DE1508226C - Method of making cast iron hot rolling - Google Patents

Description

The invention relates to a method for producing cast iron hot rolls with 1.7 to 3.8% carbon, 0.4 to 2.5% silicon, less than 1.0% manganese, less than 2.0% chromium, less than 2.0% molybdenum, less than 1.0% vanadium, less than 1.0% tungsten, the remainder iron, with the total

'Existing harmful elements, such as phosphorus, sulfur, copper, tin, arsenic, lead, antimony, bismuth and zinc, less than 0.20%, in particular less than 0.15%. A cast body with a structure similar to white pig iron is brought to 50 ° C below the solidus line and then forged at 900 to 1125 ° C, followed by slow cooling in a known manner in a furnace or in sand, tempering at temperatures between 750 and 850 ° C, quenching in water, quenching in oil or normalization after maintaining the temperature in a range between 850 and 950 ⁰ C, tempering at temperatures between 400 and 700 ° C and between 150 and 250 ° C and machining follows U.S. Patent 1,287,593.

With the main patent a way of producing hot cast iron rolls was recorded, the by far superior to known rollers in terms of their mechanical and physical properties are in that uniformly distributed, fine cementite grains are included in their structure and in in some cases small amounts of graphite deposited by forging would. The hot forming fulfills the task of destroying the because of the selected

. Alloying elements of white pig iron have a similar cast structure, with carbides or graphites being finer Granules are distributed in the base mass. The heat treatment that follows the hot forming gives the cast body an adequate one Abandoned toughness.

In contrast, the present invention is based on the object of adding more suitable substances Alloying elements provide an improvement in the mechanical properties of such hot cast iron rolls and to achieve a finer cast structure. This is possible when the cast iron alloy additionally still less than 5.0% cobalt and / or nickel and / or one or more of the elements Aluminum with less than 1.0%, titanium with less than 0.15%, zirconium with less than 0.30%, boron with less than 0.10%, beryllium less than 0.20%, tellurium less than 0.05% and niobium and Contains tantalum along with less than 0.10%. Regarding the influences of these different alloying elements, the following can be noted:

If nickel and cobalt are added as alloying elements to the cast body, you can use Each of these alloying elements stabilizes the austenite at the temperatures of the non-cutting Deformation of the cast body, because these elements go into a solid solution with the austenitic Basic mass of the structure, so that the hot deformation of the cast body is improved. The alloying elements nickel and cobalt therefore have the property of improving hot deformation to influence and to bring about an improvement in terms of mechanical properties, but it is it should be noted that both of these elements favor a graphite enrichment in the structure of the cast body, it is therefore necessary to add relatively large amounts of such elements, the one Prevent graphite formation; such elements are, for example, manganese and chromium, those mentioned Elements are to be added.

If more than 5% cobalt and nickel are added to the molten metal; then it should be noted that within the permitted amount of graphite formation preventing alloying elements in the cast body a relatively large amount of Graphite is deposited, so that thereby the

ίο hot formability is worsened. The addition the amount of nickel and cobalt should therefore not exceed 5%. Furthermore, it is desirable Add aluminum, titanium, zirconium, boron, beryllium, tellurium, niobium and tantalum in the desired quantities, It should be pointed out that niobium and tantalum usually occur together and one Bring a similar effect, these alloying elements are therefore added to improve the hot workability and to improve the mechanical properties, these elements have the property of being a to achieve a fine primary structure. However, care should be taken to ensure that these elements are only used in one in such an amount as individually specified above, because larger amounts cause deterioration of mechanical properties.

The following tables and drawings show test results in which the mechanical Properties and the microscopic structure achieved through various heat treatments are recorded, taken as samples from the cast iron rolls produced according to the invention became.

The F i g. 1 shows a function of the amount of harmful components contained in the cast body (a temperature graduation is plotted on the abscissa) the number of the Deformability reproducing twisting up to breakage, whereby the individual curves with Numbers are designated, which are listed in detail in Table 1 below; both Samples according to Fig. La was nickel and the Samples according to 1 b contained cobalt.

The F i g. 2 shows the hardness distribution over the cross section of a cast iron roller produced by the method according to the invention, the distance in millimeters from the surface of the cast iron roller on the abscissa and the hardness on the ordinate. The individual values for the curves identified by the reference numerals A, B and C can be found in Table 3.

