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.

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 Embrittling Components in Sintered Steels: Comparison of Phosphorus and Boron

2017 ◽  
Vol 17 (1) ◽  
pp. 47-64 ◽  
Author(s):  
Herbert Danninger ◽  
Vassilka Vassileva ◽  
Christian Gierl-Mayer
Keyword(s):  
Powder Metallurgy ◽  
Liquid Phase ◽  
Fracture Surface ◽  
Transient Liquid Phase ◽  
Sintering Process ◽  
Iron Matrix ◽  
Sintered Iron ◽  
Transgranular Cleavage ◽  
Sintered Steels ◽  
Long Time

Abstract In ferrous powder metallurgy, both boron and phosphorus have been known to be sintering activators for a long time. However, the use has been widely different: while P is a standard additive to sintered iron and steels, boron has been frequently studied, but its use in practice is very limited. Both additives are also known to be potentially embrittling, though in a different way. In the present study the differences between the effects of both elements are shown: while P activates sintering up to a certain threshold, in part by stabilizing ferrite, in part by forming a transient liquid phase, boron is the classical additive enhancing persistent liquid phase, being virtually insoluble in the iron matrix. The consequence is that sintered steels can tolerate quite a proportion of phosphorus, depending on composition and sintering process; boron however is strongly embrittling in particular in combination with carbon, which requires establishing a precisely defined content that enhances sintering but is not yet embrittling. The fracture mode of embrittled materials is also different: while with Fe-P the classical intergranular fracture is observed, with boron a much more rugged fracture surface appears, indicating some failure through the eutectic interparticle network but mostly transgranular cleavage. If carbon is added, in both cases transgranular cleavage dominates even in the severely embrittled specimens, indicating that no more the grain boundaries and sintering necks are the weakest links in the systems.

Boron Nitride Ceramic Composite Obtained by High Pressure and High Temperature Sintering

2012 ◽  
Vol 727-728 ◽  
pp. 736-739 ◽  
Author(s):  
Ana Lucia D. Skury ◽  
Carlos A. Oliveira Monteiro ◽  
Guerold Sergueevitch Bobrovinitchii ◽  
Sérgio Neves Monteiro
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Composite Material ◽  
High Temperature ◽  
Boron Nitride ◽  
Chemical Reactions ◽  
Ceramic Composite ◽  
Sintering Process ◽  
Polycrystalline Structure ◽  
Binding Agents

In the present work, by selecting Si3N4, TiB2 and Al2O3 as binding agents as well as La3O2 as an additive, sintered wBN composites were studied. By modifying the number of sintering cycles, the composites processed at 4.5GPa and 1800°C showed improved mechanical properties. The degree of transformation of the wBN, as well as the chemical reactions during the sintering process were discussed. This new composite material was found to present polycrystalline structure that provides superior cutting properties. Moreover, owing to superior properties, the wBN composite sharpens itself during cutting.

Effects of Heat Treatment on Strength Wear Sintered Alloy Steels

2015 ◽  
Vol 1128 ◽  
pp. 315-321
Author(s):  
Ionela Gabriela Bucse ◽  
Olimpia Ghermec ◽  
Mariana Ciobanu ◽  
Christian Ghermec ◽  
Claudiu Nicolicescu
Keyword(s):  
Heat Treatment ◽  
Mechanical Alloying ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Sintered Alloy ◽  
Sintering Process ◽  
Wear Coefficient ◽  
Sintered Steels ◽  
Alloy Steels ◽  
Size Powder

This paper presents the results of experimental research on thermal treatment of alloyed sintered steels and much the development of Fe‒3Mn‒1Mo‒1.5Cr‒0.5B‒0.45Graphite powder using mechanical alloying (MA). It was analyzed the influence of MA time on the morphology of the compound by electron microscopy SEM. The research has followed the study of the particle size powder mixtures influence obtained by mechanical alloying, compaction parameters and sintering process on the chemical and structural characteristics of the alloyed sintered steels. Thus there were compacted samples at 600, 700 and 800 MPa. The samples were heated using argon at a temperature of 1150°C using 60 minutes as a maintaining time. Cooling to the room temperature was achieved using a speed of about 30°C/ minutes. With the resulting steels, we have made metallographic determinations using optic microscopy and determinations of the main mechanical properties. Heat treatment took place (heating at 960°C and cooling in the H2O solution and 10% NaCl) in order to improve the properties of alloyed sintered steel hardness and strength. Specimens quenched and tempered have high wear coefficient compared with specimens as-sintered.

