JPH0428837A - Continuous casting mold material made of high strength cu alloy having high cooling capacity and its manufacture - Google Patents

Abstract

PURPOSE:To provide a continuous casting mold material with high cooling capacity while it combines high temp. strength and high temp. elongation, required for a continuous casting mold, by subjecting Cu alloy stock having a specified compsn. to soln. treatment, cold rolling and two stage aging treatment under specified conditions. CONSTITUTION:A Cu alloy constituted of, by weight, 0.1 to 1.5% Cr, 0.01 to 0.2% Zr, 0.005 to 0.7% Ti, 0.003 to 0.1% Si, 0.005 to 1.5% of one or more kinds among Fe, Ni and Co and the balance Cu with inevitable impurities is used as stock. This alloy is subjected to ordinary soln. treatment and is thereafter cold-rolled at 5 to 30% draft. Next, the alloy is subjected to primary aging treatment at 425 to 475 deg.C and is furthermore subjected to secondary aging treatment at 525 to 575 deg.C to sufficiently precipitate fine precipitates as well as to reduce the content of the alloy components entering into solid soln. in the matrix. In this way, the continuous casting mold material provided with >=55kg/mm<2> cold tensile strength, >=33kg/mm<2> high temp. tensile strength (500 deg.C) and >=73% electrical conductivity by IACS% can be manufactured.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is composed of a Cu alloy that has high strength and high thermal conductivity, and therefore enables thinning of the wall, and combines this thinning and high thermal conductivity. Demonstrates excellent cooling ability,
The present invention relates to a continuous casting mold material that enables high-speed casting, and a method for manufacturing the same.

[Conventional technology]

The same applicant had previously filed a patent application No. 81-271103 (Japanese Unexamined Patent Publication No. 63-125632) for a Cu alloy used in the production of continuous casting mold materials.

This conventional continuous casting mold material composed of a Cu alloy has the following content in weight% (hereinafter, % in terms of composition indicates weight%): Cr: 0.1 to 2.5%, Zr: 0.01
~0.5%, Ti:0.01~0.7%, Si
: Contains 0.003 to 0.1%, one or more of Fe, Ni, and Co20.1 to 1.2%, with the remainder consisting of Cu and unavoidable impurities. A molten Cu alloy is prepared, cast in a mold, and subjected to hot processing such as hot forging or hot rolling to obtain a Cu alloy material.Then, this Cu alloy material is heated to a predetermined temperature within the range of 950 to 1050°C. After solution treatment under normal conditions of holding for a predetermined time, aging treatment is carried out once under normal conditions of holding at a predetermined temperature in the range of 450 to 550°C for a predetermined time to eliminate precipitates in the matrix. It is manufactured by precipitation to improve strength.

[Problem to be solved by the invention]

On the other hand, in recent years, there has been a remarkable improvement in productivity in continuous steel casting technology, with casting speeds from 1 to 2 m/win to 3 to 4 m/sin, and with this The surface temperature of the inner surface of the mold that comes into contact with the mold also increases, and depending on the casting conditions, it may reach 500°C or more.

However, including the conventional continuous casting mold material made of Cu alloy,
Many other continuous casting mold materials made of Cu alloys, such as 50
Tensile strength: approx. 20-30 kg in high temperature tensile test at 0℃
/-1 elongation: Since it is composed of a Cu alloy that exhibits approximately 20 to 30%, it has high temperature strength that can withstand large thermal stress and high temperature elongation that can withstand severe thermal fatigue environments, but it does not have sufficient thermal conductivity. 40-60% in electrical conductivity (IAC 8%)
Therefore, in high-speed casting as described above, the mold is easily deformed and cracked, and the service life is reached in a relatively short period of time.

