Optimization of laser repair parameters for precracked 304 stainless steel components with nanocomposites addition

2020 ◽  
Vol 234 (9) ◽  
pp. 1280-1288
Author(s):  
Wei Jiang ◽  
Yinyin Li ◽  
Fenglei Guo ◽  
Guanglei Fang ◽  
Qun Yu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Process Parameters ◽  
Laser Power ◽  
Fracture Property ◽  
Crack Opening ◽  
Heating Time ◽  
304 Stainless Steel ◽  
Process Conditions ◽  
Spot Diameter ◽  
Laser Parameters

The optimization of process parameters is usually essential for achieving improved properties at efficient and cost-effective process conditions. The influence of laser parameters, i.e. laser power, spot diameter, and laser heating time, on the fracture property of repaired specimens was investigated by Taguchi experiment. Cracks were first fabricated on 304 stainless steel compact tension specimens by wire cutting and then repaired by adding nanocomposites at crack tips under different combinations of laser parameters. The repairing effects were evaluated by crack opening displacement measured by digital image correlation and microstructure characterized by scanning electron microscope. The analysis of variance was used to investigate the contribution of factor variables to the fracture parameter of crack opening displacements. The fracture property was improved most at the optimal repair process parameters of laser power of 1800 W, spot diameter of 3 mm, and heating time of 0.5 s within the selected range of experiments. The influence of laser parameters on the fracture properties of repaired specimens is found in the sequence of spot diameter, laser power, and heating time. This paper reveals the relationship of process–microstructure–fracture property in laser repair and provides a guideline for the selection of laser parameters to improve the quality of crack repair.

Investigation of Corrosion Properties of Welded and Laser-Surface Melted SUS 304 in Nuclear Power Operating Conditions

2009 ◽  
Author(s):  
Joung Soo Kim ◽  
Chin-Man Chung ◽  
Sung-Hoon Baik ◽  
Sang-Bae Lee
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Laser Beam ◽  
Laser Power ◽  
Nuclear Power ◽  
Laser Surface ◽  
Operating Conditions ◽  
Laser Surface Melting ◽  
304 Stainless Steel ◽  
Process Conditions

Welded SUS 304 stainless steel surface was melted using an Nd:YAG laser beam in order to increase its corrosion resistance in operating conditions of nuclear power plants. The optimum process conditions for laser-surface melting of welded SUS 304 stainless steel were determined by measuring the depth melted by the laser beam of welded regions through an optical microscope, observing the microstructures of the laser-melted surface, and measuring the double-loop electrochemical potentio-dynamic reactivation (DL-EPR) curves in a 1L aqueous solution of 0.5M H2SO4 and 0.01M KSCN. From the test results, the optimum laser-surface melting process conditions were as follows; a laser power of 170W, a N2 gas flow rate of 20L/min, a beam scan rate of 600mm/min, and laser power density of 20J/mm2. The microstructure of the laser-surface melted (LSM) region was observed to be very fine and homogenous, and of cellular structure. Grain growth in the LSM region from the substrate occurred epitaxially. No Cr depletion along the grain boundary in the LSM region was detected, which would result in increasing the corrosion, specially intergranular corrosion (IGC) including intergranular stress corrosion resistance (IGSCC) of the welded SUS 304.

Parametric Study and Optimization of Pulsed Laser Thermal Micro-Forming of Thin Sheets

2019 ◽  
Vol 9 (2) ◽  
pp. 47-61
Author(s):  
Kuntal Maji
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Process Parameters ◽  
Laser Power ◽  
Steel Sheet ◽  
Pulsed Laser ◽  
Stainless Steel Sheet ◽  
Micro Forming ◽  
Spot Diameter ◽  
Pulse On Time

This article presents the investigations on deformation behavior in precision forming of thin sheet metal by laser pulses using finite element analysis. The temperature and deformation fields were estimated and analyzed in pulsed laser micro-forming of AISI 304 stainless steel sheet of rectangular and circular shape considering the effects of different process parameters such as laser power, spot diameter and pulse on time. Response surface models based on finite element simulation results were developed to study the effects of the process parameters on deformations for the rectangular and circular workpieces. The amount of deformation was increased with the increase in laser power and pulse on time, and it was decreased with the increase in spot diameter. The effects of pulse frequency and sample size on deformations were also explained. Experiments were conducted on pulsed laser micro-forming of stainless-steel sheet to validate the finite element results. The results of finite element simulations were in good agreement with the experimental results.

