Additive manufacturing of 17–4 PH steel using metal injection molding feedstock: Analysis of 3D extrusion printing, debinding and sintering

Gurminder Singh,Jean-Marc Chaix,Jean-Michel Missiaen,Didier Bouvard

doi:10.1016/j.addma.2021.102287

Abstract

The amalgamation of 3D extrusion printing (3DEP) and sintering results in a low-cost process compared to other laser-based additive manufacturing techniques. This work used metal injection molding (MIM) raw material of 17–4 PH steel for additive manufacturing. The 3D printing, debinding, and sintering steps were thoroughly evaluated to achieve the highest sintered density. First, the 3DEP of the MIM feedstock was carried out using a screw-based extrusion system at optimum parameters to acquire the high green density and fine surface roughness. The solvent debinding step was carried out on 3D printed samples to remove water-soluble polymer by immersion method. Thermogravimetric analysis was performed to evaluate the decomposition temperature of the backbone material. Further, thermal debinding and sintering steps were conducted in a single step. The thermal debinding temperature was 500 ℃ , and the sintering temperatures were chosen as 1100, 1200, 1300 and 1360 ℃ . The highest density of ~95.6% was attained at a high sintering temperature. The micro-tomography evaluation was carried out on the 3D printed green and high-density sintered samples to evaluate the internal porosity. The mechanical properties and the microstructure were also evaluated for sintered samples. The work opens a way to fabricate metal complex-shaped parts at low cost using market available MIM feedstock.

Highlights

In the past two decades, development innovations, which dramati cally shorten the period between design and finished parts, have gained substantial attention because of the availability of digital design in struments
The present study aims at exploring additive manufacturing of SS 17–4 PH metal injection molding (MIM) feedstock granules
Printing voids formed between the printing layers. Both types of voids directly depend on the values of the 3D printing parameters

Summary

Introduction

In the past two decades, development innovations, which dramati cally shorten the period between design and finished parts, have gained substantial attention because of the availability of digital design in struments This refers to additive manufacturing (AM), where the products are fabricated by adding material layer-by-layer [1]. Other AM processes such as binder jetting [4,5], rapid tooling [6,7,8,9], stereolithography [10,11,12] and 3D extrusion printing (3DEP) [13] combined with sintering require more than one step for the fabrication of metal/ceramic parts These processes require a longer processing time to fabricate a solid part, but they are cheaper than direct processes in initial investments, equipment, and skilled labor costs. This introduces the need for an affordable AM production system where the metal samples can be made quickly at low cost with design and material freedom and, possibly, upgradable to mass pro duction like the metal injection molding process (MIM)

Methods

Results

Conclusion