Enhancement of Erosion Resistance on AISI H13 Tool Steel by Oxynitriding Treatment

Abstract

In order to effectively improve erosion resistance and evaluate the effects of an oxy layer on AISI H13 tool steel after the oxynitriding process, this study used three different nitriding surface treatments, namely oxynitriding process 1 (using air), oxynitriding process 2 (using steam) and normal gas nitride. To evaluate the effects of microstructure and the erosion resistance of AISI H13 tool steel after different nitride processes, evaluated micro hardness, erosion tests and SEM microstructure inspections were conducted. Experimental results showed that the oxide layer can protect and improve the aluminum erosion for AISI H13 tool steel. Erosion tests of 2 and 4 h for oxynitriding process 1 could produce a thicker and complex oxide layer, which has higher hardness (HV 1021.9) and optimal weight loss (0.16 %). This procedure is proven to effectively reduce the ratio of Al-Fe-Si compounds during the A380 alloy erosion test.KEY WORDS: erosion resistance; AISI H13 tool steel; oxynitriding; A380 alloy. 421© 2009 ISIJ erosion test as shown in Fig. 1(b). The specimen was then dipped in aluminum alloy A380 for melting and maintained at 1 023 K. The rotational speed of the specimen was kept at 50 rpm. The dip time was 2 and 4 h for specimens to evaluate the erosion resistance and weight loss. After removing the aluminum, the specimens were cleaned with NaOH to remove oxide or other residues. The weight loss percentage of the erosion test was calculated as follows:IW is the initial weight and AW is the weight of after erosion test. In the experiment, three different kinds of surface treatments were: 1) normal gas nitriding: at temperature of 843 K for 1 h; 2) oxynitriding process 1: gas nitriding was carried out at temperature of 843 K for 1 h, and air oxidation at 823 K for 3 h; 3) oxynitriding process 2: gas nitriding was carried out at temperature of 803 K for 1 h, and steam oxidation at 798 K for 1 h. To evaluate the effects of erosion resistance on AISI H13 tool steel by nitriding process, erosion test, surface hardness and microstructure inspections were performed. Microhardness tests were measured by HV with loading of 200 g, which complied with the CNS 2115 Z8004 standard. Results and DiscussionThe microstructure of AISI H13 tool steel substrate obtained after quenching and tempering processes is shown in Fig. 2. This is the typical microstructure obtained through commercial heat treatment, which comprises the structure of tempered martensite and proeutectoid carbides. Figure 3 shows the microhardness test of AISI H13 tool steel after gas nitriding and different oxynitriding treatments. Gas nitriding was done with ammonia, decomposition NH 3 was used to dilute the ammonia so that it was not too aggressive. Normally, pure decomposition NH 3 is used to reduce the compound layer (white layer). Both carbon content and alloying additions raise surface hardness, thereby enhancing wear resistance. The actual hardness of the compound layer is usually substantially higher. However, a better thickness of the compound l...

Deposition of DLC Films onto Oxynitriding-Treated V4E High Vanadium Tool Steel through DC-Pulsed PECVD Process

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Improvement of the Wear and Corrosion Behaviors of DLC/oxynitriding Duplex-treated PM60 High-speed Steel <i>via</i> Various Power Densities of DC-pulsed Plasma Enhanced CVD

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Improvement of Aluminum Erosion Behavior and Corrosion Resistance of AISI H13 Tool Steel by Oxidation Treatment

“…8) Furthermore, oxidation is one of the most economical and effective methods to improve erosion and corrosion resistance of steels. 4,11,12) The objective of this study is to explore the possibility of surface engineering of the AISI H13 steel surface to reduce erosion and corrosion of the die surfaces.…”

“…1,2) During hot work steel processes, the die surface is rapidly heated and then quenched, thus resulting in a decrease of surface hardness and toughness. 3,4) However, thermal gradients lead to dimensional variations, and generate stress and deformation. In aluminum die casting, tools are exposed to erosion, corrosion, and soldering; they are under frequent contact of a tool surface on the casting alloy, and are subject to oxidation due to high pouring temperatures.…”

“…Die steel dissolves in the aluminum alloy melt forming complex aluminum-iron-silicon intermetallics. Furthermore, previous study has proposed 4,14) intermetallic layers (Al x Fe y Si z ) form at the cast metal-die steel interface when the liquid metal is brought in intimate contact with the die steel. Their morphology depends on the composition of the cast metal and die steel.…”