Development of Mathematical Models for Prediction of Weld Bead Geometry of GTAW Stainless Steel

2017 ◽  
Vol 867 ◽  
pp. 88-96
Author(s):  
S.M. Ravikumar ◽  
P. Vijian
Keyword(s):  
Stainless Steel ◽  
Process Parameters ◽  
Welding Current ◽  
Weld Bead ◽  
304 Stainless Steel ◽  
Graphical Form ◽  
Bead Geometry ◽  
Depth Of Penetration ◽  
Weld Bead Geometry ◽  
Bead Width

Welding input process parameters are playing a very significant role in determining the weld bead quality. The quality of the joint can be defined in terms of properties such as weld bead geometry, mechanical properties and distortion. Experiments were conducted to develop models, using a three factor, five level factorial design for 304 stainless steel as base plate with ER 308L filler wire of 1.6 mm diameter. The purpose of this study is to develop the mathematical model and compare the observed output values with predicted output values. Welding current, welding speed and nozzle to plate distance were chosen as input parameters, while depth of penetration, weld bead width, reinforcement and dilution as output parameters. The models developed have been checked for their adequacy. Confirmation experiments were also conducted and the results show that the models developed can predict the bead geometries and dilution with reasonable accuracy. The direct and interaction effect of the process parameters on bead geometry are presented in graphical form.

Research on NC Electrochemical Mechanical Complex Machining Stainless Steel

2010 ◽  
Vol 458 ◽  
pp. 331-336
Author(s):  
Wei Min Gan ◽  
Xi Lian Xie ◽  
Bo Xu ◽  
W.B. Huang
Keyword(s):  
Stainless Steel ◽  
Machine Tool ◽  
Process Parameters ◽  
High Speed ◽  
Orthogonal Experiment ◽  
High Strength ◽  
304 Stainless Steel ◽  
Depth Of Cut ◽  
Tool Electrode ◽  
Feed Speed

For hard machining metal materials with high rigidity，high strength or high toughness, the method of electrochemical mechanical complex machining is proposed. A NC high-speed machine tool for carving and milling is transformed into a NC electrochemical mechanical complex machine tool in which complex tool-electrodes, particular tool holders, a new rotary table, a protective flume for electrolyte and pipelines are made and assembled, so that machine tool can achieve a series of machining, such as milling, drilling, grinding and polishing by utilizing complex tool-electrode motion generated by NC. For 304 stainless steel orthogonal experiment is carried out, and five principal process parameters that are spindle rev, feed speed, voltage, pressure of electrolyte and depth of cut, are investigating in the method of NC Electrochemical Mechanical complex machining. The optimization process parameters are obtained.

Effect of nanosecond pulsed laser parameters on the color making of 304 stainless steel

2020 ◽  
Vol 126 ◽  
pp. 106104 ◽  
Author(s):  
Xiaolei Ma ◽  
Xihan Nie ◽  
Jingnan Zhao ◽  
Pranav Shrotriya ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Pulsed Laser ◽  
304 Stainless Steel ◽  
Laser Parameters ◽  
Nanosecond Pulsed Laser

Residual Stresses Prediction for CO2 Laser Butt-Welding of 304-Stainless Steel

2006 ◽  
Vol 3-4 ◽  
pp. 125-130 ◽  
Author(s):  
Khaled Y. Benyounis ◽  
Abdul Ghani Olabi ◽  
M.S.J. Hashmi
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Laser Power ◽  
Travel Speed ◽  
304 Stainless Steel ◽  
Hole Drilling ◽  
Design Matrix ◽  
Butt Welding ◽  
Input Variables

