JP5960629B2 - High temperature wear resistant material - Google Patents

Description

  The present invention relates to a high-temperature wear-resistant material used for a protective liner of a blast furnace member, an inner liner of a bucket that receives high-temperature red hot coke discharged from a coke oven, and the like.

In general, various members used for distributing charges such as iron ore, lime, and coke to the center of the blast furnace include a swivel chute, movable armor, and ore receiving metal. These blast furnace members have a liner embedded in the surface layer portion thereof, and are protected from impact caused by dropping of the charged material and wear caused by sliding after contact.
As liners for these blast furnace members, for example, high-chromium steel and high-temperature wear-resistant materials made of cast-in materials of high-chromium steel and carbide (WC) particles are used (see, for example, Patent Documents 1 and 2). .

  Moreover, Ni-Cr steel may be used as a high temperature wear resistant material. For example, in a bucket that receives high-temperature red hot coke discharged from a coke oven and transports it to a coke dry fire extinguishing facility, a liner made of a high-temperature wear-resistant material is provided on the inner surface thereof. The Ni-Cr steel is used for the liner for the bucket because of high wear resistance, crack resistance and corrosion resistance at high temperatures.

  Further, Mn—Cr steel (Mn—Cr austenitic steel) in which expensive Ni is reduced and Mn is added may be used. Work hardening that appears due to external forces such as impact force and crushing force applied to the surface plays an important role in wear resistance of Mn-Cr steel. Therefore, for example, when exposed to impact caused by dropping of red hot coke or sliding after contact, a work hardened layer is formed on the surface, and excellent wear resistance is exhibited. As a result, constant wear resistance is always maintained while balancing the progress of wear and the formation of a hardened layer. In addition, it is possible to continuously exhibit certain crack resistance and corrosion resistance (see, for example, Patent Document 3).

  Examples of Mn-Cr steel with an increased Mn content instead of Ni include 0.3C-0.7Si-20Mn-17Cr-0.3N-Febal. Etc. are used.

Japanese Utility Model Publication No. 7-33964 JP 11-131114 A JP 2009-221544 A

  By the way, N is normally added to the Mn-Cr steel used for the above-mentioned various liners. This is because if N is not added, the strength is lowered and deformation is likely to occur.

  However, when N is added, since there is a limit to casting companies that can inspect N contained in the member, there is a problem that restrictions are likely to occur in time schedule management in the manufacturing process. In addition, N inspection requires a considerable cost each time. For this reason, there exists a problem that the cost of Mn-Cr steel manufactured as a high temperature wear-resistant material rises. Moreover, there is a problem that defects are easily caused by containing N, and the cost for maintaining the quality is increased.

  Furthermore, even in the above-described high temperature wear resistant material not containing Ni, further improvement in wear resistance and crack resistance is desired.

  Therefore, an object of the present invention is to provide an inexpensive high-temperature wear-resistant material that exhibits excellent wear resistance and crack resistance in a high-temperature environment.

In order to solve the above problems, the present invention provides C: 0.2 to 0.5 mass %, Si: 0.2 to 1.5 mass %, Mn: 10 to 24 mass %, Cr: 12 to 20 A high-temperature wear-resistant material containing mass %, Ni: 0.09 mass % or less , N: less than 0.1 mass %, and the balance consisting of Fe and inevitable impurities was employed.

  That is, by not adding N at the time of casting, the inspection of N on the finished product was omitted, and an inexpensive high temperature wear resistant material was realized. In addition to adding N at the time of casting, the content of other alloy elements is limited to the above range, thereby exhibiting wear resistance and crack resistance that are the same as conventional products in a predetermined high temperature environment. I confirmed that I can do it. Here, not adding N at the time of casting means that N is not added intentionally, and does not exclude the entry of N in the air.

  Here, the reason why the content of each alloy element is limited to the above range will be described.

