Multi-criteria optimization of weld bead in pulsed Nd:YAG laser welding of stainless steel 316

2018 ◽  
Vol 233 (2) ◽  
pp. 151-164 ◽  
Author(s):  
Ali Solati ◽  
Nasrollah Bani Mostafa Arab ◽  
Akbar Mohammadi-Ahmar ◽  
Hamid Reza Fazli Shahri
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Process Parameters ◽  
Welding Process ◽  
Quality Criteria ◽  
Optimization Procedure ◽  
Weld Bead ◽  
Micro Hardness ◽  
Pulsed Nd:Yag Laser Welding ◽  
Welding Processes

Laser welding is widely used for its advantages like deeper weld penetration, narrow heat affected zone, higher welding speeds and better weld quality with less damage to the workpiece compared to arc welding processes. The purpose of this paper is to determine the influence of major laser welding process parameters of beam pulse energy, travel speed and focal position on weld fusion zone geometry in stainless steel and optimizing these parameters to obtain maximum penetration and minimum weld width simultaneously. The experiments were planned according to Taguchi’s L16 orthogonal array. The grey-based Taguchi method was then employed to convert the multiple quality criteria into one single relational grade. Based on the calculated relational grade, Taguchi tools such as analysis of variance and signal-to-noise ratio were used to analyze and obtain the significant parameters and evaluate the optimum combination levels of the mentioned process parameters. Moreover, the effect of optimization procedure was studied on the microstructure and micro-hardness of the weldments. It was concluded that this optimization method can lead to elimination of chain ferrite precipitation and more uniform micro-hardness across the weld bead. The confirmation experiments verified that this method can effectively improve multiple performance characteristics and the results are reproducible in laser welding.

Laser Welding Simulations of Stainless Steel Joints Using Finite Element Analysis

2011 ◽  
Vol 383-390 ◽  
pp. 6225-6230
Author(s):  
K.R. Balasubramanian ◽  
T. Suthakar ◽  
K. Sankaranarayanasamy ◽  
G. Buvanashekaran
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Laser Beam ◽  
Laser Welding ◽  
Laser Beam Welding ◽  
Welding Process ◽  
Weld Bead ◽  
Heat Of Fusion ◽  
T Joints ◽  
Finite Element Software

Laser beam welding (LBW) is a fusion joining process that uses the energy from a laser beam to melt and subsequently crystallize a metal, resulting in a bond between parts. In this study, finite element method (FEM) is used for predicting the weld bead profile of laser welding butt, lap and T-joints. A three-dimensional finite element model is used to analyze the temperature distribution weld bead shape for different weld configurations produced by the laser welding process. In the model temperature-dependent thermo physical properties of AISI304 stainless steel, effect of latent heat of fusion and convective and radiative boundary conditions are incorporated. The heat input to the FEM model is assumed to be a 3D conical Gaussian heat source. The finite element software SYSWELD is employed to obtain the numerical results. The computed weld bead profiles for butt, lap and T-joints are compared with the experimental profiles and are found to be in agreement.

Optimization of laser welding process parameters of stainless steel 316L using FEM, Kriging and NSGA-II

2016 ◽  
Vol 99 ◽  
pp. 147-160 ◽  
Author(s):  
Ping Jiang ◽  
Chaochao Wang ◽  
Qi Zhou ◽  
Xinyu Shao ◽  
Leshi Shu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Process Parameters ◽  
Welding Process ◽  
Stainless Steel 316L ◽  
Nsga Ii ◽  
Laser Welding Process

Application of Electromagnetic Force in Laser Welding

2007 ◽  
Author(s):  
J. Zhou ◽  
H. L. Tsai
Keyword(s):  
Laser Welding ◽  
Electromagnetic Force ◽  
Solid Phase ◽  
Numerical Models ◽  
Metal Flow ◽  
Welding Process ◽  
Weld Bead ◽  
Electromagnetic Forces ◽  
Laser Welds ◽  
Welding Processes

