Fatigue strength of laser CO2, fiber laser and plasma cut edges made of S690QC and S1100
Khan, Md Udoy Hossen (2018)
Diplomityö
Khan, Md Udoy Hossen
2018
School of Energy Systems, Konetekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2018121050184
https://urn.fi/URN:NBN:fi-fe2018121050184
Tiivistelmä
Thermal cutting method are increasingly used in different applications where fatigue life estimation is needed for high strength steels. In this research, the fatigue strength of thermal cutting edges was investigated experimentally and theoretically for 12 mm thickness of S690QC and 8mm thickness of S1100 materials with stress ratio 0.1. The conventional design method and novel method 4R were used to estimate fatigue strength. The cutting method was plasma, laser CO2 and fiber laser.
The experimental results were compared with the novel method 4R and conventional design methods. The novel method 4R were able to give more reasonable fatigue strength results compare to conventional design method. In addition, the experimental results indicated that 4R method are applicable for fatigue assessment method. Although, 4R method gave some unexpected results in terms of fiber laser cutting edges.
The surface roughness, residual stresses, hardness and microstructure were measured and analysis for cut edges condition. The surface roughness measurement results were evaluate with ISO 9013. In this experiment shows that all of specimen cross the recommended FAT class and it can be categorized in FAT 125. According to EN ISO 9013 all of specimens of laser CO2 and fiber laser were meet quality range group 2 and plasma was quality range group 1. However, results show that plasma has lower fatigue strength compare to laser CO2. No fatigue estimation can be made based on ISO 9013 standard and it has poor connection to fatigue strength.
The experimental results were compared with the novel method 4R and conventional design methods. The novel method 4R were able to give more reasonable fatigue strength results compare to conventional design method. In addition, the experimental results indicated that 4R method are applicable for fatigue assessment method. Although, 4R method gave some unexpected results in terms of fiber laser cutting edges.
The surface roughness, residual stresses, hardness and microstructure were measured and analysis for cut edges condition. The surface roughness measurement results were evaluate with ISO 9013. In this experiment shows that all of specimen cross the recommended FAT class and it can be categorized in FAT 125. According to EN ISO 9013 all of specimens of laser CO2 and fiber laser were meet quality range group 2 and plasma was quality range group 1. However, results show that plasma has lower fatigue strength compare to laser CO2. No fatigue estimation can be made based on ISO 9013 standard and it has poor connection to fatigue strength.