Fatigue Behaviour of Case-Hardened P/M Steels

Powder-metallurgical (P/M) produced components may be used as mass parts in a very large quantity. Due to the multistage manufacturing process which consists of the pressing of the prepared powder and the sintering of the green bodies also complex shaped components can be produced very economically and precisely. They can be utilised without any further post-processing if the whole production process is optimised. However, it is still difficult and only possible with considerable technical and financial effort to produce highly stressable components profitably using the sinter technique. Therefore, the examinations on hand had the intention to create the basis for the use of the sinter technology also for the production of highly stressable case-hardened components. To this, at first bending specimens were fabricated with modern pressing procedures and sinter facilities and first characterized in the as sintered state. Then the conditions for the case-hardening was analysed and the parameters for an optimised case-hardening procedure fixed. With these parameters specimens were case-hardened and their lifetime behaviour estimated under different bending loading conditions. Finally it should be checked whether the knowledge gained from the specimens could be applied to complex components. To this, gear wheels were produced using powder-metallurgy. The cyclical tooth foot strength of this gear wheels were analysed in the only sintered as well as in the case-hardened state. It could be demonstrated that the improvement of the fatigue strength of the bending specimens by case-hardening also appears at the tooth foot strength of the gear wheels.

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Continuous and pulsed selective laser melting of Ti6Al4V lattice structures: Effect of post-processing on microstructural anisotropy and fatigue behaviour

Additive Manufacturing ◽

10.1016/j.addma.2020.101433 ◽

2020 ◽

Vol 36 ◽

pp. 101433

Author(s):

K. Karami ◽

A. Blok ◽

L. Weber ◽

S.M. Ahmadi ◽

R. Petrov ◽

...

Keyword(s):

Selective Laser Melting ◽

Fatigue Behaviour ◽

Lattice Structures ◽

Post Processing ◽

Laser Melting ◽

Microstructural Anisotropy

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Bending Fatigue Behaviour of Diffusion and Thermal Barrier Coating Systems

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.592-593.716 ◽

2013 ◽

Vol 592-593 ◽

pp. 716-719 ◽

Cited By ~ 1

Author(s):

Karel Slámečka ◽

Karel Němec ◽

Ladislav Čelko ◽

Marta Kianicová ◽

Jana Horníková ◽

...

Keyword(s):

Room Temperature ◽

Fatigue Crack Initiation ◽

Fatigue Behaviour ◽

Thermal Barrier ◽

Air Plasma ◽

Bending Fatigue ◽

Aluminide Coatings ◽

Barrier Coating ◽

Plasma Sprayed ◽

Bending Loading

Room temperature fatigue behaviour of two variants of diffusion aluminide coatings and conventional air plasma sprayed CoNiCrAlY + ZrO2-Y2O3 thermal barrier system, which were deposited on a cast nickel-based supperalloy substrate, was studied under symmetrical bending loading regime. The study elucidates the differences in a fatigue crack initiation micromechanism with respect to applied stress level and its impact on the fatigue performance of studied coating systems.

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Fretting fatigue behaviour of hard anodizing coated 2014-T6 aluminium alloy with dissimilar mating materials under plane bending loading

Fatigue & Fracture of Engineering Materials & Structures ◽

10.1111/j.1460-2695.2010.01527.x ◽

2010 ◽

Vol 34 (6) ◽

pp. 383-388 ◽

Cited By ~ 1

Author(s):

R. SADELER ◽

S. ATASOY

Keyword(s):

Aluminium Alloy ◽

Fatigue Behaviour ◽

Fretting Fatigue ◽

Hard Anodizing ◽

Plane Bending ◽

Bending Loading

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Fatigue behaviour of notched laser powder bed fusion AlSi10Mg after thermal and mechanical surface post-processing

Materials Science and Engineering A ◽

10.1016/j.msea.2021.142145 ◽

2021 ◽

pp. 142145

Author(s):

Erfan Maleki ◽

Sara Bagherifard ◽

S.M.J. Razavi ◽

Martina Riccio ◽

Michele Bandini ◽

...

Keyword(s):

Fatigue Behaviour ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Post Processing ◽

Powder Bed ◽

Mechanical Surface

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Syntactic Iron Foams’ Properties Tailored by Means of Case Hardening via Carburizing or Carbonitriding

Materials ◽

10.3390/ma14164358 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4358

Author(s):

Jörg Weise ◽

Dirk Lehmhus ◽

Jaqueline Sandfuchs ◽

Matthias Steinbacher ◽

Rainer Fechte-Heinen ◽

...

