Ƙarfin kayan ƙarfe don tsayayya da shigar da saman ta abubuwa masu wuya ana kiransa hardness. Dangane da hanyoyin gwaji daban-daban da iyakokin aikace-aikacen, za a iya raba taurin zuwa taurin Brinell, taurin Rockwell, taurin Vickers, taurin bakin teku, microhardness da taurin zafin jiki. Akwai tauri guda uku da aka saba amfani da su don bututu: Brinell, Rockwell, da taurin Vickers.
A. Brinell hardness (HB)
Yi amfani da ƙwallon ƙarfe ko ƙwallon carbide na wani diamita don danna cikin saman samfurin tare da ƙayyadadden ƙarfin gwaji (F). Bayan ƙayyadadden lokacin riƙewa, cire ƙarfin gwajin kuma auna diamita na shigarwa (L) akan saman samfurin. Ƙimar taurin Brinell ita ce adadin da aka samu ta hanyar rarraba ƙarfin gwajin ta wurin sararin samaniyar da aka ƙera. An bayyana shi a cikin HBS (ball karfe), naúrar ita ce N/mm2 (MPa).
Tsarin lissafin shine:
A cikin dabara: F-ƙarfin gwajin da aka danna cikin saman samfurin ƙarfe, N;
D-Diamita na ƙwallon ƙarfe don gwaji, mm;
d-matsakaicin diamita na ciki, mm.
Ma'aunin taurin Brinell ya fi daidai kuma abin dogaro, amma gabaɗaya HBS ya dace da kayan ƙarfe da ke ƙasa da 450N/mm2 (MPa), kuma bai dace da ƙaramin ƙarfe ko faranti ba. Daga cikin ka'idodin bututun ƙarfe, taurin Brinell shine mafi yawan amfani da su. Ana amfani da diamita na indentation d sau da yawa don bayyana taurin kayan, wanda yake da hankali da dacewa.
Misali: 120HBS10/1000130: Yana nufin cewa ƙimar taurin Brinell da aka auna ta amfani da ƙwallon ƙarfe diamita 10mm ƙarƙashin ƙarfin gwaji na 1000Kgf (9.807KN) na 30s ( seconds) shine 120N/mm2 (MPa).
B. Rockwell hardness (HR)
Gwajin taurin Rockwell, kamar gwajin taurin Brinell, hanya ce ta gwaji. Bambanci shine yana auna zurfin ciki. Wato, a ƙarƙashin aikin da aka yi na ƙarfin gwajin farko (Fo) da ƙarfin gwajin jimlar (F), an danna mashigin (mazugi ko ƙwallon ƙarfe na ƙarfe na ƙarfe) a saman samfurin. Bayan ƙayyadadden lokacin riƙewa, ana cire babban ƙarfin. Ƙarfin gwaji, yi amfani da ƙayyadaddun ƙaƙƙarfan haɓaka zurfin shigar da saura (e) don ƙididdige ƙimar taurin. Darajarta lamba ce da ba a bayyana sunanta ba, wacce alamar HR ke wakilta, kuma ma'auni da aka yi amfani da su sun haɗa da ma'auni 9, ciki har da A, B, C, D, E, F, G, H, da K. Daga cikinsu, ma'aunin da aka saba amfani da shi don karfe. Gwajin taurin gaba ɗaya sune A, B, da C, wato HRA, HRB, da HRC.
Ana ƙididdige ƙimar taurin ta amfani da dabara mai zuwa:
Lokacin gwaji tare da ma'aunin A da C, HR = 100-e
Lokacin gwaji tare da sikelin B, HR = 130-e
A cikin dabarar, e - an bayyana ragowar zurfin zurfin indentation a cikin ƙayyadaddun naúrar 0.002mm, wato, lokacin da ƙayyadaddun ƙayyadaddun ƙayyadaddun na'ura ya zama raka'a ɗaya (0.002mm), yana daidai da canji a cikin taurin Rockwell ta daya. lamba. Girman darajar e, ƙananan taurin karfe, kuma akasin haka.
Iyakar abin da ya dace na ma'auni uku na sama shine kamar haka:
HRA (Diamond Cone indenter) 20-88
HRC (indenter na lu'u-lu'u) 20-70
HRB (diamita 1.588mm karfe ball indenter) 20-100
Gwajin taurin Rockwell hanya ce da ake amfani da ita sosai a halin yanzu, daga cikinsu ana amfani da HRC a matsayin bututun ƙarfe na biyu kawai zuwa Brinell hardness HB. Ana iya amfani da taurin Rockwell don auna kayan ƙarfe daga mai taushi sosai zuwa matuƙar wuya. Yana yin sama don gazawar hanyar Brinell. Yana da sauƙi fiye da hanyar Brinell kuma ana iya karanta ƙimar taurin kai tsaye daga bugun kiran na'urar taurin. Koyaya, saboda ƙaramar shigarsa, ƙimar taurin ba daidai bane kamar hanyar Brinell.
C. Vickers hardness (HV)
Gwajin taurin Vickers kuma hanya ce ta gwaji. Yana danna maɓallin lu'u-lu'u mai murabba'i mai murabba'in pyramidal tare da haɗaɗɗen kusurwar 1360 tsakanin filaye daban-daban cikin farfajiyar gwaji a zaɓin ƙarfin gwaji (F), kuma yana cire shi bayan ƙayyadadden lokacin riƙewa. Ƙarfi, auna tsayin diagonal biyu na ciki.
Ƙimar taurin Vickers shine adadin ƙarfin gwajin da aka raba ta wurin shimfidar wuri. Tsarin lissafinsa shine:
A cikin dabara: HV-Vickers alamar taurin, N/mm2 (MPa);
F-ƙarfin gwaji, N;
d-ma'anar lissafi na diagonal biyu na indentation, mm.
Ƙarfin gwajin F da aka yi amfani da shi a cikin taurin Vickers shine 5 (49.03), 10 (98.07), 20 (196.1), 30 (294.2), 50 (490.3), 100 (980.7) Kgf (N) da sauran matakai shida. Za a iya auna ƙimar taurin Ƙimar ita ce 5 ~ 1000HV.
Misalin hanyar magana: 640HV30/20 yana nufin cewa ƙimar taurin Vickers da aka auna tare da ƙarfin gwaji na 30Hgf (294.2N) don 20S (daƙiƙa) shine 640N/mm2 (MPa).
Ana iya amfani da hanyar taurin Vickers don tantance taurin kayan ƙarfe na sirara da yadudduka. Yana da babban fa'idodin hanyoyin Brinell da Rockwell kuma yana shawo kan gazawar su na asali, amma ba ta da sauƙi kamar hanyar Rockwell. Hanyar Vickers ba a cika yin amfani da shi ba a daidaitattun bututun ƙarfe.
Lokacin aikawa: Afrilu-03-2024