CN104264055B - A kind of Cold Work Roll Material and heat treatment method thereof - Google Patents

Abstract

A kind of Cold Work Roll Material and heat treatment method thereof, it is adaptable to hardness requirement is the cold roll of 58～60HRC, it is therefore an objective to possess excellent anti-accident, fatigue resistance and wearability, hardness height；Cold roll composition of the present invention is C:0.55～0.80% by weight percentage, Si:0.60～1.20%, Mn:0.20～0.50%, Cr:7.5～8.5%, Mo:1.1～1.5%, V:0.2～0.6%, Nb:0.03～0.10%, N:0.03-0.08%, P :≤0.020%, S≤0.005%.Remaining is Fe% and inevitable impurity.The heat treatment method of roll of the present invention is to use " high temperature quenching+high tempering " pretreating process and " high temperature grading quenching+high temperature is repeatedly tempered " Technology for Heating Processing.The present invention at utmost improves roller substrate alloy solid solution degree and structure stability, eliminates the structural stress of roll, thermal stress, makes roll possess excellent anti-accident, fatigue resistance, wearability.

Description

A kind of Cold Work Roll Material and heat treatment method thereof

Technical field

The present invention relates to cold roll field, specifically a kind of Cold Work Roll Material and heat treatment method thereof.

Background technology

The service life of roll and roll material, roll quality, roll working service technology relevant.The seventies, Japan have come to uses the MC3 steel cold roll that main body chromium content is 3%, is effectively improved wearability and the service life of roll.The eighties, the developed country such as Japanese, German employs again the middle chromium and high chromium cold roll that main body chromium content is 5%～10% on Large Scale Cold milling train, HC milling train and sendzimir mill, makes roll campaign improve 1～2 times.China starts to research and develop Cr5 type roll material from the nineties, is widely used to all kinds of cold roll at present, and the key index such as the fatigue resistance of cold roll, anti-accident, wearability has a more substantial increase.For raising cold roll service life further, reduction cold-rolled products production cost, need innovation roll material and preparation technology further.

Summary of the invention

The technical problem to be solved is: how to provide a kind of cold roll so that it is have higher anti-fatigue performance and service life.

The technical solution adopted in the present invention is: a kind of Cold Work Roll Material and heat treatment method thereof, and this Cold Work Roll Material is according to mass percent, C:0.55%～0.80%, Si:0.60%～1.20%, Mn:0.20%～0.50%, Cr:7.5%～8.5%, Mo:1.1%～1.5%, V:0.2%～0.6%, Nb:0.03%～0.10%, N:0.03%-0.08%, P :≤0.020%, S≤0.005%, remaining is Fe and inevitable impurity；This alloying component wearability is good, and quenching degree is strong, has post-curing phenomenon and high temper resistance, structure stability.This Cold Work Roll Material carries out following heat treatment:

Step one, Cold Work Roll Material pretreatment, this Cold Work Roll Material before mechanical machining, is first placed in the temperature environment of 550 DEG C preheating, and places into and preheats under 850 DEG C of environment, use 1060 DEG C～1150 DEG C of high temperature quenchings again, after oil is as cold as 100 DEG C, then uses 720 DEG C～780 DEG C and carry out high tempering, air cooling after being down to 500 DEG C with stove, pretreatment completes, by being machined into cold roll；

Step 2, cold roll heat treatment, after cold roll machines, first roll heating is put in the temperature environment of 550 DEG C and preheat, it is then placed under 850 DEG C of environment preheating, place into 1030～1100 DEG C of environment preheating insulations, then 200-350 DEG C of grade quench, finally proceed to cold roll the nitrate furnace of 530～580 DEG C is tempered 3-4 time, roll be tempered every time after air cooling to 50 DEG C, turning tempering next time, use oil cold after last tempering, last cold roll is put in 203 DEG C of oil ovens and is carried out air cooling after qualitative tempering.

