Precipitation Strengthening in Ni–Cu Alloys Fabricated Using Wire Arc Additive Manufacturing Technology

Olexandra Marenych,Stephen Van Duin,Chen Shen,Andrii Kostryzhev,Huijun Li,Zengxi Pan

doi:10.3390/met9010105

Olexandra Marenych, Stephen Van Duin + Show 4 more

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https://doi.org/10.3390/met9010105

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Abstract

Two Ni–Cu alloys, Monel K500 and FM60, with various contents of Ti, Mn, Al, Fe and C were deposited in the form of plates on a metal base plate using wire arc additive manufacturing technology. Three deposition speeds have been applied: 300, 400 and 500 mm/min. To modify the as-welded microstructure and properties, the deposited walls/plates have been subjected to two heat treatment procedures: annealing at 1100 °C for 15 min, slow cooling to 610 °C, ageing at this temperature for 8 h and either (i) air cooling to room temperature or (ii) slow cooling to 480 °C, ageing at this temperature for 8 h and air cooling to room temperature. The microstructure characterisation and mechanical properties testing have been conducted for each of the 18 chemistry/processing conditions. The dependences of the precipitate’s parameters (size, number density and chemistry), mechanical properties and wear resistance on the alloy composition, deposition speed and heat treatment have been obtained. In Monel K500, the precipitates were mainly of the TiC/TiCN type, and in FM60, they were of the MnS and TiAlMgO types. Monel K500 has shown higher hardness, strength, toughness and wear resistance in all studied conditions. Ageing at 610 °C improved properties in both alloys following the precipitation of new particles. Ageing at 480 °C could result in a properties loss if the particle coarsening (decrease in number density) took place.

Highlights

Ni-base alloys are recognised for their superior resistance to many corrosive environments and good mechanical properties
We present a first-ever study of the effect of heat treatment on the microstructure, mechanical properties and wear resistance of Ni–Cu alloys obtained using Wire arc additive manufacturing (WAAM)
The first-ever investigation of the effect of heat treatment on the microstructure, mechanical properties and wear resistance of Ni–Cu alloys processed using the wire arc additive manufacturing technology has resulted in the following conclusions: 1

Summary

Introduction

Ni-base alloys are recognised for their superior resistance to many corrosive environments and good mechanical properties. These single-phase alloys retain an austenitic matrix from solidification to subzero temperatures. They are widely used in many applications, in the marine industry to produce valves, pumps and propeller shafts, marine fixtures and fasteners and electrical and electronic components. The 70Ni–30Cu alloy system, known as the Monel family, has a high tolerance for alloying elements in solid solutions. This resulted in the development of Monel alloys with multiple alloying additions providing a wide variety of properties [1]. Increased amounts of Ti (up to 0.85 wt.%) led to the Metals 2019, 9, 105; doi:10.3390/met9010105 www.mdpi.com/journal/metals

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