JPH0873978A - Cast iron material - Google Patents

Abstract

PURPOSE: To produce a cast iron material having a surface capable of remelting chilling by incorporating specific percentages of C, Si, Mn, P, S, Cu, and Ce into iron. CONSTITUTION: A cast iron material, consisting of, by weight ratio, 3.0-3.5% C, 1.5-2.8% Si, 0.5-0.9% Mn, <=0.1% P, 0.06-0.2% S, 0.6-1.2% Cu, 0.02-0.5% Ce, and the balance iron with impurities, is produced. By this method, the cast iron material, free from the occurrence of chill in the inner part even if a metallic material is cast in, having a surface capable of remelting chilling, and excellent in mechanical properties, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved cast iron material, and more particularly to a cast iron material whose surface can be remelted and chilled.

[0002]

2. Description of the Related Art As a cast iron material whose surface can be remelted and chilled, there is, for example, the one described in Japanese Examined Patent Publication No. 4-34605. The cast iron material described in this publication has a weight ratio of C: 3.2 to 3.8% and Si: 1.00 to 2.30 as a raw water.
%, Mn: 0.05 to 1.00%, Ni: 0 to 0.5
%, Cr: 0 to 0.8%, Mo: 0 to 0.5%, balance F
Using a molten metal composed of e and a small amount of S, the amount of S in the molten metal is adjusted to 0.025 to 0.070% in a ladle, and 0.007 to 0.025% of Ce is added, followed by cooling and solidification. It is obtained by

[0003]

However, when a cast product in which a metal member such as a steel pipe, a steel plate, an aluminum pipe is wrapped is cast using the cast iron material described in the above publication, chill is generated in the cast iron material portion near the metal member. However, there is a problem that the casting strength is reduced. Therefore, the present invention has been made in order to solve such a problem, and when casting the metal member with a cast iron material, to provide a cast iron material in which chill is unlikely to occur in a cast iron material portion in the vicinity of the metal member. It is intended.

[0004]

According to the present invention, the weight ratio of C: 3.0.
~ 3.5%, Si: 1.5 to 2.8%, Mn: 0.5 to
0.9%, P: 0.1% or less, S: 0.06 to 0.2
%, Cu: 0.6 to 1.2%, Ce: 0.02 to 0.5
%, The balance is iron containing impurities, and the surface is a cast iron material that can be remelted and chilled.

The reason for limiting the range of the amount of each alloying element added to the cast iron material of the present invention is as follows. C is
It is effective in preventing chilling, but if the added amount is less than 3.0%, the effect is not sufficient, while if it exceeds 3.5%,
The strength characteristics such as tensile strength and Young's modulus decrease, and the surface roughness decreases due to the coarsening of the graphite structure.
It was set to 3.5%.

Si is not only effective as an inoculant but also effective in promoting graphitization of the carbon component contained in the casting together with C and preventing the formation of chill. If less than 1.5%, those effects are not sufficient, while if more than 2.8%, the graphite is coarsened due to the relationship with C, and mechanical properties such as tensile strength and Young's modulus and surface roughness. In order to reduce the degree, it was set to 1.5 to 2.8%.

Since Mn is a pearlite-forming element, it is added to improve the tensile strength and wear resistance, but if the addition amount is less than 0.5%, the effect is not sufficient,
On the other hand, if it exceeds 0.9%, not only the strength is not improved, but also segregation to the grain boundaries is increased and the machinability is deteriorated, so the content was made 0.5 to 0.9%.

When P is added in excess of 0.1%, P promotes crystallization of steadite and deteriorates machinability and toughness, so P was made less than 0.1%.

[0009] S crystallizes A-type graphite and improves the machinability due to the compound with Mn.
If it is less than 06%, the effect is not sufficient, while if it exceeds 0.2%, the mechanical properties are impaired, so the content was made 0.06 to 0.2%.

Since Cu reduces the solubility of carbon in iron, it is added to prevent the formation of chill and to pearlite the matrix structure and to improve the mechanical properties.
If the added amount is less than 0.6%, the effect is not sufficient, and
If it exceeds 2%, not only the mechanical properties do not improve, but also the machinability due to segregation deteriorates, so 0.6-1.2%
And

Ce prevents the occurrence of chill, and at the same time,
It is added to prevent the formation of blowholes due to the generation of gas during remelting chilling, but due to the balance with S, if the addition amount is less than 0.02%, the effect is not sufficient and 0.5%.
On the contrary, if it exceeds, 0.02 to promote the generation of chill,
It was set to 0.5%.

