- C. R. Das
- A. K. Bhaduri
- P. Krishnamraju
- S. K. Albert
- R. Balakrishnan
- Chittaranjan Das
- Arun Kumar Bhaduri
- M. Vijayalakshmi
- Krishnam Raju
- B. Ravisankar
- M. Anandaraj
- P. Parameswaran
- S. Krishnakumar
- T. Ezhilarasi
- R. Thirumurugesan
- S. Chandramouli
- V. Ramakrishnan
- G. Padmakumar
- Shaju K. Albert
- B. K. Nashine
- V. Prakash
- P. Selvaraj
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Thomas Paul, V.
- Effect of Long-Term Post-Weld Heat Treatment on the Microstmeture and Mechanical Properties of P91 Weld Metal
Authors
1 Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, IN
2 Department of Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli 620 015, IN
Source
Indian Welding Journal, Vol 48, No 3 (2015), Pagination: 29-29Abstract
Modified 9Cr-lMo (P91) steel is used in fossil-fuel fired power plants due to its good thermo-physical, weldability, fabricability and high temperature mechanical properties. Toughness of the P91 weld metal, deposited by the shielded metal arc welding (SMAW) process, is reported to be lower than that deposited by the gas tungsten arc welding (GTAW) process. In spite of this, considering the higher deposition rate and economics, the SMAW process is very popular in industry. Thus, achieving adequate toughness in the P91 weld metal deposited using the SMAW process is an important requirement to qualify the weld joints.
Weld joints were prepared using the SMAW process and subjected to post-weld heat treatment (PWHT) at 760°C for durations of 3, 10 and 100 hours. Microstructural observations revealed coarsening of the lath martensite and the precipitates accompanied by an increase in toughness with increase in PWHT duration from 3 to 10 hours. The effect of PWHT duration on subzero toughness was found to be significant, with the subzero toughness increasing with increase in PWHT duration upto 10 hours and then decreasing on PWHT for 100 hours. Increase in sub-zero toughness could be attributed to adequate tempering, while the decrease in toughness on PWHT for 100 hours was attributable to the formation of fresh martensite during cooling from the PWHTtemperature. This variation of toughness of the SMA weld metal with duration of PWHT needs better understanding from the view point of the composition of the weld metal. Detailed microstructural analysis was carried out to understand the reasons for the variations in the mechanical properties. This paper presents and discusses the results of this experimental investigation.
- Effect of PWHT on the Toughness of Modified 9Cr-1Mo Steel Weldmetal
Authors
1 Indira Gandhi Centre for Atomic Research, Kalpakkam 60310, IN
2 Indira Gandhi Centre for Atomic Research, IN
3 National Institute of Technology, Tiruchirapalli 62001, IN
4 Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, IN
Source
Indian Welding Journal, Vol 47, No 4 (2014), Pagination: 24-24Abstract
Modified 9Cr-1Mo steel is extensively used for high temperature applications due to its good thermo-physical, weldability, fabricability and high temperature properties. While Type IV cracking is of concern during service of weld joints, toughness of its weldmetal is an important consideration during qualification of weld joints, especially for those made by SMAW process. The weldmetal toughness is significantly influenced by deposition process and sequence, and temperature and duration of PWHT. For a special-purpose mod.9Cr-1Mo steel weldmetal, containing intentional addition of 2.4wt% of nickel and manganese, the A and A transformation temperatures, calculated using ThermoCalc software, was found as 945 and 1065K, respectively. To understand its tempering behavior, the weldmetal was subjected to PWHT at 1013, 1033 and 1053K for different durations. The weldmetal hardness decreased significantly on PWHT at 1013K compared to that at 1033 and 1053K. The weldmetal toughness increased monotonically with PWHT temperature; from 27J for 923K PWHT to 32J and 132J for 973K and 1023K PWHTs, respectively, and then decreased marginally to 113J on PWHT at 1153K. These results suggested formation of fresh martensite during PWHT at 1053K. Bright-field transmission electron microscopic examination revealed formation of lath martensite in the weldmetal, with the lath sizes being finer than those reported in other mod. 9Cr-1Mo steel weldmetal prepared using similar process. Hence, detailed microstructural analyses was carried out to investigate this anomalous variation in mechanical properties, as also to study the effect of temperature and duration of PWHT on the microstructure and toughness of this modified 9Cr-1Mo steel weldmetal.- Optimization of Parameters for Welding of Spark Plug Detector
Authors
1 Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, India - 603 102, IN
2 Metallurgy & Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, India - 603 102, IN
Source
Indian Welding Journal, Vol 53, No 1 (2020), Pagination: 67-73Abstract
One of the spark plug leak detectors employed in high temperature liquid sodium systems had failed to detect a sodium leak and systematic failure analysis was carried out to identify the ischolar_main cause of the failure. Radiography image of the leak port nozzle revealed that the extension wire which was welded with spark plug electrode had snapped. Since the failure originated from the cracks present in the weld, it was decided to standardize the welding procedure of spark plug electrode to extension wire to prevent the possibility of similar failures in future. Three different materials viz, stainless steel, nickel, inconel were chosen as extension wires as well as filler wires to optimize the welding parameters. Microstructural studies in terms of presence of defects, interface integrity between the weld and extension wire as well as that of spark plug electrode were carried out. Based on this, the final choice of welding parameters, material for extension wire and for filler wire to achieve a sound weld was proposed.Keywords
Spark Plug Detector, Extension Wire, Failure Analysis, Metallography, Welding Procedure Qualification.References
- Chaudhari R, Parekh R and Ingle A (2014); Reliability of dissimilar metal joints using fusion welding, Int Conf on Machine Learning and Mechanical Engineering (ICMLEME'2014), Dubai, UAE.
- Kaya H, Cadrl E, Boyuk U and Maras N (2008); Variation of microindentation hardness with solidification and microstructure parameters in the aluminium based alloys, Applied Surface Science, 255, p. 3071.
- https://www.nickelinstitute.org/~/Media/Files/Technical Literature/Copper_Nickel Alloys Properties and Applications_12007_.pdf
- Ramirez JE, Han B and Liu S (1994); Effect of welding variables and solidification substructure on weld metal porosity, Metal and Mat Trans A, 25, p. 2285.
- Sireesha M, Albert SK, Shankar V and Sundaresan S (2000); A comparative evaluation of welding consumables for dissimilar welds between 316LN austenitic stainless steel and alloy 800, Materials Science and Engineering A, 292, p. 74.
- Hidnert P (1957); Thermal expansion of some nickel alloys, Journal of Research of the National Bureau of Standards, 58.