scholarly journals Probabilistic Surface Layer Fatigue Strength Assessment of EN AC-46200 Sand Castings

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 616
Author(s):  
Sebastian Pomberger ◽  
Matthias Oberreiter ◽  
Martin Leitner ◽  
Michael Stoschka ◽  
Jörg Thuswaldner
Keyword(s):  
Heat Treatment ◽  
Surface Layer ◽  
Fatigue Strength ◽  
Treatment Condition ◽  
Heat Treatment Condition ◽  
Assessment Model ◽  
Sand Cast ◽  
Strength Assessment ◽  
Long Life ◽  
Cast Surface

The local fatigue strength within the aluminium cast surface layer is affected strongly by surface layer porosity and cast surface texture based notches. This article perpetuates the scientific methodology of a previously published fatigue assessment model of sand cast aluminium surface layers in T6 heat treatment condition. A new sampling position with significantly different surface roughness is investigated and the model exponents a 1 and a 2 are re-parametrised to be suited for a significantly increased range of surface roughness values. Furthermore, the fatigue assessment model of specimens in hot isostatic pressing (HIP) heat treatment condition is studied for all sampling positions. The obtained long life fatigue strength results are approximately 6% to 9% conservative, thus proven valid within an range of 30 µm ≤ S v ≤ 260 µm notch valley depth. To enhance engineering feasibility even further, the local concept is extended by a probabilistic approach invoking extreme value statistics. A bivariate distribution enables an advanced probabilistic long life fatigue strength of cast surface textures, based on statistically derived parameters such as extremal valley depth S v i and equivalent notch root radius ρ ¯ i . Summing up, a statistically driven fatigue strength assessment tool of sand cast aluminium surfaces has been developed and features an engineering friendly design method.

scholarly journals Modification of a Defect-Based Fatigue Assessment Model for Al-Si-Cu Cast Alloys

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2546 ◽  
Author(s):  
Roman Aigner ◽  
Martin Leitner ◽  
Michael Stoschka ◽  
Christian Hannesschläger ◽  
Thomas Wabro ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Fatigue Testing ◽  
Threshold Value ◽  
Fatigue Behaviour ◽  
Mechanical Tests ◽  
Assessment Model ◽  
Fatigue Assessment ◽  
Strength Assessment ◽  
Assessment Approach ◽  
Long Life

Cast parts usually inherit internal defects such as micro shrinkage pores due to the manufacturing process. In order to assess the fatigue behaviour in both finite-life and long-life fatigue regions, this paper scientifically contributes towards a defect-based fatigue design model. Extensive fatigue and fracture mechanical tests were conducted whereby the crack initiating defect size population was fractographically evaluated. Complementary in situ X-ray computed tomography scans before and during fatigue testing enabled an experimental estimation of the lifetime until crack initiation, acting as a significant input for the fatigue model. A commonly applied fatigue assessment approach introduced by Tiryakioglu was modified by incorporating the long crack threshold value, which additionally enabled the assessment of the fatigue strength in the long-life fatigue regime. The presented design concept was validated utilising the fatigue test results, which revealed a sound agreement between the experiments and the model. Only a minor deviation of up to about five percent in case of long-life fatigue strength and up to about 9% in case of finite-lifetime were determined. Thus, the provided extension of Tiryakioglu’s approach supports a unified fatigue strength assessment of cast aluminium alloys in both the finite- and long-life regimes.

Optimization of post-weld heat treatment condition of arc-welded T91 steel tubes

2020 ◽  
Vol 188 ◽  
pp. 104213
Author(s):  
Ranjeet Kumar ◽  
Anand Varma ◽  
Y. Ravi Kumar ◽  
Himanshu Vashishtha ◽  
Jayant Jain ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Treatment Condition ◽  
Heat Treatment Condition ◽  
Post Weld Heat Treatment ◽  
Steel Tubes ◽  
Weld Heat

Effect of Heat Treatment Condition on the Characteristics of MnO2 Added-Fe2TiO5 Ceramics for NTC Thermistors Using Local Iron Oxide

2018 ◽  
Vol 917 ◽  
pp. 64-68
Author(s):  
Wiendartun ◽  
Jaenudin Kamal ◽  
Dadi Rusdiana ◽  
Andhy Setiawan ◽  
Dani Gustaman Syarief
Keyword(s):  
Heat Treatment ◽  
Iron Oxide ◽  
Treatment Condition ◽  
Treatment Time ◽  
Heat Treatment Condition ◽  
Heat Treatment Time ◽  
Second Phase ◽  
Room Temperature Resistivity ◽  
Electrical Characteristics ◽  
Ntc Thermistor

A study on the effect of heat treatment condition on the characteristics of MnO2 added-Fe2TiO5 ceramics for NTC thermistor has been carried out. The ceramics were produced by pressing an homogenous mixture of Fe2O3 (local/ yarosite), TiO2 and MnO2 (2.0 mole %) powders in appropriate proportions to produce Fe2TiO5 based ceramics and sintering the pressed powder at 1050 °C for 3 hours in oxygen gas. Some sintered pellets were heat treated by heating them at 300 °C for 5, 15 and 25 minutes in Ar + 7% H2 gas. The XRD analyses showed that the Fe2TiO5 ceramics with and without heat treatment time had orthorhombic structure. No peak from second phase was observed from the XRD profiles. From the electrical characteristics data, it was known that the heat treatment could change the electrical characteristics of the Fe2TiO5 based-thermistor. The thermistor constant (B) and room temperature resistivity (ρRT) decreased with the increasing of heat treatment time. All ceramics made had thermistor characteristics namely B = 3459-7596 K and ρRT = 1.056-6936.062 MΩcm. Thermistor constant of the ceramics was relatively big, indicated that ceramics made from local iron oxide in this work fit the market requirement for NTC thermistor.

Effect of Post-Weld Heat Treatment on Hardness in Superduplex Stainless Steel ASTM A890/A890M - Grade 6A

2020 ◽  
Vol 1012 ◽  
pp. 296-301
Author(s):  
Clélia Ribeiro de Oliveira ◽  
Eloá Lopes Maia ◽  
Solange T. da Fonseca ◽  
Marcelo Martins ◽  
Julián Arnaldo Ávila Díaz ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Arc Welding ◽  
Treatment Condition ◽  
Heat Treatment Condition ◽  
Shielded Metal Arc Welding ◽  
Metal Arc Welding ◽  
Superduplex Stainless Steel ◽  
Secondary Austenite ◽  
Welding Processes

Superduplex stainless steel alloy exhibit high mechanical and corrosion resistance, which main industrial application is in the petrochemical industry. The manufacture and maintenance of such equipment usually involve welding processes, followed by post-welded heat treatment and it often becomes impossible to apply heat treatments. Thereby, the purpose of this work is to verify the effect of a post-welded heat treatment on shielded metal arc welding in steel grade ASTM A890/A890M - grade 6A. The microstructure in the as-welded condition consisted of austenite, secondary austenite, and ferrite phases and, the post-welded heat treatment condition exhibited only austenite and ferrite. The hardness in the melt zone reached values of 300 HV after welding and, the value was reduced to 260 HV in the post-welded heat treatment condition.

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