5Hardness and Hardness testing

1、Rockwell test :洛氏硬度實(shí)驗(yàn) http:/ and Hardness testing詞匯VocabularyWhy hardness testing?In manufacturing applications, materials are primarily tested for two reasons: to research the characteristics of a new materialfor quality check to ensure that the sample meets a particular specification.研究新材料的特性/特點(diǎn) 質(zhì)

2、量檢查，為保證樣本符合技術(shù)要求。 Hardened steel ball: 淬火鋼球淬火鋼球/硬化鋼球硬化鋼球Ball indentation test: 鋼球壓痕試驗(yàn) Hardness and Hardness testingHardened steel is a type of carbon steel 碳鋼. This material consists of steel that has been specially treated to improve its hardness and strength. Indentation:壓痕,壓凹 Indentation test: 壓痕試

3、驗(yàn),壓痕硬度試驗(yàn)， 壓凹硬度試驗(yàn)Hardness and Hardness testingIndenter：壓頭A device used in a hardness test that is pressed into the test material. A type of hardness test in which a hardened indenter is forced against a material under a fixed load. The size of the indentation indicates the hardness of the material. b

4、all indenter: 鋼球壓頭A spherical indenter used in the Brinell test and certain Rockwell tests. hardness testing 硬度試驗(yàn)/硬度測試 Standardized experiments designed to determine how a material responds to external forces that attempt to scratch, penetrate, or indent the material. hardness value：硬度值 A number fro

5、m a hardness testing scale that indicates the ability of a material to resist scratching and penetration depth of indentation 壓痕深度Holder：保持器Right angle: 直角Graduated: 分度的，刻度的Subsequent: 后來的Slack： Moving slowly 松馳 的average curvature 平均曲率平均曲率 average diameter 平均直徑平均直徑 Hardness and Hardness testingIndic

6、ator: 指標(biāo)器， 測量儀表indicator A device that displays a measurement. An indicator may be a dial with a needle or a digital readout.Represent: 代表， 表示Supplement: 補(bǔ)充， 補(bǔ)加Denote: 代表，表示Routine: 日常的， 常規(guī)的Finished: 已精加工的Ferrous: 鐵的Alloy: 合金Hardness and Hardness testingminor load：小載荷/預(yù)載荷預(yù)載荷 The first and smallest s

7、tatic load delivered during a hardness test.Hardness and Hardness testingA minor load of 10 kg is first applied, which causes an initial penetration and holds the indenter in place.Then, the dial is set to zero major load：大載荷/主載荷主載荷 The second and largest static load delivered during a hardness test

8、. Hardness and Hardness testingstatic load：靜載荷 An external force that is applied and held in a fixed position for a specific amount of time. Example：Static loads are an important component of standardized hardness tests. Radii：半徑 The distance from the center of a circle to a point on its circumferen

9、ce. The plural term for radius is radii. Circumference：圓周circumference of a circle ：圓周圓周RadiiCircumferenceRange：范圍 The limit of measurement values that an instrument is capable of reading.Example：The dimension being measured must fit inside the range of the instrument. Casting: 鑄件A workpiece formed

10、by pouring molten metal into a mold and cooling it into a solid shape. Example：Castings are formed near their finished shape. cold working: 冷加工 The shaping of metal at temperatures much lower than the metals molten state 熔化狀態(tài)熔化狀態(tài), often at room temperature （常溫，房間溫度常溫，房間溫度）. Example：Cold working adds

11、 certain properties to the metal, such as increased strength and improved surface finish. Forging：鍛壓，鍛造鍛壓，鍛造 A workpiece that has been made by forming bulk solid metal（大塊材料（大塊材料、基體材料基體材料）into a specific shape at elevated temperatures. 在高溫條件下使用大塊金屬材料造型一定形狀。heat treatment：熱處理 The controlled heating an

12、d cooling processes used to change the structure of a material and alter its physical and mechanical properties. Heat treating is often used to adjust a materials hardness. 通過加熱和冷卻過程改變材料的組織（結(jié)構(gòu)）或性能（如密度，強(qiáng)度等）。nonferrous material：有色金屬材料 A metal that does not contain iron as a main ingredient. Common non

13、ferrous metals include aluminum, titanium, copper, and nickel. Aluminum：鋁鋁；Titanium：鈦；鈦；Copper：銅；銅；Nickel：鎳鎳Text:The hardness of a metal is its resistance to surface indentation under standard test conditions. Two main test methods are used: Brinell and Rockwell.Hardness and Hardness testing對對金屬金屬而言

