CN102744528A - Flux-cored wire, method for manufacturing coil box bending roller, and coil box bending roller - Google Patents

Abstract

The invention discloses a coil box bending roller and a manufacturing method thereof. The manufacturing method includes manufacturing a roller core; overlaying a priming coat on the outer surface of a working section of the roller core; overlaying a working layer on the priming coat; and performing stress relief annealing on the coil box bending roller. A flux-cored wire used by the overlaid working layer comprises, by weight percentage, 0.16-0.6% of C, 0.5-1.1% of Mn, 0.5-1.9% of Si, 13.5-28.0% of Cr, 2-6% of V, 2-10% of Ni, 1-8% of Mo, 0.05-0.5 of Nb, 0.05-0.5% of Ti, 0.5-3% of W, 1-6% of Al, 0.02-0.5% of RE, 0-0.03% of S, 0-0.03% of P and balance Fe. By means of the technical scheme, an overlaying layer containing Cr, Al, Si, rear-earth elements and the like can be formed on the surface of the coil box bending roller so as to improve abrasion resistance and oxidation resistance of the surface of the coil box bending roller.

Description

Flux-cored welding wire, method for manufacturing hot coil box bending roll, and hot coil box bending roll

technical field

The present invention relates to hot rolling equipment, in particular to a flux-cored wire, a method for making a hot-coil box bending roll by using the flux-cored wire, and a hot-coil box bending roll manufactured by the method.

Background technique

The hot coil box bending roll is an important part of the hot-rolled plate production line. It is used to curl the rough-rolled plate into a coil, so that the coiled plate is transported to the finishing rolling equipment, and then unfolded and finished rolling by the finishing rolling equipment. In the prior art, stainless steel or low-carbon low-alloy steel solder with a hardness of about HRC35 is usually used to surfacing the surface of the bending roller to maintain certain wear resistance and heat resistance. However, since the strip is not curled at an angle completely parallel to the roll surface of the bending roll in the process of curling the strip into a roll, but is rolled in a slightly convex shape, the width direction of the strip When both sides contact with the bending roller, it is not 180°, but less than 180°. Therefore, the two sides of the strip have a slight cutting effect on the bending roller, especially when the two sides of the strip are in contact with the bending roller, it is easy to roughen the surface of the roller, that is, the metal of the bending roller sticks to the strip, resulting in sticky meat Phenomenon. In addition, when rolling a high-strength steel strip, because the physical properties of this steel strip are close to those of the surfacing material on the surface of the bending roll, it is easier to stick to the meat. Meat sticking not only affects the surface quality of the crimped strip, but also reduces the service life of the bending rolls due to the loss of heat-resistant, wear-resistant surfacing.

Contents of the invention

The object of the present invention is to provide a method for making a hot coil box bending roll and a hot coil box bending roll that can reduce sticking and improve the service life and the surface quality of the strip.

In order to achieve the above object, the present invention provides a flux-cored welding wire, the composition of the flux-cored wire is 0.16-0.6% C, 0.5-1.1% Mn, 0.5-1.9% Si, 13.5-28.0% Cr, 2- 6%V, 2～10%Ni, 1～8%Mo, 0.05～0.5%Nb, 0.05～0.5%Ti, 0.5～3%W, 1～6%Al, 0.02～0.5%RE, 0～0.03 %S, 0-0.03%P, and the balance is Fe.

In addition, the present invention also provides a method for manufacturing a bending roll of a hot coil box, the method comprising: step (a): making a roll core; step (b): surfacing and laying a bottom layer on the outer surface of the working section of the roll core ; Step (c): On the said backing layer, surfacing the working layer to obtain the bending roll of the hot coil box, wherein the flux-cored welding wire used for the surfacing of the working layer is the flux-cored welding wire of the present invention; Step (d): for all Stress-relief annealing is carried out on the bending roll of the hot coil box.

Preferably, in step (a), the roll core is made by forging any one of 40Cr, 40CrMo, 40CrV, 40CrMn, 40CrNi, 30CrMo and 35CrMo.

Preferably, in the step (b), the welding wire used for surfacing the primer layer is any one of H08, H08A and H08Mn ₂ Si.

Preferably, the thickness of the primer layer is 2-4mm.

Preferably, in step (d), the annealing temperature is 550-600° C., and the annealing time is 5-8 hours.

Preferably, in step (c), the thickness of the surfacing layer is 5-8mm.

The present invention also provides a thermal coil bending roll manufactured by the method for manufacturing a thermal coil bending roll.

