JPS6123728A - Method for controlling composition of alloy containing al and ti - Google Patents

Abstract

PURPOSE:To control the composition of an alloy contg. Al and Ti with high reproducibility by calculating the amounts of Al and Ti lost from the amounts of Al and Ti in the alloy and the amount of reactive oxygen in electro-slag remelting. CONSTITUTION:When an alloy contg. Al and Ti is obtd. by electro-slag remelting, the ratio in loss between Al and Ti is calculated from the amounts of Al and Ti in steel, the amount of reactive oxygen is calculated from the melting rates of Al and Ti in the alloy, the reaction interface and the composition of slag, and the total amount of Al and Ti lost are further calculated. The amounts of Al and Ti lost are calculated from said ratio in loss and the total amount of Al and Ti lost, and electro-slag remelting is carried out after adding said calculated amounts of Al and Ti preliminarily to a consumable electrode to obtain an alloy having a prescribed composition contg. Al and Ti.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for remelting Al and T by electroslag remelting.
The present invention relates to a suitable method for controlling Al and Ti components, which are considered to be extremely difficult to control when producing alloys containing i.

Electro Slag remelting (Electro SlagR)
The emQlting (hereinafter referred to as ESR) method generally
A method in which a consumable electrode (hereinafter simply referred to as an electrode) is melted by the electrical resistance heat of the molten slag, and the molten steel that drips and settles in the slag is continuously solidified in a water-cooled mold. There are advantages such as the ability to obtain clean steel with few inclusions, and the ability to obtain steel with a dense structure and little segregation due to layered solidification.Similarly, steel can be obtained by remelting. (Vacuum Arc
Compared to the remelting method, since the surface of the steel ingot is covered with slag and formed into an ingot, it has the advantage of being smooth and requiring no care such as surface scraping.

Conventionally, /j tar and Ti-containing alloys (hereinafter referred to as A-containing alloys)
Al, Ti superalloys containing particularly high percentages of Al and Ti (referred to as 1, Ti alloys) have been produced by the VAR process in vacuum.

This is because the ESR method (hereinafter simply referred to as ESR) performed in the atmosphere has large fluctuations in AJJ and Ti components, making it difficult to obtain an Al and Ti superalloy with the desired content. This was due to the fact that it was difficult to control.

Fluctuations in the Al and Ti components are mainly due to the loss of these components, so conventionally it has been considered to add eye-measured amounts of these components to the consumable electrode in advance. , but it was not possible to control component fluctuations, and even if it happened to be a good method, it was not a reproducible control method.

As shown in L, in the ESR of AA-containing, Ti alloys, A
M and Ti react with the slag, and the Al and Ti components vary, ie, decrease or increase.

The inventors have developed Nimonic 80A (+9 Cr
-L, SA l -2,5Ti -Ni), In
conel 718 (20cr-18Fe-0,6
A l -ITi -3No -5Nb -U i )
Regarding Al-containing, Ti-containing superalloys such as
When we analyzed the behavior of Al and Ti elements and also analyzed the slag-metal reaction, we found that [AM] and [Ti
l and (AchiO,) in the slag, (T I OJ)
It turns out that there is a relationship as shown in Figure 1 regarding the equilibrium with
The following equation for equilibrium with Oρ, (T i OL) (
1) % formula %] and the following experimental formula (2) also confirmed its correctness.

[%Al] [%Ti] II... Concentration in metal (wt%) NAAlO,, NTi0, No. 11 - Mole fraction in slag And, based on the relationship with the Sungu metal reaction,
Loss ratio of A l / Ti in metal △Ti/Δ
When the relationship between AM and the [%T i ]/[%Al1 cultivation ratio in the electrode was plotted, it was found that the relationship was as shown in FIG. 2. By determining the content ratio of Ti and Al in the electrode from FIG. 2, it is possible to know the loss ratio of these components.

Furthermore, by analyzing the fluctuations in Al and Ti components, it was found that the cause of loss of AIL and Ti was due to oxidation loss due to the reaction of atmosphere (0) → slag → metal.