14、，而言，硬度硬度是是抵抗抵抗壓痕壓痕或或穿透穿透的的能力能力。采用兩種主要試驗(yàn)方法：布氏硬度試驗(yàn)布氏硬度試驗(yàn)和洛氏硬度洛氏硬度實(shí)驗(yàn)。實(shí)驗(yàn)。 Hardness is defined as the resistance to indentation, and it is determined by measuring the permanent depth of the indentation. Hardness impressionHardness is a resistance to deformation.Brinell Hardness TestBrinell Hardness TestB

15、rinell hardness press: 布氏硬度試驗(yàn)機(jī)The Brinell hardness press includes anvil, indenter (ball penetrator) and load indicator and load control valve 載荷控制閥 .Indenter: 壓頭 The specimen is mounted in a anvil(1) Set the required load on the dial. Operation of Brinell Testing Machine: For steel and other hard ma

16、terials the load is 3,000 kg. for 1530 seconds. For non-ferrous materials (有色金屬材料) a 500 kg. load is used for 60 seconds. (2) Place the specimen on the anvil Apply a preload by bringing the specimen surface to contact with the ball penetrator.Operation of Brinell Testing Machine:Operation of Brinell

17、 Testing Machine: The indenter is brought in contact with the tests specimen perpendicular to the surface and the specified test force is applied. The test force held for fifteen seconds and then withdrawn. Remove the specimen and measure the diameter of the indentation. Operation of Brinell Testing

18、 Machine: Measure the diameter of the indention from the Brinell test using a microscope. The diameter of the circular indentation 圓形壓圓形壓痕痕 left in the surface after removal of the load is measured in two directions at right angles using a low-power graduated microscope （低倍（低倍顯微鏡）顯微鏡）. The numbers r

19、ead from the microscope are in millimeters. Brinell hardness impression Use the indention diameter to find the Brinell hardness number (HB) using the chart 圖標(biāo) on the front of the machine. Select the value closest to your HB and use that value to estimate tensile strength.HB= If your diameter is not

20、on the chart, use Equation below to calculate HB. The Brinell hardness value is computed from the mean of the diameter measurements by the use of a mathematical formula designed for this purpose. The Brinell hardness number (HB ) is expressed as the load F divided by surface area of the indentation.

21、Hardness and Hardness testing (the hardness calculated as)The Brinell hardness number (HB) may be calculated from the formula 公式公式 Where D= ball diameter (mm) d= diameter of circular indentation (mm) F= Load, which, in hardness testing, has units of kilogramme-force where 1kgf=9.81N Area of curvatur

22、e of indentation: 曲率面積 Hardness and Hardness testing (the hardness calculated as)How to read equations and formula, HB=HB equals F over (divided by) by D over 2 open brackets D minus root of (square root of) D square (to the power 2) minus d square close brackets.Rockwell Hardness TestRockwell Hardn

23、ess TestIn the Rockwell test the depth of the indentation is measured by the instrument 在洛氏硬度實(shí)驗(yàn)中采用儀器直接測量壓痕深度 and this is directly indicated on a dial as a hardness value 這是直接表示在標(biāo)度盤 上為硬度值. No subsequent measurement of the indentation is involved 沒有后續(xù)壓痕測量.Its advantage is its ability to display hardne

24、ss values directly, thus obviating tedious calculations involved in other hardness measurement techniquesRockwell Hardness TestAdvantage The test-piece is placed on the table of the machine 測試件放在機(jī)器表面上測試件放在機(jī)器表面上 Test Procedure:The Rockwell test Procedure Position the surface area to be measured close

25、 to the indenter. The Rockwell test consist of two step procedure. The first step sets the indenter in the material and the second step is the actual indentation test. Test Procedure:The Rockwell test Procedure A minor load of 10 kg is first applied, which causes an initial penetration and holds the

26、 indenter in place.Then, the dial is set to zero. Test Procedure:The Rockwell test Procedure First step: Minor load application A minor load is first applied to properly seat the penetrator. After the minor load has been fully applied, the dial indicator (depth-indicating device) is set to zero indi

27、cation (百分表設(shè)置為零（回零）百分表設(shè)置為零（回零） a zero reference position is established) when a minor load of 10 kg is first applied major load is applied Second step: Major load applicationThe rockwell test Procedure minor load is appliedThe dial indicator is set to zero Then, a major load (larger additional test

28、force of 140KG) is applied for a specified time period to the indenter for a total force on the sample of 150KG. This large total force causes the indenter to penetrate the sample much further. The rockwell test Procedure Second step: Major load application Major load applicationThe rockwell test Pr

29、ocedure After the total force is fully applied, it is maintained for a short time to make sure that all penetration has stopped. major load is applied Major load applicationThe rockwell test Procedure minor load is appliedThe dial indicator is set to zero When the reading of the dial indicator is st

