JPH0421995B2 - - Google Patents
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- Publication number
- JPH0421995B2 JPH0421995B2 JP9945784A JP9945784A JPH0421995B2 JP H0421995 B2 JPH0421995 B2 JP H0421995B2 JP 9945784 A JP9945784 A JP 9945784A JP 9945784 A JP9945784 A JP 9945784A JP H0421995 B2 JPH0421995 B2 JP H0421995B2
- Authority
- JP
- Japan
- Prior art keywords
- heating element
- electric heating
- electric
- resistant steel
- less
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- 238000005485 electric heating Methods 0.000 claims description 34
- 238000010438 heat treatment Methods 0.000 claims description 34
- 229910000831 Steel Inorganic materials 0.000 claims description 28
- 239000010959 steel Substances 0.000 claims description 28
- 239000000463 material Substances 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 10
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 238000005520 cutting process Methods 0.000 claims description 6
- 230000001590 oxidative effect Effects 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- 229910000859 α-Fe Inorganic materials 0.000 claims description 5
- 238000005452 bending Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 229910001566 austenite Inorganic materials 0.000 claims description 2
- -1 C: 0.4wt % or less Inorganic materials 0.000 claims 1
- 229910052684 Cerium Inorganic materials 0.000 claims 1
- 229910052804 chromium Inorganic materials 0.000 claims 1
- 229910052742 iron Inorganic materials 0.000 claims 1
- 229910052746 lanthanum Inorganic materials 0.000 claims 1
- 229910052748 manganese Inorganic materials 0.000 claims 1
- 229910052750 molybdenum Inorganic materials 0.000 claims 1
- 229910052758 niobium Inorganic materials 0.000 claims 1
- 239000002244 precipitate Substances 0.000 claims 1
- 239000000047 product Substances 0.000 claims 1
- 229910052761 rare earth metal Inorganic materials 0.000 claims 1
- 229910052721 tungsten Inorganic materials 0.000 claims 1
- 229910052727 yttrium Inorganic materials 0.000 claims 1
- 229910052726 zirconium Inorganic materials 0.000 claims 1
- 238000012360 testing method Methods 0.000 description 12
- 230000003647 oxidation Effects 0.000 description 9
- 238000007254 oxidation reaction Methods 0.000 description 9
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000000137 annealing Methods 0.000 description 4
- 238000009434 installation Methods 0.000 description 4
- 238000000465 moulding Methods 0.000 description 4
- 238000003466 welding Methods 0.000 description 4
- 238000002788 crimping Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- 230000004584 weight gain Effects 0.000 description 2
- 235000019786 weight gain Nutrition 0.000 description 2