C is an element effective for improving high-temperature strength and wear resistance, and is contained in an amount of 0.2% by mass or more in order to ensure strength and wear resistance. On the other hand, since the toughness decreases as the content increases, the upper limit is set to 0.5% by mass so that cracking due to insufficient toughness does not occur.

Si acts as a deoxidizer during the melting of steel, improves the flow of hot water, improves castability, and improves heat resistance. Therefore, Si is contained in an amount of 0.2% by mass or more. On the other hand, if the content increases, the toughness decreases and the possibility of cracking increases, so the upper limit is made 1.5 mass %.

Mn is an element having a deoxidizing action and detoxifying by fixing S, and stabilizes the austenite phase and improves strength and work curability, so it is contained in an amount of 10% by mass or more. In particular, when Ni is not contained or when the content is small, it is desirable to contain 14% by mass or more of Mn in order to maintain the stability of the austenite phase. On the other hand, if it is excessively contained, the price increases, so the upper limit is set to 24% by mass .

Cr needs to be contained in an amount of 12% by mass or more in order to stabilize austenite by a synergistic effect with Mn and improve oxidation resistance and heat resistance. On the other hand, when it is contained excessively, the toughness decreases, so the upper limit is set to 20% by mass . In addition, Ni shall be 0.09 mass% or less .

Conventionally, N has been required to be contained in an amount of 0.1% by mass or more in order to stabilize the austenite phase and improve the strength. However, in the present invention, even if N is less than 0.1% by mass , the predetermined mechanical properties are realized by limiting the content of other alloy elements to the above range. However, N can theoretically be 0% by mass, but normally, since N is present in the air, even if N is not added intentionally, the finished product contains a small amount of N.
Here, as described above, if N is not contained at all, the strength may decrease and deformation may easily occur. Therefore, the lower limit of N can be set to 0.01% by mass .

Since S combines with Mn to become MnS, excessive inclusion of S deteriorates toughness. For this reason, S is desirably 0.1% by mass or less. P is preferably 0.1% by mass or less. Here, S and P are positioned as inevitable impurities.

  In the present invention, N is not added at the time of casting, so that inspection of N on the finished product is omitted, and an inexpensive high temperature wear resistant material is realized. In addition to adding N at the time of casting, the content of other alloy elements is limited to a specified range, thereby exhibiting the same wear resistance and crack resistance as conventional products in a specified high-temperature environment. I confirmed that I can do it.