30、eady the major load is released leaving the minor load applied.等待百分表讀數(shù)穩(wěn)定后，把重載荷（重力）卸載。等待百分表讀數(shù)穩(wěn)定后，把重載荷（重力）卸載。The rockwell testThe test-piece remains under the minor load while the hardness value is read directly from the dial indicator。Specimen under minor loadRockwell hardness indentation for a minor

31、 load and for a major load.The rockwell testNine scales of hardness are available (A to K inclusive) 可以使用的可以使用的 9個硬度標(biāo)個硬度標(biāo). Both express hardness as an arbitrary dimensionless number 無單位的數(shù)無單位的數(shù). . Nine scales of hardness are available (A to K inclusive) but the most commonly used are the B and C scal

32、es 最常用的最常用的 是B和C標(biāo)。 The rockwell testThe symbol HR is supplemented by a letter (e.g B or C) which denotes the particular hardness scale used 硬度標(biāo). Supplemented：補(bǔ)充, 補(bǔ)充,增補(bǔ)Something added to complete a thing Something that completes another Denotes：代表HRB 100 HRC 55Example: Very hard steel:Soft steel:The

33、rockwell testThe C scale is used mainly for hardened steels C C標(biāo)度主要用于淬硬過的鋼材標(biāo)度主要用于淬硬過的鋼材,the B scale is used for unhardened steels and the harder non-ferrous alloys B B標(biāo)度用于標(biāo)度用于沒淬硬過的鋼材沒淬硬過的鋼材和非鐵合金比較硬和非鐵合金比較硬. .The B-scale is used for softer materials (such as aluminum, and softer steels). The rockwell

34、 testThe Rockwell test is particularly suitable for rapid routine checks on finished material 在已精加工的材料的快速日常檢查時，采用快速日常檢查時，采用洛氏硬度實(shí)驗(yàn)洛氏硬度實(shí)驗(yàn)比較比較合適合適. Differences between Brinell and Rockwell Hardness testBrinell Hardness test: Rockwell Hardness Test : The Rockwell Hardness test differs from the Brinell t

35、est in that the measurement of hardness is based on the depth of penetration, not on the surface area of indentation. Differences between Brinell and Rockwell Hardness test In the Brinell hardness test, the width of the depression then becomes the measure of the materials hardness. The hardness is m

36、easured according to the depth of indentation, under a constant load.Thanks !Thanks !How do you calculate Hardness? Who Invented Brinell testing?Is automobile engineering and mechanical engineering same?No. automobile engineering and mechanical engineering r different. Mech. engg. deals with overall

37、 study of production engineering, designe engineering, automobile engineering, thermal engineeringand many other topic. Automobile engineering can be considered as a specific branch which deals with the topics specific to automobile engineering. What is Rockwell C?Rockwell C is a method to measure t

38、he hardness of a metal object. The hardness of the metal is a direct correlation to its strength properties: i.e., Tensile Strength. The scales can be found in any engineering or matierals reference books. A test devise is used to strick a metal object with a small pointed hammer. The size of the di

39、mple is compared to a chart to give you the Rockwell C hardness value. There are 3 charts for measuring hardness: A scale, B scale and C scale. Rockwell C is for the hardest of metals such as very high strength steel. Rockwell A is for much softer materials including something as soft as clay, I bel

40、ieve. During manufacture, a hardness test will be performed to ensure that the finished product meets the design engineers criteria to ensure the part.What is mechanical engineering Scope of mechanical engineering in these days?mechanical engineering is a stream of engineering which deals with desig

41、n and manufacturing.It has a tremendous scope in automobile engineering,cement industry,steel,power sector, Hydraulics,etc.It involves applications of all streams of engineering like Civil engineering(mechanics), computer engineering(CAD,CAM,CAE), electronics engineering(mechatronics). It is rightly

42、 called a EVERGREEN BRANCH. What is the difference between mechanical engineering and industrial engineering?Mechanical Engineering is HVAC and Piping. Industrial engineer looks at full product flow through a plant mechanical engineering is mostly related to the technical specifications of machines

43、and thier working principles. industrial engineering is interested in efficiency, correct planning, productivity of sources, supply chain management and fault minimizing etc. Purpose of heat treatment process? Heat treatment process hardens the metal, after tempering In fact heat treatment is very s

44、imilar to cooking! Why you cook? to make sth you want! to make sth better.more delicious and . . you are doing this process to make the thing you want.for example you want Fe in perlite with special hardness and other mechanical features.so you do heat treatment in a way you want and in pattern that

