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Gourav Rao, A.
- Hot Tensile Properties of Filler Added Constant Current Gas Tungsten Arc Welded AISI 304HCu Super Austenitic Stainless Steel Joints
Abstract Views :359 |
PDF Views:8
Authors
Affiliations
1 Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar, Tamil Nadu - 608002, IN
2 Naval Material Research Laboratory (NMRL), Ambernath, Mumbai - 421506, IN
1 Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar, Tamil Nadu - 608002, IN
2 Naval Material Research Laboratory (NMRL), Ambernath, Mumbai - 421506, IN
Source
Indian Welding Journal, Vol 48, No 4 (2015), Pagination: 61-67Abstract
AISI 304HCu austenitic stainless steel containing 2.3 to 3 (% wt) of Cu is mainly used in superheaters and reheater of ultra super critical (USC) boilers which operates over 600°C of steam temperature. Austenitic stainless steels welded by gas tungsten arc welding (GTAW) alters the phase composition, and microstructure of the steel in the fusion zone of welds and may affect the mechanical properties. In our previous investigation, it is found that autogenous welding of AISI 304HCu tubes resulted in segregation of alloying elements in the weld metal and resulted in joints with inferior tensile strength. Hence, in this study the high temperature tensile properties of filler added GTA welded AISI 304HCu tube joints were evaluated and correlated with the microstructural features. The tensile strength of the filler added GTA weld joints was higher than the parent metal at all test temperatures and the weld joint with filler addition was recommended for application in USC boilers.Keywords
AISI 304HCu, Gas Tungsten Arc Welding, High Temperature Tensile Properties, Ultra Super Critical Boilers.
- Hot Tensile Properties of Autogenous Pulsed Current Gas Tungsten Arc Welded Super 304HCu Austenitic Stainless Steel Joints
Abstract Views :196 |
PDF Views:0
Authors
Affiliations
1 Dept. of Manufacturing Engineering, Annamalai University, Annamalai Nagar, Tamil Nadu, IN
2 Center for Materials Joining and Research (CEMAJOR), Dept. of Manufacturing Engg., Annamalai University, Annamalai Nagar, Tamil Nadu, IN
3 Naval Material Research Laboratory (NMRL), Ambernath, Mumbai, IN
1 Dept. of Manufacturing Engineering, Annamalai University, Annamalai Nagar, Tamil Nadu, IN
2 Center for Materials Joining and Research (CEMAJOR), Dept. of Manufacturing Engg., Annamalai University, Annamalai Nagar, Tamil Nadu, IN
3 Naval Material Research Laboratory (NMRL), Ambernath, Mumbai, IN
Source
Manufacturing Technology Today, Vol 14, No 9 (2015), Pagination: 11-17Abstract
The super 304HCu austenitic stainless steel tubes containing 2.3 to 3 (% wt) of Cu is mainly used in superheaters and reheater of ultra super critical boilers. The addition of Cu to super 304HCu has caused improvement in its corrosion and creep resistance. Austenitic stainless steels welded by constant current gas tungsten arc welding (GTAW) produce coarse columnar grains, increase alloy segregation and may result in low mechanical properties of the weld joint. Hence, autogenous pulsed current GTAW (PC-GTAW) was used to weld super 304HCu tubes of 57.1 mm outer diameter and 3.5 mm thick to control the solidification structure by altering the prevailing thermal gradients in the weld pool. The microstructure, hot tensile properties (550 °C, 600 °C and 650 °C), and fracture surface of the autogenous PC-GTAW welded joint was evaluated. Current pulsing in PC-GTAW joint cannot eliminate segregation in weld metal and exhibited lower tensile strength than the parent metal at all test temperature.Keywords
Super 304HCu Stainless Steel, Autogenous Pulsed Current Gas Tungsten Arc Welding, Hot Tensile Properties, Microstructure.- Developing Empirical Relationship to Predict the Diameter of Multiwall Carbon Nano Tubes (MWCNTs) Synthesized by Chemical Vapor Deposition (CVD) Process
Abstract Views :225 |
PDF Views:2
Authors
Affiliations
1 Centre for Materials Joining & Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Chidambaram, Tamil Nadu, IN
2 Department of Chemistry, Annamalai University, Chidambaram, Tamil Nadu, IN
3 VB Ceramic Research Centre (VBCRC), Chennai, IN
4 NMRL, Mumbai, IN
1 Centre for Materials Joining & Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Chidambaram, Tamil Nadu, IN
2 Department of Chemistry, Annamalai University, Chidambaram, Tamil Nadu, IN
3 VB Ceramic Research Centre (VBCRC), Chennai, IN
4 NMRL, Mumbai, IN
Source