The invention has the beneficial effects as follows: the present invention is applicable to the cold roll that hardness requirement is 56～60HRC.On the premise of ensureing that roll hardness requires, the present invention at utmost improves roller substrate alloy solid solution degree and structure stability, eliminate the structural stress of roll, thermal stress, make roll possess excellent anti-accident, fatigue resistance, wearability, thus meet the use requirement of milling train.Cold roll of the present invention has carried out batch on 20 roller mills and has used, and in use shows excellent anti-accident, and anti-fatigue performance, roll consumption is greatly reduced.

Detailed description of the invention

The composition of the cold roll of the present invention is by mass percentage by following elementary composition, C:0.55～0.80%, Si:0.60～1.20%, Mn:0.20～0.50%, Cr:7.5～8.5%, Mo:1.1～1.5%, V:0.2～0.6%, Nb:0.03～0.10%, N:0.03-0.08%, P :≤0.020%, S≤0.005%, remaining is Fe% and inevitable impurity.

Relevant alloys producing in the present invention, is described below:

C: 0.55～0.80%, carbon mainly determines intensity, hardness after steel heat treatment, and according to calculating and test, carbon content 0.55～0.80% of the present invention is the most suitable.

Si:0.60 1.20%: element silicon, in addition to can improving the quenching degree of steel, also can strengthen matrix, improves steel belt roof bolt stability and thermal shock drag, and Si content controls 0.8～1.20%.

Mn:0.20～0.50%, manganese is deoxidizing alloying elements.

Cr:7.5 8.5%, on the one hand chromium is combined formation M with carbon₇C₃Type carbide, it is thus achieved that the Carbide Phases of a number of high rigidity, is greatly enhanced wearability and the macrohardness of roll, and the chromium being on the other hand solidly soluted in austenite can significantly improve the quenching degree of steel, increases depth of hardening zone., roll Cr content desired value is 7.5%～8.5%.

Mo:1.1～1.5%, molybdenum element forms carbide when tempering and dissolves in cementite, prevents crystal grain to grow up, has dispersion-strengthened action, can be effectively improved temper resistance, wearability and suppression temper brittleness, it is the most beneficial to improving the hardness of steel, intensity, yield strength and impact flexibility.For making designed steel grade have post-curing phenomenon and high temper resistance, steel adds 1.10～1.50%Mo.

V:0.2～0.6%, vanadium is strong carbide element, exists with the independent thin particle of VC, VN form, is suitably added V, it is possible to obtain preferably structure stability, tiny crystal grain and the proeutectoid carbide of high rigidity Dispersed precipitate, can improve hardness and the wearability of roll.The V of 0.2 0.6% is added in steel.

Nb:0.03～0.10%, niobium is a kind of strong carbon, nitride forming element, and the affinity of niobium and carbon, nitrogen is more than vanadium, it is higher that this carbonitride containing niobium forms temperature, can exist in high-temperature molten steel, and its lattice paprmeter is close with austenite, can be as the crystallization nuclei of austenite.The niobium adding trace can be with thinning solidification structure, and additionally separating out niobium carbide in heat treatment process is typically small and dispersed distribution, beneficially dispersion-strengtherning, and high temperature austenite can be stoped to grow up.Nb (w) desired value is 0.08%～0.10%.

N:0.04-0.08%, the addition of nitrogen can be played the precipitation strength having the carboritride strengthening solution strengthening and formation high stability concurrently, can delay the effect that M23C6 silicon carbide thing separates out, hence it is evident that improve its heat resistance and wearability.The span of control of N is 0.03-0.08%.

This Cold Work Roll Material carries out following heat treatment:

Step one, Cold Work Roll Material pretreatment, this Cold Work Roll Material before mechanical machining, is first placed in the temperature environment of 550 DEG C preheating, and places into and preheats under 850 DEG C of environment, use 1060 DEG C～1150 DEG C of high temperature quenchings again, after oil is as cold as 100 DEG C, then uses 720 DEG C～780 DEG C and carry out high tempering, air cooling after being down to 500 DEG C with stove, pretreatment completes, by being machined into cold roll；This step eliminates structural heterogenity caused when ingot casting and forging, improves form and the distribution characteristics thereof of carbide, and the original structure carrying out necessity for finished heat treatment prepares.Its principle is to dissolve carbide under the condition of high temperature to greatest extent, makes carbide bulky grain dissolve and diminishes, and little granule all dissolves, all sharp wedge angles whole melt into fillet, and the most molten carbide quantity tails off, and granularity reaches unanimity.Rapid cooling suppression proeutectoid carbide is that chain separates out in crystal boundary；During high tempering, carbide even dispersion separates out.By using this technique can reduce finished product heat treatment process roll deformation degree and cracking risk.