Chemical composition table (Table 1a) showing an embodiment of the present invention Chemical composition table (Table 1b) showing an embodiment of the present invention It is a cutaway view of the 30tY block used in the test, (a) is a side view, (b) is a front view. Shows the sampling position of the test piece, (a) is a side view, (b) is a front view Shows the sampling position of the test piece, (a) is a side view, (b) is a front view A U-notch Charpy impact test piece is shown, (a) is a side view, (b) is a front view, and (c) is an enlarged view of a main part of a notch. Front view showing a room temperature tensile test piece A high temperature tensile test piece is shown, (a) is a front view, (b) is an enlarged view of the main part. (A) is a table showing U-notch Charpy impact test results at room temperature before aging heat treatment (Table 2), and (b) is a table showing U-notch Charpy impact test results at room temperature before aging treatment (Table 3). (A) is a table showing U-notch Charpy impact test results at room temperature after aging treatment (Table 4), (b) is a table showing U-notch Charpy impact test results at room temperature after aging treatment (Table 5). Graph showing U-notch Charpy impact value at room temperature before and after aging heat treatment Table showing U-notch Charpy impact test results at 500 ° C. before aging heat treatment (Table 6) Table showing U-notch Charpy impact test results at 500 ° C. after aging heat treatment (Table 7) Graph showing U-notch Charpy impact value at 500 ° C before and after aging heat treatment (A) is a table (Table 8) showing the U-notch Charpy impact test results at 700 ° C. after water toughening treatment, and (b) is a table (Table) showing the U-notch Charpy impact test results at 700 ° C. before aging treatment. 9) (A) is a table showing the U-notch Charpy impact test results at 700 ° C. after aging heat treatment (Table 10), and (b) is a table showing the U-notch Charpy impact test results at 700 ° C. after aging treatment (Table 11). ) Graph showing the U-notch Charpy impact value at 700 ° C before and after water toughness treatment (A) is a table showing the tensile test results at room temperature before aging heat treatment (Table 12), (b) is a table showing the tensile test results at room temperature before aging treatment (Table 13). (A) is a table showing the tensile test results at room temperature after aging treatment (Table 14), (b) is a table showing the tensile test results at room temperature after aging treatment (Table 15). Graph showing tensile strength at room temperature before and after aging heat treatment Graph showing 0.2% proof stress at normal temperature before and after aging heat treatment Graph showing the elongation at normal temperature before and after aging heat treatment Graph showing normal temperature drawing before and after aging heat treatment Table showing the results of a tensile test at 500 ° C. before aging heat treatment (Table 16) Table showing the results of a tensile test at 500 ° C. after aging heat treatment (Table 17) Graph showing tensile strength at 500 ° C before and after aging heat treatment Graph showing 0.2% yield strength at 500 ° C before and after aging heat treatment Graph showing elongation at 500 ° C before and after aging heat treatment Graph showing the drawing at 500 ° C before and after aging heat treatment Table showing the results of a tensile test at 700 ° C. before aging heat treatment (Table 18) Table showing the results of a tensile test at 700 ° C. after aging heat treatment (Table 19) Graph showing the tensile strength at 700 ° C before and after water toughness treatment Graph showing 0.2% yield strength at 700 ° C before and after water toughness treatment Graph showing elongation at 700 ° C before and after water toughness treatment Graph showing the drawing at 700 ° C before and after water toughness treatment (A) is a table showing normal temperature hardness after water toughness treatment (Table 20), (b) is a table (Table 21) showing normal temperature hardness after water toughness treatment and aging treatment, and (c) is a Y block. Table showing hardness test results before and after heat treatment (Table 22) (A) shows the sampling position of a microstructure test piece (also serves as a hardness test piece), (a) is a side view, (b) is a front view, and (c) is an enlarged view of the main part showing the hardness test position. Graph showing normal temperature hardness before and after aging heat treatment

Embodiments of the present invention will be described below. FIG. 1a (Table 1a) and FIG. 1b (Table 1b) show the compositions of the Mn—Cr austenitic steel of the embodiment (Example) and the conventional Mn—Cr austenitic steel (Comparative Example). C and S are infrared absorption methods, N is an inert gas melting thermal conductivity method, Si is a silicon dioxide gravimetric method, P is a molybdophosphate blue absorptiometric method, Cr is an ammonium peroxodisulfate oxide KMnO ₄ method, The other elements were analyzed by induction plasma emission spectroscopy.

  Various tests for confirming the performance were performed on the materials of Examples and Comparative Examples.

  In various tests, first, as-cast products obtained by pouring molten metal having the composition shown in FIGS. 1a and 1b into a sand mold for a 30 tY block were heat-treated under the following conditions to obtain the required size. A test piece was prepared by cutting.

(Heat treatment conditions)
Heating temperature: Heated from room temperature or from that temperature to 1100 ° C Heating rate: 100 ° C / hour Holding time: 5.5 hours Cooling method: Water cooling (stirring with screw)

  Here, as shown in FIGS. 2 (a) and 2 (b), the hot water of the 30tY block was cut, subjected to water toughness treatment, further cut into two equal parts, and aging heat treatment was performed on one side.

(Aging heat treatment conditions)
Heating temperature: Heated from around normal temperature to 900 ° C Heating rate: 100 ° C / hour Holding time: 200 hours Cooling method: Taken out of furnace and allowed to cool to air

(U-notch Charpy impact test results)
Next, in order to confirm the toughness against impacts at normal temperature and high temperature environment, impact tests were performed at normal temperature, 500 ° C. and 700 ° C. 3A and 3B show the sampling positions of the test pieces of Comparative Examples 1 to 11 and Examples 1 and 2. 4A and 4B show the sampling position of the test piece of Comparative Example 6. FIG. 5A, 5B, and 5C show the dimensions of a U-notch Charpy impact test piece, FIG. 6 shows a normal temperature tensile test piece, and FIGS. 7A and 7B show the high temperature tensile test piece.

