CN1242081C - Ultrapure smelting process for nickel-base high-temperature alloy - Google Patents

Abstract

The present invention discloses a method for smelting super purity nickel base high temperature alloy. The method comprises the steps that degassing processing is carried out; high temperature alloy elements are chemically cleaned and heated to be 1600 DEG C to 1650 DEG C for high temperature refining for fifteen to twenty minutes, and the power is cut off for condensing; subsequently, the temperature is raised to be 1490 DEG C to 1540 DEG C for refining for twenty to thirty minutes; after low temperature refining ends, the temperature is raised to be 1500 DEG C to 1550 DEG C, and then the high temperature alloy elements are cast into a casting ingot as a standby; elements which are degassed are used as raw material to smelt nickel base high temperature alloy, and thus, the nickel base high temperature alloy which has a low carbon content and a low gas content can be obtained. Processed raw material carries less gas, carbon can not added in the period of smelting alloy, refining time is not long, and thus, the nickel base high temperature alloy which has very low content of gas and carbon can be obtained. The present invention is mainly applied to the nickel base high temperature alloy which is required to have both low carbon content and low gas content.

Description

The smelting ultra-pure method of nickel base superalloy

Technical field

The present invention relates to vacuum melting technique, specifically a kind of smelting ultra-pure method that adopts common raw material to realize the nickel base superalloy of low gas and carbon content.

Background technology

Gas in the alloy can make alloy produce pore and loose, and pore can become the alloy fracture formation of crack usually with loose.Therefore, reducing the alloy gas content is a kind of important means that improves superalloy intensity.For some nickel base superalloys, carbide is harmful phase, and too much carbide can endanger alloy property, therefore needs a kind of smelting ultra-pure method that reduces gas content and carbon content simultaneously of invention.

Usually adopt the method that adds carbon to come deoxidation during conventional high-temperature alloy vacuum metling technology.Want the superalloy of smelting low carbon, need decarburization in deoxidation, this just requires to prolong refining time, improves refining temperature, Volatile Elements is difficult to control under some vacuum but can therefore cause, and decarburization, degasifying effect are unsatisfactory, gas content can't drop to the level of expectation, and low-carbon (LC) and low-gas content can't be taken into account especially.Traditionally, can also realize the purpose of low gas and carbon content by selecting high pure raw material for use, but can improve smelting cost greatly.

Summary of the invention

The purpose of this invention is to provide the smelting ultra-pure method that a kind of assurance realizes the nickel base superalloy of low carbon content and low-gas content cheaply simultaneously.

For realizing above purpose, technical scheme of the present invention is:

1) degassing was handled: to the clear back temperature raising to 1600 of superalloy elementization～1650 ℃ high temperature refining 15～20 minutes, the power failure condensation is saturating, temperature raising to 1490 then～1540 ℃ low-temperature refining 20～30 minutes, low-temperature refining finish back temperature raising to 1500～1550 ℃, and to pour into ingot casting standby.

2) adopting the above-mentioned element of handling through the degassing is that raw material is smelted nickel base superalloy: temperature raising to 1490～1540 ℃ low-temperature refining was 15～20 minutes after change was clear, the power failure condensation is saturating, temperature raising to 1500～1550 ℃ cast can obtain the nickel base superalloy of low carbon content and low-gas content.

Wherein: nickel, cobalt simple substance alloying element are added 0.01～0.02% carbon respectively when the degassing is handled; To chromium, tungsten simple substance alloying element, when handling, the degassing adds 40～60% nickel respectively.

The present invention has following advantage:

1. have the characteristics that low-gas content and low carbon content have concurrently.The present invention makes alloying element have lower gas content by rational starting material treatment process (that is: all have during raw-material processing and the alloy smelting process that condensation is saturating), and general oxygen, nitrogen content all can reach below the 5ppm; The present invention does not add carbon during alloy smelting, make alloy have lower carbon content, generally can reach below the 30ppm.

2. have low-cost characteristics.The present invention is owing to adopt common raw material to greatly reduce smelting cost.

3. low, the refining time weak point of the refining temperature of alloy smelting of the present invention makes alloying constituent be easy to control.

4. the present invention is mainly used in the nickel base superalloy that requires low-carbon (LC) and low-gas content simultaneously.

Description of drawings

Fig. 1 is nickel of the present invention, cobalt, nickel chromium triangle, nickel tungsten degassing treatment process curve.

Fig. 2 is a kind of Ni75-Co5-W6-Cr6-Al6-Ti2 experiment of one embodiment of the present of invention nickel base superalloy smelting technology curve.

Embodiment

Below in conjunction with embodiment and accompanying drawing in detail the present invention is described in detail.

With a kind of Ni75-Co5-W6-Cr6-Al6-Ti2 experiment nickel base superalloy is embodiment, at first wherein nickel, cobalt, chromium, tungsten is carried out the following degassing and handles:

Get electrolytic nickel, electrolytic cobalt and add the clear back of 0.015% carbonization temperature raising to 1600 ℃ high temperature refining 15 minutes respectively, the power failure condensation is saturating, and temperature raising to 1490 ℃ low-temperature refining is 20 minutes then, and low-temperature refining finishes back temperature raising to 1500, and ℃ to pour into ingot casting standby.Referring to Fig. 1 process curve.

