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Vickers Hardness Test

Vickers Hardness Test


The Vickers hardness test was developed in the early 1920s and uses a pyramid-shaped indenter made of diamond. It is based on the principle that impressions made by this indenter are geometrically similar regardless of load. Accordingly, loads of various size are applied, depending on the hardness of the material to be measured. The Vickers Hardness (HV) is then determined from the formula HV = (1.854 F / D^2) where F= applied load, kg; and D= the diagonal of the impression made by the indenter, mm, as indicated in the figure. The Vickers test can be used for all metals and has one of the widest scales among hardness tests. nl:Vickers (hardheid)

Brinell Hardness Test


The Brinell scale characterises the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. It is one of several definitions of hardness in materials science. Brinelling refers to surface fatigue caused by repeated impact or overloading. It is a common cause of roller bearing failures, and loss of preload in bolted joints when a hardened washer is not used. Engineers will use the Brinell hardness of materials in their calculations to avoid this mode of failure. Fretting corrosion can cause a similar-looking kind of damage and is called false brinelling even though the mechanism is different. Proposed by a Swedish engineer Johann August Brinell (1849 - 1925) in 1900, it was the first widely used and standardised hardness test in engineering and metallurgy. The large size of indentation and possible damage to test-piece limits its usefulness. The typical test uses a 10 mm diameter steel ball as an indenter with a 3,000 kgf (29 kN) force. For softer materials, a smaller force is used and for harder, a tungsten carbide ball. The indentation is measured and hardness calculated as: :\mbox{BHN}=\frac{P}{\pi D t} - where:

Common values

When quoting a Brinell hardness number (HB), the conditions of the test used to obtain the number must be specified. The standard format for specifying tests can be seen in the example "HBW 10/3000". "HBW" means that a tungsten carbide ball indenter was used, as opposed to "HBS", which means a hardened steel ball. The "10" is the ball diameter in millimetres. The "3000" is the force in kilograms force.

Standards

  • International (ISO) and European (CEN) Standard :* EN ISO 6506-1 : Metallic materials - Brinell hardness test - Part 1 : test method. :* EN ISO 6506-2 : Metallic materials - Brinell hardness test - Part 2 : verification and calibration of testing machine. :* EN ISO 6506-3 : Metallic materials

    Knoop Hardness Test


    The Knoop hardness test is a microhardness test - a test for mechanical hardness used particularly for very brittle materials or thin sheets, where only a small indentation may be made for testing purposes. A pyramidal diamond point is pressed into the polished surface of the test material with a known force, for a specified dwell time, and the resulting indentation is measured using a microscope. The Knoop hardness ''HK'' or ''KHN'' is then given by the formula: :HK=={P \over {C_pL^2}} where: :L = length of indentation along its long axis :Cp = correction factor related to the shape of the indenter, usually about 0.07 :P = load HK values are typically in the range from 100 to 1000, when specified in the conventional units of kg·mm-2. SI units (pascals) are sometimes used instead. The test was developed by F. Knoop and colleagues at the National Bureau of Standards (now NIST) of the USA in 1939, and is defined by the ASTM D-1474 standard. The advantages of the test are that only a very small sample of material is required, and that it is valid for a wide range of test forces. The main disadvantages are the difficulty of using a microscope to measure the indentation (with an accuracy of 0.5 micrometres), and the time needed to prepare the sample and apply the indenter.

    Sample values

  • Vickers hardness test, another microhardness test

  • http://www.efunda.com/units/hardness/convert_hardness.cfm?cat=Steel&HD=HK efunda
  • http://www.lib.umich.edu/dentlib/Dental_tables/Knoophard.html Dental hardness tables

    Hard Nuts And Hard Cunts


    ''Hard Nuts And Hard Cunts'' is an album that sold nearly 100,000 copies, released by Hard Skin in 1996, and rereleased in 2003. At the time of release the band members were:
  • Johnny Takeaway - Vocals, Guitar
  • Fat Bob - Vocals, Bass
  • Nosher(d) - Vocals, Drums

    Tracklisting

    # Hard Skin # Oi Not Jobs # ACAC # Jocky On The Ocke # XR3 # My One Skin # Every Day, Every Weekend # Fax Of Life # The Good Times # First Day Angry Song # Beer And Fags # Me And The Boys # 12 Bars Of Gold # Desperation Street # Bunch Of Pissed Up Cunts (Only available on the re-release, band quoted as saying "It's shit anyway") Helen Of Oi! Records HOO31, Broken Rekids SKIP67 (re-release with extra track)

  • http://www.householdnamerecords.co.uk/releases/haus073.php Hard Skin homepage

    Hard Times/ Hard Cash


    Hard Times/ Hard Cash is the next album from Kyreese and Coney. It is there second album. It is two seperate disks, Hard Times is a "Street" album and Hard Cash is a "Club" album. Hard times will be produced by Coney and Hard Cash by Kyreese. A lot is expected for this one because their first album, "Brooklyns Back", flopped and only sold a couple copies. Songs that were recorded: Show Me Love Street Soljaz U Gon Bleed I Wish Intro On My mind It may be released by July, but usually Kyreese and Coney albums aren't done by the proposed date.

    November 1951 Nuclear Test At Nevada Test Site.Jpg


    Public domain photo from http://www.dtra.mil/press_resources/photo_library/CS/CS-3.cfm Test is shot "Dog" from Operation Buster, 21 kilotons. It was the first U.S. nuclear field exercise conducted on land; troops shown are a mere 6 miles from the blast. Category:Images of Nevada

    List Of Australian Test Batsmen Who Have Scored Over 5000 Test Runs


    List of Australian batsmen who have scored over 5,000 runs in Test match cricket: Based on all Test matches up to and including Test # 1723: Australia v New Zealand at Adelaide, 2nd Test, 26-30 November, 2004. Name
  • Allan Border
  • Steve Waugh
  • Mark Waugh
  • Mark Taylor
  • David Boon
  • Greg Chappell
  • Sir Don Bradman
  • Neil Harvey
  • Doug Walters
  • Ian Chappell
  • Michael Slater
  • Bill Lawry
  • Ricky Ponting
  • Matthew Hayden
  • Justin Langer Category:Australian batsmen


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