Residual stresses are an integral part of the total stress acting on any component in service. It is important to determine and/or predict the magnitude, nature and direction of the residual stress to estimate the life of important engineering parts, particularly welded components. This work aims to introduce experimental models to predict residual stresses in the heat-affected zone (HAZ). These models specify the effect of laser welding input parameters on maximum residual stress and its direction. The process input variables considered in this study are laser power (1.03 - 1.368 kW), travel speed (26.48 – 68.52 cm/min) and focal point position (- 1 to 0 mm). Laser butt-welding of 304 stainless steel plates of 3 mm thick were investigated using a 1.5 kW CW CO2 Rofin laser as a welding source. Hole-drilling method was employed to measure the magnitude, and direction of the maximum principal stress in and around the HAZ, using a CEA-06- 062UM-120 strain gauge rosette, which allows measurement of the residual stresses close to the weld bead. The experiment was designed based on Response Surface Methodology (RSM). Fifteen different welding conditions plus 5 repeat tests were carried out based on the design matrix. Maximum principal residual stresses and their directions were calculated for the twenty samples. The stepwise regression method was selected using Design-expert software to fit the experimental responses to a second order polynomial. Sequential F test and other adequacy measures were then used to check the models adequacy. The experimental results indicate that the proposed mathematical models could adequately describe the residual stress within the limits of the factors being studied. Using the models developed, the main and interaction effect of the process input variables on the two responses were determined quantitatively and presented graphically. It is observed that the travel speed and laser power are the main factors affecting the behavior of the residual stress. It is recommended to use the models to find the optimal combination of welding conditions that lead to minimum distortion.

Experimental Study of Biaxial Creep Damage for Type 304 Stainless Steel

2002 ◽  
Vol 11 (3) ◽  
pp. 247-262 ◽  
Author(s):  
Masao Sakane ◽  
Hiroto Tokura
Keyword(s):  
Stainless Steel ◽  
Biaxial Tension ◽  
Crack Opening ◽  
Equivalent Stress ◽  
Creep Damage ◽  
304 Stainless Steel ◽  
Creep Tests ◽  
Biaxial Creep ◽  
Type 304 ◽  
Type 304 Stainless Steel

This paper studies the biaxial creep damage of type 304 stainless steel at 923 K. Biaxial tension creep tests were carried out using cruciform specimens and the effect of stress biaxiality on rupture lifetime and creep voiding was discussed. Mises equivalent stress and the equivalent stress based on crack opening displacement were a suitable parameter to assess the biaxial creep damage. The equivalent stress proposed by Huddleston overestimated the biaxial creep damage by more than a factor of two. Stress biaxiality had almost no influence on the orientation of voided grain boundaries and the critical value ofparameter A. Tests of alternative loading direction significantly dispersed the biaxial creep damage resulting in larger creep lifetime.

scholarly journals Preliminary Testing to Determine the Best Process Parameters for Polymer Laser Sintering of a New Polypropylene Polymeric Material

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Fredrick M. Mwania ◽  
Maina Maringa ◽  
Jakobus. G. van der Walt
Keyword(s):  
Mechanical Properties ◽  
Polymeric Material ◽  
Process Parameters ◽  
Laser Power ◽  
Scanning Speed ◽  
Laser Sintering ◽  
Process Conditions ◽  
Preliminary Testing ◽  
Chamber Temperature ◽  
Suitable Process

Polymer laser sintering is an elaborate additive manufacturing technique because it is subject to process parameters and material properties. In this regard, each polymeric material necessitates a different set of process conditions. To this end, testing was done to determine the most suitable process parameters for a new commercially available polymer (Laser PP CP 60), from Diamond Plastics GmbH. It was established that the material requires slightly different settings from those provided by the supplier for the values for the removal chamber temperature, building chamber temperatures, and laser power to achieve the best mechanical properties (ultimate tensile strength). The preliminary testing indicates that the process parameters that yielded the best mechanical properties for the laser PP CP 60 powder were 125°C, 125°C, 0.15 mm, 250 μm, 4500 mm/s, 34.7 W, 1500 mm/s, and 21.3 W for the removal chamber temperature, building chamber temperature layer thickness, hatch distance, scanning speed fill, laser power fill, scanning speed contour, and laser power contour, respectively.

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