The F i g. Fig. 3 shows a function of the amount of harmful constituents contained in the cast body (a temperature graduation is plotted on the abscissa) the number of deformability reproducing rotations up to the break, whereby the individual curves with numbers are indicated, which are listed in Table 4 in detail; in the samples according to FIG. 3a was Aluminum, titanium and zirconium and for the samples according to FIG. 3 b was boron, beryllium, tellurium, Contains niobium and tantalum.

The F i g. 4 shows an enlargement of KX): 1 the microscopic structure of the cast body produced according to the invention, in both cases

in the stage after casting, wherein in the sample according to FIG. 4a does not contain aluminum and titanium was, while in the sample according to FIG. 4b aluminum was contained as an alloy element.

5 shows, as a function of the amount of harmful constituents contained in the cast body (a temperature graduation is plotted on the abscissas), the number of twists up to the break, which reflect the deformability, the individual curves being denoted by numbers that are in the table T are listed in detail; the samples according to FIG. 5a contained nickel and cobalt together with aluminum and titanium, according to FIG. 5b nickel and 'cobalt' together with zirconium and boron and according to FIG. 5c nickel and cobalt together with beryllium, tellurium, niobium and tantalum.

The F i g. 6 shows the microscopic structure of the cast body produced according to the invention, which Nickel and cobalt had been added, namely FIG. 6 a in the stage after casting and FIG. 6 b in the stage after the hot working and after the heat treatment.

The F i g. 7 shows the microscopic structure of the cast body produced according to the invention, which Aluminum and titanium had been added.

The F i g. 8 shows the microscopic structure of the cast body produced according to the invention, which both nickel and cobalt and aluminum and titanium had been added at the same time, namely F i g. 8 a in the stage after casting and F i g. 8 b in the stage after the hot forming and after the Heat treatment. -

In the following, experiments will now be described which are carried out in support of the method according to the invention became:

Attempt 1

This experiment was carried out to determine the relationship between the amount of cobalt and nickel as alloy elements and the mechanical properties as well as the hot formability. This test was carried out under the same conditions as the tests according to the main patent, the cast had the following composition here as well: 3.0 to 3.1% carbon, 0.55 to 0.58% silicon, 0.56 to 0.57% manganese, 1.05 to 1.10% chromium and 0.37 to 0.39% molybdah. A 100 kg sample was first melted in a high-frequency furnace and then poured into a block. This cast body was then hot worked by forging and subjected to a heat treatment as specified in the main patent. The forge ratio was 4.1 S, i.e. that is, the cross-section of the cast body was 4.1 times larger than after forging Forging, where S is the forging force defined by JIS. After the sample is on for 40 minutes was maintained at a temperature of 900 "C, a slow air cooling was carried out at an intermediate station Hold at a temperature of 630 ° C for 60 minutes.

In Table 1 below is the chemical Composition of the individual samples recorded:

Table 1
Chemical composition in%

60

sample

No.'

3.15
3.22

Si Mn Cr to to Mon Ni Co 0.63
0.61 0.82.
0.75 0.36
0.35 0.03
0.30

sample
No. C. Si Mn Cr Mon Ni Co U). 3.11 0.59 0.72 0.43 1.50 0.03 4th 3.10 0.53 0.76 0.35 2.70 0.08 5 3.08 0.47 0.73 0.33 3.60 0.10 6th 3.18 0.41 0.79 0.38 4.80 0.13 7th 3.09 0.42 0.70 0.36 0.06 2.30 8th 3.14 0.41 0.77 0.39 0.05 4.50 9 3.15 0.62 0.72 0.35. 2.50 2.32 , 35 , 63 , 75 , 93 , 56 1.88 1.95

The mechanical properties of these samples are recorded in Table 2 below in Fig. 1 of the drawing shows the influence of these alloying elements on hot deformability.

