Hardness Testing Services
Rockwell & Superficial
Rockwell and Superficial hardness testing shall be performed in accordance with the latest revision of ASTM E18.
There are two general classifications of the Rockwell test: the Rockwell hardness and the Rockwell superficial hardness test. In the Rockwell hardness test the preliminary test force is 10 kgf. Total test forces are 60 kgf, 100 kgf and 150 kgf. In the Rockwell superficial hardness test, the preliminary test force is 3 kgf and total test forces are 15 kgf, 30 kgf, 45 kgf. The indenter of either test shall be of spheroconical or spherical configuration The standard indenters are the diamond spheroconical and tungsten carbide ball indenters' 1/16, 1/8, 1/4, 1/2 inch in diameter. CMS can report hardness in the following value scales:
Rockwell Scales: A, B, C, D, E, and F
Superficial Scales: 15N, 30N, 45N, 15T, 30T, and 45T
After testing the final report will include Rockwell hardness number, scale used, and readings to nearest the whole number by rounding in accordance with ASTM E29.
Vickers Macro Hardness
This type of hardness is very useful for doing weld profiles and determination of hardness in Heat Affected Zones (HAZ). There are several specifications which call out the use of this type of hardness method. The testing method which governs the macro hardness Vickers is ASTM-E-92.
Other specifications which reference the use of Vickers hardness testing are:
ASME Section IX
Leeb Rebound Hardness
Leeb rebound hardness testing is a hardness testing technique used for field testing or large components that are not readily available for laboratory testing. This type of testing is done in accordance with newest revision of ASTM A956. This hardness testing can be done with minimal indentation remaining on the surface after testing is performed. It can test a variety of base metals, and the hardness can be converted into known hardness scales.
Brinell Hardness Testing
Brinell hardness (HB) testing shall be performed in accordance with the latest revision of ASTM E10.
Brinell testing is done with the calibrated Brinell machine that applies a predetermined indenting load to a ball in contact with the specimen. The ball is a 10 mm tungsten carbide ball used to apply load of 3000 or 500 kgf depending on the material for 15 seconds. After the load is applied, the indentation on the surface is measured with a scope which measures in millimeters. The dimension of the indentation and the load used is the calculated to give the Brinell Hardness value of the metal.
Microhardness Testing Knoop
Microhardness testing shall be performed in accordance with ASTM E384 unless otherwise specified by the client If the client does identify an alternative test method or procedure, it shall be documented on Lab work-sheet Microhardness is performed by two methods. Knoop (HK) and Vickers (HV).
Questions: What would I use Microhardness testing for?
Answer: Microhardness testing gives you the advantage of testing materials hardness on very thin layers or sheet. It also allows you to measure case hardness and the depths of case hardness. It can also be used in to determine decarburization depth or verification that limits were not exceeded during the heat treatment process.
CMS uses Knoop for microhardness from 10 gf to 500 gf load evaluation- The number obtained by dividing the applied load in kilograms force by the projected area of the indentation in square millimeters, computed from the measurement of the long diagonal of the indentation. The Knoop number can then be converted by ASTM E 140 to Rockwell, Brinell or any other desired scale requested. Please remember that some scales may fall out of conversion requested.
Wilson hardness conversion chart is a great reference in determining what hardness you currently have to an approximate value in a different scale.