Effect of processing conditions on microstructural features in Mn-Si sintered steels
Artikel i vetenskaplig tidskrift, 2014

Sintering of steels containing oxidation sensitive elements is possible if such elements are alloyed with others which present lower affinity for oxygen. In this work, a master alloy powder containing Fe-Mn-Si-C, specifically designed to create a liquid phase during sintering, has been used for such purpose. The effect of processing conditions such as sintering temperature and atmosphere was studied with the aim of describing the microstructural evolution as well as the morphology and distribution of oxides in the sintered material, evaluating the potential detrimental effect of such oxides on mechanical properties. Chemical analyses, metallography and fractography studies combined with X-ray photoelectron spectroscopy analyses on the fracture surfaces were used to reveal the main mechanism of fracture and their correlation with the chemical composition of the different fracture surfaces. The results indicate that the main mechanism of failure in these steels is brittle fracture in the surrounding of the original master alloy particles due to degradation of grain boundaries by the presence of oxide inclusions. Mn-Si oxide inclusions were observed on intergranular decohesive facets. The use of reducing atmospheres and high sintering temperatures reduces the amount and size of such oxide inclusions. Besides, high heating and cooling rates reduce significantly the final oxygen content in the sintered material. A model for microstructure development and oxide evolution during different stages of sintering is proposed, considering the fact that when the master alloy melts, the liquid formed can dissolve some of the oxides as well as the surface of the surrounding iron base particles.

Fe-Mn-Si-C

SELECTIVE SURFACE OXIDATION

Master alloys

Oxygen-sensitive elements

POWDERS

PM

INCLUSIONS

ALLOYS

MANGANESE

BEHAVIOR

Sintering behavior

SI/MN

NUCLEATION

Powder metallurgy

FERRITIC STEEL

Författare

Raquel De Oro Calderón

Chalmers, Material- och tillverkningsteknik, Yt- och mikrostrukturteknik

Eduard Hryha

Chalmers, Material- och tillverkningsteknik, Yt- och mikrostrukturteknik

Monica Campos Gomez

Universidad Carlos III de Madrid

Jose Manuel Torralba Castello

IMDEA Institute

Universidad Carlos III de Madrid

Materials Characterization

1044-5803 (ISSN)

Vol. 95 105-117

Ämneskategorier

Materialteknik

Styrkeområden

Produktion

Materialvetenskap

DOI

10.1016/j.matchar.2014.06.011