Table 2
• Mechanical properties

sample hardness tensile strenght strain No. (BHN) (kg / mm ² ) <%) 1 331 , 72.1 3.8 2 341 73.0 4.6 3 388 75.2 4.5 4th 401 81.9 3.7 5 415 83.6 3.6 6th 444 85.2 3.2 7th 401 81.5 .3.8 8th 461 84.3 3.4 9 .461 84.0 3.4

From Tables 1 and 2 and from Fig. 1 it can be seen that by adding nickel and cobalt to the remaining alloy elements that are in Main patent mentions found a substantial improvement in mechanical properties and the hot deformability is achievable. However, if nickel and cobalt are used in an amount of more than 5% added, then this adversely affects the mechanical properties and the hot deformability evoked.

Attempt 2

This experiment was carried out to investigate the influence of nickel and cobalt as alloying elements on the Find out the hardness distribution over the cross section of a cast iron roller produced according to the invention. Rolls with a diameter of about 400 mm made by forging were examined had been hot worked, the forging ratio being 4.1 S, these rolls were 8 hours Normally annealed to a temperature of 900 ° C for a long time and then to a temperature for 1 hour tempered at 650 "C. In Table 3 below the chemical composition is recorded and

in Fig. 2 the hardness distribution over the cross-section of rolls A, B and C.

Table 3
Chemical composition in%

sample
No. C. Si Mn Cr Mon Ni Co A.
B.
C. 3.20
3.19
3.25 0.55
0.00
0.58 0.77
0.80
0.79 1.02
1.05
1.95 0.35
0.37
0.39 0.04
1.16
3.71 0.25
0.50

From Table 3 and FIG. 2 it can be seen that when the amount of nickel and cobalt increases, the decrease in hardness, based on the roll surface, decreases and that nickel and cobalt promote hot workability.

Attempt 3

This experiment was carried out to determine the influence of alloying elements such as aluminum, titanium, zirconium, Boron, beryllium, tellurium, niobium and tantalum, on the mechanical properties and hot formability to find out, so samples containing these elements have been compared with such Samples that do not contain these elements. This experiment was carried out similar to experiment 1, the chemical composition of the individual samples is recorded in Table 4 below:

Table 4 Chemical composition in%

sample
No. C. Si Mn Cr Mon Al Ti Zr B. Be Te Nb + Ta 1 3.15 0.63 0.82 0.30 .0,010 0.006 ' . ' ■ 2 3.19 0.58 0.77. 0.33 0.033 0.006 - - - - - ' 3 3.21 0.57 0.81 0.36 0.011 0.060 - -: '; - - - 4th 3.20 0.57 0.82 0.32 0.010 0.005 0.183 - '- - ■ - 5 3.16 0.60 0.79 0.37 0.015 0.005 - ' 0.065. - - - 6th 3.22 0.59 0.85 0.36 0.012 0.006 - 0.121 ; - - 7th 3.09 0.60 0.79 0.38 0.011 0.007 - - - 0.030 - 8th 3.12 0.57 0.80 0.35 0.013 0.006 - ■ - - . .— 0.018 9 3.27 0.56 0.83 0.39 0.028 0.053 - - - - - , 12 , 12 , 08 , 07 , 10 , 10 1.20 , 13 , 15

In Table 5 below are the properties that change as you add each one Elements recorded, the changes in hot formability are shown in FIG. 3 recorded.

Table 5
Mechanical properties

sample hardness tensile strenght strain No. (BHN) (kg mm ² ) do) 1 331 72.1 3.8 2 341 74.2 4.6 3 352 76.4 5.1 4th 352 76.3 5.3 5 331 74.8 5.0 6th 331 74.8 4.6 7th 321 74.0 4.9 8th 341 75.5 4.5 9 352 77.0 5.6

Attempt 4

In this experiment, the microscopic structure in the stage after the casting of such samples, that contain aluminum and titanium compared to samples that do not contain these alloy elements contain. The chemical composition of these samples is given in Table 6 below :

Table 6

Chemical composition Si Mn Cr Mon in 7o. Ti sample
No. C. 0.70
0.62 0.75
0.68 1.10
1.17 0.39
0.34 Al 0.005
0.043 A.
B. 2.82
2.76 0.011
0.020

From Tables 4 and 5 and FIG. 3 it can be seen that with the addition of aluminum, titanium. Zirconium, boron, beryllium, tellurium, niobium and tantalum make a major improvement in terms of that mechanical properties and hot moldability can be achieved.