[0012]

Embodiments of the present invention will be described below.

The molten metal of this example was prepared by melting the FC return material and steel scrap in the atmosphere in a 20 kg high-frequency melting furnace, adding a Fe-Mn alloy to prepare the molten metal, and then receiving the molten metal in a ladle. It was prepared by pouring hot water, adding pure Cu and Ce (Misch metal), and further inoculating the Fe—Si alloy and the graphite-based inoculum at about 1500 ° C. A test piece for composition analysis and a test material with an as-cast diameter of 30 mm were cast with the molten metal to prepare test pieces for tensile strength, Young's modulus and surface hardness tests, and each test was carried out.
The composition was analyzed with a fluorescent X-ray analyzer, and the tensile strength was measured according to JIS
Z 2241 "Metallic material tensile test method" and Young's modulus were measured according to JIS Z 2280 "High temperature Young's modulus test method of metal materials" according to the static Young's modulus test method using a strain gauge. , Hardness is JIS Z 22
44 "Vickers hardness test method".

Table 1 shows the component composition and the test results of this example.
Shown in

[0015]

[Table 1]

The present example showed performance equivalent to FC300 in any of tensile strength, Young's modulus and hardness.

Further, the molten metal has an outer diameter of 18 mm and a wall thickness of 2 mm.
Outline 2 in which the steel pipe is poured into a sand mold having a cylindrical cavity for accommodating the steel pipe at a tapping temperature of about 1400 ° C.
A 4 mm tubular casting was cast. Laser irradiation was performed on the outer peripheral surface of this tubular casting to remelt and chill the outer peripheral surface to produce a remelted and chilled tubular casting. Base structure of cast iron part as cast, presence or absence of chilling near steel pipe and structure of re-melt chilled tubular casting, presence or absence of chilling near surface, hardness of re-melt chilled casting surface, chill depth Is shown in Table 2. In addition,
The hardness of the remelted and chilled casting is JIS Z 2251.
It was measured according to the "microhardness test method".

[0018]

[Table 2]

In the present embodiment, even when the steel pipe was cast and wrapped, chill did not occur in the cast iron material portion near the steel pipe, and the entire cast structure became a pearlite structure. In addition, chilling near the casting surface was favorably performed by remelting chilling. The maximum HV value of the hardness of the remelted and chilled casting surface is 819.

Next, as Comparative Example 1, a remelted chilled tubular casting was produced by using a cast iron material equivalent to FC300 and performing the same casting and laser irradiation as in the above-mentioned Examples. The composition and tensile strength, Young's modulus, and hardness measurement results of this cast iron material are also shown in Table 1, and the matrix structure of the cast iron part as cast, the presence or absence of chilling near the steel pipe, and the remelted chilled tubular casting Table 2 also shows the structure, the presence or absence of chilling near the surface, the hardness of the remelted chilled casting surface, and the chill depth.

In Comparative Example 1, the tensile strength, Young's modulus and hardness were about the same as those of the Examples, and remelting and chilling was performed well. However, about half of the cross-sectional area of the cast iron material in which the steel pipe was cast was chilled after casting. The hardness of the remelted and chilled casting surface was similar to that of the example.

Next, as Comparative Example 2, a cast iron material equivalent to FC150 was prepared. Table 1 also shows the component composition, tensile strength, Young's modulus, and hardness measurement results of this cast iron material. In Comparative Example 2, since the eutectic graphite was crystallized in the as-cast cast iron portion, the matrix structure became ferrite, and the structure had a ferrite structure of 60% and the balance being a pearlite structure, unlike the above examples. In Comparative Example 2, casting and laser irradiation were performed in the same manner as in the above Example to produce a remelted chilled tubular casting, but gas defects occurred and a good chill layer could not be obtained.

[0023]

According to the present invention, it is possible to obtain a cast iron material having excellent mechanical properties, in which chill does not occur inside even when a metal material is cast in and the surface is remelted and chilled.

Claims (1)

[Claims] 1. A weight ratio of C: 3.0 to 3.5%, Si:
1.5-2.8%, Mn: 0.5-0.9%, P: 0.
1% or less, S: 0.06 to 0.2%, Cu: 0.6 to
1.2%, Ce: 0.02 to 0.5%, the balance consisting of iron containing impurities, and the surface thereof being capable of remelting and chilling, a cast iron material.