  The impact test was performed using the Charpy impact test method defined in JIS Z 2242. Similarly, the Charpy impact value was determined from a U-notch test piece defined in JIS Z 2242.

(U-notch Charpy impact test results at normal temperature before and after aging heat treatment)
The test results are shown in FIG. 8 (a) (Table 2), FIG. 8 (b) (Table 3), FIG. 9 (a) (Table 4), FIG. 9 (b) (Table 5), and FIG. 8A and 8B show the results of a U-notch Charpy impact test at room temperature before aging heat treatment, and FIGS. 9A and 9B show the results of a U-notch Charpy impact test at room temperature after aging heat treatment. . FIG. 10 is a graph plotting U-notch Charpy impact test results at normal temperatures before and after aging heat treatment (data corresponds to FIG. 8 (a) and FIG. 9 (a)).

From these test results, it was found that all of the materials other than the test pieces of Comparative Example 4 and Comparative Example 8 satisfied the measured values of the material of Comparative Example 1 before the aging heat treatment.
In addition, after the aging heat treatment, the impact values of all materials are greatly reduced. The crack resistance at normal temperature after heating is equal to or greater than the measured value of the material of Comparative Example 1 except for the test pieces of Comparative Example 4, Comparative Example 6, Comparative Example 8, and Comparative Example 11 .

Here, since Comparative Example 5 contains 6% by mass of Ni, it was thought that the impact value might increase, but the result was lower than that of Comparative Example 2 in which Ni was 2% by mass. Was. The reason for this decline is unknown.

Moreover, the impact value of the comparative example 4 which increased C of Example 1 fell significantly. It has been found that when N and Ni are not added (N includes a case where a small amount of N in the air is contained), an increase in the amount of C promotes a decrease in impact value.

Further, as in Example 2 , the impact value is greatly increased by adding N based on Comparative Example 6 without addition of N (also including the case where a small amount of N in the air is contained. The same applies hereinafter). It turned out to increase. Thereby, it is estimated that the crack resistance at normal temperature is improved by adding no N.

(U-notch Charpy impact test results at 500 ° C before and after aging heat treatment)
The test results are shown in FIG. 11 (Table 6), FIG. 12 (Table 7), and FIG. FIG. 11 shows the results of U-notch Charpy impact test at 500 ° C. before aging heat treatment, and FIG. 12 shows the results of U-notch Charpy impact test at 500 ° C. after aging heat treatment. FIG. 13 is a graph plotting U-notch Charpy impact test results at 500 ° C. before and after aging heat treatment (data corresponds to FIGS. 11 and 12).

From these test results, before and after the aging heat treatment, it was found that except for Comparative Example 4 , the measured values of the material of Comparative Example 1 were satisfied.
In addition, after the aging heat treatment, the impact values of all the materials are greatly reduced. However, after the aging heat treatment, it was found that all of the materials except Comparative Example 4 were equal to or more than the measured values of the material of Comparative Example 1. That is, the crack resistance at room temperature after being heated is equal to or greater than the measured value of Comparative Example 1 except for Comparative Example 4 .

(U-notch Charpy impact test results at 700 ° C before and after aging heat treatment)
The test results are shown in FIG. 14 (a) (Table 8), FIG. 14 (b) (Table 9), FIG. 15 (a) (Table 10), FIG. 15 (b) (Table 11), and FIG. 14A and 14B show the results of a U-notch Charpy impact test at 700 ° C. before aging heat treatment, and FIGS. 15A and 15B show the results of the U-notch Charpy impact test at 700 ° C. after aging heat treatment. Indicates. FIG. 16 is a graph plotting U-notch Charpy impact test results at 700 ° C. before and after aging heat treatment (data corresponds to FIG. 14A and FIG. 15A).