Behaviour of Some Unalloyed and Alloyed Sintered Steels at Static and Dynamic Loads

2011 ◽  
Vol 672 ◽  
pp. 315-318
Author(s):  
Liviu Brânduşan
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Iron Powder ◽  
Fine Powder ◽  
Steel Powder ◽  
Sintering Process ◽  
Powder Mixtures ◽  
Sintered Steels ◽  
Static And Dynamic Loads ◽  
Sintered Materials

The behaviour of alloyed and unalloyed sintered steels in static and dynamic loading is influenced by their macro and microstructure. The characteristics of the used powder, their chemical composition, the conditions of shaping by pressing, and the parameters of the sintering process are some factors determining the structure of the steels [1, 2]. Under the same technological conditions, sintered materials were produced using iron powder of different particle size or in different powder mixtures for establishing the structure influence on some mechanical properties, The results obtained shows that the sintered materials present a higher sensitivity towards the dynamic and variable loads [2]. In the same time, it was shown that a material made from a fine powder fraction behaves, at mechanical loads, almost in the same way as an elaborated material from the same powder but with a wider particle size distribution or particles size. Using of the different powder mixtures lead to some microstructures with better mechanical properties at the intergranulars necks. Using the copper powder or the low or high alloyed iron powder in a mixture with the basic iron powder determines an improvement of the mechanical properties by changing the materials microstructure. It was found that the addition of high alloyed steel powder has the strongest effect on the fatigue resistance.

Dilatometry Coupled with Mass Spectrometry as Instrument for Process Control in Sintering of Powder Metallurgy Steels

2016 ◽  
Vol 835 ◽  
pp. 106-115 ◽  
Author(s):  
Christian Gierl-Mayer ◽  
Herbert Danninger
Keyword(s):  
Mass Spectrometry ◽  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Process Control ◽  
Analytical Data ◽  
Sintering Process ◽  
Sintering Atmosphere ◽  
Surface Oxides ◽  
The Press ◽  
Sintering Behaviour

The production of ferrous powder metallurgical parts by the press-and-sinter route becomes more and more attractive. Today, parts are produced for loading requirements that until now only could be fulfilled by conventional produced steel components. The high mechanical properties that must be attained require the use of alloying elements so far not common in powder metallurgy because of their high affinity for oxygen. The sintering of chromium containing steels is a challenge for the whole production process, because the reduction of the surface oxides is critical for successful sintering.Dilatometry can be a useful instrument to control the sintering behaviour of the materials, especially the combination with mass spectrometry allows analysing the very complex sintering process and simultaneously monitoring the solid-gas reactions. This work shows that the sintering atmosphere plays a major role in the entire process. Degassing and deoxidation processes during sintering are demonstrated for different alloying systems (Fe, Fe-C, Fe-Mo-C, Fe-Cr-Mo-C). Dilatometry coupled with MS is shown to be a very good instrument for process control of the sintering process. The generated analytical data can be related to the mechanical properties of the sintered steels if the size of the specimen is large enough.

Microstructure and Mechanical Properties of Sn-1.0Ag-0.7Cu (SAC107) Lead-Free Solder Reinforced Silicon Nitride (Si3N4) Particles

2015 ◽  
Vol 754-755 ◽  
pp. 535-539
Author(s):  
Norhayanti Mohd Nasir ◽  
Norainiza Saud ◽  
Mohd Arif Anuar Mohd Salleh ◽  
M.N. Derman ◽  
Mohd Izrul Izwan Ramli ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Silicon Nitride ◽  
Powder Metallurgy ◽  
Microstructural Analysis ◽  
Lead Free ◽  
Lead Free Solder ◽  
Sintering Process ◽  
Homogeneous Microstructure ◽  
Free Solder

This research has investigated the microstructural analysis and shear strength of Sn-1.0Ag-0.7Cu (SAC107) alloy used as matrix while silicon nitride (Si3N4) as reinforcement particles with different weight fractions (0, 0.25, 0.5, 0.75 and 1.0 wt. %). The composite solders were fabricated using powder metallurgy (PM) method consisting of mixing, compaction and sintering process. With additions of Si3N4 particles, the composite solders experienced a corresponding increase in strength due to fine and homogeneous microstructure. This is signified that the presence of Si3N4 particles effectively refines the microstructure.

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.

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