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Evaluation of heat treatment methods for fatigue design of PM parts
Literature Iron and Steel
MICROSTRUCTURALAND MECHANICALCHARACTERIZATION OFION-NITRIDEDSUREACESOF SINTEREDSTEEL A Molinari, et al, (University of Trento, Italy). Vol 1, Paper 29,407-414. Fe-Cr and Fe-Cr-Cu alloys were ion-nitrided at 823K for v a r y i n g l e n g t h s of time. Microstructures were studied and depth of penetration (by microhardness profiling) measured. Effects of alloy composition and process variables on character of nitrided layers were investigated. Cu has a negative effect on microstructure and properties of nitrided surfaces.
Tests were carried out to establish the effect of density on the fatigue limit of sintered steels. A resonance pulsator was used and the increase in temperature of specimens was measured. Hysteresis loops were plotted. Results for Fe-l.2%Cu are presented. EVALUATION OF HEAT TREATMENT METHODS FOR FATIGUE DESIGN OF PM PARTS F J Esper, C M Sonsino, (Fraunhofer Institut, Darmstadt, Germany). Vol 1, Paper 34, 446--456. Fatigue behaviour of sintered Fe-l.5%Cu, Fe-1.5%Cu-0.6%C and Fe-0.8%Mn-0.95%Cr-0.24%Mo-0.6%C in as-sintered and heat treated conditions was investigated. Tests were carried out on notched and un-notched specimens under a range of testing conditions. Microstructures and test results are given.
CORROSION OF SINTERED STAINLESS STEELS E Ahlberg, et al, (Chalmers University, Goteborg, Sweden). Vol 1, Paper 31,419-432. The corrosion of sintered stainless steels (9304L, 316, 410L and 430L) in sulphuric acid was studied. All samples showed active corrosion in this electrolyte. Density of the samples had no clear influence on the corrosion behaviour. It is suggested that the surface condition is of great importance but ferritic 430L showed general corrosion in spite of a large number of pores in the samples. EFFECT OF POROSITY ON STATIC AND DYNAMIC PROPERTIES OF PM Fe H Danninger, et al, (Technical University of Vienna, Vienna, Austria). Vol 1, Paper 32, 433--439. The porosity of sintered Fe was studied. It was found that the change from isolated to interconnecting pores takes place in the range 6-14% total porosity. Measurements of properties show that properties depend not only on total porosity but also on pore shape and connectivity. FATIGUE BEHAVIOUR OF SINTERED STEELS A Piotrowski, H Harig, (University of Essen, Essen, Germany). Vol 1, Paper 33 440--445.
786
INFLUENCE OF AS-SINTERED STRENGTH ON IMPROVEMENT OF FATIGUE STRENGTH BY SURFACE ROLLING
THE ROLE OF MnS IN IMPROVING THE MACHINABILITY OF PM PARTS K S Chopra, D S Madan, (Elkem Metals Co, Niagara Falls, NY, USA). Vol 2, Paper 12, 61-65. The role of MnS in improving machinability of PM steel parts and the effects on properties is examined. It is reported that MnS does not interact with other alloy elements and has minimal and predictable effects on physical and mechanical properties.
HEAT TREATMENT OF SINTERED STEELS MADE FROM ELEMENTAL AND PREALLOYED POWDERS J M Torralba, et al, (Polytechnical University, Madrid, Spain). Vol 2, Paper 14, 69-74. Two steels were produced (composition Fe- 1.5%Cu-4%Ni-0.5%Mo-0.7%C), one from elemental powders and the other from pre-alloyed powder. Mechanical properties, microstructure, dimensional stability and hardenability are compared.
C M Sonsino, et al, (Fraunhofer Institut, Darmstadt, Germany). Vol 1, Paper 39, 497-508.
FATIGUE STRENGTH OF PM MATERIALS WITH NON-MACHINED SURFACES
Fatigue life curves of Fe-l.5%Cu (density 7.15gm/cm 3) and Fe-8%Ni-1.0%Mo-0.5%C (density 7.35gm/cm 3) were compared for three different notch factors in as-sintered and surface rolled conditions under constant and variable amplitude loading. Results were interpreted on the basis of microstmcture, m i c r o h a r d n e s s and r e s i d u a l stress distributions. The paper presents statistically based design data about the improvement of fatigue strength as a result of surface rolling of PM parts.
T M Cadle, C J Landgraf, (Zenith Sintered Products, Milwaukee, USA). Vol 2, Paper 25, 124-128.
PROPERTIES AND STRUCTURES OF COLD-FORGED STAINLESS STEEL-PARTICULATE COMPOSITES N Petersen, (Technical U n i v e r s i t y of Denmark). Vol 1, Paper 40, 509-518. Stainless steel matrix composites with up to 30vo1% of CrC or T'tB were produced by PM. Tensile strength was reduced and porosity increased by hard particles. Properties improved by cold forging. Adhesive wear is improved by hard particles, attributed to the load carrying ability of the hard particles.
The paper draws attention to the need for improved fatigue strength in PM materials. Fatigue tests were carried out on PM specimens with machined and non-machined surfaces. It is concluded that machining reduces endurance, and non-machined flexural bend test pieces give more consistent data. STRUCTURES AND DYNAMIC PROPERTIES OF EXTRUDED PM FERROUS MACROCOMPOSITE M N H Ahmed, et al, (A1-Azhar University, Cairo, Egypt). Vol 2, Paper 26, 129-134. Mechanical properties of extruded coaxial cylindrical duplex structures were evaluated with respect to heat treatment, residual stresses and plastic constraint. Experimental results gave good agreement with predictions. The effects of residual stresses in the sheath component of a duplex structure on dynamic properties were also modelled.
