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 / (π 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 Meyer's index (n) from Meyer's law. If Meyer's index is less than 2.2 then the ratio of UTS to BHN is 0.36. If Meyer's index is greater than 2.2, then the ratio increases.[1]BHN is designated by the most commonly used test standards (ASTM E10-12[2] and ISO 6506–1:2005[3]) 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 values[edit]When quoting a Brinell hardness number (BHN or more commonly HB), the conditions of the test used to obtain the nu。