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 A New Test Method for Evaluation of Solidification Cracking Susceptibility of Stainless Steel during Laser Welding

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3178 ◽  
Author(s):  
Wenbin Wang ◽  
Li Xiong ◽  
Dan Wang ◽  
Qin Ma ◽  
Yan Hu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Cooling Rate ◽  
Weld Joint ◽  
Stainless Steels ◽  
Welding Speed ◽  
Hot Cracking ◽  
Weld Bead ◽  
Test Method ◽  
Solidification Cracking

A new test method named “Trapezoidal hot” cracking test was developed to evaluate solidification cracking susceptibility of stainless steel during laser welding. The new test method was used to obtain the solidification cracking directly, and the solidification cracking susceptibility could be evaluated by the solidification cracking rate, defined as the ratio of the solidification cracking length to the weld bead length under certain conditions. The results show that with the increase in the solidification cracking rate, the solidification cracking susceptibility of SUS310 stainless steel was much higher than that of SUS316 and SUS304 stainless steels during laser welding (at a welding speed of 1.0 m/min) because a fully austenite structure appeared in the weld joint of the former steel, while the others were ferrite and austenitic mixed structures during solidification. Besides, with an increase in welding speed from 1.0 to 2.0 m/min during laser welding, the solidification cracking susceptibility of SUS310 stainless steel decreased slightly; however, there was a tendency towards an increase in the solidification cracking susceptibility of SUS304 stainless steel due to the decrease in the amount of ferrite under a higher cooling rate.

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.

A study of laser welding modes with varying beam energy levels

2008 ◽  
Vol 223 (5) ◽  
pp. 1141-1156 ◽  
Author(s):  
G Buvanashekaran ◽  
Siva N Shanmugam ◽  
K Sankaranarayanasamy ◽  
R Sabarikanth
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Laser Welding ◽  
Weld Pool ◽  
Welding Speed ◽  
Laser Power ◽  
Beam Energy ◽  
Energy Levels ◽  
Three Dimensional ◽  
Laser Source

The energy of a laser beam is generally calculated based on the laser power and its processing speed. In this work, the laser welding modes such as conduction, conduction—penetration, and keyhole welding of thickness 1.6, 2, and 2.5 mm AISI304 stainless steel sheets, respectively, are studied at different beam energy levels. A series of bead-on-plate trials are conducted using a 500 W continuous wave Nd:YAG laser source to study the beam—material interaction and the influence of laser power and welding speed on the formation of weld pool. In addition to the experimental study, a three-dimensional finite-element model is developed to analyse the transient heat flow and to predict the formation of the weld pool. The correlation among the parameters including laser power, welding speed, beam incident angle, and the characteristic geometry of weld pool are established. Temperature-dependent thermal properties of AISI304 stainless steel, the effect of latent heat of fusion, and the convective and radiative aspects of boundary conditions are considered in the model. The heat input to the developed model is assumed to be a three-dimensional conical Gaussian heat source. Finite-element simulations are carried out by using finite-element code, SYSWELD, and FORTRAN subroutines available within the code are used to obtain the numerical results. The result of the numerical analysis provides the shape of the molten pool with different beam energy levels, which is then compared with the results obtained through experimentation. It is observed that the results obtained from finite-element simulation and the experimental trials are in good agreement.

The Connection of Welded Seam Three Dimensional Appearance with Performance for Joints of Stainless Steel Plate Laser Welding

2010 ◽  
Vol 168-170 ◽  
pp. 2293-2298
Author(s):  
Shu Ying Liu ◽  
Xiao Jiao Zhang ◽  
Guang Bao Liu ◽  
Lei Zhang ◽  
Kui Fei Zhao ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Welding Speed ◽  
Pulse Width ◽  
Steel Plate ◽  
Three Dimensional ◽  
Critical Value ◽  
Stainless Steel Plate ◽  
Value Range ◽  
Welded Seam

It has been carried out the test and research to the stainless steel plate laser welding welded seam, by two-dimensional, three-dimensional appearance observation and tensile methods. Its result is: The YAG laser welding, is welding speed, frequency, pulse width and so on technological parameter influences to be big. In the power limit, raising the power or reducing welding speed; or increasing the frequency, or increasing the pulse width in critical value range, it be possible to increasing joints strength, however, when the pulse width surpasses critical value range its joints strength instead fall. In this study, the parameter that the appearance and the quality are all good of welded seam for welds speed 60mm/min, frequency 10Hz, pulse width 3ms, defocusing amount -1mm, the tensile strength of joints may reach 390MPa. The joints that the performance is good, its keyhole's microscopic appearance is also more complete good, but the joints that the macroscopic appearance is good, it has fine mechanical properties certain by no means. The three-dimensional observation of keyhole appearance is relatively feasible to be appraisal laser welding welded seam newest method，it is worthy discussing and carrying out.

Parametric Study of Underwater Laser Welding on 304 Austenite Stainless Steel

2019 ◽  
Vol 972 ◽  
pp. 222-228
Author(s):  
Yun Long Fu ◽  
Ning Guo ◽  
Ji Cai Feng
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Welding Speed ◽  
Laser Power ◽  
Single Layer ◽  
Working Environment ◽  
Laser Weld ◽  
Butt Welding ◽  
Austenite Stainless Steel ◽  
Underwater Laser

The underwater laser welding assisted by a single-layer gas torch was carried out on the austenite stainless steel based on the underwater laser welding experimental platform. Butt welding experiments under shallow water were performed to investigate the effects of laser power, welding speed and defocusing distance on the underwater laser welding quality and optimized the process parameters. It was found that the ideal underwater laser weld can be obtained with the laser power of 2.0 kW, the welding speed of 2.0 m/min and the defocusing distance of 1 mm, demonstrating the self-developed single-layer gas-assisted drainage device could create working environment similar to onshore laser welding, by analyzing the metallographic structure and mechanical properties of underwater laser weld and in-air laser weld.

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.

Sign in / Sign up

Export Citation Format

Share Document