In FIG. 4a is the microscopic structure of sample A and in FIG. 4b the microscopic structure of sample B. It turns out that the microscopic structure is a cementitic network shows that the pearlitic matrix has penetrated. From Fig. 4b it can be seen that the aluminum and titanium-containing sample shows relatively smaller primary crystals than the sample according to 1 · "i g. 4a, in which no aluminum and titanium were added.

Attempt 5

This experiment was carried out to investigate the influence of the alloying elements nickel and cobalt on the mechanical properties and on the hot formability to find out if these alloy elements Aluminum, titanium, zirconium, boron,

Beryllium, tellurium, niobium and tantalum were added at the same time. Again there were those the same test conditions as in the first test, given the chemical composition of the individual samples is recorded in Table 7 below:. ■

Table 7
Chemical composition in%

sample
No. - C Si ' Mn Cr Mon Ni Co Al Ti Zr B. Be Te Nb + Ta 1 3.15 0.63 0.82 U2 0.36 0.03 - 0.010 0.006 - - -. - ■ - 2 3.10 0.53 0.76 1.63 0.35 2.70 0.08 0.011 0.006 - - - - - 3 3.22 0.54 0.77 1.65 0.32 2.64 0.08 0.028 0.007 - .— - - ' ■ - 4th 3.16 0.57 0.85 , 68 0.34 2.71 ' 0.09 0.011 0.057 - - - - - 5 3.21 0.58 0.81 0.35 2.62 0.08 0.012 0.005 0.191 - - - - 6th 3.16 0.60 0.83 0.35 2.73 0.09 0.011 0.005 - 0.074 - - ■ - 7th 3.23 0.58 0.80 0.28 2.70 0.07 0.013 0.005 - - 0.121 - '- 8th 3.19 0.57 0.80 0.34 2.66 0.07 0.015 0.006 - - ■. - 0.030 - 9 3.17 0.65 0.7.9 0.38 2.68 0.07 0.012 0.007 - '. - - ■ - 0.165 10 3.23 0.62 0.80 0.38 2.74 0.09 0.021 0.055 ..— ■ - . ■ -. . - , 63 , 66 , 72 , 68 , 77 1.65

The changes in the mechanical properties are recorded in Table 8 below, as a function the added amounts of alloying elements. The changes in hot formability are in Fig. 5 recorded. . *

Table 8
Mechanical properties

sample hardness tensile strenght strain No. (BHN) (kg / mm ² ) <%) 1 331 72.1 3.8 2 401 81.9 3.7 3 401 81.9 3.9 4th 415 82.2 3.6 5 401 82.1 3.5 6th 375 80.2 4.4 7th 375 80.6 4.0 8th 388 80.6 4.5 9 388 80.3 4.5 10 415 82; 5 4.0

From Tables 7 and 8 and from FIG. 5 it can be seen that if Aluminum, titanium, zirconium, boron, beryllium, tellurium, niobium and tantalum to the alloy elements Nickel and cobalt significantly improve the mechanical properties and hot formability is achievable.

Trial 6

The following experiments were carried out to determine the change in mechanical properties Heat treatment of samples according to the method of the main patent and the present one Invention. In Table 9 below is the chemical composition of the samples are recorded in Table 10 below and their size in Table 10 below Table showing the mechanical properties and the microscopic structure after the heat treatment:

Table 9
Chemical composition in. "■■"

sample C. Si No. 3.00 0.51 1 2.76 0.62 2 3.05 0.68 3

Mn

0.61 0.68 0.79

Mon

0.29
0.34
0.45

0.009
0.008
0.10

Ni Co 3.94 0.11 0.02 ■ 0.75 0.02

Al

0.015 0.020 0.043

109 608 104

Table 9 (continued ¹ ,

10

"Sample
No. Ti P. S. Cu As Sn Pb Sb Bi Zn 1 0.005 0.009 0.008 ■ 0.010 0.008 0.008 tr. tr. tr. tr. 2 0.043 0.012 0.008 0.021 0.010 0.009 tr. tr. tr. tr. 3 0.035 0.009 0.008 0.021 0.009 0.007 tr. tr. tr. tr.

