Simple Hardness testing Methods:

Simple Hardness testing Methods:

• The file and scratch test is a quick procedure for checking hardness. This method is most frequently used by the workmen to check the machinability of the metal. This method involves scratching or trying to cut the surface of the metal with a pointed object of known hardness. This practice just gives the hardness of the material on the outer surface only.

File Hardness Test Data:

Brinell Hardness	File Action
100	File bites into surface very easily
200	File removes metal with slightly more pressure
300	Metal exhibits its first real resistance to the file.
400	File removes metal with difficulty
500	File just barely removes material
600	File slides over surface without removing metal, file teeth are dulled

Simple Hardness Tester:

• It is possible for welders to make their own set of hardness tester, by heat treating 1/4in. steel electrodes to give a graduated series of hardness. The rods are labelled with their respective Rockwell C Hardness. A sharp point is then ground on the end of each rod, taking care not to soften the steel by overheating.
• By scratching these scratch testers one at a time over a different metal surface the welder can determine which rod has hardness about the same metal being scratched.
• If the sharp point of the scratcher digs and leaves a scratch mark on the metal this indicates that the hardness of the scratcher is more than that of the metal being tested.
• If it does not leave any scratch and the scratcher is slipped from the surface of metal then this indicates that the hardness of the metal being tested is greater than that of scratcher being used.

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