Experimental Investigations of Nd:YAG Laser Welding of 630 and 321 Stainless Steel and their Effects on Process Parameters

2009 ◽  
Vol 83-86 ◽  
pp. 384-391
Author(s):  
Seyed Ali Asghar Akbari Mousavi ◽  
A.R. Sufizadeh
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Laser Welding ◽  
Welding Speed ◽  
Gas Flow ◽  
Experimental Investigations ◽  
Welding Parameters ◽  
Beam Diameter ◽  
Electron Microscopic ◽  
Pulse Welding

In this paper, the laser welding of the 630 precipitation hardening stainless steel with the 321 austenitic stainless steel was considered. The experiments were carried out with the pulsed Nd: YAG laser under various welding parameters. The effects of power of laser, voltage, duration of pulse, welding speed, beam diameter and frequency, on the weld volume are investigated. The results show that the weld volume increases with voltage and frequency. The weld volume decreases with welding speed and beam diameter. Moreover, the study shows two effects for the duration of pulse. Up to some value of duration of pulse, the weld volume increases. Exceeding, this limit reduces the weld volume. The optical and scanning electron microscopic tests were carried out. The results show that the martensitic structure is produced in the 630 stainless steel side and the austenitic stainless steel is produced in the 321 stainless steel side. The microhardness tests across the samples were carried out. The results show the maximum hardness is for the 630 stainless steel side and the minimum weld hardness is for the 321 stainless steel side. The high voltage may cause hot cracks in the 321 stainless steel side. The effects of gas flow rate on the microstructure were also considered.

Study on the Predictive Model for Shear Strength in Laser Welding Stainless Steel

2006 ◽  
Vol 505-507 ◽  
pp. 205-210
Author(s):  
Wen T. Chien ◽  
S.W. Chang
Keyword(s):  
Stainless Steel ◽  
Shear Strength ◽  
Taguchi Method ◽  
Laser Welding ◽  
Predictive Model ◽  
Welding Speed ◽  
Welding Parameter ◽  
Average Error ◽  
Welding Parameters ◽  
Neuron Network

A predictive model is presented for the prediction of shear strength in laser welding AISI304 stainless steel. Welding experiments conducted using a pulsed Nd:YAG laser machine while the laser welding parameters and their levels have been arranged according to design of experiments of Taguchi method. The tensile tests are performed after welding and the measurements of tensile strength are further calculated for shear strength. The data can be analyzed using the principles of Taguchi method for determining the optimal laser welding parameters and for investigating the most significant laser welding parameter on shear strength. Furthermore, the results are treated as the training and recalling patterns for constructing a predictive model using back-propagation neuron network to predict shear strength for the range of laser welding operation tested. It is indicated that welding speed is the most significant affecting parameters on shear strength. In addition, an increase in welding speed causes a decrease in shear strength is found. An average error 5.75％for shear strength can be found by comparing the experimental results obtained from conducting verification tests with the predicting values obtained from the established predictive model. It shows that the predictive model is capable of good predicting behavior of laser welding AISI304 stainless steel.

INVESTIGATION OF TENSILE BEHAVIOUR OF TIG WELDED 316 STAINLESS STEEL USING TAGUCHI TECHNIQUES

2019 ◽  
Vol 14 (4) ◽  
Author(s):  
Karthimani T ◽  
Babu N
Keyword(s):  
Stainless Steel ◽  
Welding Speed ◽  
Gas Flow ◽  
Welding Process ◽  
Welding Current ◽  
Tig Welding ◽  
Filler Material ◽  
Tensile Behaviour ◽  
Welding Parameters ◽  
Taguchi Technique

This works aims at the analysis and optimization of joining similar grades of stainless steel by TIG welding. TIG welding may use a filler material. There is a variant in the process which does not require filler material. Such process is known as Autogenous TIG welding process. The parameters like current, welding speed and gas flow rate are the variables in the study. The objective of this research is to determine the influence of various welding parameters on the weld bead of 316 SS by using Taguchi technique. A plan of experiments based on Taguchi technique method has been carried out. Orthogonal array, signal to noise (S/N) Ratio, Analysis of variance (ANOVA) are employed for studying the welding characteristics of material & to optimize the weld parameters. The result obtained are the output from each parameter, through which optimal parameters are found out for maximum tensile strength. It is found that -welding current followed by welding speed are major parameters influencing mechanical properties of welded joint

Experimental Investigations for Reducing Effect of Sensitization in Tungsten Inert Gas Welding

2008 ◽  
Author(s):  
Rupinder Singh ◽  
Sehijpal Singh
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Inert Gas ◽  
Experimental Investigations ◽  
Welding Parameters ◽  
Work Piece ◽  
Tungsten Inert Gas Welding ◽  
Stainless Steel 316L