Table size of the samples

sample
No. diameter length Forging ratio U) K) - 25 mm
25 mm
25 mm 200mm
200 mm
200 mm 2.8 p
3.6 p
4.5 p

Table 11
Mechanical properties and microscopic structure after heat treatment

Heat treatment sample
No. tensile strenght
(kg / mm ² ) strain hardness
(BHN) Microscopic structure A. Tempering at 950 ° C
for 10 hours U) K) - . 60.0
60.3
56.0 5.6
7.2
6.6 U) U) U)
K) K) - eutectic cementite,
Ferrite, extremely fine
distributed graphite B. Hold at 950 ° C
for 40 minutes
Air cooling
Hold at 630 ° C
for 60 minutes
Air cooling
Hold at 180 ^° C
for 60 minutes
Air cooling U) K) - · 81.6
80.6
77.3 3.2
4.2
4.0 415
388
401 eutectic cementite,
sorb. Perlite, extremely fine
distributed graphite C. Hold at 850 ° C
for 40 minutes
oil cooling
Hold at 630 ° C
for 40 minutes
Air cooling
Hold at 180 "C
for 40 minutes
Air cooling U) K) - 95.3
97.8
96.8 3.0
4.3
3.7 401
444
444 eutectic cementite,
Sorbitol, extremely fine
distributed graphite

The hardness of the cast iron roller produced according to the invention can be within certain limits can be freely selected by the heat treatment. In the F i g. 6, 7 and 8 are the microscopic The structure of the above samples is shown, namely FIG. 6 shows an example of the microscopic structure of FIG Sample # 1 (this sample was taken from a cast iron roller to which nickel and cobalt were added had been), namely the Fi g. 6a the structure in the stage after casting and FIG. 6 b that Structure in the stage after heat treatment that

is recorded in Table 11 under B. The F i g. 7th shows the microscopic structure of sample no.2 (this sample was taken from a cast iron roller, which aluminum and titanium had been added), this sample was also the heat treatment B the tables have been subjected. Finally, FIG. 13 shows the microscopic structure of the sample No. 3 (this sample was a cast iron roller taken, which nickel, cobalt, aluminum and titanium · have been added at the same time was), the F i g. 8a shows the structure in the stage

the casting and Fig. 8b the microscopic Structure in the stage after the heat treatment analogous to heat treatment B in Table 11. Es shows that the microscopic structure according to FIGS. 6a and 8a has a dendritic structure, which is formed during casting, in the structure is also cementite C and a pearlitic one Contain mesh structure P that was split during hot working. In FIGS. 6b, 7 and 8 b shows the microscopic structure of finely divided graphite G in the sorbitic perlite matrix P is distributed, the eutectic cementite C is fine-grained.

Cast iron rolls are generally exposed to high bending stresses at relatively high temperatures, and they are also subjected to torsion stress. By repeated heating and Cooling arise. Thermal stresses in the cast body, which lead to fine cracks and finally to a Can lead to fatigue failure. Due to the abrasion between the roll surface and the rolling stock during the The rolling process, the roll surface is subject to constant wear, so that for all these reasons it is desirable to give the roll body sufficient toughness against pressure, shock, temperature and wear to give for the time of rolling. It should be noted that so far this has not succeeded in technology is to meet these conditions at the same time.

It should be noted that the cast iron roller produced by the method of the main patent, their additional alloy elements according to the present invention to improve the mechanical properties and to achieve a finer cast structure serve, almost the same cheihic composition has like the usual cast iron rollers, but that, compared to cast steel rollers, one greater toughness is present. It should also be noted that the cast iron rollers produced according to the invention a much higher wear resistance and a much better resistance have against cracking. The cast iron rollers made according to the invention are therefore particular Can be used where the roller bodies are exposed to high stress and where previously Cast steel rolls were used, which are known to have sufficient toughness is, however, insufficient wear resistance, or where so-called Adamit rolls for Came used that have a sufficiently good wear resistance compared to cast steel rollers and therefore were used wherever large rolling forces had to be exerted. Coming form rollers relatively complicated outline shape used, then these are exposed to increased risk of breakage, this applies in particular to the mentioned cast steel and Adamit rolls, but this risk of breakage is comparative with those manufactured according to the invention Rolls significantly reduced, so that the rolls produced according to the invention have a much longer service life.