MPR November 1990
MICROSTRUCTURALAND MECHANICALCHARACTERIZATION OFION-NITRIDEDSUREACESOF SINTEREDSTEEL A Molinari, et al, (University of Trento, Italy). Vol 1, Paper 29,407-414. Fe-Cr and Fe-Cr-Cu alloys were ion-nitrided at 823K for v a r y i n g l e n g t h s of time. Microstructures were studied and depth of penetration (by microhardness profiling) measured. Effects of alloy composition and process variables on character of nitrided layers were investigated. Cu has a negative effect on microstructure and properties of nitrided surfaces.
Tests were carried out to establish the effect of density on the fatigue limit of sintered steels. A resonance pulsator was used and the increase in temperature of specimens was measured. Hysteresis loops were plotted. Results for Fe-l.2%Cu are presented. EVALUATION OF HEAT TREATMENT METHODS FOR FATIGUE DESIGN OF PM PARTS F J Esper, C M Sonsino, (Fraunhofer Institut, Darmstadt, Germany). Vol 1, Paper 34, 446--456. Fatigue behaviour of sintered Fe-l.5%Cu, Fe-1.5%Cu-0.6%C and Fe-0.8%Mn-0.95%Cr-0.24%Mo-0.6%C in as-sintered and heat treated conditions was investigated. Tests were carried out on notched and un-notched specimens under a range of testing conditions. Microstructures and test results are given.
CORROSION OF SINTERED STAINLESS STEELS E Ahlberg, et al, (Chalmers University, Goteborg, Sweden). Vol 1, Paper 31,419-432. The corrosion of sintered stainless steels (9304L, 316, 410L and 430L) in sulphuric acid was studied. All samples showed active corrosion in this electrolyte. Density of the samples had no clear influence on the corrosion behaviour. It is suggested that the surface condition is of great importance but ferritic 430L showed general corrosion in spite of a large number of pores in the samples. EFFECT OF POROSITY ON STATIC AND DYNAMIC PROPERTIES OF PM Fe H Danninger, et al, (Technical University of Vienna, Vienna, Austria). Vol 1, Paper 32, 433--439. The porosity of sintered Fe was studied. It was found that the change from isolated to interconnecting pores takes place in the range 6-14% total porosity. Measurements of properties show that properties depend not only on total porosity but also on pore shape and connectivity. FATIGUE BEHAVIOUR OF SINTERED STEELS A Piotrowski, H Harig, (University of Essen, Essen, Germany). Vol 1, Paper 33 440--445.
786
INFLUENCE OF AS-SINTERED STRENGTH ON IMPROVEMENT OF FATIGUE STRENGTH BY SURFACE ROLLING
THE ROLE OF MnS IN IMPROVING THE MACHINABILITY OF PM PARTS K S Chopra, D S Madan, (Elkem Metals Co, Niagara Falls, NY, USA). Vol 2, Paper 12, 61-65. The role of MnS in improving machinability of PM steel parts and the effects on properties is examined. It is reported that MnS does not interact with other alloy elements and has minimal and predictable effects on physical and mechanical properties.
HEAT TREATMENT OF SINTERED STEELS MADE FROM ELEMENTAL AND PREALLOYED POWDERS J M Torralba, et al, (Polytechnical University, Madrid, Spain). Vol 2, Paper 14, 69-74. Two steels were produced (composition Fe- 1.5%Cu-4%Ni-0.5%Mo-0.7%C), one from elemental powders and the other from pre-alloyed powder. Mechanical properties, microstructure, dimensional stability and hardenability are compared.
C M Sonsino, et al, (Fraunhofer Institut, Darmstadt, Germany). Vol 1, Paper 39, 497-508.
FATIGUE STRENGTH OF PM MATERIALS WITH NON-MACHINED SURFACES
Fatigue life curves of Fe-l.5%Cu (density 7.15gm/cm 3) and Fe-8%Ni-1.0%Mo-0.5%C (density 7.35gm/cm 3) were compared for three different notch factors in as-sintered and surface rolled conditions under constant and variable amplitude loading. Results were interpreted on the basis of microstmcture, m i c r o h a r d n e s s and r e s i d u a l stress distributions. The paper presents statistically based design data about the improvement of fatigue strength as a result of surface rolling of PM parts.
T M Cadle, C J Landgraf, (Zenith Sintered Products, Milwaukee, USA). Vol 2, Paper 25, 124-128.
PROPERTIES AND STRUCTURES OF COLD-FORGED STAINLESS STEEL-PARTICULATE COMPOSITES N Petersen, (Technical U n i v e r s i t y of Denmark). Vol 1, Paper 40, 509-518. Stainless steel matrix composites with up to 30vo1% of CrC or T'tB were produced by PM. Tensile strength was reduced and porosity increased by hard particles. Properties improved by cold forging. Adhesive wear is improved by hard particles, attributed to the load carrying ability of the hard particles.
The paper draws attention to the need for improved fatigue strength in PM materials. Fatigue tests were carried out on PM specimens with machined and non-machined surfaces. It is concluded that machining reduces endurance, and non-machined flexural bend test pieces give more consistent data. STRUCTURES AND DYNAMIC PROPERTIES OF EXTRUDED PM FERROUS MACROCOMPOSITE M N H Ahmed, et al, (A1-Azhar University, Cairo, Egypt). Vol 2, Paper 26, 129-134. Mechanical properties of extruded coaxial cylindrical duplex structures were evaluated with respect to heat treatment, residual stresses and plastic constraint. Experimental results gave good agreement with predictions. The effects of residual stresses in the sheath component of a duplex structure on dynamic properties were also modelled.
MPR November 1990