Skip to main content

The Brinell Hardness Test

The Brinell Hardness Test

The Brinell hardness test method consists of indenting the test material with a 10 mm diameter
hardened steel or carbide ball subjected to a load of 3000 kg. For softer materials the load can be reduced to 1500 kg or 500 kg to avoid excessive indentation. The full load is normally applied for 10 to 15 seconds in the case of iron and steel and for at least 30 seconds in the case of other metals. The diameter of the indentation left in the test material is measured with a low powered microscope. The Brinell harness number is calculated by dividing the load applied by the surface area of the indentation.

The Brinell Hardness Test


The diameter of the impression is the average of two readings at right angles and the use of a Brinell hardness number table can simplify the determination of the Brinell hardness. A well structured Brinell hardness number reveals the test conditions, and looks like this, "75 HB 10/500/30" which means that a Brinell Hardness of 75 was obtained using a 1Omm diameter hardened steel with a 500 kilogram load applied for a period of 30 seconds. On tests of extremely hard metals a tungsten carbide ball is substituted for the steel ball. Compared to the other hardness test methods, the Brinell ball makes the deepest and widest indentation, so the test averages the hardness over a wider amount of material, which will more accurately account for multiple grain structures and any irregularities in the uniformity of the material. This method is the best for achieving the bulk or macro-hardness of a material, particularly those materials with heterogeneous structures.
Labels:

Popular posts from this blog

Part -4 Most commonly asked Mechanical Interview Questions

Most commonly asked Mechanical Interview Questions with answer 1.          What is Difference between stamina and strength? Ans.     Strength is capability over a short length of time and Stamina is the ability to keep going continuously. 2.          What is Hydro-static System? Ans.     Hydrostatics is the study of fluid bodies that are At rest Moving su ffi cient slowly so there is no relative motion between adjacent parts of the body For hydrostatic situations There are no shear stresses There are only pressure forces that act perpendicular to any surface. It’s a closed loop hydraulic systems. It comprises of motor and pump. Here pump supplies energy to motor and motor gives return energy to pump supply. 3.          What is Cotter joint? Ans.      A cotter j...
Read more

Part -7 Most commonly asked Mechanical Interview Questions

Most commonly asked Mechanical Interview Questions What are the different types of fits? Explain? On the basis of Indian standards fits can mainly be categorised into three groups: > Clearance Fit : These types of fits are characterised by the occurrence of a clearance between the two mating parts. The difference between the minimum size of the hole and the maximum size of the shaft is called the minimum clearance, the difference between the maximum size of the hole and the minimum size of the shaft is known as maximum clearance. > Interference Fit : In these types of fits the size of the mating parts are predefined so that interference between them always occurs. The tolerance zone of the hole is completely below the tolerance zone of the shaft. > Transition Fit : As the name suggests these type of fit has its mating parts sized limited to allow either clearance or interference. The tolerance zone of the hole and the shaft overlaps in case of such fits. For a shaf...
Read more

MACRO SECTION

MACRO SECTION Object: To examine a cross section of a weld for internal defects and soundness. Method:  A transverse section of the weld is cut out. The cross section is then visually inspected. The section is filed down from rough to smooth, then emery or wet/dry papered down to a surface finish of 600 grit. The surface is then etched in NITAL (5% - 10% nitric acid in alcohol), washed off, rinsed and dried. (Possibly a final clean with acetone and mount in Bakelite) The specimen is then inspected at up to 10-x magnification. Reporting Results: Material. Welding process. Specimen identification. Sentencing standard. Thickness. Geometric flaws - type, size and location. Internal flaws - type, size and location. Parent metal flaws - type, size and location. Accept or reject, to standard, for each flaw.    Comparison of macro section and micro section:                             ...
Read more