维氏硬度和洛氏硬度

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 Test has fairly wide acceptance for research work,5-1500DPH also named diamond-pyramid hardness Indenter: a square-base diamond pyramid(方锥形

2、金刚石) Angle: 136 the 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 =136 Advantages and Disadvantages Advantages: 1

3、. provide a continuous scale of hardness* ，5-1500 2. DPH is independent of load.* Disadvantages: 1. it is slow and need more time 2. require careful surface preparation of specimen 3. greater chance for personal error in the determination of the diagonal length Indentation types There are three kind

4、s of diamond-pyramid indentations: a) perfect indentation b) pincushion indentation(枕形压痕) c) barreled indentation（桶状压痕） Perfect Indentation made with a perfect diamond indenter square but is just ideal. Pincushion Indentation Reason: sinking in of the metal Objects: annealed metals（退火金属） Result : an

5、 overestimate of the diagonal length and DPH is lower Barreled Indentation Reason : ridging or piling up of the metal Objects: cold-worked metals Result: a low value of the contact area so the DPH is higher Rockwell hardness test The most widely used hardness among the three methods. Why is it most

6、widely used? 1. speed is fast 2. few personal errors 3. distinguish small hardness differences 4. indentation is small and tested without damage 5. reproducible(可重复的可重复的) Test Steps Use 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 maj

7、or load60,100,150kg 3. Unload the major load Purpose of minor load 1. seat the specimen 2. minimize the amount of surface preparation 3. reduce ridging or sinking in Introduction of a dial gage contains 100 divisions each division 0.002 mm reversed： small penetration high hardness number purely arbi

8、trary(non-dimensional) Introduction of the test device total 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 150kg Three frequently-used scales* Attentions for hardness test 1. Indenter: clean and well seated 2. 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 indentation 3. Indentation spacing: 3 to 5 times the diameter of t