According to these test results, the impact values of all the materials are greatly reduced after the aging heat treatment. In addition, after the aging heat treatment, except for the test pieces of Comparative Example 4, Comparative Example 5, Comparative Example 6, and Comparative Example 8 , Comparative Example 3, Comparative Example 2 , Example 1, Example 2, Comparative Example 7, and Comparative Example 9, it was found that the test pieces of Comparative Example 10 and Comparative Example 11 all had an impact value higher than the standard value (measured value of the material of Comparative Example 1).
Therefore, in an environment where cracking occurs at 700 ° C., these materials are considered to have crack resistance equal to or higher than that of Comparative Example 1. On the contrary, Comparative Example 4, Comparative Example 5, Comparative Example 6, and Comparative Example 8 are considered to be inferior in crack resistance at 700 ° C. to Comparative Example 1.

(Tensile test result)
In order to confirm the mechanical strength at normal temperature and high temperature environment, a tensile test was performed at normal temperature, 500 ° C. and 700 ° C. The tensile test was performed using the tensile test method prescribed | regulated to JISZ2241 (normal temperature) and JISG0567 (500 degreeC, 700 degreeC), and the tensile strength, the yield strength, elongation, and the drawing were calculated | required from the result.

(Tensile test results at normal temperature before and after aging heat treatment)
The test results are shown in FIG. 17 (a) (Table 12), FIG. 17 (b) (Table 13), FIG. 18 (a) (Table 14), FIG. 18 (b) (Table 15), and FIGS. Show. 17 (a) and 17 (b) show the tensile test results at normal temperature before aging heat treatment, and FIGS. 18 (a) and 18 (b) show the tensile test results at normal temperature after aging heat treatment. FIGS. 19 to 22 show tensile strength, 0.2% proof stress, and elongation based on tensile test results at normal temperatures before and after aging heat treatment (data correspond to FIGS. 17 (a) and 18 (a)), respectively. It is the graph which plotted the aperture_diaphragm | restriction.

According to these test results, by performing an aging heat treatment, the tensile strength is almost the same or increased in all the test pieces except for the test pieces of Comparative Example 7 and Comparative Example 8 , whereas the tensile strength is increased. Is falling. However, although the 0.2% proof stress of Comparative Example 3, Comparative Example 2, Comparative Example 5 , Example 1, Comparative Example 4, Example 2, and Comparative Example 9 is reduced, the reason is unknown. Moreover, it is Comparative Example 6, Comparative Example 7, Comparative Example 8, Comparative Example 9, Comparative Example 10, and Comparative Example 11 that satisfy all the measured values of Comparative Example 1 before aging heat treatment.
Before and after the aging heat treatment, the 0.2% proof stress of all the materials except the test pieces of Comparative Example 6, Comparative Example 8, Comparative Example 10, and Comparative Example 11 is lower than that of Comparative Example 1, and therefore, deformation resistance at room temperature. However, all the materials except the test pieces of Comparative Example 6, Comparative Example 8, Comparative Example 10, and Comparative Example 11 are considered to be inferior to Comparative Example 1. Before and after the aging heat treatment, the elongation and drawing at normal temperature exceeded the measured values of Comparative Example 1 for all the test pieces except Comparative Example 4 (see FIGS. 21 and 22).

(Results of tensile test at 500 ° C before and after aging heat treatment)
The test results are shown in FIG. 23 (Table 16), FIG. 24 (Table 17), and FIGS. FIG. 23 shows the tensile test results at 500 ° C. before aging heat treatment, and FIG. 24 shows the tensile test results at 500 ° C. after aging heat treatment. FIGS. 25 to 28 plot the tensile strength, 0.2% proof stress, elongation and drawing based on the tensile test results at 500 ° C. before and after aging heat treatment (data corresponds to FIGS. 23 and 24), respectively. FIG.