Manufacturing Technology Today, Vol 16, No 6 (2017), Pagination: 3-11Abstract
The thermal chemical vapor deposition (CVD) route was used to synthesize multi walled carbon nano tubes (MWCNTs) and metal NiO powders was used as catalyst and it supported on crystalline alumina nano particles. Acetylene was used as the carbon source gas and Argon was used as the carrier gas. An empirical relationship was developed to predict the diameter of MWNTs incorporating important CVD process parameters. Three factors, five levels central composite design was used to minimize number of experimental conditions. The CVD parameters such as reaction temperature, gas flow rate and process time were chosen as the important parameters. The diameter of MWNTs was measured using field emission scanning electron microcopy (FESEM). Analysis of variance (ANOVA) method was used to identify significant main and interaction factors. Final empirical relationship was developed using these significant factors. The developed empirical relationship can be effectively used to predict the diameter of MWNTs synthesized through CVD process at 95% confidence level.Keywords
Carbo Nano Tube, Chemical Vapor Deposition, Design of Experiments, Analysis of Variance.References
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- Microstructure Evolution and Mechanical Properties of Friction Stir Welded Thick HSLA Steel
Abstract Views :345 |
PDF Views:11
Authors
Affiliations
1 Naval Metallurgy Division, Naval Materials Research Laboratory, Ambernath, Thane - 421 506, Maharashtra, IN
1 Naval Metallurgy Division, Naval Materials Research Laboratory, Ambernath, Thane - 421 506, Maharashtra, IN
Source
Indian Welding Journal, Vol 51, No 3 (2018), Pagination: 54-58Abstract
Friction stir welding (FSW) is known for joining low softening alloys metals such as aluminum, magnesium and copper, however joining of high softening alloys like steel, titanium and nickel base alloys is still a challenge due to tool material stringent property requirements and its availability. Presently, due to development new generation tool material FSW of high softening alloys is possible and also reported. FSW can effectively join different grade of low thickness steel, however the questions about joining thick section steel still remains a challenge.
In this paper, FSW of 7 mm, 12 mm and 24 mm thick HSLA steel in single and double pass was carried out to develop the processing window for defect free weld joints and understanding the structure-property correlation. The increase in thickness of the base metal resulted in generation of higher load, higher heat input and consequently lower cooling rate. Therefore, the microstructure obtained after FSW in different thickness of steel also shows varying microstructures (grain boundary ferrite, acicular ferrite, widmensttan ferrite and upper bainite). Optical and scanning electron microscope (SEM) with electron back scattered diffraction (EBSD) detector was utilized to characterize the microstructure of FSW nugget zone. Tensile and hardness properties were also evaluated and correlated with the microstructure.
Keywords
Friction Stir Welding, High Strength Low Alloy Steel (HSLA), Microstructure, Tensile Properties, Scanning Electron Microscopy.References
- Shinoda T and Takegami H (2005); Development of FSW process for steel assembly to shipbuilding and offshore structure, Proc. 15th Int. Offshore and Polar Eng. Conf., Seoul, pp.19-24.
- Show BK, Veerababu R, Balamuralikrishnan R and Malakondaiah G, (2010), Effect of vanadium and titanium modification on the microstructure and mechanical properties of a microalloyed HSLA steel, Materials Science and Engineering A, 527, pp. 1595–1604.
- Rai R, De A, Bhadeshia HKDK and Debroy TT (2011); Review: friction stir welding tools, Science and Technology of Welding and Joining, 16(4), pp. 325-342.
- Thompson B and Babu SS (2010), Tool degradation dharacterization in the friction stir welding of hard metals, Edison Welding Institute, 89, pp. 21-26.
- Ragu Nathan S, Malarvizhi S, Balasubramanian V and Rao AG (2016), Failure analysis of tungsten based tool materials used in friction stir welding of high strength low alloy steels Engineering Failure Analysis, 66, pp. 88–98.
- Ragu Nathan S, Malarvizhi S, Balasubramanian V and Rao AG (2015), Effect of welding processes on mechanical and microstructural characteristics of high strength low alloy naval grade steel joints, Defence Technology, 11, pp.308–317.