JPS628497B2 - - Google Patents

Description

[Detailed description of the invention]

This invention exhibits excellent high-temperature compression resistance, high-temperature oxidation resistance, high-temperature corrosion resistance, and high-temperature wear resistance (hereinafter collectively referred to as high-temperature properties), especially in high-temperature combustion atmospheres such as heavy oil and blast furnace gas. This relates to Fe-Ni-Cr heat-resistant alloys. Generally, heavy oil, blast furnace gas, etc. are used as fuel in heating furnaces, soaking furnaces, heat treatment furnaces, etc. for iron manufacturing, and for this reason, skid metal fittings, which are the structural members of these furnaces, and other furnaces are used as fuel. Floor materials must be exposed to a high-temperature combustion atmosphere of 1,200 to 1,350°C and containing highly corrosive and oxidizing vanadium oxides (V oxides) and sulfur oxides (S oxides). Moreover, the conditions under which these furnaces are used are becoming increasingly severe. Under such circumstances, currently Fe-30% Cr-22% is mainly used to manufacture the structural members of these furnaces.
Fe-based heat-resistant alloy with Ni composition, Co-28%Cr
A Co-based heat-resistant alloy with a composition of −20% Fe has been used, but the former Fe-based heat-resistant alloy does not exhibit satisfactory high-temperature properties when used under particularly harsh conditions, while the latter Co-based heat-resistant alloy Although these alloys exhibit better high-temperature properties than the Fe-based heat-resistant alloys, they do not have sufficient high-temperature compression resistance in the above-mentioned high-temperature combustion atmosphere of 1,300 to 1,350 degrees Celsius. Currently, the scope of use is limited. Therefore, from the above-mentioned viewpoint, the present inventors conducted research to develop a material with excellent high-temperature properties, and as a result, the results were as follows: C: 0.1-0.6%, Si: 0.1-2%, Contains Mn: 0.1 to 2%, Cr: 25 to 35%, Ni: more than 30% to 47%, Co: 1 to 10%, Hf: 0.001 to 0.45%, and further contains W: 0.1 as necessary. ~6%, Mo: 0.1~6%, Ti: 0.1~3%, Nb: 0.1~3%, Ta: 0.1~3%.
Fe-Ni with a composition consisting of Fe and unavoidable impurities
-Cr-based alloys have excellent high-temperature properties, that is, high-temperature compression resistance, especially in high-temperature combustion atmospheres of 1200 to 1300°C and containing extremely corrosive and oxidizing V oxides and S oxides. They obtained the knowledge that it exhibits high-temperature oxidation resistance, high-temperature corrosion resistance, and high-temperature wear resistance. This invention was made based on the above knowledge, and the reason why the component composition range was limited as described above will be explained below. (a) C The C component includes Cr, which is a solid solution in the base material to improve strength (compression resistance) and is an alloying component.
By combining W, Hf, Mo, Ti, Nb, and Ta, etc., carbides such as M ₇ C ₃ , MC, and M ₂₃ C ₆ are formed to improve hardness (wear resistance and It has the effect of improving weldability and castability, but if the content is less than 0.1%, the desired effect cannot be obtained, while if the content exceeds 0.6%, the precipitation of the carbides will increase. In addition, the particle size becomes coarser and reduces toughness, which further lowers the melting point of the substrate and causes a decrease in heat resistance.
%. (b) Si Along with Cr, the Si component has the effect of improving high-temperature corrosion resistance and high-temperature oxidation resistance in a high-temperature combustion atmosphere, as well as deoxidizing effect and the effect of improving the fluidity of molten metal to improve castability. Cr has the effect of improving high-temperature compression resistance (high-temperature strength), but if the content is less than 0.1%, the desired effect cannot be obtained, while if the content exceeds 2%, Cr As the solder properties and weldability decrease in relation to
Its content was set at 0.1-2%. In addition, since the Si component has the deoxidizing effect as described above, when it is used as a deoxidizing agent, it may be contained as an unavoidable impurity in a range of less than 0.1%. The total content, including the content of unavoidable impurities, should be 0.1% or more. (c) Mn In addition to stabilizing austenite by solid solution in the base material, Mn component has a deoxidizing effect, and also has thermal shock resistance and high-temperature wear resistance (high-temperature hardness).
It has the effect of improving the
If it is less than %, the desired effect cannot be obtained,
On the other hand, if the content exceeds 2.0%, the high-temperature corrosion resistance and high-temperature oxidation resistance tend to deteriorate, so the content was set at 0.1 to 2.0%. In addition, the Mn component also has a desulfurization effect in addition to the deoxidizing effect as mentioned above, so when it is used as a deoxidizing and desulfurizing agent, it is used as an unavoidable impurity in the range of less than 0.1%. However, in this case as well, the ingredients should be adjusted so that the total content, including the content of unavoidable impurities, is 0.1% or more. (d) Cr A part of the Cr component forms a solid solution in the base material, improving high-temperature corrosion resistance and high-temperature oxidation resistance, especially in a combustion atmosphere, and the remaining part forms carbide to improve hardness. , which has the effect of improving high-temperature wear resistance, but its content is 25%.
