Determination of nitrogen and carbon interstitially dissolved in continuously‐annealed steel sheets by means of a fully automatic torsion pendulum

Abstract

A fully automatic torsion pendulum of the Collette type was built to test continuously‐annealed steels in the thickness range between 0.15 and 0.4 mm for their contents of dissolved nitrogen and carbon. The influence of composition and production conditions on unalloyed steels which had been annealed commercially and in the laboratory were investigated. It was found that, with an increase in the total carbon and aluminium contents, the percentages of the dissolved nitrogen and carbon decrease, whereas higher nitrogen contents resulted in an increase of the percentages dissolved. A higher coiling temperature of the hot band leads to a decrease in the nitrogen dissolved due to the formation of AIN, but to an increase of the carbon dissolved. As these effects almost compensate each other, the coiling temperature is not a suitable means to influence the aging potential. During the continuous annealing process, temperatures of more than 750°C result in a decrease of the nitrogen dissolved, which is completely precipitated as AIN leaving the carbon content nearly unaffected. No major differences were observed, when the material was annealed either with or without a subsequent overaging treatment. However, rapid cooling to low temperatures definitely increased the percentages of elements dissolved.

Kinetics of strain aging in drawn pearlitic steels

“…[8] is applied to aging at 100 ЊC (373 K) for 5400 seconds, using the diffusion coefficient of C in ferrite [32] (the diffusion coefficient of N in ferrite is very close to that of C at this temperature), a diffusion distance of approximately 47 nm is found. When Eq.…”

Strain-Ageing of Low-Alloyed Multiphase High-Strength Steels

“…ULC steels and LC steels are known to exhibit a Snoek peak [21][22][23][24][25][26][27][28] due to the very low amount of interstitials. Figure 17 shows the internal friction measurement for prestrain levels in the range of 0-2% of the TRIP5 steel.…”

The microstructure and mechanical properties of drawn and aged pearlitic steel wires

“…Stage I of strain aging occurs at temperatures below 100°C and progresses even at room temperature. This is attributed to the migration of interstitially dissolved carbon atoms to dislocations in ferrite, since the apparent activation energy in this stage is close to that of carbon diffusion in ferrite (84.2 kJ mol −1 [42]). In this stage, the yield stress rises and elongation and reduction of area decrease because of locking of dislocations.…”