On-site residual stress distribution profiling of hot rolled sheets at Hot strip mill, TSL Jamshedpur site
To evaluate residual stress pattern and distribution in six selected grades of hot rolled steel sheet across the width and length & to correlate it with sheet distortion problems which is encountered at the customer end during slitting.
The problem pertaining to which this project has been initiated actually lies with the distortion of the hot rolled cut to length sheets when they are being slit at the customer end. The expected reason of this is the presence of residual stresses within the steel sheets. Thus to tackle this problem the approach includes: evaluation of residual stress pattern using strain gauge and stresscoat technique and further quantitatively using portable XRD. Based upon the so obtained correlation suitable recommendations will be made either to optimize the processing parameters or to change the slitting pattern at the customer end.
Residual stress pattern measurements have been carried out at the plant on the hot rolled cut to length sheets using strain gauges. The experiments involved strain gauge fixation at different locations of the sheet followed by different pattern of sequential cutting. The residual stress limits were found to outside any deleterious range. Further the efficacy of stresscoat technique has to be established by correlating its outcomes with the same of strain gauge experiments and portable XRD technique.
This project aims at providing an easily implementable technique for the determination of residual stress pattern in hot rolled sheets. The laid out correlations will be useful for establishing the accuracy and applicability range of the stress coat technique. If found applicable this technique would be highly beneficial for the purpose of minimizing rejections at customer end owing to distortion in steel sheets.
Work in progress Photos
Strain Gauge fixation on the HR sheets
Strain Gauge results