[Means to solve the problem]

Therefore, from the above-mentioned viewpoints, the present inventors developed Cu that has good thermal conductivity, that is, high cooling ability, while having the high-temperature strength and high-temperature elongation required for continuous casting molds.
As a result of research to develop alloy continuous casting mold material, Cr: 0.1-1.5%, Zr: 0.01
~0.2%, Ti: 0.005~0.7%, S j
: 0.003-0.1%, Fe, Ni, and Co(
One or more of the following (hereinafter referred to as iron group metals):
A slab made of a Cu alloy with a composition of 0.005 to 1.5% and the remainder consisting of Cu and unavoidable impurities is subjected to hot working such as hot forging and hot rolling under normal conditions. After preparing a Cu alloy material, this Cu alloy material was subjected to solution treatment under normal conditions, and then cold rolled at a reduction rate of 5 to 30%.
When a continuous casting mold material made of Cu alloy is manufactured by performing a primary aging treatment at a predetermined temperature within the range of 5 to 475 °C and a secondary aging treatment at a predetermined temperature within the range of 525 to 575 °C, In the above primary aging treatment, Cr and Zr dissolved in the matrix are finely precipitated in the matrix mainly in the form of Cr and CuSZr, and in the secondary aging treatment, Cr and Zr are also precipitated finely in the matrix. Iron group metals are finely precipitated in the form of (Fe, Ni, Co) Tiy, and in this case, the rolling reduction applied prior to aging treatment is 5 to 3.
A large amount of working strain and dislocations are formed in the Cu alloy material due to 0% cold rolling, and these working strains and dislocations significantly inhibit the precipitation of the above precipitates during the aging treatment in the next process. The resultant Cu alloy continuous casting mold material maintains high elongation at room temperature and high temperature.
High room temperature and high temperature strength, i.e. 55 kg/mm
It has a room temperature tensile strength of 33 kg/mm2 or more and a high temperature tensile strength (500°C) of 33 kg/mm2 or more, and is solid-solved in the base material by cold rolling after the above solution treatment and two aging treatments. The content of the alloying components is reduced, and the base material becomes substantially composed of Cu, so it has a low thermal conductivity of more than 73% (IAC 3%) in terms of electrical conductivity. In practical use, it is possible to make the wall thinner due to improved strength, and the research results showed that this thinner wall and high thermal conductivity combined with excellent cooling performance.

This invention was made based on the above research results, and includes (a) Cr: 0.1 to 1.5%, Zr: 0.01
~0.2%, Tj20, 005~0.7%, Si:0.
003-0.1%, one of Fe, Ni, and Co
A Cu alloy material containing one or more species: 0.005 to 1.5%, with the remainder consisting of Cu and unavoidable impurities, is subjected to solution treatment under normal conditions. After that, it is cold rolled at a reduction rate of 5 to 30%, and
A primary aging treatment at a predetermined temperature within the range of 475°C and a secondary aging treatment at a predetermined temperature within the range of 525 to 575°C are performed to remove sufficient precipitation of fine precipitates. A method for manufacturing a continuous casting mold material made of a high-strength Cu alloy that has high cooling ability and improves strength and thermal conductivity by reducing the content of alloy components dissolved in solid solution in the base material.

(b) Cr: 0.1-1.5%, Zr: O, 0I
-0.2%, Ti: 0.005-0.7%, Si: 0
．． 003 to 0.1%, one or more of Fe, Nj, and Co: 0.005 to 1.5%, and the remainder is Cu and inevitable impurities. It is composed of a large amount of precipitates that are finely and uniformly dispersed in the substrate and substantially Cu.
A highly cooled material with a tensile strength at room temperature of 55 kg/m or more, a tensile strength at high temperature (500°C) of 33 kg/mJ or more, and an electrical conductivity of near 3% (IAC 3%) or more. Continuous casting mold material made of high-strength Cu alloy.

It has the following characteristics.

Next, in the continuous casting mold material and the manufacturing method thereof of the present invention, the reason why the composition of the Cu alloy constituting the continuous casting mold material, the reduction ratio of cold rolling, and the aging treatment temperature are limited as described above will be explained.

A. Composition of Cu alloy (a) Cr Most of the Cr dissolved in the base material during solution treatment is actively and finely precipitated within the crystal grains of the base material during the primary aging treatment. If the content is 0.1
If the content is less than 15%, it is possible to secure a high strength of room temperature tensile strength (T: 55 kg/mJu) and high temperature tensile strength (501) °C (T) of 33 kg/m4 or more, while the content is 15% or more.
If it exceeds 739a (I ACS9δ
) Since it would be difficult to ensure an electrical conductivity of 0.1 to 1.59.6, the content was set at 0.1 to 1.59.6.