  According to these test results, the tensile strength and the 0.2% proof stress are not significantly different between before and after the aging heat treatment, but the elongation and drawing are reduced by performing the aging heat treatment. Before and after the aging heat treatment, the 0.2% proof stress of all the materials listed in FIGS. 23 to 28 is lower than that of Comparative Example 1, so that the deformation resistance at 500 ° C. is all the materials listed in FIGS. Is considered inferior to Comparative Example 1.

(Results of tensile test at 700 ° C before and after aging heat treatment)
The test results are shown in FIG. 29 (Table 18), FIG. 30 (Table 19), and FIGS. FIG. 29 shows the tensile test results at 700 ° C. before aging heat treatment, and FIG. 30 shows the tensile test results at 700 ° C. after aging heat treatment. 31 to 34 plot the tensile strength, 0.2% proof stress, elongation, and drawing based on the tensile test results at 700 ° C. before and after aging heat treatment (data corresponds to FIG. 29 and FIG. 30), respectively. FIG.

From these test results, it was found that there was no significant difference in tensile strength and 0.2% yield strength before and after aging heat treatment. Although the elongation decreased by applying an aging heat treatment, the reverse tendency of the drawing was observed in the test pieces of Comparative Example 3, Comparative Example 4, and Example 2 . Before and after the aging heat treatment, the 0.2% proof stress of all the materials listed in FIGS. 29 to 34 is lower than that of Comparative Example 1, so that the deformation resistance at 700 ° C. is all the materials listed in FIGS. Is considered inferior to Comparative Example 1.

(Hardness after water toughness treatment and after water toughness treatment and heat treatment)
Fig. 35 (a) (Table 20) shows normal temperature hardness after water toughness treatment (HV10), and Fig. 35 (b) (Table 21) shows water toughness treatment and normal temperature hardness after aging treatment (HV10). Indicates. Further, the upper part of FIG. 35 (c) (Table 22) shows the normal temperature hardness (HV10) before the Y block heat treatment, and the lower part shows the normal temperature hardness (HV10) after the Y block heat treatment . 36A, 36B, and 36C show the sampling position of the test piece and the hardness test execution position in the test piece. FIG. 37 is a graph plotting the normal temperature hardness (HV10) before and after aging heat treatment.

According to these results, the hardness after aging heat treatment is increased in all materials. This is thought to be due to the precipitation of carbides. The specimens of Comparative Example 2, Example 1, Comparative Example 4, Comparative Example 6, and Comparative Example 8 showed hardness equal to or higher than that of Comparative Example 1 before and after aging heat treatment. On the contrary, it was comparative example 3, comparative example 5, example 2, comparative example 7, comparative example 9, comparative example 10, comparative example which showed lower hardness than comparative example 1 either before and after aging heat processing. Example 11 . Therefore, it is considered that the test pieces of Comparative Example 2 , Example 1, Comparative Example 4, Comparative Example 6, and Comparative Example 8 have wear resistance equal to or higher than that of Comparative Example 1 at room temperature.

(Summary)
Since Comparative Example 6 has a similar Charpy impact value and 0.2% proof stress at normal temperature to Comparative Example 1 after aging heat treatment, use of Comparative Example 6 is necessary when characteristics close to Comparative Example 1 are required. It is considered desirable. Further, when N is not added, the Charpy impact values at room temperature, 500 ° C., and 700 ° C. after the aging heat treatment are Comparative Example 3, Comparative Example 2 , Example 1, Example 2, Comparative Example 7, Comparative Example 9, Since the test pieces of Comparative Example 10 and Comparative Example 11 were equivalent to Comparative Example 1, the use of these materials is desirable when importance is attached only to cracking resistance. In terms of cost, Example 1 is considered most advantageous.

Claims (1)

C: 0.2-0.5 mass %, Si: 0.2-1.5 mass %, Mn: 10-24 mass %, Cr: 12-20 mass %, Ni: 0.09 mass % or less , N : High-temperature wear-resistant material containing less than 0.1% by mass, with the balance being Fe and inevitable impurities.

Images