ƙarfen aluminum: Babban ƙarfin lantarki mai zafi yana buƙatar babban ƙarfin kwarara don tsawaita lokacin kariya. Ga ƙarfen aluminum mai kauri mm 3 mai 7075, ƙimar porosity shine mafi ƙanƙanta (0.3%) lokacin da ƙimar kwararar ta kasance L/min 25-30. Duk da haka, ga faranti masu kauri sosai (>10 mm), ya zama dole a haɗa su da iska mai haɗaka don guje wa hayaniyar.
Tasirin yanayin iskar gas
Yanayin iskar gas mai hura yana shafar tsarin kwararar ruwan tafkin da aka narkar da shi kai tsaye da kuma tasirin danne lahani ta hanyar sarrafa alkibla da rarraba kwararar iskar gas. Yanayin iskar gas mai hura yana daidaita kwararar ruwan tafkin ta hanyar canza yanayin tashin hankali a saman da kwararar Marangoni (kwararar Marangoni). Busawa a gefe na iya sa tafkin mai narkar ya gudana a wani takamaiman alkibla, yana rage ramuka da haɗakar tarkace; busawa mai haɗaka na iya inganta daidaiton samuwar walda ta hanyar daidaita rarrabawar makamashi ta hanyar kwararar iskar gas mai hanyoyi da yawa.
Manyan hanyoyin busawa sun haɗa da:
• Busawa mai haɗaka: Ana fitar da iskar gas ɗin ta hanyar haɗakar hasken laser, tana rufe wurin da aka narke da kyau, wanda ya dace da walda mai sauri. Amfaninsa shine kwanciyar hankali mai yawa, amma kwararar iskar gas na iya tsoma baki ga mai da hankali kan laser. Misali, lokacin amfani da busawa mai haɗaka akan takardar ƙarfe mai galvanized na mota (1.2 mm), ana iya ƙara saurin walda zuwa 40 mm/s, kuma ƙimar watsawa ƙasa da 0.1.
• Busawa a gefe: Ana shigar da iskar gas daga gefen wurin da aka narke, wanda za a iya amfani da shi don cire ƙazanta a cikin plasma ko ƙasa ta hanya madaidaiciya, wanda ya dace da walda mai zurfi. Misali, lokacin da ake busawa a kan ƙarfe Q345 mai kauri mm 12 a kusurwar 30°, shigar walda yana ƙaruwa da kashi 18%, kuma ƙimar porosity na ƙasa yana raguwa daga kashi 4% zuwa 0.8%.
• Busawa mai hadewa: Idan aka haɗa busawa mai coaxial da gefe, zai iya danne iskar shaka da tsangwama a lokaci guda a cikin jini. Misali, ga ƙarfen aluminum mai kauri mm 3 mai siffar 6061 tare da ƙirar bututun ƙarfe biyu, ƙimar porosity za ta ragu daga 2.5% zuwa 0.4%, kuma ƙarfin tensile ya kai kashi 95% na kayan tushe.
Tasirin iskar gas mai kariya akan ingancin walda ya samo asali ne daga tsarin canja wurin makamashi, yanayin zafi na wurin narkakken ruwa, da kuma halayen sinadarai:
1. Canja wurin makamashi: Babban ƙarfin wutar lantarki na helium yana hanzarta sanyaya wurin dumama, yana rage faɗin yankin da zafi ya shafa (HAZ); ƙarancin ƙarfin wutar lantarki na argon yana tsawaita lokacin wanzuwar wurin dumama, wanda ke da amfani ga samuwar faranti masu sirara a saman.
2. Daidaiton wurin wanka mai narkewa: Guguwar iskar gas tana shafar kwararar wurin wanka mai narkewa ta hanyar ƙarfin yankewa, kuma saurin kwararar da ta dace na iya danne watsewa; yawan kwararar da ta wuce kima zai haifar da vortex, wanda ke haifar da lahani ga walda.
3. Kariyar sinadarai: Iskar gas mara aiki tana ware iskar oxygen kuma tana hana iskar shaka daga abubuwan da ke cikin ƙarfe (kamar Cr, Al); iskar gas mai aiki (kamar N₂) tana canza halayen walda ta hanyar ƙarfafawa ko samuwar sinadarai masu ƙarfi, amma ana buƙatar a sarrafa yawan da ke cikin.
Lokacin Saƙo: Afrilu-09-2025