(b) Zr Similarly, most of the Zr dissolved in the matrix during the solution treatment precipitates finely in the form of an intermetallic compound of Cu3Zr at the grain boundaries of the matrix during the primary aging treatment, and as a result, Since the grain boundary slip in is suppressed,
Grain boundary strength is improved, and as a result, embrittlement (decrease in ductility) due to grain boundary fracture at high temperatures is prevented, and thermal fatigue resistance is improved, but if the content is less than 0.01%, the above-mentioned The desired effect cannot be obtained in the action, and on the other hand, if the content is 0.2
%, like Cr, the proportion of solid solution in the matrix increases and it becomes difficult to secure the desired high electrical conductivity, so the content was set at □01-0.2%. .

(c) Like Ti and iron group metals, these components are dissolved in the base material by solution treatment, and 1
In the second aging treatment, almost no precipitation occurred, and in the second aging treatment (F
e, Ni, Co) Ti is precipitated finely and actively within the crystal grains of the base material mainly in the form of an intermetallic compound of (Fe, Ni, Co)2Ti, and is mixed with the above-mentioned fine Cr precipitates. In addition to significantly improving room temperature and high temperature strength, it also improves high temperature strength and high temperature elongation in coexistence with the Cu 3Z r precipitated at grain boundaries, but the content is 0.005 for both T1 and iron group metals. %, the desired effect of improving the above-mentioned action cannot be obtained; on the other hand, when the content exceeds 0.7% for TI, and 1.5% for iron group metals, Cr and Zr As with the case of the components, the proportion of solid solution in the matrix increases and it becomes difficult to secure electrical conductivity of 73% (IAC 3%) or more, so the content is determined as Ti :
0.005-0.7%, iron group metal: 0.005-1.5
%.

The (cl)Si St component includes the above (Fe, Ni, Co) Ti
If the content of y is less than 0.003%, the desired effect may not be obtained. However, if it exceeds 0.1%, coarse crystallites of St will appear during casting, and these will not disappear even in solution treatment, reducing high temperature strength and elongation. o, ooa~mouth, was set as 1%.

B. Manufacturing conditions (a) Reduction rate of cold rolling As mentioned above, cold rolling promotes the precipitation of precipitates in the solution-treated Cu alloy material in the aging treatment of the next step, and If the reduction rate is less than 5%, the desired effect will not be obtained; on the other hand, if the reduction rate is less than 5%, If it exceeds this, the elongation at room temperature and high temperature will decrease, so the rolling reduction ratio was set at 5 to 30%.

(b) Aging treatment temperature In this invention, as mentioned above, the alloy components are completely dissolved in solid solution by solution treatment, and a large amount of work strain and dislocations are formed by cold rolling, and then the aging treatment is performed in the next step. By precipitating as much of the alloy component as solid solution in the base material as possible, this precipitation increases the tensile strength at room temperature to 55 kg/md or more and the tensile strength at high temperature (5 (10
℃), ensuring high strength of 33 kg/mm2 or more, - The solid solution of blade metal components is extremely low, and ensuring high electrical conductivity of 73% (IAC 5%) or more due to the base material consisting essentially of Cu. It is. In other words, it is generally known that electrical conductivity is determined by the alloy matrix, and the lower the solid solution components in the matrix, the higher the electrical conductivity. If done properly, high electrical conductivity and high strength can be obtained.

From this point of view, when we investigated the types of precipitates and the temperature at which they tend to precipitate in the Cu alloy of the present invention having the above composition, we found that the precipitates were Cr, Cu3Zr, and (Fe,
Ni, Co) Ti accounts for most, y Cr and Cu a Z r in the temperature range of 425-475 °C, and (Fe, Ni, Co) Ti accounts for 5
It has been found that each aging process actively precipitates in the temperature range of 25 to 575°C x y, so even if the aging treatment temperature deviates from the above range to the lower or higher range, it is sufficient It is not possible to carry out such precipitation.

〔Example〕

Next, the present invention will be specifically explained using examples.

Using a normal vacuum melting furnace, each first
5 kg of each Cu alloy molten metal having the chemical composition shown in the table was melted, cast in a mold, and after facing, hot forged and hot rolled under normal conditions. Width: lOOmm x Thickness = 5
A hot rolled plate material of 11I11 was made, and then a Cu alloy material cut into a predetermined length from this was held at a temperature of 980 for 30 minutes, then subjected to solution treatment of water quenching, and then subjected to a rolling reduction rate shown in Table 1. cold rolling, as well as primary and secondary rolling under the conditions of holding for 1 hour at the temperatures shown in Table 1.
Methods 1 to 29 of the present invention and comparative methods 1 to 25 were carried out by performing a subsequent aging treatment to produce continuous casting mold materials 1 to 29 of the present invention and comparative continuous casting mold materials 1 to 25.