In the following, exemplary embodiments are given that were carried out in practice:

At s ρ i e 1 1

a) Type of roller manufactured:

Trio rolling mill for roughing profiles,

b) Roll dimensions:

Diameter of the roller body 680 mm,
Length of the roller body 1800 mm,
Total length of the roller 2760 mm,

c) roller weight: 6590 kg,

d) Outline shape of the cast body:

The cast body would be in an 11 t octagonal metal mold manufactured,

e) Chemical composition in% ^:

see table 12 below.

table

roller
No. C. Si Mn Cr Mon V Ni Co Al Ti .1
2 1.93
1.91 0.64
0.65 0.57
0.83 1.32
1.29 0.26
0.41 0.23
0.008 1.53
2.27 0.03
0.05 0.021
0.019 0.007
0.008

Zr P. ^: s .- Cu As Sn Pb Zn Sb Bi Total
harmful elements 1
2 0.151 0.009
0.009 0.011
0.008 0.028
0.029 0.008
0.007 0.010
0.007 tr.
tr. tr.
• tr. tr.
tr. tr.
tr. 0.066
0.060

f) Hot working temperature and forging ratio: see tables.

Table 13

roller
No. temperature
of hot deformation Forging ratio , ■ - .. 1 ^.:
,, 2. 1090 to 950 "C
.1090 to 950 "C , 2.6 p
2.6 p

60

g) 'Heat treatment:

Hold at 900 "C for 10 hours, air cooling, holding at 68O ⁰ C for 15 hours, air cooling, holding at 200 ⁰ C for 15 hours, air cooling, h) Mechanical properties: s. Table 14.

Table 14

roller
No. train
strength
(kg / mm ¹ ) strain
T / o) A
lacing
<%) Notch
impact
toughness
(kgm / cm ² ) hardness
(BHN) 1
2 93.5
95.0 7.8
7.7 9.2
8.0 0.9
0.9 302
360

i) Total rolling capacity: see table 15.

Table 15

roller
No. Overall performance
(Embarrassment barrel) 1
2 61.110
68,070

IO

k) Comparison between the rolls according to the invention and the known rolls:

In comparison with conventional special cast steel rollers (C: 1.03%, Cr: 0.98%, Mo: 0.30%) had roll no. 1 (this cast iron roll made according to the invention had nickel and Cobalt as alloy elements) has a 3.1 times longer service life, and roller no. 2

(This cast iron roller manufactured according to the invention had nickel and cobalt as alloying elements and zirconium) had a 3.5 times longer service life.

Example 2

a) Type of roller manufactured:

Trio middle mill for rolling steel bars,

b) Dimensions of the rollers:

Diameter of the roller body 330 mm, length of the roller body 1000 mm, Total length of the roller 1570 mm,

c) roller weight: 820kg,

d) Outline shape of the cast body:

The cast body was in a 5 t octagonal metal mold manufactured,

e) Chemical composition in%: see table 16.

table

C. Si Mn Cr Mon V Al Ti P. S. 2.36 OJO 0.64 1.23 0.36 0.12 0.035 0.006 0.012 0.01 i

Cu As Sn Pb Zn Sb Bi Total
harmful elements 0.027 0.010 '0.008 tr. tr. tr. tr. 0.068

Hot working temperature and forging ratio:

1080 to 960 ¹ C, 4.3 S, '

g) heat treatment:

Hold at 900 ⁰ C for 5 hours, air cooling, hold at 680 ¹ C for 8 hours, air cooling, hold at 180 ° C for 5 hours, air cooling,

h) Mechanical properties: see table 17.

Table 17

tensile strenght
(kg, mm ² )

8 /, 0

strain

3.4

Constriction
<"■■>

2.5

Notched impact strength (kgm / cm ² )

0.6

i) Total rolling capacity: 62.850 t.

50

Hardness (BHN)

321

k) Comparison:.

Compared with an ordinary roller made of spheroidal graphite cast iron (C: 3.15%, Si: 1.98%, Mn: 0.60%, Cr: 0.33 ° / ,,, Ni: 0.80%, Mo: 0.35%) the roller according to the invention had a 2.5 fold longer service life.

