JP3498289B2 - Manufacturing method of high chromium cast iron castings - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to the striker plate, such as crushers and mills, impingement plate, a method for producing a high chromium cast iron cast product to be used as a liner or the like.

[0002]

2. Description of the Related Art Heretofore, as this type of high chromium cast iron casting, there have been known as-cast, cast-blast hardened, and naturally-cooled cast.

[0003]

However, among the conventional high chromium cast iron castings, as-cast ones have the drawbacks of low hardness and high residual stress, although heat treatment costs are not required. On the other hand, a cast product obtained by quenching and quenching with an air blast has high hardness, but has a problem of high residual stress. On the other hand,
Natural cooling quenching and tempering of castings (350-600 ° C)
Although the residual stress can be reduced, there is a problem that the hardness decreases.

[0004] Therefore, the present invention is useful life longer, and aims to provide a method for producing a high chromium cast iron cast material capable of preventing damage in use.

[0005]

In order to solve the above-mentioned problems , the first method for producing a high chromium cast iron casting of the present invention is C
2.0-3.8 wt%, Si 0.5-1.5 wt%, Mn
0.5-2.5 wt % , Cr 15-30 wt % , Mo 7 wt %
Hereinafter , after heating a casting containing Ni 7 wt % or less and the balance of Fe and unavoidable impurities to a temperature of 900 to 1100 ° C.,
Impulsive cooling to a temperature of 300 to 600 ° C, and then,
Characterized by natural cooling. The second method for producing a high-chromium cast iron casting is C3.0-3.8 wt%, Si0.
5 ~ 1.5wt%, Mn0.5 ~ 2.5wt%, Cr15 ~
900 to 110 of a casting containing 20 wt %, Mo 2 to 4 wt %, Ni 3 wt % or less , and the balance Fe and inevitable impurities.
It is characterized in that after heating to a temperature of 0 ° C., it is cooled with an air blow to a temperature of 300 to 600 ° C., and then naturally cooled.

C is for ensuring the hardness (wear resistance) of cast iron, and the content thereof is 2.0 in the first method .
If it is less than wt%, or less than 3.0 wt% in the second method , the desired hardness cannot be obtained. On the other hand, 3.8 wt%
If it exceeds, the desired impact value (toughness) cannot be obtained, and
Hardenability cannot be obtained.

Si, together with Cr and Mo, has the property of transferring the low temperature tempering brittleness to the high temperature side, and if its content is less than 0.5 wt%, the strength decreases. On the other hand, if it exceeds 1.5 wt%, the impact value and hardness decrease.

Mn contributes to deoxidation and desulfurization,
If the content is less than 0.5 wt%, the deoxidizing / desulfurizing effect cannot be obtained. On the other hand, if it exceeds 2.5 wt%, the impact value decreases, the amount of residual γ increases, and the hardness also decreases.

[0009] Cr has the property of transferring the low temperature tempering brittleness to the high temperature side, and its content is 15 wt%.
If it is less than 100%, hardenability is deteriorated. On the other hand, in the first method , it exceeds 30 wt%, and in the second method , 2%.
If it exceeds 0 wt%, the wear resistance is lowered and the toughness is also lowered.

Mo has the property of enhancing the hardenability and the strength. If the content of Mo is less than 2 wt% in the second method , the desired hardenability is obtained. I can't get it. On the other hand, when the amount exceeds 7 wt% in the first method and exceeds 4 wt% in the second method , the above effect becomes constant and there is no economic merit.

Ni contributes to the improvement of hardenability in cooperation with Cr and Mo, the content of which exceeds 7 wt% in the first method , and the second method. At 3 wt
If it exceeds%, the above effect can be obtained, but the residual γ amount increases, the hardness decreases, and there is no economic merit.

On the other hand, in the first and second methods, 130
If the heating temperature of the cast product that has been cast at a temperature of 0 to 1350 ° C and naturally cooled is less than 900 ° C, the C concentration in the matrix decreases and the hardness also decreases.
On the other hand, when the temperature exceeds 1100 ° C, C and C in the matrix
The concentration of alloying elements such as r becomes too high, the amount of residual γ increases, and the hardness decreases. The heating temperature of the casting is 950 to 105.
0 degreeC is preferable, More preferably, it is 950-1000 degreeC.

If the cast air after cooling is heated to a temperature of less than 300 ° C., the residual stress increases. On the other hand, 6
When the temperature is higher than 00 ° C, pearlite precipitates and the hardness decreases. The cooling of the cast after heating is 350 ~.
The temperature is preferably up to 550 ° C, more preferably 400 to 500 ° C. The cooling rate of the airflow cooling is preferably 20 to 200 ° C / min, more preferably 30 to 100 ° C / min.

[0014]

[Example 1, Comparative Example 1]

First, each element of C, Si, Mn, Cr, Mo, and Ni is contained in a ratio shown in Table 1 (in Table 1, the content ratios of C and Cr, which particularly affect the hardness and toughness of the cast, are changed. ,
The content ratios of Si, Mn, Mo, and Ni were set to appropriate values within the respective ranges. ), And the balance Fe is an unavoidable impurity at a required casting temperature (1300 to 135).
Casting at 0 ° C.), releasing from the mold after 3 hours, and then cooling naturally, various test pieces having a thickness of 80 mm and a weight of 100 kg (No. 1 to 6: Example 1, No. 7 to 1)
0: Comparative Example 1) was obtained.

