ImageVerifierCode 换一换
格式:PDF , 页数:8 ,大小:140.92KB ,
资源ID:462221      下载积分:10000 积分
快捷下载
登录下载
邮箱/手机:
温馨提示:
如需开发票,请勿充值!快捷下载时,用户名和密码都是您填写的邮箱或者手机号,方便查询和重复下载(系统自动生成)。
如填写123,账号就是123,密码也是123。
特别说明:
请自助下载,系统不会自动发送文件的哦; 如果您已付费,想二次下载,请登录后访问:我的下载记录
支付方式: 支付宝扫码支付 微信扫码支付   
注意:如需开发票,请勿充值!
验证码:   换一换

加入VIP,免费下载
 

温馨提示:由于个人手机设置不同,如果发现不能下载,请复制以下地址【http://www.mydoc123.com/d-462221.html】到电脑端继续下载(重复下载不扣费)。

已注册用户请登录:
账号:
密码:
验证码:   换一换
  忘记密码?
三方登录: 微信登录  

下载须知

1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。
2: 试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓。
3: 文件的所有权益归上传用户所有。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 本站仅提供交流平台,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。

版权提示 | 免责声明

本文(ASTM B771-1987(2006) Standard Test Method for Short Rod Fracture Toughness of Cemented Carbides《硬质合金短杆断裂韧度的试验方法》.pdf)为本站会员(testyield361)主动上传,麦多课文库仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知麦多课文库(发送邮件至master@mydoc123.com或直接QQ联系客服),我们立即给予删除!

ASTM B771-1987(2006) Standard Test Method for Short Rod Fracture Toughness of Cemented Carbides《硬质合金短杆断裂韧度的试验方法》.pdf

1、Designation: B 771 87 (Reapproved 2006)Standard Test Method forShort Rod Fracture Toughness of Cemented Carbides1This standard is issued under the fixed designation B 771; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of

2、 last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the fracturetoughness of cemented carbides (KIcSR) by testing slotted s

3、hortrod or short bar specimens.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of

4、 this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 399 Test Method for Linear-Elastic Plane-Strain FractureToughness KIcof Metallic Materials3. Terminology Definitio

5、ns3.1 stress intensity factor, Kl,(dimensional units FL3/2)the magnitude of the ideal-crack-tip stress field for mode 1 ina linear-elastic body.NOTE 1Values of K for mode l are given by:Kl5 limit sy=2pr#r0 (1)where:r = distance directly forward from the crack tip to alocation where the significant s

6、tress syis calculated,andsy= principal stress normal to the crack plane.3.2 Abbreviations:fracture toughness of cemented carbide,KIcSR,(dimensional units FL3/2)the material-toughnessproperty measured in terms of the stress-intensity factor Klbythe operational procedure specified in this test method.

7、4. Summary of Test Method4.1 This test method involves the application of an openingload to the mouth of the short rod or short bar specimen whichcontains a chevron-shaped slot. Load versus displacementacross the slot at the specimen mouth is recorded autographi-cally. As the load is increased, a cr

8、ack initiates at the point ofthe chevron slot and slowly advances longitudinally, tending tosplit the specimen in half. The load goes through a smoothmaximum when the width of the crack front is about one thirdof the specimen diameter (short rod) or breadth (short bar).Thereafter, the load decreases

9、 with further crack growth. Twounloading-reloading cycles are performed during the test tomeasure the effects of any macroscopic residual stresses in thespecimen. The fracture toughness is calculated from themaximum load in the test and a residual stress parameter whichis evaluated from the unloadin

10、g-reloading cycles on the testrecord.5. Significance and Use5.1 The property KIcSRdetermined by this test method isbelieved to characterize the resistance of a cemented carbide tofracture in a neutral environment in the presence of a sharpcrack under severe tensile constraint, such that the state of

11、stress near the crack front approaches tri-tensile plane strain,and the crack-tip plastic region is small compared with thecrack size and specimen dimensions in the constraint direction.A KIcSRvalue is believed to represent a lower limiting value offracture toughness. This value may be used to estim

12、ate therelation between failure stress and defect size when theconditions of high constraint described above would be ex-pected. Background information concerning the basis fordevelopment of this test method in terms of linear elasticfracture mechanics may be found in Refs (1-4).35.2 This test metho

13、d can serve the following purposes:5.2.1 To establish, in quantitative terms significant to ser-vice performance, the effects of fabrication variables on thefracture toughness of new or existing materials, and5.2.2 To establish the suitability of a material for a specificapplication for which the st

14、ress conditions are prescribed andfor which maximum flaw sizes can be established withconfidence.1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.06 on Cemented Carbides.Current edition a

15、pproved April 1, 2006. Published April 2006. Originallyapproved in 1987. Last previous edition approved in 2001 as B 771 87 (2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informa

16、tion, refer to the standards Document Summary page onthe ASTM website.3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Specimen Configu

17、ration, Dimensions, and Preparation6.1 Both the round short rod specimen and the rectangularshaped short bar specimen are equally acceptable and havebeen found to have the same calibration (5). The short roddimensions are given in Fig. 1; the short bar in Fig. 2.6.2 Grip SlotDepending on the apparat