Keyword(s):

Mechanical Properties ◽

Surface Hardening ◽

Metal Foam ◽

Mechanical Performance ◽

Syntactic Foam ◽

Metal Foams ◽

Metal Injection Molding ◽

Case Hardening ◽

Two Phase ◽

Gear Wheels

Metal foam inserts are known for their high potential for weight and vibration reduction in composite gear wheels. However, most metal foams do not meet the strength requirements mandatory for the transfer of sufficiently high levels of torque by the gears. Syntactic iron and steel foams offer higher strength levels than conventional two-phase metal foams, thus making them optimum candidates for such inserts. The present study investigates to what extent surface hardening treatments commonly applied to gear wheels can improve the mechanical properties of iron-based syntactic foams. Experiments performed thus focus on case hardening treatments based on carburizing and carbonitriding, with subsequent quenching and tempering to achieve surface hardening effects. Production of samples relied on the powder metallurgical metal injection molding (MIM) process. Syntactic iron foams containing 10 wt.% of S60HS hollow glass microspheres were compared to reference materials without such filler. Following heat treatments, the samples’ microstructure was evaluated metallographically; mechanical properties were determined via hardness measurements on reference samples and 4-point bending tests, on both reference and syntactic foam materials. The data obtained show that case hardening can indeed improve the mechanical performance of syntactic iron foams by inducing the formation of a hardened surface layer. Moreover, the investigation indicates that the respective thermo-chemical treatments can be applied to composite gear wheels in exactly the same way as to monolithic ones. In the surface region modified by the treatment, martensitic microstructures were observed, and as consequence, the bending limits of syntactic foam samples were increased by a factor of three.

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RESEARCH OF WEAR RESISTANCE OF IRON GEAR WHEELS WITH DIFFUSE CARBIDE LAYER

Vestnik of Ulyanovsk state agricultural academy ◽

10.18286/1816-4501-2020-3-28-32 ◽

2020 ◽

pp. 28-32

Author(s):

А. А. Veselovsky ◽

Keyword(s):

Experimental Data ◽

Wear Resistance ◽

Cast Iron ◽

Linear Wear ◽

Case Hardening ◽

Carbide Layer ◽

Steel 20 ◽

Gear Wheels ◽

Reverse Gear ◽

Case Hardening Steel

The article is concerned with wear resistance increase of saw-tooth enclosed drives applying instead of iron gear wheels, made from cement steel quality, gear wheels from high-duty cast iron of HF 60 with thermodiffusion carbide layer. Elements- diffusants were chosen according to level of carbide forming and hardness of formed layersvanadium- for forming very hard, chrome-medium according to coating and manganese- for low layers according to coating hardness. Layers are formed on spur gears, which are reverse gear of light vehicle. Setting for research included draw gear- asynchronous electric drive, placed on lathe-bed with the help of which rotation of gear shift transmission with powered reverse gear was done. Transmission output shaft was pressed into chunk. Kinematick of disconnected machine provided necessary moment resistance. Through given number of cycles the box was taken down, gear set was removed and metal graphic research was carried out. Residual layer thickness and linear wear were diagnosed, on the basis of obtained experimental data we built characteristic curves of linear wear from number of stress cycles. For comparative evaluation in this type of research we carried out experiments on measurement of linear wear of case – hardening steel 20 ChGn after cementation and further quenching and research of hardened cast iron HF mark 60. It was found out that the highest quality wearing in this type of research vanadium layers have, slightly lower quality wear chromium plate have and on the 3rd place manganese layers. The worst quality wear we observed in steel 20 ChGN. On the basis of obtained –experimental data empirical regularities of wear rate of layers from their Brinnel hardness and diameter of obtained copy were determined.

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Electron Beam Welding of Gear Wheels by Splitted Beam

Research Papers Faculty of Materials Science and Technology Slovak University of Technology ◽

10.2478/rput-2014-0025 ◽

2014 ◽

Vol 22 (34) ◽

pp. 35-41

Author(s):

Daniel Dřímal

Keyword(s):

Electron Beam ◽

Critical Point ◽

Electron Beam Welding ◽

High Strength ◽

Optical Measurements ◽

Welding Parameters ◽

Case Hardening ◽

Weld Root ◽

Gear Wheels ◽

Welding Procedure

Abstract This contribution deals with the issue of electron beam welding of high-accurate gear wheels composed of a spur gearing and fluted shaft joined with a face weld for automotive industry. Both parts made of the high-strength low-alloy steel are welded in the condition after final machining and heat treatment, performed by case hardening, whereas it is required that the run-out in the critical point of weldment after welding, i. e. after the final operation, would be 0.04 mm max.. In case of common welding procedure, cracks were formed in the weld, initiated by spiking in the weld root. Crack formation was prevented by the use of an interlocking joint with a rounded recess and suitable welding parameters, eliminating crack initiation by spiking in the weld root. Minimisation of the welding distortions was achieved by the application of tack welding with simultaneous splitting of one beam into two parts in the opposite sections of circumferential face weld attained on the principle of a new system of controlled deflection with digital scanning of the beam. This welding procedure assured that the weldment temperature after welding would not be higher than 400 °C. Thus, this procedure allowed achieving the final run-outs in the critical point of gearwheels within the maximum range up to 0.04 mm, which is acceptable for the given application. Accurate optical measurements did not reveal any changes in the teeth dimensions.

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