Comparative study on the densification of chromium pre-alloyed powder metallurgy steel through nanopowder addition using design of experiments
Artikel i vetenskaplig tidskrift, 2021

There is a constant demand for high density press and sinter powder metallurgical components for automotiveapplications. Steel powder pre-alloyed with chromium is an attractive material for such applications, but newways to further increase the sinter density are required for successful processing of these powders to high density.Nanopowder could be used as a potential sintering aid in order to boost the densification of the steel powdercompact. In this study, steel powder pre-alloyed with chromium, without and with admixed nickel, is used as basepowder, to which nanopowder was added. Surface oxide removal, crucial for successful sintering of such mate-rials, was studied by thermogravimetry analysis in order to understand the influence of nanopowder addition onthe oxide reduction. Powder compacts containing nanopowder showed higher mass loss in comparison to the oneswithout nanopowder. Linear shrinkage obtained from dilatometric curves increased with the addition of nano-powder. To depict the influence of the critical parameters; sintering temperature, powder size, addition ofnanopowder and composition (with or without nickel), a design of experiment approach was applied. The criticalparameters were then adjusted at 2 different values (categorical parameters) and a‘full factorial design model’was used involving 16 experiments, with sinter density and hardness as output measures of the experimentsdetermined. The results were analyzed using polynomialfit to determine which of the parameter exerts themaximum influence. Presence of nickel increased the hardness whereas sintering temperature and presence ofnanopowder enhanced the sinter density. This led to the tentative design of optimum conditions that resulted inincrease in sinter density from 7.25 g/cm3(92.5% of the theoretical density) to 7.4 g/cm3(94% of the theoreticaldensity) with an addition of 5% nanopowder to Ni-containing grade when sintered at 1350C instead of 1250C.

Författare

Swathi Kiranmayee Manchili

Chalmers, Industri- och materialvetenskap, Material och tillverkning

Johan Wendel

Chalmers, Industri- och materialvetenskap, Material och tillverkning

Maheswaran Vattur Sundaram

Chalmers, Industri- och materialvetenskap, Material och tillverkning

Eduard Hryha

Chalmers, Industri- och materialvetenskap, Material och tillverkning

Lars Nyborg

Chalmers, Industri- och materialvetenskap, Material och tillverkning

Results in Materials

2590-048X (ISSN)

Vol. 10

Drivkrafter

Hållbar utveckling

Styrkeområden

Produktion

Ämneskategorier

Keramteknik

Annan materialteknik

Metallurgi och metalliska material

Fundament

Grundläggande vetenskaper

DOI

10.1016/j.rinma.2021.100173

Mer information

Skapat

2021-06-24