After carburazing , the steel or high carbon steel will have carbon loss phenomenon after heat process. The surface layer of carbon loss is called "decarburizing layer" .The decarburization layer surface have partial and full decarburization, the the sum of partial and full decarburization is called total decarburization.

The total decarburization depth refers to the distance from the low carbon content surface to the substrate carbon content .

The decarburization depth of steel is measured by hardness method, it is suitable for sub-eutectoid, eutectoid and hypereutectoid steel which the decarburization layer have certian depth but smaller than the thickness of quenching zone.

Micro Vickers Hardness Test Method

1.The decarburization depth test according to GB 244?87

(1).Test from the edge of sample to hardness value required.

(2).Test from the edge of sample to stable hardness value.

(3).Test from the edge of sample to stable hardness value percentage.

Which test method to be adopted according to technical requirement.Dectection at least in a certain destance from each other for two groups, the average of two tested resules are the depth of total decarburization.

2.Micro vickers test according to GB/T 4340.1, test force better to choose between 0.49?4.9N（50?500gf）,the distance of indenters is at least 2.5 times than diagonal length.

Specimen preparation is the same to general metallographic specimen, through taking sample, grinding and polishing,but please don't cut rounded coner edge. φ25mm round steel or length 20mm square steel need test the whole round of specimen.

Rockwell Hardness Test Method

When use rockwell hardness test, it is suitable for product not allowed decarburization, directly test on the surface of original product, for allowed decarburization product, remove decarburization layer then test.Rockwell test only jugde the product if decarburizated or the decarburization layer if removed.