Zida zapamwamba kwambiri ndizo maziko opangira zomangira zapamwamba. Komabe, zinthu zambiri zopangidwa ndi fasteners zimakhala ndi ming'alu. Chifukwa chiyani izi zimachitika?

Pakali pano, zizindikiro zodziwika bwino za carbon structural steel zitsulo zoperekedwa ndi zitsulo zapakhomo ndi φ 5.5- φ 45, mtundu wokhwima kwambiri ndi φ 6.5- φ 30. Pali ngozi zambiri zamtundu zomwe zimachitika chifukwa cha kusiyana kwa phosphorous, monga kugawanika kwa phosphorous. chingwe chaching'ono ndi kapamwamba. Chikoka cha kulekanitsa phosphorous ndi kusanthula mapangidwe a ming'alu akufotokozedwa pansipa kuti afotokoze. Kuwonjezera phosphorous mu chitsulo mpweya gawo chithunzi adzakhala molingana kutseka austenite gawo dera ndi mosalephera kuonjezera mtunda pakati pa solidus ndi liquidus. Phosphorous yomwe ili ndi chitsulo ikakhazikika kuchokera kumadzi kupita ku yolimba, imayenera kudutsa kutentha kwakukulu.

Kufalikira kwa phosphorous muzitsulo kumachepa, ndipo chitsulo chosungunula chokhala ndi phosphorous yambiri (chotsika chosungunuka) chimakhala chodzaza ndi dendrites yoyamba yolimba, yomwe imayambitsa kugawanika kwa phosphorous. Pazinthu zomwe nthawi zambiri zimakhala ndi ming'alu panthawi yozizira kapena kuzizira, kufufuza ndi kusanthula kwazitsulo kumasonyeza kuti ferrite ndi pearlite zimagawidwa m'mizere, ndipo pali ferrite yoyera mu matrix. Pali madera ophatikizika amtundu wa grey sulfide pa matrix a banded ferrite. Mapangidwe amtundu wa sulfide amatchedwa "ghost line" chifukwa cha tsankho la sulfide.
Chifukwa chake ndikuti dera lomwe lili ndi tsankho lalikulu la phosphorous limapereka malo oyera owala m'dera lokulitsa phosphorous. Mu slab yosalekeza, chifukwa cha kuchuluka kwa phosphorous m'dera loyera, makhiristo olemera kwambiri a phosphorous, amachepetsa phosphorous. Pamene billet imalimba, ma austenite dendrites amayamba kupatukana ndi chitsulo chosungunuka. Phosphorous ndi sulfure m'madendritewa amachepetsedwa, koma chitsulo chosungunuka cholimba chimakhala ndi phosphorous ndi sulfure. Zimakhazikika pakati pa nkhwangwa za dendrite chifukwa phosphorous ndi zinthu za sulfure ndizokwera. Panthawi imeneyi, sulfide imapangidwa, ndipo phosphorous imasungunuka mu matrix. Chifukwa phosphorous ndi zinthu za sulfure ndizokwera, sulfide imapangidwa pano, ndipo phosphorous imasungunuka mu matrix. Chifukwa chake, chifukwa cha kuchuluka kwa phosphorous ndi sulfure, mpweya wa phosphorous mu njira yolimba ndi yayikulu. Kumbali zonse za lamba wa carbonaceous, ndiye kuti, mbali zonse za malo opangira phosphorous, lamba wautali komanso wopapatiza wa pearlite wofanana ndi lamba woyera wa ferrite amapangidwa, ndipo minofu yoyandikana nayo imasiyanitsidwa. Pansi pa kutenthedwa kwa kutentha, billet idzafikira kumalo opangira pakati pazitsulo, chifukwa lamba la ferrite lili ndi phosphorous yambiri, ndiye kuti, kusiyana kwa phosphorous kudzatsogolera kupanga lamba wolemera kwambiri wa ferrite wokhala ndi lamba wowala kwambiri wa ferrite. . Zitha kuwoneka kuti palinso mizere yopepuka ya sulfide mu lamba wowala kwambiri wa ferrite, womwe umagawidwa ndi lamba wautali wa sulfide wolemera wa phosphorous ferrite, womwe nthawi zambiri timawutcha "ghost line". (Onani Chithunzi 1-2)