[0015]

[Table 1]

Next, when each test piece was heat-treated under the following normalizing conditions and tempering conditions, the hardness and the residual stress were as shown in Tables 2 and 3 (each table, ′).
No. with The product was unmolded 5 days after casting. ). Normalizing conditions A: None B: After cooling with blast from 980 ° C to 200 ° C, natural cooling C: With blast cooling from 980 ° C to 300 ° C, and then with natural cooling D: From 980 ° C to 400 ° C After that, natural cooling E: after cooling with blast from 980 ° C to 600 ° C, natural cooling F: after cooling with blast from 980 ° C to 700 ° C, natural cooling G: from 980 ° C natural cooling and tempering condition a: none b: Hold at 200 ° C for 5 hours c: Hold at 400 ° C for 5 hours d: Hold at 600 ° C for 5 hours

[0017]

[Table 2]

[0018]

[Table 3]

As can be seen from Tables 1 to 3, C2.0-
3.8 wt%, Si 0.5-1.5 wt%, Mn 0.5-
2.5 wt%, Cr 15 to 30 wt % , Mo 7 wt % or less , N
i 7 wt % or less , and the balance consisting of Fe and inevitable impurities is heated to a temperature of 900 to 1100 ° C., and then 300 to
By cooling with a wind blow to a temperature of 600 ° C. and then naturally cooling, hardness 63 to 67 HRC, residual stress −50
A high chromium cast iron casting of ˜50 MPa is obtained.

[Example 2 and Comparative Example 2] First, each element of C, Si, Mn, Cr, Mo and Ni was contained in the ratio shown in Table 4 (in Table 4, the hardness and toughness of the casting are Change the content ratio of C and Cr, which especially affects
The content ratios of Si, Mn, Mo, and Ni were set to appropriate values within the respective ranges. ), And the balance Fe is an unavoidable impurity at a required casting temperature (1300 to 135).
Casting at 0 ° C.), releasing the mold after 3 hours, and then cooling naturally, various test pieces having a thickness of 80 mm and a weight of 100 kg (No. 11 to 14: Example 2, No. 15).
-18: Comparative example 2) was obtained.

[0021]

[Table 4]

Next, when each test piece was heat-treated under the following normalizing conditions and tempering conditions, the hardness and the residual stress were as shown in Tables 5 and 6, respectively (each table, ′).
No. with The product was unmolded 5 days after casting. ). Normalizing conditions A: None B: After cooling with blast from 980 ° C to 200 ° C, natural cooling C: With blast cooling from 980 ° C to 300 ° C, and then with natural cooling D: From 980 ° C to 400 ° C After that, natural cooling E: after cooling with blast from 980 ° C to 600 ° C, natural cooling F: after cooling with blast from 980 ° C to 700 ° C, natural cooling G: from 980 ° C natural cooling and tempering condition a: none b: Hold at 200 ° C for 5 hours c: Hold at 400 ° C for 5 hours d: Hold at 600 ° C for 5 hours

[0023]

[Table 5]

[0024]

[Table 6]

As can be seen from Tables 4 to 6, C3.0-
3.8 wt%, Si 0.5-1.5 wt%, Mn 0.5-
2.5 wt%, Cr 15-20 wt%, Mo 2-4 wt%, N
i 3 wt % or less , and the balance consisting of Fe and inevitable impurities is heated to a temperature of 900 to 1100 ° C.
Hardness is 65 to 70 HRC, residual stress is -5 by cooling with wind blow to a temperature of 600 ° C and then naturally cooling.
A high chromium cast iron casting of 0 to 50 MPa can be obtained.

[0026]

As described above, according to the high chromium cast iron casting and the method for producing the same of the present invention, since it has high hardness and low residual stress, it has a wall thickness of 100 as compared with the conventional one.
Long life of high chrome cast iron castings of about mm, and
It is possible to prevent damage during use and at the same time tempering
Since it is omitted, heat treatment cost can be reduced.
Can .

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-11-236615 (JP, A) JP-A-11-229071 (JP, A) JP-A-2001-81527 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C21D 5/00 C22C 37/08 C22C 37/10

Claims (2)

(57) [Claims] 1. C2.0-3.8 wt%, Si0.5-
1.5 wt%, Mn 0.5-2.5 wt%, Cr 15-30
wt%, Mo 7 wt % or less , Ni 7 wt % or less , and the balance F
Castings consisting of e and inevitable impurities at 900-1100 ° C
The method for producing a high-chromium cast iron casting, which comprises heating to a temperature of 3 ° C., cooling with an impinging wind to a temperature of 300 to 600 ° C., and then naturally cooling. 2. C3.0-3.8 wt%, Si0.5-
1.5 wt%, Mn 0.5-2.5 wt%, Cr 15-20
wt%, Mo2~4wt%, Ni 3 wt% or less, and the balance F
Castings consisting of e and inevitable impurities at 900-1100 ° C
The method for producing a high-chromium cast iron casting, which comprises heating to a temperature of 3 ° C., cooling with an impinging wind to a temperature of 300 to 600 ° C., and then naturally cooling.