- 229910002060 Fe-Cr-Al alloy Inorganic materials 0.000 description 1
- 229910018487 Ni—Cr Inorganic materials 0.000 description 1
- 238000005219 brazing Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 229910001293 incoloy Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
Landscapes
- Resistance Heating (AREA)
Description
〔産業上の利用分野〕
この発明は電気炉用電熱体及びその製造方法に
おいて、特にその通常雰囲気下における耐酸化性
並びに靭性の改良に関するものである。
〔従来の技術〕
一般に、通常雰囲気下で稼動する電気炉は内部
に電熱体を配し、500〜1200℃の温度領域におい
て、金属の熱処理、低融点金属の溶融・保温の他
セラミツクの焼き付け、ろう接など広汎な用途に
利用されている。
ところでこの種の電熱体としては、例えば第４
図に示すごとく、電熱材を切断及び曲げ加工して
丸線状に形成してなる発熱体９の両端部に、電気
端子１０，１０をそれぞれ接続したものがあつ
て、特にこの電熱材としては従来より、Ni−Cr
系すなわちオーステナイト系発熱体よりもむし
ろ、表面にAl2O3を形成するFe−Cr−Al系すな
わちフエライト系の発熱体が、耐熱体・耐酸化性
に優れ、かつ安価であるとされることから、この
点で好んで用いられてきたのが実情である。しか
るに実際のところでは、フエライト系発熱体を電
熱材として用いたこの種の電熱材にあつては、今
度はフエライト系固有の欠点である脆性が問題と
なり、また1000℃以上の高温使用の繰り返しで結
晶粒が増大化する等高温強度が小さいという難点
を有するものである。
これらの欠点は、電熱材として発熱体に利用す
るにあたつては、きわめて重大な致命的な欠点で
あり、好ましくは、オーステナイト系の利点とフ
エライト系の利点を両者兼ね備えた特性の発熱体
を有する電熱材が嘱望されていたものである。
〔発明が解決しようとする問題点〕
この点で特公昭53−43498号公報に開示された
含Alオーステナイト系耐熱鋼を電熱材としてこ
の種電熱体に利用すれば、上記の欠点につきほぼ
解消されることが判明した。すなわち、主として
高温使用の際の結晶粒の成長を抑制するために、
δ−フエライト相の析出に対し成分調整を行な
い、かつAlを4.5wt％超えて含有させ、800℃〜
1200℃で熱処理し、鋼表面に安定なAl2O3皮膜を
生成させるもので、たとえ1200℃の高温酸化性雰
囲気下での使用においても最も酸化増量の少い長
寿命のものを得たものである。
しかしながら、実際の成形上の観点からすれ
ば、あらかじめ熱処理して、Al2O3皮膜を形成し
た後では表面硬度が増大し、加工性の点において
問題がある。しかも熱処理前のこの種鋼は、650
℃で脆化が発生し、切断や溶接あるいは塑性加工
による内部歪を惹起させた部分においては結晶粒
子の増大化が認められ、衝撃もしくは引張応力を
与えると破断することが判明した。さらにまた、
一方でこの種電熱体を電気端子をも含めた全体に
おいて、この種素材で構成することが理論上望ま
しいとも考えられるが、実際に炉内に配設する場
合、この端子は炉外に導出しなければならず、こ
の点端子の温度は部分的に炉内の温度より低くな
り、丁度この種素材の脆化温度である650℃の温
度領域に入る場合も生じてきわめて好ましくない
ことも判明したものである。
そこでこの発明の目的とするところは、上述の
ごとき含Alオーステナイト系耐熱鋼のきわめて
好ましい属性をこの種用途に最大限利用するにあ
たり、特に問題となつた欠点あるいは難貼を悉く
解決しようとしたもので、成形時に発生する残留
応力や熱脆化に対してきわめて有効な除去がなさ
れるとともに、加工性に優れ、さらには、実際に
電気炉に設置した場合にあつても電熱体全体が耐
酸化性に優れ、しかも靭性に優れて著しく強度の
ある長寿命の電気炉用電熱体及びその製造方法を
提供するところにある。
〔問題点を解決するための手段〕
上記目的達成のためこの発明は、まず電熱材と
しては特に４〜10wt％のAlを含有する含Alオー
ステナイト系の耐熱鋼を用い、これに熱処理を施
し、表面に均質なAl2O3を形成して耐酸化性並び
に高温強度を増大させ、フエライト系及びオース
テナイト系両者のきわめて好ましい属性を併有さ
せたものであり、他方炉外に導出せざるを得ない
電気端子については、上述の含Alオーステナイ
ト系耐熱鋼を用いず、使用時において現われる温
度領域に脆化現象が生じない非含Alオーステナ
イト系耐熱鋼を用いたものである。またこの発明
は含Alオーステナイト系耐熱鋼の熱脆化温度が
650℃であり、しかも電熱体の成形時には、この
種発熱体の耐久性等の影響を与える残留応力がか
なりの割合で発生しているとの認識から、少なく
とも800℃の焼きなまし処理を成形後に加えるこ
とが、上述の残留応力及び脆性を可及的に除去な
らしめるとと同時に、均質なAl2O3皮膜の形成を
達成し得るとの知見を得たものである。さらにま
たこの発明は、この種用途における加工性の点並
びに既述の脆性除去及び残留応力除去の点を格別
に考慮して、含Alオーステナイト系耐熱鋼の電
熱材に、切断及び曲げ加工を施して所定の抵抗値
を有する発熱体を形成し、この発熱体の両端部に
非含Alオーステナイト系耐熱鋼を素材とする電
気端子を溶着もしくは圧着して、しかる後、全体
を少なくとも800℃以上の高温酸化性雰囲気下に
おいて焼きなまし処理を施す方法を採用したもの
である。
〔実施例〕
第１図は板状形態に係る電熱体の一例を示す斜
視図で、１は含Alオーステナイト系耐熱鋼の発
熱体であり、平板材を、所定の抵抗値が得られる
ように数値制御方式によつてガス切断し、長手方
向に交互にしかも対向させて複数のスリツト２が
設けられている。３はこの発熱体１の端部におい