Flange Bolt

M'nyengo yotentha, malinga ngati pali kusiyana kwa phosphorous, n'zosatheka kupeza microstructure yofanana. Chofunika kwambiri, chifukwa kugawanika kwa phosphorous kwapanga dongosolo la "ghost line", mosakayika kudzachepetsa makina azinthuzo. Kusiyanitsa kwa phosphorous muzitsulo zomangika ndi carbon ndizofala, koma digiri yake ndi yosiyana. Kusiyanitsa kwakukulu kwa phosphorous (mapangidwe a "ghost line") kudzabweretsa zotsatira zoyipa kwambiri pazitsulo. Mwachiwonekere, kulekanitsa kwakukulu kwa phosphorous ndi chifukwa cha kuzizira kwa mutu. Chifukwa cha phosphorous mumagulu osiyanasiyana achitsulo ndi osiyana, zipangizozo zimakhala ndi mphamvu zosiyana komanso zolimba. Kumbali inayi, imapangitsa kuti zinthuzo zikhale ndi nkhawa zamkati, zomwe zimapangitsa kuti zinthuzo zikhale zosavuta kusweka. Pazinthu zomwe zimakhala ndi "ghost line", ndi chifukwa cha kuchepa kwa kuuma, mphamvu, kutalika pambuyo pa kusweka ndi kuchepetsa dera, makamaka kuchepa kwa mphamvu ya mphamvu, kuti phosphorous yomwe ili muzinthu imakhala ndi ubale wabwino ndi kapangidwe kake. katundu zitsulo.
Mu minofu ya "ghost line" yomwe ili pakati pa gawo la masomphenya, kuchuluka kwa sulfide yopyapyala, yowala kwambiri inadziwika ndi metallography. The sanali zitsulo inclusions mu structural zitsulo makamaka amakhala mu mawonekedwe a oxides ndi sulfides. Malinga ndi GB/T10561-2005 Standard Classification Diagram for Content of Non metallic Inclusions in Steel, sulfide content of Class B inclusions is 2.5 or above. Nonmetallic inclusions ndi gwero lomwe lingathe kusweka. Kukhalapo kwake kudzawononga kwambiri kupitiriza ndi kuphatikizika kwazitsulo zachitsulo, motero kuchepetsa kwambiri mphamvu ya intergranular.
Zimaganiziridwa kuti sulfide mkati mwa "ghost line" yachitsulo ndi gawo losweka kwambiri. Choncho, ambiri fasteners losweka mu ozizira mutu ndi kutentha mankhwala quenching pa kupanga malo, amene chifukwa cha kuchuluka kwa kuwala imvi yaitali sulfides. Nsalu iyi yopanda nsalu inawononga kupitiriza kwa zitsulo ndikuwonjezera chiopsezo cha kutentha kwa kutentha. "Mzere wa Ghost" sungathe kuchotsedwa mwa kukhazikika ndi njira zina, ndipo zinthu zonyansa ziyenera kuyendetsedwa mosamalitsa musanasungunuke kapena zopangira zisanalowe m'mbewu. Malinga ndi kapangidwe ndi deformability, non-metal inclusions amagawidwa mu alumina (mtundu A) silicate (mtundu C) ndi ozungulira okusayidi (mtundu D). Maonekedwe ake adzadula kupitiriza zitsulo ndi kukhala maenje kapena ming'alu pambuyo peeling, amene n'zosavuta kupanga ming'alu pa kuzizira mutu ndi kuchititsa nkhawa ndende pa kutentha mankhwala, motero kuchititsa kuzimitsa ming'alu. Chifukwa chake, zophatikiza zopanda zitsulo ziyenera kuyendetsedwa mosamalitsa. Zida zamakono za Structural Carbon Structural Steels GB/T700-2006 ndi GB T699-2016 High Quality Carbon Steels zimayika patsogolo zofunikira pazophatikiza zopanda zitsulo. Pamagawo ofunikira, nthawi zambiri amakhala A, B, C amtundu wa coarse, mndandanda wabwino supitilira 1.5, D, Ds mtundu wa coarse system ndi level 2 osapitilira mulingo 2.

Hebei Chengyi Engineering Materials Co., Ltd. Zomangamanga zathu zimagwiritsa ntchito zida zapamwamba kwambiri, ukadaulo wapamwamba wopanga komanso ukadaulo wopanga, komanso kasamalidwe koyenera kuti zitsimikizire mtundu wazinthu. Ngati mukufuna kugula zomangira, chonde titumizireni.