Step 2, cold roll heat treatment, after cold roll machines, first roll heating is put in the temperature environment of 550 DEG C and preheat, it is then placed under 850 DEG C of environment preheating, place into 1030～1100 DEG C of environment preheating insulations, then 200-350 DEG C of grade quench, finally proceed to cold roll the nitrate furnace of 530～580 DEG C is tempered 3-4 time, roll be tempered every time after air cooling to 50 DEG C, turning tempering next time, use oil cold after last tempering, last cold roll is put in 203 DEG C of oil ovens and is carried out air cooling after qualitative tempering.Use high temperature quenching purpose to be to be dissolved in by many alloying element carbides as far as possible matrix, improve the alloy degree in matrix, thus improve roll temper resistance；High tempering purpose is the Cr that drawing process diffusion-precipitation is distributed, and Mo, V, Nb carbide particle is to strengthen the wearability of roll；After high tempering, roll structure stability is high, and residual austenite content controls below 3%, it is to avoid the roll cracking phenomena caused because of Transformation of Retained Austenite during work roll cooling, by qualitative tempering, it is possible to ensure the stability of material.

Embodiment 1

The alloy material of the following one-tenth of synthesis:

C:0.65%, Si:0.92%, Mn:0.40%, Cr:8.0%, Mo:1.2%, V:0.3%, Nb:0.08%, N:0.53%, P::0.015%, S:0.001%, remaining is Fe% and inevitable impurity.

Carry out following heat treatment before mechanical machining:

Pretreatment completes, and by being machined into φ 102 × 1624mm specification one intermediate calender rolls 30, carries out following heat treatment after machining:

Roll quality and service condition:

Title	Hardness (HRC)	Uniformity of hardness (Hs)	Depth of hardening zone (mm)	Use roller consumption (kg/t steel)
					Standard-required	56～60	≤3	≥15	0.16
Actual effect	58～59	≤2.3	Through hardening	0.10

Claims (1)

1. the heat treatment method of a Cold Work Roll Material, it is characterised in that: this Cold Work Roll Material is according to mass percent, C:0.55%～0.80%, Si:0.60%～1.20%, Mn:0.20%～0.50%, Cr:7.5%～8.5%, Mo:1.1%～1.5%, V:0.2%～0.6%, Nb:0.03%～0.10%, N:0.03%-0.08%, P :≤0.020%, S≤0.005%, remaining is Fe and inevitable impurity；

This Cold Work Roll Material carries out following heat treatment:

Step one, Cold Work Roll Material pretreatment, this Cold Work Roll Material before mechanical machining, is first placed in the temperature environment of 550 DEG C preheating, and places into and preheats under 850 DEG C of environment, use 1060 DEG C～1150 DEG C of high temperature quenchings again, after oil is as cold as 100 DEG C, then uses 720 DEG C～780 DEG C and carry out high tempering, air cooling after being down to 500 DEG C with stove, pretreatment completes, by being machined into cold roll；

Step 2, cold roll heat treatment, after cold roll machines, first roll heating is put in the temperature environment of 550 DEG C and preheat, it is then placed under 850 DEG C of environment preheating, place into 1030～1100 DEG C of environment preheating insulations, then 200-350 DEG C of grade quench, finally proceed to cold roll the nitrate furnace of 530～580 DEG C is tempered 3-4 time, roll be tempered every time after air cooling to 50 DEG C, turning tempering next time, use oil cold after last tempering, last cold roll is put in 203 DEG C of oil ovens and is carried out air cooling after qualitative tempering.