JP5753430B2 - High chrome cast iron - Google Patents

Description

  The present invention relates to high chromium cast iron.

  Conventionally, a wear-resistant alloy cast iron having a manganese (Mn) content of 0.5 wt% to 1.5 wt% and a molybdenum (Mo) content of 0.5 wt% to 2.0 wt% is provided. Known (Patent Document 1).

  Further, a method for producing a high chromium cast iron casting in which the Mn content is 0.5 wt% to 2.5 wt% and the Mo content is 0 wt% to 7 wt% is known (Patent Document). 2).

  The method for producing the high chromium cast iron casting comprises heating high chromium cast iron containing 0.5 wt% to 2.5 wt% Mn and 0 wt% to 7 wt% Mo at 900 to 1100 ° C. This is a method of cooling to 600 ° C. with impact air and then further naturally cooling.

Japanese Patent Publication No. 05-046991 JP 2002-294389 A

  However, the conventional wear-resistant alloy cast iron or high-chromium cast iron has a problem that the cooling rate at the time of quenching at the thickness center of the large-sized casting is slowed down and the wear resistance is lowered due to a decrease in hardness.

  Therefore, the present invention has been made to solve such a problem, and an object thereof is to provide a high chromium cast iron capable of improving the wear resistance.

  The high chromium cast iron according to the embodiment of the present invention has a manganese content of 2.15 wt% to 3.5 wt%.

  According to the embodiment of the present invention, the high chromium cast iron has a manganese content of 2.15 wt% to 3.5 wt%. As a result, even if the cooling time during quenching of the high chromium cast iron is greatly different from 207 minutes to 828 minutes, the hardness of the high chromium cast iron is 61 HRC or more. That is, even if it takes a cooling time that is difficult to burn, the high chromium cast iron has a hardness of 61 HRC or more.

  Therefore, the wear resistance of the high chromium cast iron can be improved.

It is a perspective view which shows the test piece of high chromium cast iron. It is a chart which shows the relationship between the temperature at the time of hardening, and time. It is a side view of the test piece shown in FIG. It is a figure which shows the relationship between the hardness of high chromium cast iron, and the content of Mn.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  The high chromium cast iron according to the embodiment of the present invention includes carbon (C), silicon (Si), manganese (Mn), chromium (Cr), nickel (Ni), molybdenum (Mo), copper (Cu), vanadium (V ), Niobium (Nb), phosphorus (P) and sulfur (S), and the content of manganese (Mn) is 2.15 wt% to 3.5 wt%.

  The high chromium cast iron according to the embodiment of the present invention contains 2.15 wt% to 3.5 wt% of Mn. As a result, the cooling time during quenching is 207 minutes in each part in the thickness direction of the high chromium cast iron. Even if it differs greatly from the minute and 828 minutes, the hardness in each part in the thickness direction of the high chromium cast iron has a value equal to or higher than the reference value. And a reference value is 61HRC which is the minimum value which can prevent the acceleration | stimulation progress of wear.

  An experimental method for measuring the hardness of high chromium cast iron will be described. FIG. 1 is a perspective view showing a test piece of high chromium cast iron. With reference to FIG. 1, the test piece 10 has a size of 40 mm × 30 mm × 20 mm.

  Test pieces 10 are cut out from flat high chromium cast iron having different Mn contents, and all the test pieces 10 are quenched.

  And after hardening, the test piece 10 is cut | disconnected with a broken line, and the hardness of the site | part a is measured.

  FIG. 2 is a chart showing the relationship between temperature and time during quenching. In FIG. 2, the vertical axis represents temperature and the horizontal axis represents time.

  Referring to FIG. 2, test piece 10 is placed in a hearth raising / lowering high temperature furnace (manufactured by Marusho Denki), heated from room temperature to 1000 ° C. at a temperature rising rate of 100 ° C./h, and thereafter Heat treated at 1000 ° C. for 2 hours.

  And the test piece 10 is cooled from 1000 degreeC to 300 degreeC in t minutes. Thereafter, the test piece 10 is naturally cooled to a temperature of 100 ° C. or lower in the hearth raising / lowering high temperature furnace in a state where the power source of the hearth raising / lowering high temperature furnace is turned off, and is taken out from the hearth raising / lowering high temperature furnace. This completes quenching.

  The temperature of the test piece 10 is a temperature measured by welding a thermocouple to the test piece 10.

  The cooling time t for cooling the test piece 10 from 1000 ° C. to 300 ° C. was determined as follows.

  If the cooling time from 975 ° C. to 300 ° C. is 200 minutes, the cooling rate is (975-300) /200=3.375 (° C./min). Therefore, the time required for cooling at 1 ° C. is 200 / (975-300) = 0.296 (min / ° C.).

  As a result, if cooling is performed at the same rate from 1000 ° C. to 300 ° C., the cooling time is 0.296 × (1000−300) = 207 (minutes).

  In the case of a product having a large wall thickness (such as a vertical crusher tire and a table), the product is cooled quickly on the surface of the product. Thus, the cooling rate varies depending on the position in the thickness direction. Therefore, the cooling rate of the surface of the product is V, the cooling rate of the center of the thickness is V / 4, and the cooling rate of the center of the surface and the center of the thickness is V / 2. Assumed. Corresponding to these cooling rates, test specimens 10 were prepared with cooling times set to 207 minutes, 828 minutes (= 207 minutes × 4), and 414 minutes (= 207 minutes × 2), respectively.

