1、Hardness Test陈政陈政01441390010144139001 2012015.5.14 5.5.14 Two parts:1. Vickers Hardness Test(维氏硬度维氏硬度)2. Rockwell hardness test（洛氏硬度）（洛氏硬度）Vickers Hardness Testhas fairly wide acceptance for research work,5-1500DPHalso named diamond-pyramid hardnessIndenter: a square-base diamond pyramid(方锥形金刚石)Angl
2、e: 136the diamond-pyramid hardness number (DPH)Definition: the load divided by the surface area of the indentation(压痕)Equation:Where, P= applied load, kg L=average length of diagonals, mmmicroscope = angle between opposite faces of diamond =136Advantages and DisadvantagesAdvantages:1. provide a cont
3、inuous scale of hardness* ，5-15002. DPH is independent of load.*Disadvantages:1. it is slow and need more time2. require careful surface preparation of specimen3. greater chance for personal error in the determination of the diagonal lengthIndentation typesThere are three kinds of diamond-pyramid in
4、dentations:a) perfect indentationb) pincushion indentation(枕形压痕)c) barreled indentation（桶状压痕）Perfect Indentationmade with a perfect diamond indentersquarebut is just ideal.Pincushion IndentationReason: sinking in of the metalObjects: annealed metals（退火金属）Result : an overestimate of the diagonal leng
5、th and DPH is lowerBarreled IndentationReason : ridging or piling up of the metalObjects: cold-worked metalsResult: a low value of the contact area so the DPH is higherRockwell hardness testThe most widely used hardness among the three methods.Why is it most widely used? 1. speed is fast 2. few pers
6、onal errors3. distinguish small hardness differences4. indentation is small and tested without damage5. reproducible(可重复的可重复的)Test StepsUse the depth of indentation to express the hardness, the steps are : 1. apply minor load(初始小载荷初始小载荷)10kg 2. apply major load60,100,150kg 3. Unload the major loadPu
7、rpose of minor load1. seat the specimen 2. minimize the amount of surface preparation3. reduce ridging or sinking in Introduction of a dial gage contains 100 divisions each division 0.002 mm reversed： small penetration high hardness numberpurely arbitrary(non-dimensional)Introduction of the test dev
8、icetotal 9 scales combinations of 3 types of indenters and 3 different loads Brale indenter (120)3 types of indenters 1.6 mm-diameter steel ball 3.2 mm -diameter steel ball 60 kg 3 different loads 100kg 150kgScale TypeApplication objectIndenter and major loadA scalemost extended*the diamond indenter
9、, 60kg B scalesofter material 1.6 mm-diameter steel ball ,100kgC scalehardened steelthe diamond indenter, 150kg Three frequently-used scales*Attentions for hardness test1. Indenter: clean and well seated2. Specimen: clean and dry, smooth, and free from oxide（氧化物）. flat surface and perpendicular(垂直) to the indenter thickness:at least 10 times the depth of the indentation3. Indentation spacing: 3 to 5 times the diameter of the indentation.4. Speed: standardized*, by adjusting the dashpot(缓冲器) The end Thanks for your attention!The end Thanks for your attention!
