scholarly journals Energy Coupling of Laser Radiation on AISI 304 Stainless Steel: Effect of High Temperatures and Surface Oxidation

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2802 ◽  
Author(s):  
Hipp ◽  
Mahrle ◽  
Beyer

The industrial application of laser materials processing methods is still far ahead of research into the physical phenomena occurring during these processes. In particular, the effect of high temperatures on the energy coupling of laser irradiation of metals is poorly understood. However, most processes in laser materials treatment involve temperatures above the melting point or even cause evaporation. This study therefore evaluates the effect of high temperatures on the energy coupling efficiency of stainless steel experimentally for three typical laser wavelengths (515 nm, 1.07 µm, 10.6 µm). As a result, it is shown that the effect of temperature on the energy coupling efficiency depends on the wavelength. In this context the relevance of the X-point phenomenon known from the emissivity theory could be demonstrated for laser material processing. Further, the effect of a process-induced surface oxidation is analyzed. At temperatures above 650 °C the energy coupling efficiency dramatically increases to around 65% at melting point and stays at this high level even in the liquid phase.

Author(s):  
Nathalia M. R. Jesus ◽  
Millena G. R. S. Contente ◽  
Rudimar Riva ◽  
Aline Capella ◽  
Romario Pinheiro ◽  
...  

2004 ◽  
Vol 449-452 ◽  
pp. 881-884 ◽  
Author(s):  
Do Won Seo ◽  
Ho Chel Yoon ◽  
Jin Yi Lee ◽  
Jae Kyoo Lim

Ceramics are significantly used in many industrial applications due to their excellent mechanical and thermal properties such as high temperature strength, low density, high hardness, low thermal expansion and good corrosion properties. To combine the specific advantages of ceramics with that of metals, they are often used together within one composite component. In this study, the effect of temperature on fracture characteristics of silicon nitride joined to 304 stainless steel brazed with Ti active alloy are investigated in room and high temperature regions. And analytical studies on the residual stress of dissimilar brazed joint are performed by the finite element method. Four-point bending strength and deflection of interlayer increase with increasing strain rate in room temperature. As the test temperature increases, the bending strength decreases, but the deflection of interlayer is almost constant. The residual stresses redistribute after cutting of joint and the maximum tensile stress occurs on the new free surface at the ceramic near the interface. The singularity of residual stresses at the ceramic near the interface is characterized by elastic-plastic properties of ceramic and inserted materials.­


2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Gang Ma ◽  
Xiang Ling

Effect of temperature and chloride content on the stress corrosion cracking (SCC) susceptibility of 304 stainless steel welded joints treated by ultrasonic impact treatment (UIT) is investigated in this study. High tensile weld residual stress is an important factor contributing to SCC. UIT can produce compressive stresses on the surface of welded joints that negate the tensile stresses to enhance the SCC resistance of welded joints. In the SCC testing, the specimens were immersed in sodium chloride solution at the temperatures of 200 °C–280 °C in the range of sodium chloride solution from 50 g/L to 200 g/L. During the testing, treated specimens show good SCC resistance with different temperature and consistency of chloride ion. The results show that the SCC susceptibility of 304 stainless steel welded joints reduces with increase of temperature and decrease of chloride ion consistency. The surface roughness of sample after UIT was investigated by portable surface roughness tester. The results reveal that surface of the samples becomes rougher than the original plate with the increase of the impact duration, which contribute to the pitting corrosion of treated specimens. And, the level of pitting corrosion is reduced with increase of temperature.


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