Fatigue Crack Growth in Maraging Steel Obtained by Selective Laser Melting

Fernando Antunes,Joel Jesus,Luís Santos,Pedro Prates,José Ferreira,José Costa,Carlos Capela

doi:10.3390/app9204412

Fernando Antunes, Joel Jesus + Show 5 more

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https://doi.org/10.3390/app9204412

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Abstract

Selective Laser Melting (SLM) is an additive manufacturing technology, ideal for the production of complex-shaped components. Design against fatigue is fundamental in the presence of cyclic loads, particularly for these materials which typically have significant porosity, high surface roughness and residual stresses. The main objective here is to study fatigue crack growth (FCG) in the 18Ni300 steel obtained by SLM. Typical da/dN-ΔK curves were obtained in C(T) specimens, indicating that cyclic plastic deformation may be the controlling mechanism. A complementary analysis, based on plastic CTOD range, showed a relatively low level of crack tip plastic deformation, and consequently a reduced level of plasticity induced crack closure. The curve da/dN versus plastic CTOD range is clearly above the curves for other materials.

Highlights

Selective Laser Melting (SLM) is a technology for additive manufacturing consisting of the fusion of a fine metal power layer by layer
The geometry is defined in a CAD model which is read by the SLM equipment
Crack tip reverse slipping, the fracture surfaces approach, but the new surface cannot be removed by According to this model, plastic deformation at the crack tip is highly concentrated along the 45o re-connection of the atomic bonds, which isof in aaccordance withsurface

Summary

Introduction

Selective Laser Melting (SLM) is a technology for additive manufacturing consisting of the fusion of a fine metal power layer by layer It is an iterative procedure consisting of (1) deposition of a thin layer of powder; (2) selective melting with a laser; and (3) descent of the manufacturing platform. The geometry is defined in a CAD model which is read by the SLM equipment This procedure is very interesting to generate components with complex geometry and eventually composed of different materials. SLM is becoming prominent in the automotive, aerospace, medical and injection molds industries. Various materials, such as titanium alloys [1], nickel-based alloys, iron, aluminum, bronze, copper, stainless steels [2] and high-speed steels of metal matrix, can be considered in this process

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