If the content is less than 35%, the desired effect cannot be obtained, while if the content exceeds 35%, the toughness will decrease, so the content was set at 25 to 35%. (e) Ni In addition to stabilizing the austenite base and increasing its toughness, the Ni component has the effect of improving high-temperature water resistance and high-temperature oxidation resistance in a combustion atmosphere together with Cr, but its content is 30% or less. In this case, the desired effect cannot be obtained in the above-mentioned action, and on the other hand, even if the content exceeds 47%, no further improvement effect appears, so the content was set at more than 30% to 47%. (f) Co The Co component has the effect of further improving thermal shock resistance and high-temperature hardness (high-temperature abrasion resistance) when dissolved in the base material, but its content is 1.
If the content is less than 10%, the desired effect cannot be obtained in the above action, and on the other hand, if the content exceeds 10%, no further improvement effect will be obtained.
Its content was set at 1 to 10%. (g) Hf The Hf component improves high-temperature strength (high-temperature compression resistance) and high-temperature oxidation resistance by solidly dissolving in the austenitic matrix, which is mainly composed of Fe, Ni, and Cr components, and also combines with C. to form MC-type carbide, which has the effect of improving high-temperature hardness (high-temperature wear resistance), but if the content is less than 0.001, the desired effect cannot be obtained;
Even if the content exceeds 0.45%, not only will further improvement effects not be achieved, but the content yield will decrease upon dissolution in the atmosphere, making it uneconomical.
Its content was determined to be 0.001 to 0.45%. (h) W and Mo These components dissolve solidly in the base material, strengthen it, and form carbides to further improve high-temperature strength (high-temperature compression resistance and high-temperature hardness (high-temperature wear resistance)). Therefore, it is included as necessary when further improvement effects are required due to these properties, but the content is 0.1%.
If the content is less than 6%, the desired effect cannot be obtained, while if the content exceeds 6%, the toughness will decrease. %. (i) Ti, Nb, and Ta These components significantly suppress the growth of crystal grains in the base material, rather they make the crystal grains finer and
It forms MC-type carbides and nitrides to further improve high-temperature strength (high-temperature compression resistance) and high-temperature hardness (high-temperature wear resistance), so it is necessary when these properties are required. However, the content varies depending on the
If the content is less than 0.1%, the desired effect of improving the above action cannot be obtained, while if the content exceeds 3%, not only will the formation of carbides at high temperatures be promoted and the toughness will decrease, but also the Since the formation of Ti oxides becomes noticeable and the high-temperature corrosion resistance and high-temperature oxidation resistance deteriorate, the content is reduced to Ti: 0.3 to 3.
%, Nb: 0.1-3%, and Ta: 0.1-3%. In addition, Zr may be contained as an unavoidable impurity, but if the content exceeds 0.3%,
The content of Zr should not exceed 0.3%, as it will have a negative effect on toughness, castability, and weldability. Next, the Fe-Ni-Cr heat-resistant alloy of the present invention will be specifically explained with reference to Examples. Example By melting molten metals having the compositions shown in Table 1 in the atmosphere using an ordinary high-frequency melting furnace, and then casting them into sand molds,
Various test pieces of heat-resistant alloys 1 to 28 of the present invention, comparative heat-resistant alloys, and conventional heat-resistant alloys 1 and 2 were manufactured, and subjected to high-temperature tensile tests and high-temperature compression creep tests for the purpose of evaluating high-temperature compression resistance. Vanadium attack resistance tests and oxidation resistance tests were conducted to evaluate high-temperature corrosion resistance and high-temperature oxidation resistance in an atmosphere, and further to evaluate high-temperature wear resistance.
The Vickers hardness at 1000°C was measured. In the high-temperature tensile test, tensile strength, 0.2% proof stress, and elongation at 1000°C were measured. The high-temperature compression creep test was conducted using a restrained welding thermal cycle reproduction device, and the compression deformation resistance at 1200°C was determined by the stress value at the time when the amount of compression deformation was 0.05%/hr. In addition, the vanadium attack resistance test was conducted based on the Jakushin Law, in which corrosive ash (85% V ₂ O ₅ + 15% Na ₂ SO ₄ ) was applied to the test piece at a rate of 20 mg/cm ² and the test piece was heated to 800°C. The test was carried out under conditions of heating and holding in a type electric furnace for 20 hours, and the corrosion weight loss after the test was measured. Furthermore, in the oxidation resistance test, the specimen was heated to 1300℃.