45、 you make.very simple but you must expert! What is a machine shop?A facility that uses machines to fabricate devices from stock raw materials, or to modify mechanisms based upon provided specifications. The common machines in a machine shop are a lathe, a drilling m/c, a miller, a shaper/planer, gri

46、nding machine and so on. What is a mechanism?A mechanism is a system of moving parts that changes an input motion and force into a desired output motion and force. These are hidden in most machines. What is the difference between engineering stress and true stress?Engineering stress assumes that the

47、 area a force is acting upon remains constant, true stress takes into account the reduction in area caused by the force. Engineering stress is more easily calculated and measured. What is the difference betweeen stress and strain?Answer Stress is load per unit Area Its unit is N/M2 in SI system And

48、Strain is Change in Dimension(dL) Divided by Original Dimension(L). dL/L. Its a dimensionless quantity. When a body is loaded within its elastic limit Stress is directly preportional to strain. What are some mechanical laboratory apparatuses?Answer welding machine What is Engineering Workshop practi

49、ce?Engineering workshop practice refers to a series of operations done regularly in a small establishment where handcraft and manufacturing works are done. These operations include production of machine components, metal work and woodwork. Describe lathe machine? A lathe (pronounced /le/) is a machi

50、ne tool which spins a block of material to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation. What are the importance of steel alloys?1.improving the ap

51、pearance of a metal 2.increasing the strength and hardness of a metal 3.increase the resistance to corrosion of the pure metal Rockwell Hardness TestTo perform the Rockwell tests, the penetrator is pressed against the specimen with an initial 10-kg preload to properly seat the penetrator. The remain

52、ing load is applied gradually after the dial on the hardness tester has been zeroed. After the penetrator has stopped moving into the specimen, the final position of the dial pointer indicates the Rockwell hardness number that is related to the depth of penetrationThe Rockwell Hardness Test:The test

53、 begins when a preliminary test force (pre-load or minor load) is applied to a sample using a diamond (or sometimes a tungsten carbide ball). This breaks through the surface to reduce the effects of surface finish and provide a reference or zero position. Next, an additional test force (or major loa

54、d) is applied to reach the total test force. This force is then held for a specified period of time to overcome elasticity. This additional force is then released and the resulting indentation is measured against the preliminary position. And then the measurement is converted into a hardness number

55、using the appropriate Rockwell scale.硬度 硬度表示材料抵抗硬物體壓入其表面的能力。它是金屬材料的重要性能指標(biāo)之一。一般硬度越高，耐磨性越好。常用的硬度指標(biāo)有布氏硬度和洛氏硬度。 布氏硬度（HB） 以一定的載荷（一般3000kg）把一定大?。ㄖ睆揭话銥?0mm）的淬硬鋼球壓入材料表面，保持一段時間，去載后，負(fù)荷與其壓痕面積之比值，即為布氏硬度值（HB），單位為公斤力/mm2 (N/mm2)。 洛氏硬度（HR） 當(dāng)HB450或者試樣過小時，不能采用布氏硬度試驗(yàn)而改用洛氏硬度計量。它是用一個支持角120的金剛石圓錐體或直徑為1.59、3.18mm的鋼球，在一定載

56、荷下壓入被測材料表面，由壓痕的深度求出材料的硬度。根據(jù)試驗(yàn)材料硬度的不同，分三種不同的標(biāo)度來表示： 1.What is this? It is a book.2.What is that? It is a notebook.3.I am a student.4.You are a teacher.5.We are students.6.You are teachers.7.Is this a pen?Yes, it is.It is a green pen.8.Open your books.9.Close your books. 10Read the text.11Write down th

57、e sentence.12.This is our classroom.13.There is a blackboard in our classroom.14.There are two doors and four windows in it.15.There are many desks and chairs.16.There are some pictures on the wall. 17.There are slogans near the windows. 18.Who is he?He is our monitor.What is his name?His name is Li

58、u Wei.How old is he?He is twenty.Where is he from?He is from Shanghai.19.When do you get up? We get up at six.19.When do you get up? We get up at six.20.It is eight oclock in the morning.20.It is eight oclock in the morning.21.It is autumn now.21.It is autumn now.22.It is hot in summer.22.It is hot

59、in summer.23.It often rains here.23.It often rains here.24.There are seven days in a week. They are 24.There are seven days in a week. They are Sunday, Monday, Tuesday, Wednesday, Sunday, Monday, Tuesday, Wednesday, Thursday, Friday and Saturday.Thursday, Friday and Saturday. The Rockwell scale char

60、acterizes the indentation hardness of materials through the depth of penetration of an indenter, loaded on a material sample and compared to the penetration in some reference material. It involves the application of a minor load followed by a major load, and then noting the hardness value directly f