Stainless steels are considered to have very good resistance to general and localized corrosion due to their chromium content. This property of corrosion resistance constitutes the main criterion for selecting austenitic grades of steels for service in the chemical, nuclear and aerospace industries although their mechanical properties are relatively modest. However, this resistance can degrade when structural components manufactured from these steels are used in a chemically aggressive environment, especially when service involves exposure to high temperatures like in welding. This exposure gives rise to precipitation of chromium carbides producing chromium depletion at grain boundaries that brings about the inter-granular corrosion or sensitization of these materials. Austenitic stainless steel (316L) is one of the corrosion resistance material used extensively in the oil production, chemical and power generation industries for transportation and reservoir of corrosive products. In spite of its corrosion resistance property there exist severe problems of sensitization. In the present work an effort has been made to reduce the effect of sensitization in Tungsten Inert Gas welding of Austenitic stainless steel (316L). Three welding procedures (namely conventional, back step and skip welding) in Tungsten Inert Gas welding have been used to control exposure time of the weld pool to higher temperatures, in order to study the effect of sensitization on mechanical properties (such as tensile strength, yield strength, percentage elongation and hardness). The results of this study suggested that the better mechanical properties were attained by the skip welding procedure and recommended welding parameters are 90 Amp current and 10 L/min of gas flow rate for a 5 mm thick work piece. Noticeable change in amount/extent of sensitization was observed using a scanning electron microscope (SEM) analysis within the various welding specimens prepared using the various procedures. Further mechanical properties (like strength and hardness) have been correlated with the extent of sensitization, which show remarkable decreases when the amount/extent of sensitization increases.

A Study on Laser Welding of Titanium and Stainless Steel

2018 ◽  
Author(s):  
Angshuman Chattopadhyay ◽  
Gopinath Muvvala ◽  
Vikranth Racherla ◽  
Ashish Kumar Nath
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Weld Joint ◽  
Welding Speed ◽  
Fusion Process ◽  
Longitudinal Stress ◽  
Transverse Cracks ◽  
Cooling Rates ◽  
Melt Pool ◽  
Longitudinal Cracks

Joining of dissimilar metals and alloys has been envisioned since a long time with specific high end applications in various fields. One such combination is austenitic stainless steel grade SS304 and commercial grade titanium, which is very difficult to join under conventional fusion process due to extensive cracking and failure caused by mismatch in structural and thermal properties as well as formation of the extremely brittle and hard intermetallic compounds. One of the methods proposed in literature to control the formation of intermetallics is by fast cooling fusion process like laser beam welding. The present study has been done on laser welding of titanium and stainless steel AISI 304 to understand the interaction of these materials during laser welding at different laser power and welding speed which could yield different cooling rates. Two types of cracks were observed in the weld joint, namely longitudinal cracks and transverse cracks with respect to the weld direction. Longitudinal cracks could be completely eliminated at faster welding speeds, but transverse cracks were found little influenced by the welding speed. The thermal history, i.e. melt pool lifetime and cooling rate of the molten pool during laser welding was monitored and a relation between thermo-cycle with occurrence of cracks was established. It is inferred that the longitudinal cracks are mainly due to the formation of various brittle intermetallic phases of Fe and Ti, which could be minimized by providing relatively less melt pool lifetime at high welding speeds. The reason of the transverse cracks could be the generation of longitudinal stress in weld joint due to the large difference in the thermal expansion coefficient of steel and titanium. In order to mitigate the longitudinal stress laser welding was carried out with a novel experimental arrangement which ensured different cooling rates of these two metals during laser welding. With this the tendency of transverse cracks also could be minimized significantly.

scholarly journals Evaluation of Microstructure and Impact Toughness of Shielded Metal Arc Dissimilar Weldments of High Strength Low Alloy Steel and Austenitic Stainless Steel

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Misbahu A Hayatu ◽  
Emmanuel T Dauda ◽  
Ola Aponbiede ◽  
Kamilu A Bello ◽  
Umma Abdullahi
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Impact Toughness ◽  
Impact Energy ◽  
High Strength ◽  
Impact Testing ◽  
Welding Parameters ◽  
Dissimilar Weld ◽  
Weld Joints ◽  
The Impact

There is a growing interest for novel materials of dissimilar metals due to higher requirements needed for some critical engineering applications. In this research, different dissimilar weld joints of high strength low alloy (HSLA) and 316 austenitic stainless steel grades were successfully produced using shielded metal arc welding (SMAW) process with 316L-16 and E7018 electrodes. Five variations of welding currents were employed within the specified range of each electrode. Other welding parameters such as heat inputs, welding speeds, weld sizes, arc voltages and time of welding were also varied. Specimens for different weld joint samples were subjected to microstructural studies using optical and scanning electron microscopes. The impact toughness test was also conducted on the samples using Izod impact testing machine. The analysis of the weld microstructures indicated the presence of type A and AF solidification patterns of austenitic stainless steels. The results further showed that the weld joints consolidated with E7018 electrode presented comparatively superior impact energy to the weldments fabricated by 316L-16 electrode. The optimum impact energy of E7018-weld joints (51J) was attained at higher welding heat inputs while that of 316L-16-weld joints (35J) was achieved at lower welding heat inputs, which are necessary requirements for the two electrodes used in the experiment. Hence, the dissimilar weld joints investigated could meet requirement for engineering application in offshore and other critical environments.Keywords—Dissimilar metal weld, heat input, impact toughness, microstructures

Influence of Side Assist Gas on Microstructure and Corrosion Resistance of Welds of Austenitic Stainless Steel in Laser Welding

2017 ◽  
Vol 44 (5) ◽  
pp. 0502005
Author(s):  
周媛 Zhou Yuan ◽  
蔡艳 Cai Yan ◽  
衡昊坤 Heng Haokun ◽  
盛洁 Sheng Jie ◽  
李芳 Li Fang
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Laser Welding
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