Final Report Bilateral Comparison Report on Hardness Measurement Rockwell scale A and B Between PTB and NIMT

Transcription

1 Date: October 16, 009 Fnal Report Blateral Comparson Report on Hardness Measurement Rockwell scale A and B Between PTB and NIMT Tassana Sanponpute 1, Apchaya Meesaplak, Konrad Herrmann 3, Febo Menelao 4 1. NIMT(Plot Insttute): Natonal Insttute of Metrology(Thaland), 3/5 Moo 3, Klong 5, Klong Luang, Pathumthan Provnce, 110, Thaland 3,4 PTB : Physkalsch-Technsche Bundesanstalt, Bundesallee 100, Braunschweg, Germany

2 Date: October 16, 009 Page of 16 Abstract Ths blateral comparson hardness measurement Rockwell scale A and B was arranged by Natonal Insttute of Metrology (Thaland), NIMT as a plot laboratory comparng wth Physkalsch-Technsche Bundesanstalt (PTB). The objectve of the comparson s to confrm the calbraton and measurement capabltes of NIMT n hardness measurement. The perod was between March to August 009. There are two sets of artfacts: scale A artfact set and scale B artfact set. The scale A artfact conssts of 7 hardness blocks; 35 HRA, 40 HRA, 55 HRA, 60 HRA, 70 HRA, 80 HRA, 85 HRA. The artfact for scale B conssts of 9 hardness blocks; 5 HRB, 30 HRB, 40 HRB, 50 HRB, 60 HRB, 70 HRB, 80 HRB, 90 HRB, 100 HRB. Laboratory must ensure that the prmary Rockwell hardness machne pass the verfcaton accordng to ISO Then, partcpants measure hardness value by makng 10 ndentatons n the desgnated area for each artfact block. Hardness measurement result and uncertanty budget are then reported to plot laboratory and are used to compute the degree of equvalence n terms of Comparson Reference Value (CRV) and En rato.

3 Date: October 16, 009 Page 3 of 16 Content 1. Introducton 4. Partcpatng Insttutes 4 3. Artfacts 4 4. Measurement of Artfacts 5 5. Measurement Data 6 6. Analyzng Method of Comparson Results Comparson Results 1 8. Dscusson and Concluson References 16

4 Date: October 16, 009 Page 4 of Introducton The Natonal Insttute of Metrology (Thaland), NIMT establshed the hardness natonal measurement standard on hardness scale HRA and HRB snce 006. NIMT would lke to partcpate n an nter-laboratory comparson wth a well-known natonal metrology nsttute to confrm the calbraton and measurement capabltes (CMCs) of NIMT n hardness. Physkalsch-Technsche Bundesanstalt (PTB) s one of the NMI s that have well supported NIMT. Also ths tme, the blateral comparson on HRA and HRB, ploted by NIMT, has been arranged wth Physkalsch-Technsche Bundesanstalt (PTB).. Partcpatng Insttutes Natonal Insttute of Metrology (Thaland), NIMT Physkalsch-Technsche Bundesanstalt, PTB 3. Artfacts The artfacts are Rockwell hardness scale A and scale B reference block manufactured by Asah Gken Co.,Ltd. Japan. Each scale conssts of hardness block wth seral number as n the table 1. The dmensons of the blocks are 65 mm n dameter and thckness of each block as n the table 1. Table 1 HRA Set S/N Thckness HRB Set S/N Thckness 35 HRA A mm 5 HRB A mm 40 HRA A mm 30 HRB A mm 55 HRA mm 40 HRB A mm 60 HRA A mm 50 HRB A mm 70 HRA B mm 60 HRB A mm 80 HRA mm 70 HRB A mm 85 HRA A mm 80 HRB A mm 90 HRB mm 100 HRB mm The surface of each artfact block was engraved wth dvded segments for ndcatng the ndentaton postons (Fgure 1). Each segment s used for sngle ndentaton n the comparson. There are 10 areas of measurement on each block. The rest of the segments on the block surface are reserved as alternatve places for tral and error measurements

5 Date: October 16, 009 Page 5 of 16 Fgure 1 The plastc sheet ndcatng the ndentaton poston of each partcpant wll be enclosed wth the artfact sets. It shall be placed on the artfact block n order to ensure the ndentaton poston before makng the ndentaton. The two set of artfacts, a set for scale A and a set for scale B wll be transferred between partcpants accordng to a tmetable n whch the date of measurement has been agreed between partcpants. Insttute/Country Tme of measurement NIMT, Thaland March, 009 PTB, Germany May Measurement of Artfacts The prmary Rockwell hardness machnes used for the comparson must be passed the verfcaton accordng to ISO [1]. Before makng the ndentaton on each block, the testng cycle must be adjusted to comply wth ISO Then start to measure the hardness value of artfact blocks by makng 10 ndentatons each block on the desgnated area on the ndentaton-postonng sheet. Fgure

6 Date: October 16, 009 Page 6 of Measurement Data Table NIMT HRA Measurement Result Measured value Hardness Block Number A308 A A1603 B A039 Nomnal Value (HRA) Secton Secton Secton Secton Secton Secton Secton Secton Secton Secton Average Value Correcton Value Corrected Value

7 Date: October 16, 009 Page 7 of 16 Table 3 PTB HRA Measurement Result Measured value Hardness Block Number A308 A A1603 B A039 Nomnal Value (HRA) Secton Secton Secton Secton Secton Secton Secton Secton Secton Secton Average Value Correcton Value Corrected Value