In recent years, lasers have been widely used in the welding processes for automotive, aerospace, electrical and heavy manufacturing industries due to their high power density, small heat-affected zone and high productivity. Especially, with high depth-to-width ratio and high welding efficiency, keyhole-mode laser welding is more promising compared to the conventional welding processes. However, a number of defects, such as porosity, irregular beads, undercut and humping are frequently observed in laser welds, which deteriorates the strength and quality of the welded parts. In current study, an externally controllable electromagnetic force is introduced into the laser welding process to prevent porosity formation and to control weld bead shape. Numerical models are developed to study the transport phenomena in laser welding and to accurately calculate the current density and magnetic flux fields and the resulting electromagnetic forces in three-dimensional weldments. Effects of the electromagnetic force on metal flow, heat and mass transfer and weld bead shape are investigated. The continuum model is used to handle the entire domain including solid phase, liquid phase and mush zone. The enthalpy method is employed to handle the absorption and release of latent heat during melting and solidification. Inverse Bremsstrahlung (IB) absorption, Fresnel absorption and multiple reflections of laser beam energy at the keyhole walls are considered for the study of laser-plasma interaction. Volume of Fluid (VOF) technique is adopted to calculate the free surface evolution in the computation. As indicated by this study, porosity-free laser welds with desired bead shapes can be achieved with appropriate applications of electromagnetic forces.

Effect of Process Parameters on Weld Penetration During Pulsed Nd:YAG Laser Welding

2014 ◽  
Author(s):  
Mathew Hudon ◽  
Anil Saigal
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Process Parameters ◽  
Nd:Yag Laser ◽  
Gas Flow ◽  
Weld Penetration ◽  
Pulsed Nd:Yag Laser ◽  
Reproducibility Study ◽  
Repeatability And Reproducibility ◽  
Pulsed Nd:Yag Laser Welding

Weld penetration is an important parameter to be considered for given process parameters on a pulsed Nd:YAG laser welding machine. A gauge repeatability and reproducibility study (GR&R), components of variation study (COV), and design of experiments (DOE) are used to understand the relationship between the process parameters and weld penetration on 17-4PH H900, 304 Annealed, and 420 Hardened stainless steel pins joined to a 17-4PH H900 stainless steel block. These stainless steels are selected because of their common use for laser welding of medical devices. The function determined via the DOE is then confirmed empirically by trial laser welds at the determined process settings for different weld penetrations. For a given pulse duration (8 ms), laser beam focus diameter (0.4 mm) and cover gas flow rate (5 L/min), the linear regression equation describing the weld penetration, h(mm) as a function of Peak Pulse Power, Pp(W) is found to be h = 0.001657 (Pp) – 0.389 where 300W < Pp < 1100W.

Effect of Corrosion of Stainless Steel Welded within Lithium Chloride

2016 ◽  
Vol 869 ◽  
pp. 470-473
Author(s):  
Juliete N. Pereira ◽  
David Márcio Macêdo Dias ◽  
Natal Nerímio Regone ◽  
Marcos A. Fernandes ◽  
Sandra Nakamatsu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Base Metal ◽  
Lithium Chloride ◽  
Welding Process ◽  
Weld Bead ◽  
Mechanical Resistance ◽  
Martensitic Steels ◽  
Cyclic Potentiodynamic Polarization ◽  
Lithium Chloride Solution ◽  
Welding Processes

The difficulties experienced in welding processes of martensitic stainless steel led to development of a new class of them, known as stainless mild martensitic steels. Also, due to the current high demand for energy and materials to oil extraction at great depths, scientists have being developing specific researches about mechanical resistance and corrosion of steels and how these properties are influenced by high temperature processes. This research studies the effect of welding process over the corrosion resistance of the 13Cr4Ni0.02C steel in a lithium chloride solution with a concentration of 120,000 PPM Cl-. The corrosion tests were conducted by cyclic potentiodynamic polarization in the base metal, weld bead and heat affected zone (HAZ) areas of the steel, in average temperatures of 23°C (as reference) and 3°C. The results revealed that the weld bead and heat affected zones of the 13Cr4Ni0.02C steel in a temperature of 3°C are less resistant to corrosion in this environment than the base metal in the same conditions.

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