2個步驟壓入試樣表面。卸除主試驗力后，在規定條件下，將壓頭（金剛石圓錐、鋼球或球）分在初試驗力下測量壓痕殘余深度h。以壓痕殘余深度h代表硬度的高低。洛氏硬度試驗原理如圖2-1所示。
1—在初始試驗力Fo下的壓入深度;
2一在總試驗力Fo+F1下的壓入深度;
3—去除主試驗力F1后的彈性回復深度;
4—殘余壓入深度h;
5一試樣表面:
6一測量基準面:
7一壓頭位置
圖 2-1洛氏硬度試驗原理圖
洛氏硬度值按下式計算:
N一常數，對于A、C、D、N、T標尺，N=100:其他標尺，N=130;
h一殘余壓痕深度，mm :
S一常數，對于，S=0.002mm，對于，S=0.001mm。每一洛氏硬度單位對應的壓痕深度，洛氏硬度為0.002mm，表面洛氏硬度為―0.001mm。壓痕越淺，硬度越高。洛氏硬度試驗分為―2種，一種是普通洛氏硬度試驗，一種是表面洛氏硬度試驗。洛氏硬度試驗采用120°金剛石圓錐和1.588mm D3.175mm鋼球三種壓頭，采用6Okg、100kg、150kg 三種試驗力，它們共有九種組合，對應于洛氏硬度的九個標尺，即 HRA、HRB、HRC、HRD、HRE、HRF、HRG、HRH、HRK。表面洛氏硬度試驗采用120 0金剛石圓錐和1.588mm鋼球2種壓頭，采用15kg、30kg、45kg 三種試驗力，它們共有六種組合，對應于表面洛氏的六個標尺，即 HR15N、HR30N、HR45N、HR15T、HR30T、HR45T。洛氏硬度試驗條件如表2一1所示。洛氏硬度標尺的選用如表2一2所示。
N標尺用于類似洛氏標尺C、A和D檢測的材料，但僅限于薄小試樣和淺硬化深度的試樣。
T標尺用于類似洛氏標尺B、F和G檢測的材料，但僅限于薄小試樣和較軟且覆鍍層較淺的試樣。
洛氏硬度計的特點
洛氏硬度試驗操作簡單，測量迅速，可在指示表上直接讀取硬度值，工作效率高，成為最常用的硬度試驗方法之一。由于試驗力較小，壓痕也小，特別是表面洛氏硬度試驗的壓痕更小，對大多數工件的使用無影響，可直接測試成品工件，初試驗力的采用，使得試樣表面輕微的不平度對硬度值的影響較小，因此，此儀器非常適于在工廠使用，適于對成批加工的成品或半成品工件進行逐件檢測，該試驗方法對測量操作的要求不高，非專業人員容易掌握。
洛氏硬度計的應用
洛氏硬度試驗采用了︰3種壓頭，6種試驗力，根據金屬材料材質、硬度范圍及尺寸的不同，共有15個標尺可供選擇，可以測試從很軟到很硬幾乎全部常見的金屬材料，應用范圍十分廣闊。洛氏硬度計在工業生產中得到了廣泛應用，成為檢驗產品質量，確定合理加工工藝的主要手段。可測試各種黑色和有色金屬，測試淬火鋼、回火鋼、鋼、表面硬化鋼、各種厚度的板材材料、粉末冶金材料、熱噴涂層的硬度。
表面洛氏硬度計用于測試薄板金屬、薄壁管材、表面硬化鋼和小零件的硬度。
影像測量儀技術基礎的基本結構信息由TTC影像測量儀提供。英斯特力儀器是一家集研發、生產及銷售于一體的 影像測量儀，拉力試驗機, 硬度計 ,探傷儀, 粗糙度儀, 測厚儀, 金相設備廠家, 致力于為客戶提供更好的檢測儀器。
Two steps are pressed into the surface of the sample. After the main test force is removed, the indentation residual depth h is measured by separating the indentation head (diamond cone, steel ball or ball) under the initial test force under specified conditions. Indentation residual depth h represents the level of hardness. Figure 2-1 shows the principle of rockwell hardness test.
1 - Pressing depth under initial test force Fo; The pressing depth under the total test force Fo+F1; 3 -- Elastic recovery depth after removing the main test force F1; 4 -- Residual pressing depth H; 5 a sample surface :6 a measurement datum :7 a pressure head position
Figure 2-1 Schematic diagram of Rockwell hardness test
Rockwell hardness value is calculated as follows:
N - constant, N=100 for A, C, D, N, T scales, N=130 for other scales;
H - Residual indentation depth, mm:
S is a constant, for S=0.002mm, for S=0.001mm. Each Rockwell hardness unit corresponds to the indentation depth, rockwell hardness is 0.002mm, the surface rockwell hardness is -- 0.001mm. The shallower the indentation, the higher the hardness. Rockwell hardness test is divided into 2 kinds, one is ordinary Rockwell hardness test, one is surface Rockwell hardness test. Rockwell hardness test adopts three indenters of 120° diamond cone and 1.588mm D3.175mm steel ball, and three test forces of 6Okg, 100kg and 150kg are used. There are nine combinations corresponding to nine scales of Rockwell hardness. Namely, HRA, HRB, HRC, HRD, HRE, HRF, HRG, HRH, and HRK. The surface Rockwell hardness test adopts two intakes of 120 0 diamond cone and 1.588mm steel ball, and three test forces of 15kg, 30kg and 45kg are used. They have six combinations corresponding to the six scale of the surface Rockwell, namely HR15N, HR30N, HR45N, HR15T, HR30T and HR45T. Rockwell hardness test conditions are shown in Table 2-1. Rockwell hardness scale is selected as shown in Table 2-2.
The N scale is used for materials similar to rockwell scales C, A and D, but only for thin, small specimens and specimens with shallow hardening depth.
T scale is used for materials similar to Rockwell scale B, F and G, but only for thin and small samples and soft and shallow coating samples.
Rockwell hardness tester characteristics
Rockwell hardness test is one of the most commonly used hardness test methods because of its simple operation and rapid measurement. The hardness value can be read directly on the indicator table with high efficiency. Because the test force is small, the indentation is small, especially the indentation of the surface Rockwell hardness test is smaller, the use of most of the workpiece has no effect, can directly test the finished workpiece, the use of the initial test force, making the sample surface slight roughness of the hardness value of the impact is small, therefore, this instrument is very suitable for use in the factory, Suitable for batch processing of finished or semi-finished work piece by piece inspection, the test method is not high requirements for measurement operation, non-professionals easy to master.
Rockwell hardness tester application
Rockwell hardness test uses: 3 kinds of indenter, 6 kinds of test force, according to the metal material material, hardness range and size of different, a total of 15 scales to choose from, can test from very soft to very hard almost all common metal materials, the application range is very broad. Rockwell hardness tester has been widely used in industrial production, and has become the main means of testing product quality and determining reasonable processing technology. Can test all kinds of black and non-ferrous metals, test hardened steel, tempered steel, steel, surface hardening steel, various thickness of plate materials, powder metallurgy materials, thermal spraying layer hardness.
Surface Rockwell hardness tester is used to test the hardness of sheet metal, thin-wall pipe, surface hardened steel and small parts.
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