As a result of further investigation into the loss of A l and tJ' Ti for ESR, we found that decreasing the dissolution rate of 1 increases the loss, and that the area of the slag-atmosphere reaction interface (where slag is The larger the contact area (area in contact with the slag), the larger the oxidation loss, the lower the basicity of the slag, the less the oxidation loss, and the (0) reaction amount and dissolution rate/reaction interface between slag and atmosphere. Area (K
g/)Ir/crn') When we plotted the relationship between the two by changing the type of slag, we found that
The relationship shown in Figure 3 was observed, and the AIL
The loss of Al and Ti [ashy ground with (0) in the atmosphere] is the degree to which Al and Ti combine with oxygen, and is related to factors such as dissolution rate and reaction interface area. 0) There is an important relationship between the amount of reaction oxygen (%/Kg/Hr, cm'), which is the value obtained by dividing the reaction amount (%) by the dissolution rate (Kg/) lr) and the reaction interface surface ta (Cm'). When the relationship between the amount of reacted oxygen and the slag was plotted using Proa 1, it was found that the relationship was as shown in Figure 4. In addition, in Fig. 3, regarding slag, CaF,
20CaF -80CaO and 40CaF, -30
The relationship between Ca-30Ca-30A and O5 composition was investigated using three examples. Also, Fig. 4 shows Ca0-CaF
.

The relationship between the two was investigated using the slag composition consisting of -AlO as an example.

From J2, the present inventors determined that the amount of oxygen per reaction (%
/Kg/Hr, crn'), and found that the content of Al and Ti can be controlled by the amount of reaction oxygen.

In other words, depending on the Al and Ti contents of the steel type, the loss ratio
In addition, by understanding the total loss amount of Al + Ti from the amount of reaction oxygen shown in Figure 4, A
The amount of loss of JJ and Ti can be calculated.

Therefore, by adding this amount of loss into the electrode (pole) in advance, it is possible to achieve the target content of Al and Ti.
It is possible to obtain Al-containing, Ti-containing steel.

The present invention is based on the above findings, and when obtaining an alloy containing Al and Ti by electroslag remelting,
The present invention relates to a method for controlling the content of Al and/or Ti in an alloy containing Al and Ti, which comprises controlling the content of Al and/or Ti by the amount of reactive oxygen.

Although the method of the present invention can be applied to various Al-containing and Ti-containing alloys, it is particularly effective when applied to ESH of Al-containing and Ti-containing superalloys containing 2-3% of Afl and Ti components, respectively. It is.

An example of the alloy is the old monic 80A mentioned above.

Inconel 7+8, A288 (25Ni
−+5cr −lMo−0,3A n−2,27i −
Various materials can be used for the slag used in the present invention, including Fe), but as mentioned above, the reaction rate (oxidation amount) with (0) of Al and Ti, the basicity of decrease (e.g. Siq% Al, 03, TiO in slag)
The S i OL in the slag must be kept low from the viewpoint of reducing the loss of Al and Ti.

CaO's manipulation power ■ increases the basicity of the slag and increases the loss.

Sluctosite, 80% CaF, -20% Cao
It is preferable to use one containing Ml.

In the method of the present invention, in order to suppress the loss of Al and Ti, it is preferable to spray an inert gas such as argon (Ar) or to perform Ar sealing by sealing the apparatus.

First, the present invention will be explained by way of examples.

Example Nimonic 80A (190r -1, EI A l
-2,57i -Ni) and performed ESR on A1. Control of Ti component was carried out. The A vertical position of the steel type is 1.6%, and the T
The amount of i is 2.5%, and these are the target values.

According to Fig. 2, the electrode middle part $Ti] / [zAU]
Find the loss ratio △T i /ΔAl from ≦. The slag composition was 80% CaF2-20% Can, and the apparatus was sealed with Ar. The reaction interface area of the device is 700 crn', and the dissolution rate is 370 kg
'/Hr.

According to Figure 4, the amount of reactive oxygen (
%/Kg/Hr/crn') was determined by calculation. The amount of reactive oxygen was approximately 0.5%/kg/Hr, cm'.

From this reaction 1M elementary amount and slag composition, the tortoise of Al+Ti was determined.
Calculating the amount of talos and setting the ball components, it is expected that 600g will be lost.

ESR was performed by adding 600 g of loss to AM in advance.

The results are shown in Figure 5.
imonic 80A was obtained.

[Brief explanation of drawings]

11th Δ is a graph showing the relationship between slag and metal; Figure 2 is a graph showing the relationship between [%Ti]/[%Alj in the electrode; Figure 3 is a graph showing the dissolution rate/relationship;
The figure is a graph explaining the effects of the present invention.◎ In Figure 3, B indicates Bottom and T indicates Top. Figure 1 Figure 2 Figure 3 Figure S

Claims (1)

[Claims] When an alloy containing Al and Ti is obtained by electroslag remelting, the content of Al and/or Ti is controlled by the amount of reactive oxygen during production of the alloy. A method for controlling the components in an alloy containing Al and Ti.