What is For measuring hardness of Co-Cr alloy, which hardness test is used? and explain in detail?
The Vicat apparatus is commonly used to measure the initial setting time of gypsum products. 
A method for the measurement of ductility is known as the cold bend test.
Rockwell Hardness Number (RHN) Like the Brinell hardness test, a steel ball or a conical diamond point is used. However, instead of measuring the diameter of the impression, the depth is measured directly by a dial gauge on the instrument. 

Application: The Rockwell test has a wider application for materials, since Brinell test is unsuitable for brittle materials as well as plastic materials.
Ref- Mannapallil BASIC DENTAL MATERIALS  P:24