Annealing Control Systems for Rolling Mills

Grain Size and Remanence measuring systems for cold rolling mills

"Online annealing control improves efficiency of continuous annealing lines."

Both systems are powerful tools with the following positive impacts:

  • Improved quality assurance
  • Enhanced reliability of production
  • Energy savings
  • Reduction of sampling costs
  • Increased annealing line throughput

Grain size measurement by ultrasound - FWT 25

 

Ultrasound

 

Measuring principle

Ultrasound signals reflected by metallic material. Under a certain angle a maximum signal is detected (about 31° for stainless steel). The received signal includes information on the grain size which can be compared with a calibration curve. Thus the values of the grain size can be calculated. In case of the used ultrasound frequency of 25 MHz the measuring range is about 8 to 40 mm. Typical accuracy is +/- 2 mm.

 

Remanence measurement in a continuous annealing line - FWT 100

 

Measuring

 

Measuring principle

After being cold-rolled, steel strip is annealed to achieve recrystallization. In case of ferritic stainless steel there is a clear correlation between grain structure, mechanical properties and magnetic behavior. During the annealing process the values of the apparent remanence drop significantly, reaching a minimum value in case of full recrystallization. Overannealing can be observed by increasing values because of the formation of Martensite. The measuring system consists of a magnetizing roller and a field detecting roller which are mounted over strip guiding roll.