Through the above technical scheme, a surfacing layer containing Cr, Al, Si, rare earth elements and other components can be formed on the surface of the bending roll of the hot coil box, thereby improving the surface wear resistance and oxidation resistance of the bending roll of the hot coil box. The performance is to improve the service life of the bending roller of the hot coil box. specifically:

Chromium is an extremely important alloying element in the heat-resistant steel used to make the bending roll of the hot coil box, and can form a dense Cr ₂ O ₃ film on the surface of the steel. The Cr ₂ O ₃ film can prevent the diffusion of corrosive gases such as oxygen, sulfur and nitrogen into the steel to a certain extent, and can also prevent the outward diffusion of metal atoms, and can also form a layer of good protection in a certain temperature range. Composite protective film of spinel type. By forming a layer of NiO-Cr ₂ O ₃ composite oxide film on the surface of heat-resistant steel containing nickel and chromium, the high-temperature oxidation resistance of the steel can be enhanced. The high-temperature oxidation resistance of heat-resistant steel has a certain relationship with its chromium content. When the chromium content reaches 12% (the following are weight percentages), the high-temperature oxidation resistance of heat-resistant steel has been significantly improved; when the chromium content reaches When it is about 22%, the high-temperature oxidation resistance of the heat-resistant steel is extremely good at 1000°C, and a continuous and dense oxide film is formed on the surface of the heat-resistant steel at this time. Therefore, in the method of the present invention, the chromium content of the flux-cored welding wire forming the surfacing layer is not less than 12%.

Aluminum is also an important alloying element for oxidation resistance in heat-resistant steel, and it is more economical. Aluminum can form a protective Al ₂ O ₃ film on the steel surface, and its oxidation resistance is better than that of Cr ₂ O ₃ film. When the Al content reaches 6%, the steel can have good high temperature oxidation resistance at 980°C; but when the Al content reaches 8%, the toughness and weldability of the steel will be significantly reduced. Therefore, in the method of the present invention, the flux-cored welding wire forming the surfacing layer contains no more than 6% Al.

Silicon can form a protective and dense Si ₂ O film on the steel surface. Generally, when the silicon content in the steel is about 1%, the high temperature oxidation resistance of the steel can be significantly improved. In addition, the effect of improving high temperature oxidation resistance when silicon and aluminum are co-alloyed is better than that of silicon and aluminum alone.

In addition, rare earths have a significant effect on improving the high temperature oxidation resistance of steel. The reasons are: (1) rare earth elements can increase the adhesion between the base metal and the oxide film, because rare earth oxides have a "pinning" effect on the base metal ; (2) Rare earth elements can increase the diffusion of chromium in steel and help to form Cr ₂ O ₃ oxide film on the surface of steel.

In addition, Ti, V, and Nb all have strong grain refinement and solid solution strengthening capabilities, and the effect of adding more than two elements is better than adding one alone. Among them, the effect of adding Ti and Al to refine the grain is stronger than that of Ti alone; V and Nb also have strong precipitation strengthening ability, and they, Mo and W are strong carbide-forming elements, and the high-temperature stability of these carbides Better, so that the surfacing layer metal has small grain size, high hardness, high temperature wear resistance and good toughness.

In addition, vanadium can form highly wear-resistant carbide VC (HV is about 2600), and its hardness is much higher than that of Cr ₇ C ₃ carbide. In addition, VC is approximately spherical, which is conducive to highly dispersed distribution, which not only reduces the possibility of carbide being scratched and crushed, but also protects the base metal and improves the wear resistance of the material.

Other features and advantages of the present invention will be described in detail in the following detailed description.

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

The weight percent of the composition of the flux cored welding wire of the present invention is 0.16～0.6%C, 0.5～1.1%Mn, 0.5～1.9%Si, 13.5～28.0%Cr, 2～6%V, 2～10%Ni, 1～ 8% Mo, 0.05-0.5% Nb, 0.05-0.5% Ti, 0.5-3% W, 1-6% Al, 0.02-0.5% RE, 0-0.03% S, 0-0.03% P, the balance is Fe .

Wherein, the flux-cored wire can be processed in an appropriate manner, for example, by mixing iron alloy powders such as ferromanganese, ferrosilicon, ferrochrome, ferrovanadium, ferromolybdenum, and iron powder in a certain weight ratio to form a mixture of required components, and then Pack the mixture evenly and tightly in the tubular welding wire (usually tubular steel skin), and draw it to a specified diameter. The above processing methods are known to those skilled in the art, and will not be described in detail here. It should be understood that a flux cored wire of a given composition can be self-prepared in the manner described above.

The method for making the bending roll of the hot coil box of the present invention comprises:

Step (a): Making a roll core; Step (b): Surfacing a primer layer on the outer surface of the working section of the roller core; Step (c): Surfacing a working layer on the primer layer to obtain a hot coil box The bending roll, wherein the flux-cored wire used for surfacing the working layer is the flux-cored wire of the present invention; step (d): performing stress relief annealing on the bending roll of the hot coil box.