て直角方向にTIG溶接にて溶着した電気端子で、
素材としてSUS310Sを用いている。なおここで
端子素材としてSUS310Sを用いたのは、前述し
た通り含Alオーステナイト系耐熱鋼を用いた場
合、炉外に導出した電気端子３が、650℃の脆化
領域に暴されることになり、使用中に断線するお
それも十分あり、これを防止するためにある。な
おもち論端子素材としてSUS310Sに限定される
ものではなく、要するに、炉壁を貫通するいわば
この種電熱体特有の取付け構造に起因して端子自
体が温度勾配をもつことに鑑み、この温度勾配に
おいて脆化を惹起しない、いわば非含Alオース
テナイト系耐熱鋼であれば差支えない。
また、電気端子３は、この実施例では上記のご
とく溶着しているが、無論これに限定されるもの
ではない。例えば螺着や圧着等でもよいが、螺着
の場合は、高温において使用すると、弛みの発生
が生じるおそれもあり、この種発明にあつては、
溶着及び圧着が好適である。
なお、４は発熱体支持体で、電気端子３と同じ
く発熱体１面に対し直角方向に取付けられている
が、取付方向や取付数あるいは取付位置は炉の構
造に応じて適宜選択すればよい。
なおまた、この発明は、第１図に示すいわゆる
電気炉用板状電熱体に用途は限られるものではな
いことは言うまでもなく、例えば、第２図に示す
ごとく、発熱体を含Alオーステナイト系耐熱鋼
の帯状発熱体５とし、その端部に、上記の例と同
様に、非含Alオーステナイト系耐熱鋼の電気端
子６を溶着等して、しかる後、800℃以上で焼き
なまし処理を施せば差支えない。
第３図に示すごとき、他の帯状電熱体７や第４
図に示すごとき従来の線状電熱体８についても同
様である。要するに如何なる形態の電気炉用電熱
体に対してもこの発明は適用し得るものである。
ところでこの発明に係る方法を用いて得た電気
炉用電熱体に係る発熱体について行なつた試験に
つき以下詳述する。
(イ) 抵抗温度増加係数及び比抵抗値
含Alオーステナイト系耐熱鋼を、外径φ1.0
mm、長さ400cmに成形し、1200℃で10時間熱処
理した後、ホイーストンブリツジを用いて20℃
及び1200℃の抵抗値を測定した。なお、ここで
用いた含Alオーステナイト系耐熱鋼の組成は、
重量％で、Ｃ：0.028、Si：0.59、Mn：0.32、
Ｐ：0.001、Ni：23.9、Cr：16.6、Al：4.93、
Fe：残部から成る。
その結果、抵抗値は、20℃で5.29Ω、1200℃
で7.47Ωであつた。
またJIS・Ｃ・2524の「金属抵抗材料の導体
抵抗及び体積抵抗率試験方法」に基づき比抵抗
ρ値を求めると、
ρ＝Ｒ／Ｌ・Ａ（μΩｍ）
Ｒ：抵抗値（Ω）、Ｌ：長さ（ｍ）、Ａ：断面
積（cm2）であることから、
ρ1200＝146.7（μΩcm）
ρ20＝103.9（μΩcm）
となり、発熱体として充分実用に供され得る良
好な値を得た。
なお、ρ値は、70〜200μΩcmの範囲内にお
さまることが判明した。
また抵抗温度増加係数は約1.41となり、
NCHの同係数の約1.09と比較して、ほぼ同等
の数値を得た。
(ロ) 寿命試験
JIS・Ｃ・2524「電熱線及び帯の寿命試験方
法」Ｉ法に基づき、これに近似する試験で寿命
値を求めた。
すなわち、(イ)試験で用いたものと同組成の含
Alオーステナイト系耐熱鋼をφ1.0mmの線材と
し、これをあらかじめ1200℃で10時間熱処理を
行ない、しかる後、下部端子に40gfを取付けて
行なつた。
その結果本発明品の寿命値は1027回、これに
対してNCH1は500回、NCH2は350回程度であ
り、約２〜３倍の寿命が得られることが判明し
た。
(ハ) 脆性試験
非熱処理の(イ)と同材質の電熱線を、JIS・
Ｃ・2524の5.1.1(3)の条件で、通電を繰返した
ところ、48回で端子と電熱線の接続部近傍にお
いて断線した。この部分はサーモペイントによ
れば600〜700℃の範囲内と想定された。これに
対して800℃以上で焼きなまし処理した(イ)と同
材質の電熱線では、断線の発生が認められてな
いことから、実用上800℃以上で焼きなまし処
理を施す必要があることが判明した。
(ニ) 酸化増量試験
JIS・Ｃ・2520「酸化増量試験」に基づき、(イ)
と同組成のオーステナイト系耐熱鋼からなる電
熱線を、表面積５cm2以上となるようにφ1mm×
200ｍ（6.28cm2）とし、1200℃×10時間で焼き
なまし処理して試験した。なおこの際比較のた
め、同条件下でインコロイ800、FCH2、
SUS301Sについても行なつた。
その結果を、第１表に示す。
[Industrial Field of Application] The present invention relates to an electric heating element for an electric furnace and a method for manufacturing the same, and particularly relates to improvement of its oxidation resistance and toughness under normal atmosphere. [Prior Art] In general, an electric furnace that operates in a normal atmosphere has an electric heating element inside, and in a temperature range of 500 to 1200 degrees Celsius, it is capable of heat treatment of metals, melting and heat retention of low melting point metals, baking of ceramics, It is used for a wide range of purposes such as brazing. By the way, as this type of electric heating body, for example,
