CN102766733A - Grain refinement method of forged steel cold roller - Google Patents

Abstract

The invention discloses a grain refinement method of a forged steel cold roller. The grain refinement method comprises the following steps of: (1) clamping the forged steel cold roller on a quenching machining tool, beginning rapid heat at the heating temperature of 800-950DEG C, conducting air cooling to 200-400DEG C instead of water cooling, returning the roller to an initial position after completion of heating, and enabling an austenite heating layer to complete first structure refinement conversion; and (2) heating for the second time at the heating temperature of 850-1,000DEG C, quenching while heating, completing second structure refinement conversion and forming superfine grain martensitic structures. The grain refinement method changes traditional one-time induction heating into continuous two-time rapid induction heating, continuously conducts two-time structure conversion with high nucleation rate, so that superfine structures with grain size of 11-13 levels can be obtained, further, the structures can be further refined, and the quality of the cold roller can be improved through excellent structures.

Description

The forging steel cold roll crystal fining method

Technical field

The present invention relates to a kind of quenching method of forging steel cold roll, especially a kind of forging steel cold roll is organized the grain refining quenching technology.

Background technology

Along with China's rapid economy development, every profession and trade is increasingly high to the specification of quality of cold rolled metal strip, and cold-rolling mill develops to high roll speed, production process direction increasingly automated, big rolling load.The raising of cold-rolling mill performance; Require cold roll organizing more evenly in use, wear resistance is better, the antistripping ability is stronger; One of technological approaches that can improve these quality index simultaneously is exactly the rank of organizing of further refinement product, improves product and organizes grain fineness number.

Grain refining, crystal boundary increases, because the effect of grain-boundary strengthening can improve wear resistance; And crystal boundary increases and can increase the crack propagation drag, promptly when fatigue cracking occurs, because crystal grain is very thin; Resistance was very big when the inhibition of crystal boundary made crack propagation, and expansion is slow, just machine grinding down before peeling off; Remove crackle, so can reduce pernicious generation of peeling off accident.

Grain size number and rate of heating have much relations, and rate of heating is high more, and nucleation rate is high more, and crystal grain is thin more; Induction heating speed is very fast, and technology rationally can reach very high grain fineness number, generally at 8 to 9 grades, therefore how to select induction heating technology to become the important method that improves the cold roll performance.

Summary of the invention

The technical problem that the present invention will solve provides a kind of forging steel cold roll crystal fining method of effectively refinement forging steel cold roll crystal grain.

For solving the problems of the technologies described above, the technical scheme that the present invention taked is: a kind of forging steel cold roll crystal fining method, and its key is: said method comprising the steps of:

1) with the forging steel cold roll clamping on quenching machine, the beginning rapid heating, Heating temperature is 800～950 ℃; Do not carry out water-cooled; Heating is accomplished forging steel cold roll and is returned zero position, air cooling to 200 ℃～400 ℃, and structure refinement changes to make the austenite zone of heating accomplish for the first time;

2) carry out the heating second time: Heating temperature 850-1000 ℃, structure refinement transformation is for the second time accomplished in limit heating edge spray quenching, and the acquisition grain fineness number is 11 grades～13 grades a ultra-fine brilliant martensitic stucture.

Adopt the beneficial effect that technique scheme produced to be: the present invention changes into double quick induction heating by a traditional induction heating; Carry out the structural transformation of twice high nucleation rate continuously; Can obtain the super fine organization that grain fineness number reaches 11 grades～13 grades; Make structure refinement, good tissue has guaranteed the raising of cold roll quality.

Embodiment

Below in conjunction with embodiment the present invention is done further detailed explanation.

During heating, cold roll is installed on the quenching machine, beginning is rapid heating for the first time; Only heating is not sprayed water, and heating is accomplished, roll return to primitive age position; The air cooling appropriate time; Thinning microstructure changes to make the austenite zone of heating accomplish for the first time, and air cooling carries out second time again and heats during to 200 ℃～400 ℃ of preheating temperature scopes; Heating for the second time is the same with normal induction quenching mode, and heating edge water spray in limit carries out quench cooled, realizes obtaining when thinning microstructure changes for the second time the depth of hardening zone and the hardness of technical requirements.

