维氏硬度测试方法和原理/双语

维氏硬度测试在1924年由Smith和Sandland在Vickers有限公司共同开发，该测试方法可以作为除布氏硬度测试外的另一个测试材料硬度的方法。维氏硬度测试较其他的硬度测试更为简易，它所要求的计算不受压头大小的限制，压头可以不考虑硬度值而应用于所有的测试材料。

对于所有硬度测试的方法，其基本原则是为了观察未知材料抵抗塑性形变的能力。维氏测试适用于所有的金属材料，在硬度测试中有着广泛的应用。在硬度测试中硬度值的单位是维氏硬度(HV)或金刚石棱锥硬度 (DPH)。

压头应具有特定几何形状，使得压出的压痕不论尺寸大小都与其保持几何相似；且该压痕有便于测量的界限清楚的边界点；另外，压头必须有很高的强度以抵抗自身形变。正四棱锥形的金刚石压头可以满足以上这些 要求。

维氏硬度值用xxxHVyy来表示, 例如 440HV30, 如果保荷时间在10s到15s范围之外，则用xxxHVyy/zz表示，例如440HV30/20, 其各部分含义如下：

440是硬度值
HV 表示硬度标尺（维氏）
30表示试验力值为30Kgf
20表示保荷时间

维氏硬度值一般独立于试验力值：对同一材料，从500gf到50kgf试验力的维氏硬度值有可能是一样的。维氏硬度测试对材料分析，生产工艺的质量控制和研发成果有着极其重要的作用。硬度实质上是一个经验值，对于很多材料可与拉伸强度和相关，也是耐磨性和延展性的显现。在进行硬度测试时，为避免不同试验硬化区之间的相互影响，相邻压痕之间的距离要大于3倍的压痕对角线长度。

VICKERS HARDNESS TESTER

The Vickers hardness tester uses the hardness test that was developed in 1924 by Smith and Sandland at Vickers Ltd as an alternative to the Brinell method to measure the hardness of materials. The Vickers test is often easier to use than other hardness tests, since the required calculations are independent of the size of the indenter, and the indenter can be used for all materials irrespective of hardness.

The basic measuring principle of the Vickers hardness tester, as with all common measures of hardness, is to observe the questioned material’s ability to resist plastic deformation from a standard source. The Vickers hardness tester can be used for all metals and has one of the widest scales among hardness tests. The unit of hardness given by the test is known as the Vickers Pyramid Number (HV) or Diamond Pyramid Hardness (DPH).

The indenter shape of a Vickers hardness tester should be capable of producing geometrically similar impressions, irrespective of size; the impression should have well-defined points of measurement; and the indenter should have high resistance to self-deformation. A diamond in the form of a square-based pyramid satisfied these conditions.

HOW ARE VICKERS HARDNESS TESTING NUMBERS BEING REPORTED WHILE PERFORMING A HARDNESS TEST?

Vickers hardness numbers are reported as xxxHVyy, e.g. 440HV30,
or xxxHVyy/zz if duration of force differs from 10s to 15s, e.g. 440Hv30/20, where:

440 is the hardness number,
HV gives the hardness scale (Vickers),
30 indicates the load used in kg.
20 indicates the loading time if it differs from 10s to 15s
Source: Wikipedia

FOR WHAT PURPOSES ARE VICKERS HARDNESS TESTERS BEING USED?

Vickers values are generally independent of the test force, although from 500gf to 50Kgf it is possible the results of the same material under test may produce similar results irrespective of the force used. Vickers hardness tests have been found to be very useful for material evaluation, quality control of manufacturing process and research and development efforts. Hardness, although empirical in nature, can be correlated to tensile strength for many metals and is an indicator of wear resistance and ductility. When doing a Vickers hardness test the distance between indentations must be more than 3 indentation diameters apart to avoid interaction between the work-hardened regions. Vickers hardness testers are routinely used for testing materials, components in the aerospace and automotive industry, laboratories for sample evaluation, to conduct common or advanced testing tasks.