Characterization of microstructure and residual stress in a 3D H13 tool steel component produced by additive manufacturi
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Characterization of microstructure and residual stress in a 3D H13 tool steel component produced by additive manufacturing Ryan Cottama) and James Wang Industrial Laser Applications Laboratory, IRIS, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Victoria 3122, Australia
Vladimir Luzin Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2232, Australia (Received 29 March 2014; accepted 25 June 2014)
H13 tool steel was deposited using the additive manufacturing technique Direct Metal Deposition to produce a part having a wedge geometry. The wedge was characterized both in terms of microstructure and residual stress. It was found that phase transformations were significantly influencing the microstructure, which was then linked to the residual stress distribution as seen in Fig. 8. The residual stress distribution was found to be opposite to that reported in the literature. This was attributed to the low temperature martensitic phase transformation of the H13 tool steel and the subsequent tempering of the microstructure with an increasing number of layers of deposited material. The high hardness and compressive residual stress of the top 4 mm of the wedge are ideal in die casting and forging dies, as it will resist thermal fatigue. It also has a hardness higher than that produced by typical heat treatment processes.
I. INTRODUCTION
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2014.190
is built. The advantage of this technology over DMD is support structures can be built allowing for overhanging features to be produced. Also the dimensional accuracy of this approach is superior. One of the strengths of AM processes is their low cost for producing prototypes or low volume production runs of metallic components. This has led to applications in aerospace,2,3 rapid tooling,4 and biomedical implants.5 The other major strength of AM is the production of complex shapes such as spline curves, hollow sections, and lattice structures,6 which is changing the way components can be designed. Another advantage of AM DMD technology is the production of parts made from dissimilar materials such as copper backed tool steel for increasing cycle times in die casting and injection molding.7 The production of tooling using AM draws on many of the advantages of AM and as such is the topic of this investigation. H13 tool steel is one of the most commonly used tool steels for producing die casting and forging dies. The production of these dies involves the machining of the dies from large blocks of material after which a heat treatment is used to achieve the full strength of the material. This process is costly and time consuming and AM offers the ability to reduce the amount of machining and hence wastage of this expensive material. DMD is the main technology that has been used to produce blocks of material for evaluation of the process. Hofmeister et al.8 evaluated the effect of laser parameters on the ther
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