Because in theory, owing to adopted rapid heating twice, through twice rapid phase transition recrystallization, nucleation rate is higher in final induction quenching process for cold roll, and rate of heating is shorter relatively, and crystal grain has little time to grow up, and can obtain small grains.

Embodiment 1:

Be the cold roll that A factory produces, material 9Cr2Mo, roll diameter ￠ 380mm requires hardness of roll body 90HSD～96HSD, quench-hardened case>=13mm, uniformity of hardness≤3HSD.

Cold roll is installed on the quenching machine, begins to carry out the heat refining first time, heating-up temperature is set 830 ℃; Only heating is not sprayed water, and heating is accomplished, cold roll return to primitive age position; When air cooling appropriate time, cold roll temperature drop to 220 ℃ of left and right sides, carry out the heating second time again; For the second time heating setpoint is 870 ℃, and heating edge water spray in limit carries out quench cooled, quench finish after, after testing, grain size number 11-12 level has reached the effect of ultra-fine crystalline substance.

This cold roll is 92HSD～94HSD through detecting its hardness, uniformity of hardness≤3HSD, and use to scrapping diameter through the user, its quench-hardened case is 13～15mm.

Embodiment 2:

Be a collection of cold roll that B factory produces, material MC3 (Cr3 class), roll diameter ￠ 460mm requires hardness of roll body 92HSD～95HSD, quench-hardened case>=20mm, uniformity of hardness≤3HSD.

Cold roll is installed on the lathe, begins to carry out the heat refining first time, and heating-up temperature is set 870 ℃; Only heating is not sprayed water, and heating is accomplished, cold roll return to primitive age position; When air cooling appropriate time, cold roll temperature drop to 260 ℃ of left and right sides, carry out the heating second time again; For the second time heating setpoint is 910 ℃, and heating edge water spray in limit carries out quench cooled, quench finish after, after testing, grain size number 12-13 level has reached the effect of ultra-fine crystalline substance.

This batch of cold roll is 93HSD～95HSD through detecting its hardness, uniformity of hardness≤3HSD, and use to scrapping diameter through the user, its quench-hardened case is 20～23mm.

Embodiment 3:

Be a collection of cold roll that C factory produces, material MC5, roll diameter ￠ 600mm requires hardness of roll body 92HSD～96HSD, quench-hardened case>=30mm, uniformity of hardness≤3HSD.

Cold roll is installed on the quenching machine, begins to carry out the heat refining first time, heating-up temperature is set 910 ℃; Only heating is not sprayed water, and heating is accomplished, cold roll return to primitive age position; When air cooling appropriate time, cold roll temperature drop to 300 ℃ of left and right sides, carry out the heating second time again; For the second time heating setpoint is 950 ℃, and heating edge water spray in limit carries out quench cooled, quench finish after, after testing, grain size number 12-13 level has reached the effect of ultra-fine crystalline substance.

Cold roll is 92HSD～94HSD through detecting its hardness, uniformity of hardness≤3HSD, and use to scrapping diameter through the user, its quench-hardened case is 30～33mm.

In sum, we prove that through a large amount of production tests the cold roll of producing through the inventive method can both reach the effect of grain refining, and this is consistent with theoretical analysis also.

Claims (1)

1. forging steel cold roll crystal fining method is characterized in that: said method comprising the steps of:

1) with the forging steel cold roll clamping on quenching machine, the beginning rapid heating, Heating temperature is 800～950 ℃; Do not carry out water-cooled; Heating is accomplished forging steel cold roll and is returned zero position, air cooling to 200 ℃～400 ℃, and structure refinement changes to make the austenite zone of heating accomplish for the first time;

2) carry out the heating second time: Heating temperature 850-1000 ℃, structure refinement transformation is for the second time accomplished in limit heating edge spray quenching, and the acquisition grain fineness number is 11 grades～13 grades a ultra-fine brilliant martensitic stucture.