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Bhattacharya, D. K.
- Nondestructive Measurement of Residual Stress in Carbon Steel Weld Joints
Authors
1 Indira Gandhi Centre for Atomic Research, Kalpakkam, IN
Source
Indian Welding Journal, Vol 27, No 4 (1994), Pagination: 34-41Abstract
The knowledge of the nature and magnitudes of residual stress (RS.) in a weld joint is important for avoiding distortions and premature failures. Both analytical and experimental techniques are used for getting information on RS distributions.
- Residual Stress Evaluation In Austenitic Stainless Steel Butt Weld Joints By Ultrasonic Technique
Authors
1 Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, IN
Source
Indian Welding Journal, Vol 25, No 3 (1992), Pagination: 130-136Abstract
This paper discusses the results of measurement of residual stress pattern across butt weld joints by ultrasonic velocity measurements in 15 mm and 47 mm thick AISI type 304 stainless steel plates. These are supplemented by results obtained from hole drilling strain gauge measurements. Pulse echo overlap technique was used to measure the through thickness longitudinal ultrasonic velocities. Acoustoelastic constant was determined to convert the change in ultrasonic velocities to residual stress values. The residual stress pattren obtained by the two techniques showed similar trends. Brief overview of various other residual stress measurement methods, and various techniques for ultrasonic velocity measurements are included in the paper.
Keywords
Residual Stress, Austenitic Stainless Steel, Weld Joint, Ultrasonic Velocity, Acoustoelastic Constant, Strain Guage Technique.- Ultrasonic Inspection of Austenitic Stainless Steel Weldments—Our Experiences
Authors
1 Radiometallurgy Laboratory, Reactor Research Centre, Kalpakkam—603 102, IN
Source
Indian Welding Journal, Vol 15, No 3 (1983), Pagination: 91-95Abstract
Austenitic steel welded structures are widely used in power stations, petrochemical industries and nuclear industries. These welded structures pose unique problems for ultrasonic testing not experienced with ferritic steel welds. Since X radiography cannot be used in many cases (like inservice inspection, thick welds, planar defects, etc.), it becomes imperative that ultrasonic testing be used. To do this, the problems encountered during examination of austenitic steel weldments must be understood and solved.- Investigation into Cracking of a Weld Repaired Turbine Casing
Authors
1 Material Characterization Division, National Metallurgical Laboratory, Jamshedpur-831 007, IN
Source
Indian Welding Journal, Vol 31, No 3 (1998), Pagination: 35-44Abstract
The present study was aimed at analysing the failure of a weld repaired turbine casing after 30 years of total service including 5 years after weld repair. The casing vvas weld repaired by a high alloyed weld metal (24Cr-32Ni-4Mn-Fe). The base metal consisting of ferrite-pearlite microstructure did not show any appreciable degradation during service. δ ferrite was observed at the interface of weldment and HAZ as predicted by the Schaeffler diagram. The δ- ferrite phase appeared to transform to alloy carbides and a-phase during high temperature service.
The difference between thermal expansion coefficients of ferritic and austenitic stainless steel led to the generation of stress in addition to the usual thermal stress. The resultant stress was estimated to be near to the yield stress indicating that the weld zone experienced a typical condition of low cycle fatigue. The presence of striations on the fracture surface confirmed thermal fatigue as the failure mode. Crack growth took place along the grain boundaries embrittled by a-phase and led to failure. The correct choice of the filler metal should have been a high Nibase alloy having similar coefficient of thermal expansion as the ferritic steel base metal.