Metallographic and fractographic examination of fatigue loaded PM-steel with and without MnS additive

Drar, H.

doi:10.1016/s1044-5803(00)00080-2

Cited by 19 publications

(21 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to definition [2], in PM parts cracks are nucleate and initiate from surface pores under different static (tensile) and dynamic loading (fatigue). This has been confirmed by several researchers [32,37,38]. Likewise, in this research the examination of fracture surfaces revealed that in many cases initiation sites are constituted by pores located a few microns below the tensile surface, as shown in Fig.…”

Section: Mode I: Crack Initiation and Propagationsupporting

confidence: 86%

“…6. Particle fracture, which can occur when bonding between the matrix and inclusion is strong, can accelerate the development of crack growth [32,37]. In addition, elongated pores create condition for crack growth more easily in a tensile surface.…”

Section: Mode I: Crack Initiation and Propagationmentioning

confidence: 99%

“…Several models have been proposed [13,32,37] to describe cleavage fracture. It is summarized in the following stages: under an external load, micro cracks are nucleated ahead of a dislocation pile-up and they grow through the grain of the respective particle.…”

Section: Mode Ii: Fracture Mechanismmentioning

confidence: 99%

See 2 more Smart Citations

Microstructural association between mechanical behavior with bending fracture surfaces in Astaloy CrA sintered parts alloyed by Cu and C

2014

View full text Add to dashboard Cite

a b s t r a c tApplication of powder metallurgy technique, a method presenting both economic and technical concepts for producing sintered parts, has been expanding in automobile and other engineering industries. Powder metallurgy parts usually possess residual porosity in their microstructures deteriorating mechanical performance. There have been many solutions to increasing of strength in these parts such as applying different heat treatment or adding alloying elements. It is well known that Fe-Cu-C is the one of main alloying system for both increasing the strength and decreasing cost of them. In this study, the microstructure, mechanical properties (transverse rapture strength and hardness), crack behavior and fracture modes of a low alloy Fe-Cr powder (Astaloy CrA) with different amount of copper (0, 1 and 2 wt.%) and carbon, in form of graphite (0.45, 0.6 and 0.8 wt.%) sintered at conventional condition have been investigated. Microstructural evolution showed adding copper and graphite as alloying elements could generate widespread of strength (857-1380 MPa) and hardness . Developing different phases in microstructure was the main reason for various mechanical properties. Crack coalescence phenomenon leads to fracturing with ductile (at sinter-necks) and brittle morphology. Micro-mechanism of fracture related to transparticle and interparticle crack propagation.

show abstract

Section: Mode I: Crack Initiation and Propagationsupporting

confidence: 86%

Section: Mode I: Crack Initiation and Propagationmentioning

confidence: 99%

See 1 more Smart Citation

Microstructural association between mechanical behavior with bending fracture surfaces in Astaloy CrA sintered parts alloyed by Cu and C

2014

View full text Add to dashboard Cite

show abstract

“…It is known that the difference between the thermal contraction of inclusions and the matrix during cooling can create stress fields around the inclusions leading to the adjacent matrix deformation or discontinuity between the matrix and inclusion [37][38][39]. Figure 13 illustrates the thermal expansion coefficients of conventional inclusions and includes data from different references [40][41][42].…”

Section: Influence Of Re Addition On the Accumulation Of Nb-rich Phasmentioning

confidence: 99%

The Influence of La and Ce Addition on Inclusion Modification in Cast Niobium Microalloyed Steels

Torkamani

Raygan

García‐Mateo

et al. 2017

Metals

View full text Add to dashboard Cite

The main role of Rare Earth (RE) elements in the steelmaking industry is to affect the nature of inclusions (composition, geometry, size and volume fraction), which can potentially lead to the improvement of some mechanical properties such as the toughness in steels. In this study, different amounts of RE were added to a niobium microalloyed steel in as-cast condition to investigate its influence on: (i) type of inclusions and (ii) precipitation of niobium carbides. The characterization of the microstructure by optical, scanning and transmission electron microscopy shows that: (1) the addition of RE elements change the inclusion formation route during solidification; RE > 200 ppm promote formation of complex inclusions with a (La,Ce)(S,O) matrix instead of Al 2 O 3-MnS inclusions; (2) the roundness of inclusions increases with RE, whereas more than 200 ppm addition would increase the area fraction and size of the inclusions; (3) it was found that the presence of MnS in the base and low RE-added steel provide nucleation sites for the precipitation of coarse niobium carbides and/or carbonitrides at the matrix-MnS interface. Thermodynamic calculations show that temperatures of the order of 1200 • C would be necessary to dissolve these coarse Nb-rich carbides so as to reprecipitate them as nanoparticles in the matrix.

show abstract

“…13,17,19 Since fatigue crack initiation usually occurs at/or near pores in PM steels, the presence of austenite in these regions could affect fatigue performance. [20][21][22][23][24] Indeed, an improvement in the endurance limit was observed by Unami et al 25 for PM steels and by Richman and Landgraf 26 for high carbon wrought steels for larger amounts of retained austenite. They attributed this improvement to the high ductility of austenite and to its strain induced martensitic transformation, which both consume energy that cannot be used for the initiation of cracks.…”

Section: Introductionmentioning

confidence: 99%

Microstructural characterisation of nickel rich areas and their influence on endurance limit of sintered steel

et al. 2011

View full text Add to dashboard Cite

Microstructural characterisation of nickel rich areas and their influence on endurance limit of sintered steel Bernier, F.; Plamondon, P.; Baïlon, J.-P.; L'Espérance, G. Nickel is an often used alloying element in powder metal steel to achieve high hardenability. However, when nickel is added, the slow diffusion rate between iron and nickel leads to the formation of nickel rich areas (NRAs). Two steel alloys were studied: a Fe-6?4Ni-0?7Mo-0?7C with standard sized nickel powder additions and a Fe-2?4Ni-0?7Mo-0?7C with a finer sized nickel powder. Microstructural characterisation of the parts revealed that sufficient hardenability was achieved for both materials, but that NRAs were observed when standard sized nickel is used. Xray energy dispersive spectrometry and electron diffraction show that the NRAs are composed of martensite and austenite under rapid cooling conditions. Three-point bending fatigue tests were carried out on both alloys to evaluate the effect of these soft austenitic areas on the fatigue properties of powder metal steel parts. The analysis of the endurance limit results shows that NRAs are not a governing factor.

show abstract

Metallographic and fractographic examination of fatigue loaded PM-steel with and without MnS additive

Cited by 19 publications

References 10 publications

Microstructural association between mechanical behavior with bending fracture surfaces in Astaloy CrA sintered parts alloyed by Cu and C

Microstructural association between mechanical behavior with bending fracture surfaces in Astaloy CrA sintered parts alloyed by Cu and C

The Influence of La and Ce Addition on Inclusion Modification in Cast Niobium Microalloyed Steels

Microstructural characterisation of nickel rich areas and their influence on endurance limit of sintered steel

Contact Info

Product

Resources

About