  Generally, the faster the quenching cooling rate, the easier the quenching, and the slower the quenching cooling rate, the harder the quenching and the lower the hardness.

  Therefore, even if the quenching cooling time changes, if the hardness in the thickness direction of the test piece 10 can be maintained at a certain value or more, the test piece 10 as a whole has wear resistance.

  FIG. 3 is a side view of the test piece 10 shown in FIG. Referring to FIG. 3, the hardness after quenching was measured at 7 points b, c, d, e, f, g, and h of the test piece 10 using a Rockwell hardness tester. The interval between the seven points was set to 5 mm.

  The hardness was measured for 7 points, and the average value of the 7 points was taken as the hardness of one test piece.

  FIG. 4 is a diagram showing the relationship between the hardness of high chromium cast iron and the Mn content. In FIG. 4, the vertical axis represents the hardness of the high chromium cast iron, and the horizontal axis represents the Mn content. Curve k1 shows the relationship between the hardness of the test piece with a cooling time of 207 minutes at quenching and the content of Mn, and curve k2 shows the hardness of the test piece with a cooling time of 414 minutes at quenching and the Mn content. The relationship with the content is shown, and the curve k3 shows the relationship between the hardness of the test piece with a cooling time of 828 minutes during quenching and the content of Mn.

  Referring to FIG. 4, when the Mn content is 2.15 wt% to 3.5 wt%, the hardness of the high chromium cast iron is that the cooling time during quenching is 207 minutes, 414 minutes, and 828 minutes. It becomes 61HRC or more in all the parts.

  On the other hand, in the region where the Mn content is less than 2.15% by weight, the hardness of the high chromium cast iron tends to decrease as the cooling time at the time of quenching becomes longer, and the cooling time at the time of quenching is 828 minutes. The hardness of the high chromium cast iron is significantly lower than that of 61HRC.

  Moreover, in the region where the Mn content is more than 3.5% by weight, the hardness of the test piece for all the cooling times decreases.

  And the hardness of 61HRC is the minimum value which can prevent the acceleration | stimulation progress of wear as mentioned above.

  As a result, when the Mn content is 2.15 wt% to 3.5 wt%, the hardness of the high chromium cast iron is significantly different from the cooling time of 207 minutes, 414 minutes, and 828 minutes in the thickness direction. The part has a value that is equal to or higher than a reference value that can prevent accelerated progress of wear.

  Therefore, wear resistance can be improved in high chromium cast iron containing 2.15 wt% to 3.5 wt% Mn.

  Further, when the Mn content is 3.13%, the hardness of the high chromium cast iron takes a value in the range of 62 to 63 HRC, and the variation is the smallest.

  Furthermore, when the Mn content is 3.3% by weight, the hardness of the high chromium cast iron takes a value in the range of 63 to 64 HRC and becomes the hardest.

  Therefore, the Mn content is preferably set to 3.13% to 3.3% by weight.

  High chromium with Mn content of 0.59 wt%, 2.15 wt%, 2.45 wt%, 3.13 wt%, 3.29 wt%, 3.55 wt% and 4.02 wt% Table 1 shows the content of each component of cast iron.

  As can be seen from Table 1, the Mn content is changed from 0.59 wt% to 4.02 wt%. Therefore, by changing the Mn content and setting the Mn content in the range of 2.15 wt% to 3.5 wt%, the cooling time during quenching becomes as long as 828 minutes (ie, The hardness of the high chromium cast iron is maintained at 61 HRC or more in the thickness direction of the high chromium cast iron.

  As described above, the high chromium cast iron according to the embodiment of the present invention has the hardness as a reference value even if the cooling time at the time of quenching becomes long (that is, the cooling rate becomes slow and quenching becomes difficult). (= 61HRC) The Mn content effective for maintaining the above is set in the range of 2.15 wt% to 3.5 wt%, preferably in the range of 3.13 wt% to 3.3 wt%. It is characterized by doing. As a result, the wear resistance of the high chromium cast iron can be improved.

  As described above, the high chromium cast iron according to the embodiment of the present invention contains Mn having a content of 2.15 wt% to 3.5 wt%, so that the cooling time during quenching is 207 minutes, 414 minutes, and Even if it is greatly different from 828 minutes, it has a hardness of 61 HRC or more.

  Therefore, the high chromium cast iron according to the embodiment of the present invention is used for products that require wear resistance, and is specifically suitable for a pulverizer, a smashing plate, a collision plate, and a liner, Particularly, the high chromium cast iron according to the embodiment of the present invention is suitably used for a steel-related rolling roll or the like.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to high chromium cast iron.

  10 Test piece.

Claims (2)

2.928 wt% to 3.08 wt% C;
0.28 wt% to 0.45 wt% Si;
16.3% to 17.4% by weight of Cr,
0.89 wt% to 0.92 wt% Ni;
1.98 wt% to 2.06 wt% Mo;
0.22 wt% to 0.26 wt% Cu;
0.094 wt% to 0.11 wt% V;
1.49 wt% to 1.54 wt% Nb;
0.007 wt% to 0.014 wt% P;
0.004 wt% to 0.005 wt% S;
2 . 15 wt% to 3.5 wt% Mn,
High chromium cast iron with the balance being iron . The high chromium cast iron according to claim 1, wherein the Mn content is 3.13% to 3.3% by weight.

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