8 Date: October 16, 009 Page 8 of 16 Table 4 NIMT HRB Measurement Result Measured value Hardness Block Number A30431 A30591 A33146 A305 A33301 A3409 A Nomnal Value (HRB) Secton Secton Secton Secton Secton Secton Secton Secton Secton Secton Average Value Correcton Value Corrected Value

9 Date: October 16, 009 Page 9 of 16 Table 5 PTB HRB Measurement Result Measured value Hardness Block Number A30431 A30591 A33146 A305 A33301 A3409 A Nomnal Value (HRB) Secton Secton Secton Secton Secton Secton Secton Secton Secton Secton Average Value Correcton Value Corrected Value

10 Date: October 16, 009 Page 10 of Analyzng Method of Comparson Results The measurement results are used to compute the degree of equvalence n Comparson Reference Value (CRV) and En rato. The calculaton s shown n followng formulas: -Calculaton of Comparson Reference Value (CRV) Plot laboratory determned CRV by calculatng the weghted mean of measurements of all partcpants (x ref ). x ref x1 u ( x1 ) + x u ( x ) xn u ( xn ) = Eq. 1 1 u ( x ) + 1 u ( x ) u ( x ) 1 n -The uncertanty of the CRV was calculated by followng expresson: u 1 ( x = Eq. ) u ( x ) u ( x ) u ( ) ref 1 x n Where: x = The measured value of partcpatng nsttute ( =1,,,n) u ( x ) = The standard uncertanty of x -Its devaton from CRV d = x x Eq. 3 ref -The uncertanty of ths devaton at a 95% level of confdence U d ) = k u( d ) Eq. 4 ( Where u And k = ( d ) was gven by u ( d ) = u ( x ) + u ( x ) Eq. 5 ref -Evaluaton of Coeffcent E n The equvalence between the measurements of partcpatng nsttutes was expressed by coeffcent as well. E n E n x xref = Eq. 6 U ( x ) + U ( x ) ref Where:

11 Date: October 16, 009 U U x ) = k u( x ) ( ( xref ref Page 11 of 16 ) = k u( x ) Eq. 7 The x was equvalent wth CRV x at 95% confdence level, f E 1. ref n Where CRV U(CRV) D_PTB U(D_PTB) En rato PTB D_NIMT U(D_NIMT) En rato NIMT Ue s comparson Reference Value s uncertanty of CRV s devaton value of PTB from CRV s uncertanty of devaton value of PTB from CRV s degree of equvalence of PTB s result expressed n En rato s devaton value of NIMT from CRV s uncertanty of devaton value of NIMT from CRV s degree of equvalence of NIMT s result expressed n En rato s expanded uncertanty that evaluated by each NMIs

12 Date: October 16, 009 Page 1 of Comparson Results The HRA comparson results, comparson reference value (CRV), the devaton value of PTB and NIMT from CRV and ther uncertanty (D_PTB, D_NIMT,U(D_PTB),U(D_NIMT)) and En rato, were calculated and shown n Table 6. Fgure 3 shows Table 6 Concluson of comparson evaluaton on Rockwell hardness scale A PTB PTB Comparson Result (HRA) No. A308 A A1603 B A039 Nomnal value Measured value Ue NIMT NIMT Comparson Result (HRA) No. A308 A A1603 B A039 Nomnal value Measured value Ue Comparson evaluaton Normnal (HRA) CRV U(CRV) D_PTB U(D_PTB) En rato PTB D_NIMT U(D_NIMT) En rato NIMT

13 Date: October 16, 009 Page 13 of 16 Devaton frome KCRV n HRA Comparson result on Rockwell hardness scale A hardness scale n HRA D_PTB D_NIMT Fgure 3 Degree of equvalence expressed n En rato En rato hardness scale n HRA En rato PTB En rato NIMT Fgure 4

14 Date: October 16, 009 Page 14 of 16 Table 7 Concluson of comparson evaluaton on Rockwell hardness scale B PTB No. Nomnal value A30431 A30591 A31146 A305 Measure value (HRB) A33301 A3409 A Measured value Ue NIMT No. Nomnal value Measure value (HRB) A30431 A30591 A31146 A305 A33301 A3409 A Measured value Ue Comparson evaluaton Normnal (HRA) CRV U(CRV) D_PTB U(D_PTB) En rato PTB D_NIMT U(D_NIMT) En rato NIMT

15 Date: October 16, 009 Page 15 of 16 Comparson result on Rockwell hardness scale B Devaton frome KCRV n HRB D_PTB D_NIMT hardness scale n HRA Fgure 5 Degree of equvalence expressed n En rato En rato hardness scale n HRB En rato PTB En rato NIMT Fgure 6

16 Date: October 16, 009 Page 16 of Dscusson and Concluson Ths comparson used the devaton from CRV and the uncertanty of ths devaton of a 95% level of confdence as the degree of equvalence. The E n numbers were also calculated to express the equvalence between measurements of the partcpants. Comparson result of Rockwell hardness scale A measurement s shown n fgure 3 and 4. The range of the devaton from CRV s between 0.34 HRA to 0.08 HRA. The E n numbers ranges from 0.85 to Fgure 5 and 6 shows the comparson result of Rockwell hardness scale B measurement. The range of the devaton from CRV s between 0.17 HRB to 0.30 HRB. The E n numbers ranges from 0.36 to It has been shown that the NIMT and the PTB hardness machnes compare well. Both laboratores show the ablty of measurement n hardness scale of 35 HRA to 85 HRA and 5 HRB to 100 HRB. 9. References [1] ISO : Metallc materals-rockwell hardness test-part 3: Calbraton of reference blocks (scales A, B, C, D, E, F, G, H, K, N, T)