As mentioned above, by overlaying the surfacing layer containing the above ingredients on the surface of the bending roll of the hot coil box, good wear resistance and oxidation resistance can be provided on the surface of the bending roll of the hot coil box, so that damage caused by high temperature and friction can be avoided. sticky meat.

Wherein, various appropriate materials can be used to make the roll core in various appropriate ways. Preferably, in step (a), the roll core can be made by forging any one of 40Cr, 40CrMo, 40CrV, 40CrMn, 40CrNi, 30CrMo and 35CrMo.

The function of the primer layer is to form a transition between the base metal and the working layer, and to dilute the elements in the base metal that affect the welding effect. Preferably, in step (b), the composition of the welding wire used for surfacing the primer layer is any one of H08, H08A and H08Mn ₂ Si. More preferably, the thickness of the primer layer is 2-4 mm.

In addition, preferably, in step (d), the annealing temperature is 550-600° C., and the annealing time is 5-8 hours, so as to eliminate the residual stress formed by the surfacing welding inside the bending roll of the hot coil box.

In addition, surfacing layers of different thicknesses can be formed on the working section of the surface of the roller core to meet the corresponding use requirements (ie wear strength). Preferably, in step (c), the thickness of the surfacing layer is 5-8 mm.

In addition, the present invention also provides a thermal coil bending roll manufactured by the method for manufacturing a thermal coil bending roll of the present invention. The method of the present invention is illustrated below by specific examples.

Example 1

40Cr steel is used to forge the roller core with a total length of 3450mm, the length of the working section is 1450mm, the diameter of the working section is 400mm, and the remaining length at both ends of the working section is the transition section. Among them, the composition of 40Cr steel is shown in Table 1.

Table 1

A primer layer with a thickness of 4mm is formed on the surface of the working section of the roller core by automatic submerged arc welding. Wherein, the welding wire used for the bottom layer is H08A with a diameter of 4mm (purchased from Shenzhen Xiongxing Metal Material Co., Ltd.), the flux is SSF flux produced by Shanghai Stellite Company, the preheating temperature is 250 ° C, and the interlayer temperature is 280°C, the current intensity is 360A, the voltage is 28V, and the welding speed is 0.5m/min (the welding speed in this article refers to the welding speed along the axial direction of the roller core).

A flux-cored wire with a diameter of 4 mm is used to form a surfacing layer with a thickness of 5 mm on the primer layer by submerged arc automatic welding to form a hot coil box bending roll. Among them, the composition of the flux-cored wire used in surfacing welding is: 0.16C, 0.5% Mn, 0.5% Si, 13.5% Cr, 2% V, 2% Ni, 1% Mo, 0.05% N b, 0.05% Ti, 0.5 %W, 1%Al, 0.02%RE, the balance is Fe, and the sum of the weight percentages is 100%; the SSD flux produced by Shanghai Stellite Company is used for surfacing, the interlayer temperature is 330°C, the current intensity is 430A, and the voltage It is 32V, and the welding speed is 0.5m/min.

After the surfacing is completed, the bending roll of the hot coil box is put into the heating furnace for stress relief annealing. Among them, the bending roll of the hot coil box was heat-treated at 550° C. for 8 hours, and then cooled to room temperature with the furnace.

Example 2

The method of Example 1 was used to manufacture hot coil box bending rolls. Among them, a base layer with a thickness of 3mm and a surfacing layer with a thickness of 7mm are formed on the surface of the working section of the roller core by submerged arc automatic welding to form a hot coil box bending roller. Use H08 welding wire with a diameter of 4mm (purchased from Shenzhen Xiongxing Metal Material Co., Ltd.) for backing welding. The preheating temperature is 250°C, the interlayer temperature is 300°C, the current intensity is 360A, and the voltage is 20V; The composition of the flux cored wire used is: 0.4%C, 0.8%Mn, 1.5%Si, 19.0%Cr, 4.5%V, 6%Ni, 5%Mo, 0.3%Nb, 0.2%Ti, 2%W, 4 %Al, 0.3%RE, 0.01%S, 0.02%P, the balance is Fe, and the sum of weight percentages is 100%; the interlayer temperature of surfacing welding is 350°C, the current intensity is 430A, the voltage is 33V, and the welding speed is 0.5 m/min.

Example 3

The method of Example 1 was used to manufacture hot coil box bending rolls. Among them, a base layer with a thickness of 2mm and a surfacing layer with a thickness of 8mm are formed on the surface of the working section of the roller core by submerged arc automatic welding to form a hot coil box bending roller. H08Mn ₂ Si welding wire with a diameter of 4mm (purchased from Shenzhen Xiongxing Metal Materials Co., Ltd.) was used for backing welding, the preheating temperature was 250°C, the interlayer temperature was 280°C, the current intensity was 360A, and the voltage was 32V; The composition of the flux-cored wire used in the working layer is: 0.6%C, 1.1%Mn, 1.9%Si, 28.0%Cr, 6%V, 10%Ni, 8%Mo, 0.5%Nb, 0.5%Ti, 3%W , 6% Al, 0.5% RE, 0.03% S, 0.03% P, the balance is Fe, and the sum of the weight percentages is 100%; the interlayer temperature of surfacing welding is 360°C, the current intensity is 430A, and the voltage is 34V. Speed 0.5m/min.