【table】

【table】

【table】

[Table] The test was conducted under conditions of continuous heating for 200 hours in a heated vertical electric furnace, and the oxidation loss was measured after the test. The results of these measurements are shown in Table 2. From the results shown in Table 2, the heat-resistant alloy 1 of the present invention
-28 have superior high-temperature strength (high-temperature compression resistance) and high-temperature hardness compared to conventional heat-resistant alloys 1 and 2, which have compositions corresponding to the conventional Fe-based heat-resistant alloys and conventional Co-based heat-resistant alloys. It is clear that the material has excellent properties such as high-temperature wear resistance, high-temperature corrosion resistance, and high-temperature oxidation resistance. On the other hand, as seen in Comparative Heat Resistant Alloys 1 to 9, if the content of any of the constituent components (marked with * in Table 1) falls outside the scope of this invention, the above-mentioned It can be seen that at least one of the characteristics becomes inferior. As mentioned above, the Fe-Ni-Cr heat-resistant alloy of the present invention has excellent high-temperature compression resistance, high-temperature corrosion resistance,
It has high-temperature oxidation resistance and high-temperature wear resistance, and exhibits excellent high-temperature corrosion resistance, especially against highly corrosive and oxidizing oxides at high temperatures, so it is especially suitable for use with heavy oil, blast furnace gas, etc. as fuel. Items that have industrially useful properties such as exhibiting an extremely long service life when used as structural members for steel manufacturing heating furnaces, soaking furnaces, and heat treatment furnaces, such as skid metal fittings and other hearth parts. It is.

Claims (1)

[Claims] 1 C: 0.1 to 0.6%, Si: 0.1 to 2%, Mn: 0.1 to 2%, Cr: 25 to 35%, Ni: more than 30% to 47%, Co: 1 to 10%, Fe exhibiting excellent high-temperature properties in a high-temperature combustion atmosphere, characterized by having a composition (weight %) of Hf: 0.001 to 0.45%, with the remainder consisting of Fe and unavoidable impurities.
-Ni-Cr heat-resistant alloy. 2 C: 0.1-0.6%, Si: 0.1-2%, Mn: 0.1-2% Cr: 25-35%, Ni: more than 30%-47%, Co: 1-10%, Hf: 0.001-0.45% , and further contains one or two of the following: W: 0.1 to 6%, Mo: 0.1 to 6%, and the remainder is Fe and unavoidable impurities (weight %). A Fe-Ni-Cr heat-resistant alloy that exhibits excellent high-temperature properties in a high-temperature combustion atmosphere. 3 C: 0.1-0.6%, Si: 0.1-2%, Mn: 0.1-2% Cr: 25-35%, Ni: more than 30%-47%, Co: 1-10%, Hf: 0.001-0.45% , and further contains one or more of the following: Ti: 0.1 to 3%, Nb: 0.1 to 3%, Ta: 0.1 to 3%, and the remainder is
Composition consisting of Fe and unavoidable impurities (more than % by weight)
An Fe-Ni-Cr heat-resistant alloy that exhibits excellent high-temperature properties in a high-temperature combustion atmosphere. 4 C: 0.1-0.6%, Si: 0.1-2%, Mn: 0.1-2% Cr: 25-35%, Ni: more than 30%-47%, Co: 1-10%, Hf: 0.001-0.45% , and further contains one or two of the following: W: 0.1-6%, Mo: 0.1-6%, Ti: 0.1-3%, Nb: 0.1-3%, Ta: 0.1-3 %, contains one or more of the following, and the rest is
Composition consisting of Fe and unavoidable impurities (more than % by weight)
An Fe-Ni-Cr heat-resistant alloy that exhibits excellent high-temperature properties in a high-temperature combustion atmosphere.