Numerical Simulation and Experimental Analysis of Laser Surface Remelting of AISI 304 Stainless Steel Samples

2010 ◽  
Vol 636-637 ◽  
pp. 1119-1124
Author(s):  
Noé Cheung ◽  
M.A. Larosa ◽  
Wislei R.R. Osório ◽  
M.S.F Lima ◽  
Maria Clara F. Lerardi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Stainless Steel ◽  
Laser Surface ◽  
Temperature Fields ◽  
304 Stainless Steel ◽  
Operating Parameters ◽  
Aisi 304 ◽  
Laser Surface Remelting ◽  
304 Austenitic Stainless Steel

The aim of this work is to develop a heat transfer mathematical model based on the finite difference method in order to simulate temperature fields in the laser surface remelting process. Convective heat transfer in the remelted pool is taken into account by using the effective thermal conductivity approach. Experiments of laser surface remelting of AISI 304 austenitic stainless steel samples were carried out in the present investigation, and numerical simulations were applied for the CO2 laser machine operating parameters. The work also encompasses the analysis of microstructural and microhardness variations throughout the resulting treated and unmolten zones. This study permits to conclude that numerical simulation is a useful tool in setting the laser operating parameters, enabling pre-programming of the extent of the treated area.

Numerical Simulation and Experimental Analysis of Laser Surface Remelting of AISI 420 Stainless Steel Samples

2008 ◽  
Vol 59 ◽  
pp. 265-268
Author(s):  
Noé Cheung ◽  
M.A. Larosa ◽  
Wislei R.R. Osório ◽  
Maria Clara F. Lerardi ◽  
Amauri Garcia
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Stainless Steel ◽  
Laser Surface ◽  
Temperature Fields ◽  
Operating Parameters ◽  
Laser Machine ◽  
Laser Surface Remelting ◽  
Aisi 420 ◽  
The Finite Difference Method

The aim of this work is to develop a heat transfer mathematical model based on the finite difference method in order to simulate temperature fields in the laser surface remelting process. Convective heat transfer in the remelted pool is taken into account by using the effective thermal conductivity approach. Experiments of laser surface remelting of AISI 420 stainless steel samples were carried out in the present investigation, and numerical simulations were applied for the laser machine operating parameters. The work also encompasses the analysis of microstructural and microhardness variations throughout the resulting treated and unmolten zones.

Effective hydrogen diffusivities of AISI 304 stainless steel with Ni or Au coating

2020 ◽  
Vol 62 (6) ◽  
pp. 593-596
Author(s):  
Krittayot Wannapoklang ◽  
Sirichai Leelachao ◽  
Anchaleeporn W. Lothongkum ◽  
Gobboon Lothongkum
Keyword(s):  
Stainless Steel ◽  
Hydrogen Diffusion ◽  
304 Stainless Steel ◽  
Phase Identification ◽  
Aisi 304 Stainless Steel ◽  
Aisi 304 ◽  
304 Austenitic Stainless Steel ◽  
Hydrogen Assisted Cracking ◽  
Stainless Steel Coupon ◽  
Effective Hydrogen

AbstractMetallic coatings which provide a hydrogen diffusion barrier are thought to reduce hydrogen assisted cracking on stainless steel. The influence of a metallic layer on the hydrogen migration of AISI 304 stainless steel was investigated using a commercial electroplating layer of Ni and Au on a thin stainless steel coupon. Phase identification was performed using an X-ray diffractometer to determine the average thicknesses, measured from back-scattered scanning electron images. Regarding the ASTM G148-97 practice, the effective hydrogen diffusivities of AISI 304 austenitic stainless steel, nickel and gold were measured as 7.07 × 10-13, 2.72 × 10-14 and 9.64 × 10-16 m2 × s-1, respectively. In this work, a gold layer was found to be most effective for the prevention of hydrogen diffusion when compared with untreated and Ni-plated 304 stainless steel.

