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Surface Interactions during Sintering of Chromium-alloyed PM Steels in Different Atmospheres

Dimitris Chasoglou (Institutionen för material- och tillverkningsteknik, Yt- och mikrostrukturteknik) ; Eduard Hryha (Institutionen för material- och tillverkningsteknik, Yt- och mikrostrukturteknik) ; Lars Nyborg (Institutionen för material- och tillverkningsteknik, Yt- och mikrostrukturteknik)
World Powder Metallurgy Congress and Exhibition, World PM 2010; Florence; Italy; 10 October 2010 through 14 October 2010 Vol. 2 (2010), p. 3-12.
[Konferensbidrag, refereegranskat]

Chromium is the one of the most attractive alloying elements in PM steels, nevertheless its high affinity to oxygen during sintering, especially during the heating stage, have to be considered. The type, morphology and distribution of the reaction products on the fracture surface of the pressed and sintered specimens of chromium-alloyed water atomized steel powders were studied by means of high resolution scanning electron microscopy (SEM including EDX). Specimens were sintered in three different atmospheres – nitrogen, nitrogen/10%hydrogen and vacuum. In all materials formation of particulate reaction products containing strong-oxide forming elements such as Cr, Si and Mn was detected. Positive effect of hydrogen on the oxides reduction during heating stage was observed. Preferred location of the inclusions inside the dimples of inter-particle ductile fracture indicates that they originate from fine particulates on the original powder surface that were enclosed during heating stage. Obtained results indicate that oxygen content can be significantly reduced by adjustment proper atmosphere purity/composition or high-temperature sintering.

Nyckelord: PM steel, chromium pre-alloyed powder, sintering, sintering atmosphere, surface oxide, oxide reduction, carbothermal reduction, spinel oxides



Denna post skapades 2010-10-27. Senast ändrad 2016-05-13.
CPL Pubid: 128185

 

Institutioner (Chalmers)

Institutionen för material- och tillverkningsteknik, Yt- och mikrostrukturteknik (2005-2017)

Ämnesområden

Materialteknik
Ytbehandlingsteknik

Chalmers infrastruktur

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Surface Chemical Characteristics of Chromium-alloyed Steel Powder and the Role of Process Parameters during Sintering