18、us used to test thespecimen, a grip slot may be required in the specimen frontface, as shown in Fig. 3. The surfaces in the grip slot shall havea smooth ground finish so that the contact with each grip willbe along an essentially continuous line along the entire gripslot, rather than at a few isolat

19、ed points or along a shortsegment within the grip slot.6.3 Crack-Guiding SlotsThese may be ground using adiamond abrasive wheel of approximately 124 6 3 mm (4.9 60.1 in.) diameter, with a thickness of 0.36 6 0.01 mm (0.01406 0.0005 in.). The resulting slots in the specimen are slightlythicker than t

20、he diamond wheel (0.38 6 0.02 mm, or 0.015 60.001 in.). A diamond concentration number of 50, and a gritsize of 150 are suggested. Dimensions are given in Fig. 1 andFig. 2 for two slotting options: (1) Specimens with curved slotbottoms made by plunge feeding the specimen onto a diamondcutting wheel

21、of a given radius, and (2) Specimens withstraight slot bottoms made by moving the specimen by acutting wheel. The values of aoand u for the two slotconfigurations are chosen to cause the specimen calibration toremain constant.7. Apparatus7.1 The procedure involves testing of chevron-slotted speci-me

22、ns and recording the load versus specimen mouth openingdisplacement during the test.Standard DimensionsShort Rod(mm) (in.)B = 12.700 6 0.025 0.500 6 0.001W = 19.050 6 0.075 0.750 6 0.003t = 0.381 6 0.025 0.015 6 0.001For Curved Slot Optionao= 6.3506 0.075 0.250 6 0.003u = 58.0 6 0.5R = 62.23 6 1.27

23、02.45 6 0.05For Straight Slot Optionao= 6.7446 0.075 0.266 6 0.003u = 55.2 6 0.5R=FIG. 1 Short Rod SpecimenStandard DimensionsShort Bar(mm) (in.)B = 12.700 6 0.025 0.500 6 0.001H = 11.050 6 0.025 0.435 6 0.001W = 19.050 6 0.075 0.750 6 0.003t = 0.3816 0.025 0.015 6 0.001For Curved Slot Optionao= 6.3

24、506 0.075 0.250 6 0.003u = 58.0 6 0.5R = 62.23 6 1.27 2.45 6 0.05For Straight Slot Optionao= 6.744 6 0.075 0.266 6 0.003u = 55.2 6 0.5R=FIG. 2 Short Bar SpecimenNOTE 1The dashed lines show the front face profile of Figs. 1 and 2without grip slot.FIG. 3 Short Rod and Short Bar Grip Slot in Specimen F

25、ront FaceB 771 87 (2006)27.2 Grips and Fixtures for Tensile Test Machine LoadingGrip slots are required in the specimen face for this testmethod, as shown in Fig. 3. Fig. 4 shows the grip design. Gripsshall have a hardness of 45 HRC or greater, and shall becapable of providing loads to at least 1560

26、 N (350 lbf). Thegrips are attached to the arms of tensile test machine by the pinand clevis arrangement shown in Fig. 5. The grip lips areinserted into the grip slot in the specimen, and the specimen isloaded as the test machine arms apply a tensile load to thegrips.Atransducer for measuring the sp

27、ecimen mouth openingdisplacement during the test, and means for automaticallyrecording the load-displacement test record, such as an X-Yrecorder, are also required when using the tensile test machineapparatus.Asuggested design for the specimen mouth openingdisplacement gage appears in Fig. 6. The ga

28、ge shall have adisplacement resolution of 0.25 m (10 3 106in.) or better.However, it is not necessary to calibrate the displacement axisof the test record since only displacement ratios are used in thedata analysis.7.3 Distributed Load Test Machine4An alternative specialpurpose machine that has been

29、 found suitable for the testrequires no grip slot in the front face of the specimen. A thinstainless steel inflatable bladder is inserted into the chevron slotin the mouth of the specimen. Subsequent inflation of thebladder causes it to press against the inner surfaces of the slot,thus producing the

30、 desired loading. The machine provides loadand displacement outputs, which must be recorded externallyon a device such as an X-Y recorder.7.4 Testing Machine CharacteristicsIt has been observedthat some grades of carbides show a “pop-in” type of behaviorin which the load required to initiate the cra

31、ck at the point ofthe chevron slot is larger than the load required to advance thecrack just after initiation, such that the crack suddenly andaudibly jumps ahead at the time of its initiation. Occasionally,the load at crack initiation can exceed the load maximumwhich occurs as the crack passes thro

32、ugh the critical location inthe specimen. When this occurs, a very stiff machine withcontrolled displacement loading is necessary in order to allowthe crack to arrest well before passing beyond the criticallocation. The large pop-in load is then ignored, and thesubsequent load maximum as the crack p

33、asses through thecritical location is used to determine KIcSR. Stiff machineloading is also required in order to maintain crack growthstability to well beyond the peak load in the test, where thesecond unloading-reloading cycle is initiated.8. Procedure8.1 Number of TestsA minimum of 3 replicate tes

