A Method for Measuring the Hardness of the Surface Layer on Hot Forging Dies Using a Nanoindenter

Abstract

The properties and characteristics of the surface layer of forging dies are critical for understanding and controlling wear. However, the surface layer is very thin, and appropriate property measurements are difficult to obtain. The objective of the present study is to determine if nanoindenter testing provides a reliable method, which could be used to measure the surface hardness in forging die steels. To test the reliability of nanoindenter testing, nanoindenter values for two quenched and tempered steels (FX and H13) are compared to microhardness and macrohardness values. These steels were heat treated for various times to produce specimens with different values of hardness. The heat-treated specimens were tested using three different instruments-a Rockwell hardness tester for macrohardness, a Vickers hardness tester for microhardness, and a nanoindenter tester for fine scale evaluation of hardness. The results of this study indicate that nanoindenter values obtained using a Nanoindenter XP Machine with a Berkovich indenter reliably correlate with Rockwell C macrohardness values, and with Vickers HV microhardness values. Consequently, nanoindenter testing can provide reliable results for analyzing the surface layer of hot forging dies.

Evaluation of Strain-Rate Sensitivity of Selective Laser Melted H13 Tool Steel Using Nanoindentation Tests

“…All nanoindentation hardness values in the present study are higher than the hardness value of as-built H13 steel without the SLM process (6.6 GPa) obtained from results of Mencin et al [2]. This further demonstrates that the SLM process leads to an improvement in the mechanical properties of a material, which is caused by the refined microstructure in the SLM state [9,10,12,25,26].…”

“…due to its strong temper resistance and ability to maintain high hardness and strength at elevated temperatures [1][2][3][4][5][6][7][8]. During working processes such as die casting, tool steel molds are heated using molten metals, which is then followed by cooling.…”

“…Selective laser melting (SLM), which is a powder-bed-fusion-based AM process, has been widely used due to its ability to produce intricate molds with not only near-full density but also a refined microstructure [10][11][12][13][14]. The effects of the SLM process on the microstructure and properties of H13 have been reported using scanning electron microscopy (SEM) [1][2][3]10,12]. Specifically, Yan reported that SLM resulted in martensite formation, which was mainly caused by the high residual stresses and also its partial decomposition into fine α-Fe and Fe 3 C precipitates along with retained austenite for H13 [3].…”

Mechanical properties of stabilized zirconia nanocrystalline EB-PVD coating evaluated by micro and nano indentation

“…Moreover, this is an adequate technique for evaluating adhesion and cohesion characteristics; it gives real values without the influence of substrate materials since the maximum indentation depth remains lower than 10%-15% of the coating's thickness [3,26,27]. Furthermore, Vickers micro hardness was utilized together with the Tabor equation in order to determine adhesion as well as durability of the ZrO 2 -Y 2 O 3 ceramic top coat over the micro-crack forming in the vicinity of the indentation upon applying a load [26][27][28][29][30]. Nano hardness values obtained with the Nano Indenter XP Machine and a Berkovich indenter reliably correlate with both Rockwell macro hardness and Vickers micro hardness values [31].…”

Nano-mechanical Behavior of H13 Tool Steel Fabricated by a Selective Laser Melting Method

“…due to its strong temper resistance and ability to maintain high hardness and strength at elevated temperatures. [1][2][3][4][5][6][7] Hot work tool steels fabricated by conventional methods require expensive dedicated tools and thus are not suitable for small-scale production and the production of complex shapes. [5][6][7] An additive manufacturing (AM) technique, which builds parts from 3D digital models typically by a layer additive process, has been an effective method to solve these problems.…”