What Is Hardness Scale

Hello pals,

There are different hardness scales used like HB,HRC,HV10 etc. Lets try to understand what are they and how is nomenclature of hardness scale? How to identify indenter , load from hardness scale?
I have covered few which are commonly used scales for hardness testing.

It can be understood through simplest explanation as below.

First letter :  Signifies Hardness

Second Letter(For some scale third also) : Signifies type of method, indenter and load like below

B - Brinell method , Ball indenter

Ra,RA - Rockwell method , conical indenter , A signifies 60 Kg load.
Rb,Rb-   Rockwell method , ball indenter indenter(Dia 1/16") , A signifies 100 Kg load.
Rc,RC-  Rockwell method , conical indenter , A signifies 150 Kg load.

V- Vicker method, pyramidal indenter.


Number at the end - denotes load used during hardness testing  e.g. for HV10 load used is 10 Kg.

 

Some times Brinell hardness is written as HB(1/30/10)

In this case first number denotes dia of ball indenter used , second number Load used, and third number is dwell time(in seconds) of indenter during testing e.g. HB(1/30/10)  hardness in brinell with 1mm ball dia,30 Kg load and 10 seconds dwell time.  

Few more hardness scale nomenclatures

BHN: Brinell hardness number.

VPN: Vickers pyramid number.