Numerical and Experimental Analysis of Laser Surface Remelting of Al 9wt% Si Alloy Samples

2008 ◽  
Vol 587-588 ◽  
pp. 721-725
Author(s):  
Noé Cheung ◽  
Kleber A.S. Cruz ◽  
Noman H. Khan ◽  
Amauri Garcia
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Rapid Heating ◽  
Thermal Action ◽  
High Energy ◽  
Laser Surface ◽  
High Energy Density ◽  
Temperature Fields ◽  
Laser Materials ◽  
Laser Surface Remelting

Laser materials processing has been widely applied in industrial processes due to unique precision and very localized thermal action furnished by the laser’s high energy density and power controllability. With the inherent rapid heating and cooling rates to which this surface layer is subjected, this process provides an opportunity to produce different microstructures from that of the bulk metal leading to useful properties. The aim of this work is to develop a heat transfer mathematical model based on the finite difference method in order to simulate temperature fields in the laser surface remelting process. Convective heat transfer in the remelted pool is taken into account by using the effective thermal conductivity approach. Theoretical predictions furnished by previous models from the literature were used for validation of numerical simulations performed with the proposed model. Experiments of laser surface remelting of Al-9 wt pct Si samples was carried out in the present investigation, and numerical simulations was applied for the laser machine operating parameters. The work also encompasses the analysis of microstructural and microhardness variations throughout the resulting treated and unmolten zones.

Effects of Laser Processing Parameters on Grain Boundary Character Distribution and Corrosion Resistance of Austenite Stainless Steel

2007 ◽  
Vol 561-565 ◽  
pp. 2473-2476 ◽  
Author(s):  
Sen Yang ◽  
Hiroyuki Kokawa ◽  
Zhan Jie Wang
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Laser Processing ◽  
Processing Parameters ◽  
Laser Surface ◽  
304 Stainless Steel ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Character ◽  
Laser Surface Remelting ◽  
Character Distribution

In order to modify grain boundary character distribution (GBCD) and to improve intergranualr corrosion (IGC) resistance of 304 stainless steel, laser surface remelting experiments were conducted on 304 stainless steel using a 2kW CW Nd: YAG laser, and the effects of laser processing parameters on GBCD and corrosion resistance were investigated in detail under the optimal annealing condition (1220K 28h). The experimental results showed that combination of laser surface remelting and the following annealing treatment could change the GBCD remarkably and improve the IGC resistance of 304 stainless steel. However, there are no obvious effects of laser processing parameters on the final depth of the processed zone, although the depth of the molten pool increases with the increase of the laser output power or the decrease of the scanning velocity, and the subsequent GBCD and corrosion resistance.

Corrosion Behaviour of AISI 304 Stainless Steel with Solar Salt Heat Transfer Fluid

2014 ◽  
Vol 922 ◽  
pp. 13-17 ◽  
Author(s):  
Omar Ahmed ◽  
Le Zhou ◽  
Nahid Mohajeri ◽  
Yong Ho Sohn
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Iron Oxide ◽  
Corrosion Behavior ◽  
304 Stainless Steel ◽  
Salt Mixture ◽  
Aisi 304 Stainless Steel ◽  
Aisi 304 ◽  
Solar Salt ◽  
X Ray

In an effort to understand the compatibility between the heat transfer medium and the structural materials used in concentrated solar power plants, the corrosion behavior of AISI 304 stainless steel (18 wt.% Cr, 8 wt.% Ni) in a molten solar salt mixture (53 wt. % KNO3, 40 wt. % NaNO2,7 wt. % NaNO3) has been investigated. The 304 stainless steel coupon samples were fully immersed and isothermally exposed to solar salt at 530°C for 250, 500, and 750 hours in air. X-ray diffraction and scanning electron microscopy with X-ray energy-dispersive spectroscopy were employed to examine the extent of corrosion and identify the corrosion products. Oxides of iron were found to be the primary corrosion products in the presence of the molten alkali nitrates-nitrite salt mixture because of the dissolution of the protective chromium oxide (Cr2O3) scale formed on 304 stainless steel coupons. The corrosion scale was uniform in thickness and chromium-iron oxide was found near the AISI 304. This indicates that the scale formed, particularly on the upper layer with presence of sodium-iron-oxide is protective, and forms an effective barrier against penetration of fused solar salt. By extrapolation, annual corrosion rate is estimated to reach 0.784 mils per year. Corrosion behavior of AISI 304 stainless steel is discussed in terms of thermodynamics and reaction paths.

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