Lub peev xwm ntawm cov khoom siv hlau los tiv thaiv qhov indentation ntawm qhov chaw los ntawm cov khoom tawv yog hu ua hardness. Raws li cov kev sim sib txawv thiab daim ntawv thov, qhov nyuaj tuaj yeem muab faib ua Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, microhardness thiab kub hardness. Muaj peb feem ntau siv hardnesses rau cov kav dej: Brinell, Rockwell, thiab Vickers hardness.
A. Brinell hardness (HB)
Siv lub pob steel lossis carbide pob ntawm ib txoj kab uas hla los nias rau hauv cov qauv saum npoo nrog lub zog ntsuas (F). Tom qab lub sijhawm tuav, tshem tawm lub zog ntsuas thiab ntsuas qhov indentation txoj kab uas hla (L) ntawm tus qauv nto. Brinell hardness tus nqi yog qhov quotient tau los ntawm kev faib cov kev sim quab yuam los ntawm thaj tsam ntawm qhov chaw indented. Qhia hauv HBS (steel ball), chav tsev yog N / mm2 (MPa).
Cov mis laij lej yog:
Nyob rau hauv cov mis: F-lub zog xeem nias rau saum npoo ntawm cov qauv hlau, N;
D-Txoj kab uas hla ntawm steel pob rau kev xeem, mm;
d – nruab nrab txoj kab uas hla ntawm indentation, mm.
Kev ntsuas ntawm Brinell hardness yog qhov tseeb dua thiab txhim khu kev qha, tab sis feem ntau HBS tsuas yog tsim rau cov ntaub ntawv hlau qis dua 450N / mm2 (MPa), thiab tsis haum rau cov hlau hnyav lossis cov phaj nyias nyias. Ntawm cov qauv steel yeeb nkab, Brinell hardness yog siv dav tshaj plaws. Lub indentation txoj kab uas hla d feem ntau yog siv los qhia qhov hardness ntawm cov khoom, uas yog ob qho tib si intuitive thiab yooj yim.
Piv txwv li: 120HBS10/1000130: Nws txhais tau hais tias Brinell hardness tus nqi ntsuas los ntawm kev siv lub 10 hli txoj kab uas hla steel pob nyob rau hauv lub xeem quab yuam ntawm 1000Kgf (9.807KN) rau 30s (seconds) yog 120N / mm2 (MPa).
B. Rockwell hardness (HR)
Rockwell hardness test, zoo li Brinell hardness test, yog ib qho kev xeem indentation. Qhov txawv yog tias nws ntsuas qhov tob ntawm qhov indentation. Ntawd yog, nyob rau hauv qhov kev ua ntu zus ntawm qhov kev sim thawj zaug (Fo) thiab tag nrho cov kev xeem quab yuam (F), lub indenter (cone los yog steel pob ntawm steel zeb) yog nias rau saum npoo ntawm cov qauv. Tom qab lub sijhawm tuav tau teev tseg, lub zog tseem ceeb raug tshem tawm. Test quab yuam, siv qhov ntsuas qhov seem seem indentation qhov tob increment (e) los xam tus nqi hardness. Nws tus nqi yog tus lej tsis qhia npe, sawv cev los ntawm lub cim HR, thiab cov nplais siv suav nrog 9 nplai, suav nrog A, B, C, D, E, F, G, H, thiab K. Ntawm lawv, cov nplais feem ntau siv rau cov hlau. Kev ntsuas hardness feem ntau yog A, B, thiab C, uas yog HRA, HRB, thiab HRC.
Tus nqi hardness yog xam los ntawm cov qauv hauv qab no:
Thaum kuaj nrog A thiab C nplai, HR = 100-e
Thaum kuaj nrog B nplai, HR = 130-e
Nyob rau hauv cov mis, e - qhov seem indentation qhov tob increment yog qhia nyob rau hauv lub teev teev ntawm 0.002mm, uas yog, thaum lub axial displacement ntawm lub indenter yog ib chav tsev (0.002mm), nws yog sib npaug rau ib tug hloov nyob rau hauv Rockwell hardness los ntawm ib tug. tus lej. Qhov loj dua tus nqi e, qhov qis dua qhov hardness ntawm cov hlau, thiab vice versa.
Qhov siv tau ntawm peb qhov ntsuas saum toj no yog raws li hauv qab no:
HRA (pob zeb diamond cone indenter) 20-88
HRC (pob zeb diamond cone indenter) 20-70
HRB (inch 1.588mm steel pob indenter) 20-100
Rockwell hardness test yog ib txoj kev siv dav heev nyob rau tam sim no, ntawm cov HRC yog siv nyob rau hauv steel yeeb nkab qauv thib ob tsuas yog Brinell hardness HB. Rockwell hardness tuaj yeem siv los ntsuas cov ntaub ntawv hlau los ntawm cov mos mos mus rau qhov nyuaj heev. Nws ua rau qhov tsis txaus ntawm Brinell txoj kev. Nws yog qhov yooj yim dua li Brinell txoj kev thiab tus nqi hardness tuaj yeem nyeem ncaj qha los ntawm lub xov tooj ntawm lub tshuab hardness. Txawm li cas los xij, vim nws qhov me me indentation, tus nqi hardness tsis yog raws li txoj kev Brinell.
C. Vickers hardness (HV)
Vickers hardness test kuj tseem yog ib qho kev xeem indentation. Nws nias lub square pyramidal pob zeb diamond indenter nrog lub kaum sab xis ntawm 1360 ntawm qhov sib txawv ntawm qhov sib txawv rau hauv qhov chaw kuaj ntawm qhov kev sim xaiv (F), thiab tshem tawm nws tom qab lub sijhawm tuav. Force, ntsuas qhov ntev ntawm ob kab pheeb ces kaum ntawm indentation.
Vickers hardness tus nqi yog qhov quotient ntawm qhov ntsuas quab yuam muab faib los ntawm qhov chaw indentation. Nws cov qauv kev suav yog:
Hauv cov mis: HV-Vickers hardness cim, N / mm2 (MPa);
F-test force, N;
d - tus lej lej ntawm ob kab pheeb ces kaum ntawm qhov indentation, mm.
Kev ntsuas F siv hauv Vickers hardness yog 5 (49.03), 10 (98.07), 20 (196.1), 30 (294.2), 50 (490.3), 100 (980.7) Kgf (N) thiab lwm rau qib. Tus nqi hardness tuaj yeem ntsuas Qhov ntau yog 5 ~ 1000HV.
Piv txwv ntawm txoj kev qhia: 640HV30/20 txhais tau hais tias Vickers hardness tus nqi ntsuas nrog lub zog ntsuas ntawm 30Hgf (294.2N) rau 20S (thib ob) yog 640N / mm2 (MPa).
Vickers hardness txoj kev tuaj yeem siv los txiav txim siab hardness ntawm cov khoom siv hlau nyias thiab cov txheej txheej saum npoo. Nws muaj qhov zoo ntawm Brinell thiab Rockwell txoj hauv kev thiab kov yeej lawv qhov tsis txaus, tab sis nws tsis yooj yim li Rockwell txoj kev. Vickers txoj kev tsis tshua siv nyob rau hauv cov qauv steel yeeb nkab.
Post lub sij hawm: Apr-03-2024