Lateral strip of magnetic field induction heating annealing treatment parameters

Transverse magnetic field induction heating annealing treatment is mainly used for recrystallization annealing of cold-rolled low-carbon steel strips and annealing to eliminate time-dependent changes. The purpose of recrystallization annealing is mainly to improve the plasticity and toughness of the steel strip. The purpose of annealing to eliminate the phenomenon of strain aging is to maintain the plasticity and stability of the steel strip.

There are two traditional annealing treatment methods for low carbon steel strip. One is to anneal the whole coil of steel strip in a protective atmosphere hood furnace, and the annealing cycle of each furnace is 16~ 24h; the other is to uncoil annealing in a protective atmosphere continuous annealing furnace, and the operation time is Short, but the steel strip has strain aging phenomenon after annealing. In addition, these two annealing processes have the disadvantages of high energy consumption and low thermal efficiency.

In the 1970s, foreign researches used the transverse magnetic field induction heating method to anneal cold-rolled low-carbon steel strip, which achieved certain results and was used in production practice. Table 9-3 shows the power supply and annealing process parameters of some cold-rolled low-carbon steel strip transverse magnetic field induction heating production lines.

Table 9-3 Steel strip transverse magnetic field induction heating power supply and annealing process parameters

Power /kw	Power frequency /kHz	Heating steel strip size (thickness X width) /mm	Heating temperature /°c	transfer speed / m, min_ 1	Sensor size (Long X turns)
100	8	(0.20-0.35)X(180-360)	300	30	2mX4
500	10	(0.20-0.35)X(240-360)	320	100	6mX12
1000	1	(0. 20-1. 00) X 100()	200 — 300	<60	4mX8
1500	1	(0.20 〜0.60) X(300 〜800)	800	<120	0.6mX 1
3000	1	(0.20-0.60)X(300-800)	800	<120	0.6mX 2

The 200~ 320°C annealing treatment process listed in Table 9-3 is mainly used to eliminate the strain aging phenomenon of thin steel strips. When the cold-rolled thin steel strip is subjected to rapid continuous annealing treatment, due to insufficient recovery recrystallization annealing time, the resulting annealed structure is not very stable. After being maintained at room temperature, natural aging (ie strain aging) will occur under the action of its internal stress. )Phenomenon. The occurrence of strain aging will reduce the plasticity of the steel strip and increase its brittleness, and in severe cases will cause the steel strip to brittle fracture. In order to reduce the phenomenon of strain aging, a treatment method of 200~ 300°C low temperature annealing and rapid cooling is adopted .