Influence of the PM-Processing Route and Nitrogen Content on the Properties of Ni-Free Austenitic Stainless Steel
Artikel i vetenskaplig tidskrift, 2015

Ni-free austenitic steels alloyed with Cr and Mn are an alternative to conventional Ni-containing steels. Nitrogen alloying of these steel grades is beneficial for several reasons such as increased strength and corrosion resistance. Low solubility in liquid and δ-ferrite restricts the maximal N-content that can be achieved via conventional metallurgy. Higher contents can be alloyed by powder-metallurgical (PM) production via gas–solid interaction. The performance of sintered parts is determined by appropriate sintering parameters. Three major PM-processing routes, hot isostatic pressing, supersolidus liquid phase sintering (SLPS), and solid-state sintering, were performed to study the influence of PM-processing route and N-content on densification, fracture, and mechanical properties. Sintering routes are designed with the assistance of thermodynamic calculations, differential thermal analysis, and residual gas analysis. Fracture surfaces were studied by X-ray photoelectron spectroscopy, secondary electron microscopy, and energy dispersive X-ray spectroscopy. Tensile tests and X-ray diffraction were performed to study mechanical properties and austenite stability. This study demonstrates that SLPS process reaches high densification of the high-Mn-containing powder material while the desired N-contents were successfully alloyed via gas–solid interaction. Produced specimens show tensile strengths >1000 MPa combined with strain to fracture of 60 pct and thus overcome the other tested production routes as well as conventional stainless austenitic or martensitic grades.

Författare

K. Lefor

Ruhr-Universität Bochum

M. Walter

Ruhr-Universität Bochum

Anna Weddeling

Ruhr-Universität Bochum

Eduard Hryha

Chalmers, Material- och tillverkningsteknik, Yt- och mikrostrukturteknik

Stephan Huth

Ruhr-Universität Bochum

Sebastian Weber

Bergische Universität Wuppertal

Lars Nyborg

Chalmers, Material- och tillverkningsteknik

W. Theisen

Ruhr-Universität Bochum

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

1073-5623 (ISSN)

Vol. 46 1154-1167

Drivkrafter

Hållbar utveckling

Styrkeområden

Produktion

Materialvetenskap

Ämneskategorier

Bearbetnings-, yt- och fogningsteknik

Metallurgi och metalliska material

DOI

10.1007/s11661-014-2701-7