34、ts shallbe made.8.2 Specimen Measurement:8.2.1 Measure and record all specimen dimensions. If thedimensions are within the tolerances shown in Fig. 1 and Fig.2, no correction to the data need be made for out-of-tolerancedimensions. If one or more of the parameters ao, W, u or t areout of tolerance b

35、y up to 3 times the tolerances shown in Fig.1 and Fig. 2, valid tests may still be made by the application ofthe appropriate factors to account for the deviation fromstandard dimensions (see 9.3). If the slot centering is outsidethe indicated tolerance, the crack is less likely to follow thechevron

36、slots. However, the test may still be consideredsuccessful if the crack follows the slots sufficiently well, asdiscussed in 9.2.8.2.2 The slot thickness measurement is critical on speci-mens to be tested on a Fractometer. It should be measured towithin 0.013 mm (0.0005 in.) at the outside corners of

37、 the slot4Fractometer, a trademark of Terra Tek Systems, 360 Wakara Way, Salt LakeCity, UT 84108, has been found satisfactory for this purpose.FIG. 4 Grip DesignFIG. 5 Tensile Test Machine Test ConfigurationB 771 87 (2006)3using a feeler gage. If a feeler gage blade enters the slot to adepth of 1 mm

38、 or more, the slot is said to be at least as thickas the blade. Because the saw cuts forming the chevron slotoverlap somewhat in the mouth of the specimen, and becausethe cuts may not meet perfectly, the slot width near the centerof the mouth may be larger than the width at the outsidecorners. If th

39、e slot width near the center exceeds the slot widthat the corners by more than 0.10 mm (0.004 in.), a test of thatspecimen by a Fractometer is invalid.8.3 Specimen Testing Procedure:8.3.1 Load Transducer Calibration:8.3.1.1 Calibrate the output of the load cell in the testmachine to assure that the

40、load cell output, as recorded on theload versus displacement recorder, is accurately translatableinto the actual force applied to the specimen. In those cases inwhich a distributed load test machine is used (see 7.3), thecalibration shall be performed according to the instructions inAnnex A1.8.3.1.2

41、 Install the specimen on the test machine. If using thetensile test machine (see 7.2), operate the test machine in the“displacement control” mode. Bring the grips sufficiently closetogether such that they simultaneously fit into the grip slot inthe specimen face. Then increase the spacing between th

42、e gripsvery carefully until an opening load of 10 to 30 N (2 to 7 lb)is applied to the specimen. Check the alignment of thespecimen with respect to the grips, and the alignment of thegrips with respect to each other. The grips shall be centered inthe specimen grip slot to within 0.25 mm (0.010 in.).

43、 Thevertical offset between the grips shall not exceed 0.13 mm(0.005 in.). Using a magnifying glass, observe the grips in thegrip slot from each side of the specimen to assure that thespecimen is properly installed. The grips should extend as faras possible into the grip slot, resulting in contact l

44、ines (loadlines) at 0.63 mm (0.025 in.) from the specimen front face.Correct any deviations from the desired specimen alignment.8.3.1.3 Install the specimen mouth opening displacementgage on the specimen. The gage must sense the mouth openingno farther than 1 mm (0.040 in.) from the front face of th

45、especimen. If the gage design of Fig. 6 is used, the contact forcebetween the gage arms and the specimen can be adjusted witha rubber elastic band so the gage will support itself, asindicated in Fig. 5. However, the contact force must not bemore than 2 N (0.5 lb), as it increases the measured load t

46、ofracture the specimen.8.3.1.4 Adjust the displacement (x-axis) sensitivity of theload-displacement recorder to produce a convenient-size datatrace. A 70 angle between the x-axis and the initial elasticloading trace of the test is suggested.Aquantitative calibrationof the displacement axis is not ne

47、cessary.8.3.1.5 With the load-displacement recorder operating, testthe specimen by causing the specimen mouth to open at a rateof 0.0025 to 0.0125 mm/s (0.0001 to 0.0005 in./s). Thespecimen is unloaded by reversing the motion of the gripstwice during the test. The first unloading is begun when thesl

48、ope of the unloading line on the load-displacement recordwill be approximately 70 % of the initial elastic loading slope.(For estimating the point at which the unloadings should beinitiated, it can be assumed that the unloading paths will belinear and will point toward the origin of the load-displac

49、ementrecord.) The second unloading is begun when the unloadingslope will be approximately 35 % of the initial elastic loadingslope. Each unloading shall be continued until the load on thespecimen has decreased to less than 10 % of the load at theinitiation of the unloading. The specimen shall be immediatelyFIG. 6 Suggested Design for a Specimen Mouth Opening GageB 771 87 (2006)4reloaded and the test continued after each unloading. The testrecord generated by the above procedure should be similar tothat of Fig. 8.8.3.2 Crack-Pop-InIf a sudden load dro

copyright@ 2008-2019 麦多课文库(www.mydoc123.com)网站版权所有
备案/许可证编号:苏ICP备17064731号-1