Ikon kayan ƙarfe na jure wa shigar abubuwa masu tauri a saman ana kiransa tauri. Dangane da hanyoyin gwaji daban-daban da iyakokin aikace-aikacen, ana iya raba tauri zuwa tauri na Brinell, tauri na Rockwell, tauri na Vickers, tauri na Shore, tauri na microhardness da tauri na zafin jiki mai yawa. Akwai tauri guda uku da ake amfani da su don bututu: tauri na Brinell, Rockwell, da Vickers.
A. Taurin Brinell (HB)
Yi amfani da ƙwallon ƙarfe ko ƙwallon carbide mai wani diamita don matsawa cikin saman samfurin tare da ƙarfin gwaji da aka ƙayyade (F). Bayan lokacin riƙewa da aka ƙayyade, cire ƙarfin gwaji kuma auna diamita na shigarwa (L) akan saman samfurin. Ƙimar taurin Brinell shine ƙimar da aka samu ta hanyar raba ƙarfin gwajin ta hanyar yankin saman da aka shigar da shi. An bayyana a cikin HBS (ƙwallon ƙarfe), naúrar ita ce N/mm2 (MPa).
Tsarin lissafi shine:
A cikin dabarar: F–ƙarfin gwajin da aka matse a saman samfurin ƙarfe, N;
D-Dimita na ƙwallon ƙarfe don gwaji, mm;
d - matsakaicin diamita na shigarwar, mm.
Ma'aunin taurin Brinell ya fi daidai kuma abin dogaro, amma gabaɗaya HBS ya dace ne kawai da kayan ƙarfe da ke ƙasa da 450N/mm2 (MPa), kuma bai dace da faranti masu tauri ko siriri ba. Daga cikin ƙa'idodin bututun ƙarfe, taurin Brinell shine mafi yawan amfani. Ana amfani da diamita na indentation d sau da yawa don bayyana taurin kayan, wanda yake da sauƙin fahimta kuma mai sauƙin amfani.
Misali: 120HBS10/1000130: Yana nufin cewa ƙimar taurin Brinell da aka auna ta amfani da ƙwallon ƙarfe mai diamita 10mm a ƙarƙashin ƙarfin gwajin 1000Kgf (9.807KN) na tsawon 30s (daƙiƙa) shine 120N/mm2 (MPa).
B. Taurin Rockwell (HR)
Gwajin taurin Rockwell, kamar gwajin taurin Brinell, hanya ce ta gwajin shiga. Bambancin shine yana auna zurfin shiga. Wato, a ƙarƙashin aikin da aka yi a jere na ƙarfin gwaji na farko (Fo) da jimlar ƙarfin gwaji (F), ana matse mai shiga (mazugi ko ƙwallon ƙarfe na injin niƙa ƙarfe) a saman samfurin. Bayan lokacin riƙewa da aka ƙayyade, ana cire babban ƙarfin. Ƙarfin gwaji, yi amfani da ƙarin zurfin shiga da aka auna (e) don ƙididdige ƙimar taurin. Ƙimar sa lamba ce da ba a san ta ba, wacce alamar HR ta wakilta, kuma ma'aunin da aka yi amfani da shi sun haɗa da ma'auni 9, gami da A, B, C, D, E, F, G, H, da K. Daga cikinsu, ma'aunin da aka saba amfani da shi don gwajin taurin ƙarfe gabaɗaya A, B, da C, wato HRA, HRB, da HRC.
Ana ƙididdige ƙimar taurin ta amfani da dabarar mai zuwa:
Lokacin gwaji tare da ma'aunin A da C, HR = 100-e
Lokacin gwaji da sikelin B, HR=130-e
A cikin dabarar, e - ana bayyana ƙaruwar zurfin shigar da ya rage a cikin naúrar da aka ƙayyade ta 0.002mm, wato, lokacin da canjin axial na shigar da ya zama naúrar ɗaya (0.002mm), yana daidai da canjin taurin Rockwell da lamba ɗaya. Girman ƙimar e, ƙarancin taurin ƙarfe, da akasin haka.
Tsarin da ya dace na ma'auni uku da ke sama kamar haka:
HRA (mai shigar da lu'u-lu'u) 20-88
HRC (mai shigar da lu'u-lu'u) 20-70
HRB (mai girman diamita 1.588mm na ƙwallon ƙarfe) 20-100
Gwajin taurin Rockwell hanya ce da ake amfani da ita sosai a yanzu, daga ciki ana amfani da HRC a ma'aunin bututun ƙarfe wanda ya fi ƙarfin Brinell HB. Ana iya amfani da taurin Rockwell don auna kayan ƙarfe daga mai laushi sosai zuwa mai ƙarfi sosai. Yana rama kurakuran hanyar Brinell. Ya fi sauƙi fiye da hanyar Brinell kuma ana iya karanta ƙimar taurin kai tsaye daga na'urar taurin. Duk da haka, saboda ƙaramin ƙofa, ƙimar taurin ba ta yi daidai da hanyar Brinell ba.
C. Taurin Vickers (HV)
Gwajin taurin Vickers shi ma hanya ce ta gwajin shiga ciki. Yana danna wani ma'aunin lu'u-lu'u mai siffar murabba'i mai siffar 1360 tsakanin saman da ke gaba da juna zuwa saman gwajin a wani ƙarfin gwaji da aka zaɓa (F), sannan ya cire shi bayan lokacin riƙewa da aka ƙayyade. A auna tsawon ma'aunin ma'aunin biyu na shiga ciki.
Ƙimar taurin Vickers ita ce ƙimar ƙarfin gwajin da aka raba ta yankin saman shigarwa. Tsarin lissafinsa shine:
A cikin dabarar: Alamar taurin HV–Vickers, N/mm2 (MPa);
Ƙarfin gwaji na F, N;
d–ma'aunin lissafi na diagonal biyu na ƙofa, 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. Ana iya auna ƙimar taurin. Zangon shine 5~1000HV.
Misalin hanyar bayyanawa: 640HV30/20 yana nufin cewa ƙimar taurin Vickers da aka auna 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 masu siriri da kuma yadudduka na saman. Yana da manyan fa'idodin hanyoyin Brinell da Rockwell kuma yana shawo kan gazawarsu ta asali, amma ba shi da sauƙi kamar hanyar Rockwell. Ba kasafai ake amfani da hanyar Vickers a cikin mizanin bututun ƙarfe ba.
Lokacin Saƙo: Afrilu-03-2024
