BHN硬度简介.doc

The Brinell hardness test is commonly used to determine the hardness of materials like metals and alloys.The test is achieved by applying a known load to the surface of the tested material through a hardened steel ball of known diameter. The diameter of the resulting permanent impression in the tested metal is measured and the Brinell Hardness Number is calculated asBHN = 2 P / ( D (D - (D2 - d2)1/2) (1)whereBHN = Brinell Hardness NumberP = load on the indenting tool (kg)D = diameter of steel ball (mm)d = measure diameter at the rim of the impression (mm)It is desirable that the test load are limited to a impression diameter in the range of 2.5 to 4.75 mm.Approximate loads and Brinell Hardness Numbers:Brinell Hardness NumberLoad (kg)160 - 600300080 - 300150026 - 100500Typical Brinell Hardness Numbers for MetalsMaterialBrinell Hardness NumberSoft brass60Mild steel130Annealed chissel steel235White cast iron415Nitrided surface750Steel Hardness versus StrengthBrinellVickers Rockwell Equivalent RmImpression Diameter(mm)Hardness HBHardness HVHardness BHardness C(tonf/in2)(kgf/mm2)(N/mm2)2.50601640-57.0-2.55578615-56.0-2.6055559112054.5-2.6553456911953.5-2.7051454711952.0-2.7549552811751.0-2.8047750811749.5-2.8546149111648.510116015692.9044447411547.09815515202.9542945511545.59515014713.0041544011444.59214514223.0540142511343.08813913633.1038841011242.08513413143.1537539611240.58212912653.2036338311039.08012612363.2535237211038.07712111873.3034136010936.57511811573.3533135010935.57311411183.4032133910834.57111110893.4531132810833.06810710493.5030231910732.06610410203.5529330910631.0641019903.6028530110530.063999713.6527729210429.061969413.7026928410427.559939123.7526227610326.558918923.8025526910225.556898733.8524826110224.055878533.9024125310023.053848243.952352479922.051817944.002292419820.550797754.0522323597-49777554.1021722896-48767454.1521222396-46737164.2020721895-45716964.3019720893-43686674.4018719791-41656374.5017918989-39626084.6017017987-36575594.7016317285-35555394.8015616583-34545304.9014915781-32515005.0014315079-31494815.1013714477-31494815.2013113874-30474615.3012613372-29464515.4012112770-28444315.5011612268-27434225.6011111766-26414025.7010711364-25393825.8010310861-2438373Force diagramThe Brinell scale characterizes 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.Proposed by Swedish engineer Johan August Brinell 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 millimetres (0.39 in) diameter steel ball as an indenter with a 3,000 kgf (29 kN; 6,600 lbf) force. For softer materials, a smaller force is used; for harder materials, a tungsten carbide ball is substituted for the steel ball. The indentation is measured and hardness calculated as:where:P= applied force (kgf)D= diameter of indenter (mm)d= diameter of indentation (mm)The BHN can be converted into the ultimate tensile strength (UTS), although the relationship is dependent on the material, and therefore determined empirically. The relationship is based on Meyers index (n) from Meyers law. If Meyers index is less than 2.2 then the ratio of UTS to BHN is 0.36. If Meyers index is greater than 2.2, then the ratio increases.1BHN is designated by the most commonly used test standards (ASTM E10-122 and ISO 65061:20053) as HBW (H from hardness, B from brinell and W from the material of the indenter, tungsten (wolfram) carbide). In former standards HB or HBS were used to refer to measurements made with steel indenters.HBW is calculated in both standards using the SI units aswhere:F= applied force (N)D= diameter of indenter (mm)d= diameter of indentation (mm)Common valueseditWhen quoting a Brinell hardness number (BHN or more commonly 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 (from the chemical symbol for tungsten) ball indenter was used, as opposed to HBS, which means a hardened steel ball. The 10 is the ball diameter in millimeters. The 3000 is the force in kilograms force.The hardness may also be shown as XXX HB YYD2. The XXX is the force to apply (in kgf) on a material of type YY (5 for aluminum alloys, 10 for copper alloys, 30 for steels). Thus a typical steel hardness could be written: 250 HB 30D2. It could be a maximum or a minimum.Brinell hardness numbersMaterialHardnessSoftwood(e.g., pine)1.6 HBS 10/100Hardwood2.67.0 HBS 1.6 10/100Lead5.0 HB (pure lead; alloyed lead typically can range from 5.0 HB to values in excess of 22.0 HB)Pure Aluminium15 HBCopper35 HBMild steel120 HB188 (304) stainless steel annealed200 HB4Glass1550 HBHardened tool steel600900 HB (HBW 10/3000)Rhenium diboride4600 HBNote: Standard test conditions unless otherwise statedStandardsedit International (ISO) and European (CEN) Standard o EN ISO 6506-1:2005: Metallic materials Brinell hardness test Part 1: test methodo EN ISO 6506-2:2005: Metallic materials Brinell hardness test Part 2: verification and calibration of testing machineo EN ISO 6506-3:2005: Metallic materials Brinell hardness test Part 3: calibration of reference blockso EN ISO 6506-4:2005: Metallic materials Brinell hardness test Part 4: Table of hardness values US standard (ASTM International) o ASTME10-12: Standard method for Brinell hardness of metallic materials.勃式硬度(BHN)：测量硬质铜硬度的，就是布氏硬度HB，油压式操作的勃