Power taking is separated chromium, tungsten rod and is added the clear back of 50% electrolytic nickelization temperature raising to 1650 ℃ high temperature refining 20 minutes respectively, the power failure condensation is saturating, temperature raising to 1540 ℃ low-temperature refining is 30 minutes then, and low-temperature refining finishes that back temperature raising to 1550 ℃ pours into nickel chromium triangle respectively, nickel tungsten binary alloy ingot casting is standby.Referring to Fig. 1 process curve.

Decarburization of the present invention, degassing principle:

Decarburization of the present invention and deoxidation in refining period are carbon reduction metal oxide under the high temperature, and the reaction of cloth Dorr had both taken place, and its process can be represented with following reaction formula:

(1)

(2)

(3)

Two steps of gasification that promptly comprise CO reduction MeO and carbon.

Condensation is as follows through journey degassing principle, and gas is dissolved in separately in the metal with atomic condition in solubility range, and the standard free melting energy (with oxygen is example) of gas in metal can be represented by the formula:

${\mathrm{\&Delta;<figure-callout\; id="0"\; label="G\; T"\; filenames="C0313353300062.png"\; state="\{\{state\}\}">G</figure-callout>}}_T^{}={\mathrm{\&Delta;H}}_{298}^0-{\mathrm{T\&Delta;S}}_{298}^0=A+\mathrm{BT}...\left(4\right)$

That is:

$\mathrm{<figure-callout\; id="0"\; label="log\; C"\; filenames="C0313353300062.png"\; state="\{\{state\}\}">log</figure-callout>}{C}_{}{}_0=\frac{1}{2}\log P_{O_2}-\frac{A^{\&prime;}}{T}-B^{\&prime;}...\left(5\right)$

In the formula:

$A^{\&prime;}=\frac{A}{2.303R}=\frac{{\mathrm{\&Delta;H}}_{298}^0}{2.303R}$

$B^{\&prime;}=\frac{B}{2.303R}=\frac{-{\mathrm{\&Delta;S}}_{298}^0}{2.303R}$

By formula (5) as can be seen, oxygen concentration of ordinary dissolution in alloy is decided by the dividing potential drop of oxygen in the system, and therefore reducing system pressure (promptly vacuumizing) can reduce the solubleness of oxygen in alloy.In addition, because the dissolution process of oxygen in alloy is thermo-negative reaction, temperature reduces also can reduce the solubleness of oxygen in alloy.In like manner, reduction system pressure, temperature can reduce the solubleness of other gas in alloy such as nitrogen.Technology of the present invention is in condensation process, and alloy temperature constantly reduces, and system pressure also constantly reduces, thereby gas content is constantly reduced, and reaches the purpose of the degassing.

Adopt above method to handle raw gas content and obviously reduce, table 1 is that gas content compared before and after several starting material were handled.

Gas content relatively before and after several starting material of table 1. were handled

	Ni		Ni-Cr		Co		Ni-W
									O(ppm)	N(ppm)	O(ppm)	N(ppm)	O(ppm)	N(ppm)	O(ppm)	N(ppm)
	Before the processing	42	1	328	1199	80	10	28									5
After the processing									7	1	77	74	10	1	12	2

Starting material just can be used for smelting a kind of Ni75-Co5-W6-Cr6-Al6-Ti2 experiment nickel base superalloy that present embodiment adopts after the degassing is handled, and concrete smelting process is as follows:

Learning from else's experience by alloying constituent, nickel 63%, cobalt 5%, nickel chromium triangle 12%, the nickel tungsten 12% that the degassing handles adds aluminium 6% again, titanium 2% is changed clear back temperature raising to 1500 ℃ low-temperature refining 20 minutes, the power failure condensation is saturating, temperature raising to 1550 ℃ cast can obtain the nickel base superalloy of low carbon content and low-gas content.Referring to Fig. 1 process curve.Table 2 is gas and carbon content comparison when adopting technology of the present invention and traditional technology to smelt respectively to the present embodiment alloy.

Table 2. technology of the present invention and traditional technology result are relatively

	C(ppm)	O(ppm)	N(ppm)
				The present invention	25	4	3
Traditional technology	150	15	10

As seen adopt the present invention can realize the low-cost purpose that reduces carbon content and gas content down simultaneously.

Claims (1)

1. the smelting ultra-pure method of a nickel base superalloy, it is characterized in that: 1) degassing was handled: to the clear back temperature raising to 1600 of superalloy elementization～1650 ℃ high temperature refining 15～20 minutes, the power failure condensation is saturating, temperature raising to 1490 then～1540 ℃ low-temperature refining 20～30 minutes, low-temperature refining finish back temperature raising to 1500～1550 ℃, and to pour into ingot casting standby;

Wherein: nickel, cobalt simple substance alloying element are added 0.01～0.02% carbon respectively when the degassing is handled; To chromium, tungsten simple substance alloying element, when handling, the degassing adds 40～60% nickel respectively;

2) adopting the above-mentioned element of handling through the degassing is that raw material is smelted nickel base superalloy: temperature raising to 1490～1540 ℃ low-temperature refining was 15～20 minutes after change was clear, the power failure condensation is saturating, temperature raising to 1500～1550 ℃ cast can obtain the nickel base superalloy of low carbon content and low-gas content.

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