scholarly journals Phosphorus in Sintered Steels: Interaction of Phosphorus with Mo

2016 ◽  
Vol 16 (1) ◽  
pp. 14-26
Author(s):  
H. Danninger ◽  
B. Üregen
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Solubility Product ◽  
Critical Level ◽  
Alloy Element ◽  
Group Element ◽  
Impact Testing ◽  
Phosphorus Addition ◽  
Sintered Steels ◽  
Intergranular Embrittlement

Abstract Phosphorus as an alloy element is quite common in powder metallurgy, the contents industrially used being markedly higher than those present in wrought steels. However, embrittlement effects are reported also for sintered steels, in part depending on the alloy elements present. In this study, the influence of phosphorus addition on the mechanical properties of PM steels alloyed with Mo, as the most common VI group element in sintered steels, was investigated. PM steels of the type Fe-x%Mo-0.7%Cy% P were manufactured with varying contents of Mo and P, respectively. It showed that P activates sintering also in these materials and enhances Mo homogenization, but there is in fact a risk of embrittlement in these steels that however strongly depends on the combination of Mo and P in the materials: If a critical level is exceeded, embrittlement is observed. At low Mo contents, higher P concentrations are acceptable and vice versa, but e.g. in a material Fe-1.5%Mo-0.7%C-0.45%P, pronounced intergranular embrittlement occurs, further enhanced by sinter hardening effects. This undesirable phenomenon is more pronounced at higher sintering temperatures and in case of faster heating/cooling; it was observed both in materials prepared from mixed and prealloyed powders, respectively. This typical intergranular failure observed with embrittled specimens, in particular after impact testing, indicates the precipitation of brittle phases at the grain boundaries, apparently when exceeding the solubility product between Mo and P.

scholarly journals Phosphorus in Sintered Steels: Effect of Phosphorus Content and P Carrier in Sintered Steel Fe-C-P

2016 ◽  
Vol 16 (1) ◽  
pp. 1-13 ◽  
Author(s):  
B. Üregen ◽  
C. Gierl-Mayer ◽  
H. Danninger
Keyword(s):  
Liquid Phase ◽  
Impact Energy ◽  
Phosphorus Content ◽  
Transient Liquid Phase ◽  
Alloy Element ◽  
Sintered Steel ◽  
Secondary Porosity ◽  
Phosphorus Addition ◽  
Sintered Steels ◽  
The Impact

Abstract Phosphorus as an alloy element is quite common in powder metallurgy, the contents industrially used being markedly higher than those present in wrought steels. In this study, the influence of phosphorus addition through different P carriers was investigated. PM steels of the type Fe-0.7%C-x%P (x = 0.0 … 0.8%) were manufactured by pressing and sintering in H2. It showed that Fe3P is the best phosphorus carrier, resulting in fine and regular microstructure and in high impact energy data at 0.3 … 0.45%P while red P and also Fe2P showed a tendency to agglomeration, with resulting secondary porosity. At high P levels the mechanical properties tend to drop, for the tensile strength at P > 0.60%P while for the impact energy the threshold is 0.45%P. The dimensional behaviour of Fe-C-P can be related to PM aluminium alloys, expansion by transient liquid phase being followed by shrinkage by persistent liquid phase, at least at higher temperatures. In contrast to the dimensional behaviour, degassing and reduction is hardly affected by the phosphorus content.

scholarly journals New alloying systems for ferrous powder metallurgy precision parts

2008 ◽  
Vol 40 (1) ◽  
pp. 33-46 ◽  
Author(s):  
H. Danninger ◽  
C. Gierl
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Chemical Reactions ◽  
Sintering Process ◽  
Critical Importance ◽  
Sintered Steels ◽  
Alloy Steels ◽  
The Common