Example 3

a) Type of roller manufactured:

Finishing roller for profiles.

b) Dimensions of the roller:

Diameter of the roller body 340 mm, length of the roller body 1000 mm, Total length of the roller 1570 mm,

c) roller weight: 1040 kg,

d) Outline shape of the cast body:

The cast body was in a semi-cooled mold, with a cone-shaped, lost Head poured,

e) Chemical composition in%: see table 18.

C. Si Mn Cr table 8th V
I. Ni Co Al Ti roller
No. 3.00
3.21
2.96 0.51
0.54
0.64 0.61
0.61
0.87 1.78
1.02
1.20 Mon 0.009
0.007
0.13 3.94
0.04
1.63 0.11
0.03 0.015
0.028
0.031 0.005
0.055
0.051 1
2
3 0.29
0.36
0.43

P. 15th S. Cu 1,508,226 As Sn Pb Zn Sb 16 Bi Total
harmful elements 0.009 0.008 0.010 0.008 0.008 tr. tr. tr. tr. 0.043 0.010 0.010 0.022 0.008 0.008 tr. tr. tr. tr. 0.058 roller
No. 0.008 0.007 0.027 0.007 0.007 tr. tr. tr. tr. 0.056 1 Table 18 (continued) 2 3

0 temperature of hot working and forging ratio:

Table 19

. roller
No. . temperature
of hot deformation Forging ratio 1
2
3 1080 to 960 C
1090 to 980 C
1070 to 960 C 3.5 p
■ 3.5 p
3.5 p

g) heat treatment:

Hold at 900'C for 5 hours, air cooling, 25 Hold at 630 ° C for 10 hours, air cooling, Hold at 180 ° C for 8 hours, air cooling,

h) Mechanical properties:

Table 20 30

roller
No. train
strength
(kgrnm ² ) strain
(%) A
lacing
<%) Notch
blow
toughness
(kgm / cm ² ) hardness
(BHN) 1
2
3 78.3
80.6
81.2 2.9
2.8
2.7 3.9
3.9
3.9 0.7
0.9
0.8 401
375
415

i) Total rolling capacity:

Table 21

Roller no.

2
3

Total rolling capacity (unit ton)

30,050 34,320 35,190

k) comparison:

Compared with ordinary alloyed gray cast iron rolls (C: 3.02%, Si: 1.45%. Mn: 0.66%, 55 Ni: 1.57%, Cr: 0.85%, Mo: 0.70%) had roller No. 1 (this one produced according to the invention The cast iron roller contained nickel and cobalt as alloying elements and had a 4.8 times longer service life on, the roller no. 2 (this cast iron roller produced according to the invention contained as Alloying elements aluminum and titanium) had a 5.1 times longer service life and the roller No. 3 (this cast iron roller produced according to the invention contained as alloying elements Nickel, cobalt, aluminum and titanium) had a 5.2 times longer service life.

Claims (1)

Claim: Process for producing cast iron hot rolls with 1.7 to 3.8% carbon, 0.4 to 2.5% silicon, less than 1.0% manganese, less than 2.0% chromium, less than 2.0% molybdenum, less than 1.0 ° / ₀ vanadium, less than 1.0% tungsten, balance iron, wherein the total existing harmful elements, such as phosphorus, sulfur, copper, tin, arsenic, lead, antimony, bismuth and zinc, less than 0.20%, in particular less than 0.15%, a cast body with a structure similar to white pig iron being brought to 50 ° C. below the solidus line and then forged at 900 to 1125 ° C., followed by slow cooling in a known manner in a furnace or in sand, tempering at temperatures between 750 and 850'C, quenching in water, quenching in oil or normalization after maintaining the temperature in a range between 850 and 950'C, tempering at temperatures between 400 and 700'C and between 150 and 250 C as well as machining follows, according to patent 1,287,593, thereby gekening nigns; that the cast iron alloy additionally has less than 5.0% cobalt and / or nickel and / or one or more of the elements aluminum with less than 1.0%, titanium with less than 0.15%, zirconium with less than 0.30% Contains boron less than 0.10%, beryllium less than 0.20%, tellurium less than 0.05%, and niobium and tantalum together with less than 0.10%. For this purpose 2 sheets of drawings