Influence of alloying elements on Ni distribution in PM steels

Abstract

Powder metallurgical (PM) steels with elemental Ni additions exhibit non-homogenous microstructures with soft Ni rich areas, lean in C, after conventional sintering. Though, the exact correlation between the distribution of Ni and mechanical properties is not well known and depends on the conditions, e.g. the load state, it is desirable to be able to control the distribution of Ni since it plays a major role in the properties of Ni PM components. By introducing other alloying elements, the microstructure homogeneity of Ni containing PM steels, can be influenced. Thus, the effect of common alloying elements on the homogeneity of sintered microstructures has been investigated in the present work. It is found that additions of either C or Mo have minor effect on Ni distribution in the Fe–Ni system. However, addition of both C and Mo to Fe–Ni improves the Ni distribution. In addition, a strong interaction between Ni and Cu is observed and it enhances the Ni homogeneity. Furthermore, the influence of Cu is more pronounced in presence of C.

Keywords

Sintering Powder metallurgy Steels Alloying Homogeneity

Get full access to this article

View all access options for this article.

References

Bergmark

and Alzati

‘Fatigue crack path in Cu–Ni–Mo alloyed PM steel’, Fatigue Fract. Eng. Mater. Structures, 2005, 28, 229–235.

‘Standard test method for metal powder and powder metallurgy products’, MPIF Standard 35, Metal Powder Industries Federation Publication, Princeton, NJ, USA, 2007, 128.

Sanderow

H. I.

, Spirko

J. S.

and Friedhoff

T. G.

‘Fatigue properties pf PM materials: Relatinship of RBF and Af results to material processing parameters’, Adv. Powder Metall. Part. Mater., 1997, 13, 117–135.

Carabajar

, Verdu

and Fougeres

‘Damage mechanisms of a nickel alloyed sintered steel during tensile tests’, Mater. Sci. Eng. A, 1997, A32, 80–87.

M. W.

, Hwang

K. S.

and Huang

H. S.

‘In-situ observations on the fracture mechanism of diffusion-alloyed Ni-containing powder metal steels and a proposed method for tensile strength improvement’, Metall. Mater. Trans. A, 2007, A38, 1598–1607.

Bhadeshia

HKDH

‘Steels microstructure and properties’, 3rd edn; 2006, Amsterdam, Boston, Elsevier.

Tougas

, Blais

, Larouche

, Chagnon

and Pelletier

‘Characterization of the formation of Nickel rich areas in PM Nickel steels and their effect on mechanical properties’, Adv. Powder Metall. Part. Mater., 2012, 5, 19–33.

Sozinov

A. L.

and Gavrilijuk

V. G.

‘Estimation of interaction energies Me-(C, N) in f.c.c. iron-based alloys using thermo-calc thermodynamic database’, Scr. Mater., 1999, 41, 679–683.

M. W.

, Hwang

K. S.

and Chuang

K. H.

‘Improved distribution of nickel and carbon in sintered steels through addition of chromium and molybdenum’, Powder Metall., 2008, 51, 160–165.

10.

M. W.

, Hwang

K. S.

, Huang

H. S.

and Narasimhan

K. S.

‘Improvements in microstructure homogenization and mechanical properties of diffusion-alloyed steel compact by the addition of Cr-containing powders’, Metall. Mater. Trans. A, 2006, 37A, 2559–2568.

11.

Hwang

K. S.

, Mu

M. W.

and Tsai

C. C.

‘High strength sinter-hardening powder metallurgy alloys’, Adv. Mater. Res., 2008, 51, 3–9.

12.

Frykholm

and Maroli

‘Effect of Ni additives on carbon distribution in Astaloy 85Mo’, Internal report, Höganäs AB, Sweden, 2007.

13.

Lindsley

and Murphy

‘Dimensional control in Cu–Ni containing ferrous PM alloys’, Adv. Powder Metall. Part. Mater., 2006, 2, 140–153.

14.

Singh

, Stephenson

T. F.

and Campbell

S. T.

‘Ni–Cu interaction in PM steels’, Adv. Powder Metall. Part. Mater., 2004, 7, 93–104.

15.

Dautzenberg

and Dorweiler

H. J.

‘Dimensional behavior of Cu C sintered steel’, Powder Metall. Int., 1985, 17, 279–282.

16.

Lawcock

R. L.

and Davies

T. J.

‘Effect of C on dimensional and microstructural characteristics of Fe–Cu compacts during sintering’, Powder Metall., 1990, 33, 147–150.

17.

Baran

and Murphy

T. F.

‘An investigation into the effect of copper and graphite additions to Sinter hardened steels’, Adv. Powder Metall. Part. Mater., 2004, 10, 266–274.

18.

Tahir

A. M.

, Amberg

, Hedström

, Bergman

and Frisk

‘Cu distribution in Fe–2Cu and Fe–2Cu–0·5C compacts’, unpublished work.

19.

Andersson

J. O.

, Helander

, Höglund

, Shi

P. F.

and Sundman

‘Thermo-Calc & DICTRA, computational tools for materials science’, Calphad, 2002, 26, 273–312.

20.

Hwang

K. S.

and Shiau

M. Y.

‘Effect of Ni on the sintering behavior of Fe–Ni compacts made from composite and elemental powders’, Metall. Mater. Trans. B, 1996, 27B, 203–211.

21.

Blakely

J. M.

and Mykura

‘Surface self diffusion measurements on Ni by mass transfer method’, Acta Metall., 1961, 9, 23–31.

22.

Singh

and Stephenson

T. F.

‘Ni–Cu–Mo interactions in sinter-hardening steels’, Euro PM2005, Prague, Czech, October 2005, EPMA, Vol. 1, 261–264.

23.

Svensson

L. E.

‘The effect of Cu and Ni additions to high-compressibility sponge iron powder on the sintered properties of materials with 0·3% and 0·6%C’, Powder Met., 1974, 17, 271.

24.

Maroli

, Berg

and Lewenhagen

‘Properties and microstructure of PM materials pre-alloyed with Nickel, Molybdenum and Chromium’, Paper presented at EURO PM2001 Congress & Exhibition, Nice, France, October 2001, EPMA.