Traditionally, the common alloy elements for sintered steels have been Cu and Ni. With increasing requirements towards mechanical properties, and also as a consequence of soaring prices especially for these two metals, other alloy elements have also become more and more attractive for sintered steels, which make the steels however more tricky to process through PM. Here, the chances and risks of using in particular Cr and Mn alloy steels are discussed, considering the different alloying techniques viable in powder metallurgy, and it is shown that there are specific requirements in particular for sintering process. The critical importance of chemical reactions between the metal and the atmosphere is described, and it is shown that not only O2 and H2O but also H2 and even N2 can critically affect sintering and microstructural homogenization.

scholarly journals New alloying systems for ferrous powder metallurgy precision parts

2008 ◽  
Vol 40 (1) ◽  
pp. 33-46
Author(s):  
H. Danninger ◽  
C. Gierl
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Chemical Reactions ◽  
Sintering Process ◽  
Critical Importance ◽  
Sintered Steels ◽  
Alloy Steels ◽  
The Common

Traditionally, the common alloy elements for sintered steels have been Cu and Ni. With increasing requirements towards mechanical properties, and also as a consequence of soaring prices especially for these two metals, other alloy elements have also become more and more attractive for sintered steels, which make the steels however more tricky to process through PM. Here, the chances and risks of using in particular Cr and Mn alloy steels are discussed, considering the different alloying techniques viable in powder metallurgy, and it is shown that there are specific requirements in particular for sintering process. The critical importance of chemical reactions between the metal and the atmosphere is described, and it is shown that not only O2 and H2O but also H2 and even N2 can critically affect sintering and microstructural homogenization.

Effect of Carbon Addition on the Microstructure and Properties of M3:2 High Speed Steels Processed by Powder Metallurgy

2007 ◽  
Vol 29-30 ◽  
pp. 153-158 ◽  
Author(s):  
R. Zhou ◽  
D. Wang ◽  
Jun Shen ◽  
J. Sun
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Oxygen Content ◽  
High Speed ◽  
Sintering Temperature ◽  
Experimental Results ◽  
Full Density ◽  
Bend Strength ◽  
Carbon Addition ◽  
Sintered Steels

M3:2 high speed steels with and without carbon addition were prepared by using powder metallurgy at sintering temperature between 1210 and 1280 °C. Densification, microstructure and mechanical properties of M3:2 high speed steels were investigated. Experimental results show that with 0.4wt% carbon addition, full density high speed steels were obtained at temperatures in the range 1240-1260 °C which is 40 °C lower than that of the undoped counterparts, leading to a sintering window expanded by 10 to 20 °C. By the addition of 0.4wt% carbon, the sintered steels show attractive combinations of bend strength and hardness over those of M3:2 steels without carbon addition. The results reveal that the addition of carbon will not only lower the sintering temperature and oxygen content, but also improve the mechanical properties of the sintered steels.

Ultra High Carbon Steels Obtained by Powder Metallurgy

2006 ◽  
Vol 530-531 ◽  
pp. 328-333 ◽  
Author(s):  
M.A. Martinez ◽  
J. Abenojar ◽  
J.M. Mota ◽  
R. Calabrés
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Reference Material ◽  
Carbon Content ◽  
Carbon Steels ◽  
High Carbon ◽  
High Carbon Content ◽  
Damascus Steel ◽  
Sintered Steels ◽  
Ancient Iron

The objective of the present work is to study the manufacturing process of steels with high carbon content (1.5–2.1wt%) obtained by powder metallurgy. The reference material was the Damascus steel, which was employed to manufacture swords named after it and has been widely known due to its very good mechanical properties. The main reasons of the success of this product are: the high carbon content of the initial steel and the thermomechanical treatment (forge and quenching) that ancient iron forgers kept secretly during centuries. Different carbon contents (2 to3 wt%) were added to the same Fe powder matrix (ASC 300), and compacted and sintered steels are heat laminated (750°C) with a reduction of 20%. For 2% carbon content, the result is a steel with yield strength of 450 MPa, Young’s Modulus of 14.3 GPa and hardness of 109 HV(30).

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