In addition, Comparative Methods 1 to 25 all meet one of the constituent requirements of this invention (marked with * in Table 1) or are outside the scope of this invention.

For comparison purposes, the same conditions were used except that the composition of the Cu alloy material subjected to cold rolling after solution treatment and the aging treatment applied once were as shown in Table 1. Conventional methods 1 to 3 were carried out to produce conventional continuous casting mold materials 1 to 3.

Next, the electrical conductivity of the various continuous casting mold materials obtained as a result was measured, and the materials were subjected to room temperature and high temperature tensile tests, and heat resistance tests.

In the high temperature tensile test, the bow tensile properties were measured after being held at 500°C for 10 minutes, and in the heat resistance test, the mold material was heated at 450°C + nl.
After being held at various temperatures of 0°C (n: an integer from 0 to 15) for 1 hour, the mold materials were heated under air cooling conditions, and the hardness of each mold material after heating was measured, and the hardness was 90% of the hardness before heating. The heating temperature at which the corresponding hardness was obtained was defined as the heat-resistant temperature. These results are shown in Table 2.

〔Effect of the invention〕

From the results shown in Tables 1 and 2, it can be seen that methods 1 to 1 of the present invention
Continuous casting mold materials 1 to 29 of the present invention manufactured in Step 29 are all conventional continuous casting mold materials 1 manufactured by Conventional methods 1 to 3.
It shows much better tensile strength at room temperature and high temperature than No. 3, and is much higher than that at 73% (IAC
5%) or more, whereas Comparative Methods 1~
As seen in Comparative Continuous Casting Mold Materials 1 to 25 manufactured in No. 25, even if any of the composition, rolling reduction, and aging temperature of the Cu alloy deviates from the scope of the present invention, the above characteristics cannot be achieved. It is clear that at least one of the characteristics will be inferior.

As mentioned above, according to the method of the present invention, it has a high strength of 55 kg/mm2 or more in room temperature tensile strength and 33 kg/mm2 or more in high temperature tensile strength (500 ° C.), and has an electrical conductivity of 73%. It is possible to manufacture a Cu alloy continuous casting mold material with excellent thermal conductivity of (IACS%), and therefore, in practical use of this Cu alloy continuous casting mold material, it is possible to reduce the thickness due to the above-mentioned high strength. As a result of this thinner wall thickness and the above-mentioned high thermal conductivity, it exhibits a significantly high cooling capacity, which brings about industrially useful effects such as being able to sufficiently respond to higher casting speeds.

Claims (2)

[Claims] (1) Cr: 0.1-1.5%, Zr: 0.01-0.
2%, Ti: 0.005-0.7%, Si: 0.003
-0.1%, one or more of Fe, Ni, and Co: 0.005 to 1.5%, and the remainder is Cu and unavoidable impurities (wt%). Composed of a Cu alloy with a large amount of precipitates finely and uniformly dispersed in the base material and a base material that is substantially composed of Cu, room temperature tensile strength: 55 kg/mm^2 or more, high temperature tensile strength (500 ° C.): 33kg/mm^2 or more,
A continuous casting mold material made of a high-strength Cu alloy with a high cooling ability and an electrical conductivity of 73% or more in IACS%. (2) Cr: 0.1-1.5%, Zr: 0.01-0.
2%, Ti: 0.005-0.7%, Si: 0.003
-0.1%, one or more of Fe, Ni, and Co: 0.005 to 1.5%, and the remainder is Cu and unavoidable impurities (wt%). After applying solution treatment under normal conditions to a Cu alloy material composed of a Cu alloy having The first aging treatment is performed at a predetermined temperature within the range of 525 to 575 degrees Celsius to ensure sufficient precipitation of fine precipitates, while reducing the content of alloy components dissolved in the matrix. A method for producing a continuous casting mold material made of a high-strength Cu alloy having a high cooling ability, which is characterized by improving strength and thermal conductivity by reducing the heat conductivity.