Small indention depths can be achieved with small test loads using the classic hardness testing methods to Vickers (DIN EN ISO 6507-1), Rockwell (DIN EN ISO 6508-1), and in particular, the Rockwell superficial scales, as well as to Brinell (DIN EN ISO 6506-1). The hardness test method to Martens is increasingly used for thin coatings. It is also known as an instrumented indentation test due to its precise measurement of the force-indentation depth curve; internationally it is known as IIT. The depth of the residual indention should not exceed 10% of the available sheet or coating thickness; if it does, the influence of the support or the substrate is no longer negligible. The instrumented indentation test has the advantage that even small indention or indention depths can be measured with greater accuracy and thus hardness values can be determined reliably and reproducibly. Thin sheets are often cut to a specific size as defined by the customer and welded together with other sheet metals (tailored blanks), for example, according to the roller seam welding process (DIN EN ISO 4063). The quality of the welded seams are also tested using hardness testing methods. Typically micro-hardness testing methods to Vickers and Knoop, but also Martens (DIN EN ISO 6507-1, DIN EN ISO 4545-1, DIN EN ISO 14577-1) are used on cross-sections or on the surface of the welded seam and the area around it. Positions for single or multiple tests can be defined with absolute precision using instruments that test according to these methods.