Example 4

The method of Example 1 was used to manufacture hot coil box bending rolls. Among them, after surfacing the working layer, put the bending roll of the hot coil box into the heating furnace for stress relief annealing. Among them, the bending roll of the hot coil box was heat-treated at 580° C. for 6 hours, and then cooled to room temperature with the furnace.

Example 5

The method of Example 1 was used to manufacture hot coil box bending rolls. Among them, after surfacing the working layer, put the bending roll of the hot coil box into the heating furnace for stress relief annealing. Among them, the bending roll of the hot coil box was heat-treated at 600° C. for 5 hours, and then cooled to room temperature with the furnace.

Example 6-11

The method of Example 1 was used to manufacture hot coil box bending rolls. Among them, 40CrMo, 40CrV, 40CrMn, 40CrNi, 30CrMo and 35CrMo steel forging roll cores are used respectively, and the composition of 40CrMo, 40CrV, 40CrMn, 40CrNi, 30CrMo and 35CrMo steel is shown in Table 2-7.

Table 2

table 3

Table 4

table 5

Table 6

Table 7

comparative example

The method of Example 1 was used to manufacture hot coil box bending rolls. Among them, the welding wire used in the surfacing working layer is Stoody107 welding wire produced by Shanghai Stellite Co., Ltd., and the weight percentage of the deposited metal composition is: 0.2%C, 1.5%Mn, 0.6%Si, 2.5%Cr, 0.3%Mo , 0.03% S, 0.03% P, the balance being Fe, and the sum of the weight percentages is 100%.

Table 8 shows the surface hardness (surface hardness at the time of completion) and service life of the hot coil box bending rollers made by the methods of Examples 1-11 of the present invention and comparative examples. The service time of the roll when the surfacing layer falls off by 2mm.

Table 8

serial number Hardness (HRC) life expectancy Example 1 55 more than a year Example 2 57 more than a year Example 3 59 more than a year Example 4 55 more than a year Example 5 55 more than a year Example 6 55 more than a year Example 7 55 more than a year Example 8 55 more than a year Example 9 55 more than a year Example 10 55 more than a year Example 11 55 more than a year comparative example 36 3 months

It can be seen from Table 8 that the method of the present invention for making the bending roll of the hot coil box significantly improves the service life and wear resistance of the bending roll of the hot coil box.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific implementation manners may be combined in any suitable manner if there is no contradiction. In order to avoid unnecessary repetition, various possible combinations are not further described in the present invention.

In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (8)

1. flux-cored wire; It is characterized in that the percentage by weight of the composition of this flux-cored wire is that 0.16～0.6%C, 0.5～1.1%Mn, 0.5～1.9%Si, 13.5～28.0%Cr, 2～6%V, 2～10%Ni, 1～8%Mo, 0.05～0.5%Nb, 0.05～0.5%Ti, 0.5～3%W, 1～6%Al, 0.02～0.5%RE, 0～0.03%S, 0～0.03%P, surplus are Fe.

2. method of making bending roll of heat coil box, this method comprises:

Step (a): make roller core;

Step (b): built-up welding prime coat on the outer surface of the active section of said roller core;

Step (c): the built-up welding working lining is to obtain bending roll of heat coil box on said prime coat, and wherein the flux-cored wire that uses of this working lining of built-up welding is the described flux-cored wire of claim 1;

Step (d): said bending roll of heat coil box is carried out stress relief annealing.

3. the method for making bending roll of heat coil box according to claim 2 wherein, in step (a), is made said roller core through forging among 40Cr, 40CrMo, 40CrV, 40CrMn, 40CrNi, 30CrMo and the 35CrMo any one.

4. the method for making bending roll of heat coil box according to claim 2, wherein, in step (b), the welding wire that the said prime coat of built-up welding uses is H08, H08A and H08Mn ₂Among the Si any one.

5. the method for making bending roll of heat coil box according to claim 4, wherein, the thickness of said prime coat is 2～4mm.

6. the method for making bending roll of heat coil box according to claim 2, wherein, in step (d), annealing temperature is 550～600 ℃, annealing time is 5～8h.

7. according to the method for any described making bending roll of heat coil box among the claim 2-6, wherein, in step (c), the thickness of said overlay cladding is 5～8mm.

8. a bending roll of heat coil box is characterized in that, this bending roll of heat coil box is processed by the method for any described making bending roll of heat coil box among the claim 2-7.