As shown in the figure, there is a heating element 9 formed into a round wire shape by cutting and bending an electric heating material, and electrical terminals 10, 10 are connected to both ends of the heating element 9, respectively. Conventionally, Ni-Cr
Rather than the austenitic heating element, the Fe-Cr-Al heating element, which forms Al 2 O 3 on the surface, is said to be superior in heat resistance and oxidation resistance, and is inexpensive. In fact, it has been used favorably in this respect. However, in reality, this kind of electric heating material that uses a ferrite heating element as an electric heating material has a problem of brittleness, which is an inherent drawback of ferrite heating elements, and also cannot be used repeatedly at high temperatures of 1000℃ or more. It has disadvantages such as low high temperature strength due to increased crystal grain size. These drawbacks are extremely serious and fatal drawbacks when used as a heating element as an electric heating material, and it is preferable to use a heating element with characteristics that combine the advantages of austenite and ferrite. This electric heating material has been highly desired. [Problems to be Solved by the Invention] In this regard, if the Al-containing austenitic heat-resistant steel disclosed in Japanese Patent Publication No. 53-43498 is used as an electric heating material in this type of electric heating element, the above-mentioned disadvantages can be almost eliminated. It turned out that. That is, mainly to suppress the growth of crystal grains during high-temperature use,
The composition was adjusted to prevent the precipitation of the δ-ferrite phase, and the Al content exceeded 4.5wt%, and the temperature was increased from 800℃ to
Heat treated at 1200℃ to generate a stable Al 2 O 3 film on the steel surface, resulting in a long life with the least amount of oxidation increase even when used in a high temperature oxidizing atmosphere of 1200℃ It is. However, from the viewpoint of actual molding, after the Al 2 O 3 film is formed by heat treatment in advance, the surface hardness increases and there is a problem in workability. Moreover, this type of steel before heat treatment is 650
It was found that embrittlement occurred at ℃, and an increase in crystal grains was observed in areas where internal strain was caused by cutting, welding, or plastic working, and fractures occurred when impact or tensile stress was applied. Furthermore,
On the other hand, it may be theoretically desirable to construct this type of electric heating element entirely from this type of material, including the electrical terminal, but when actually installed inside the furnace, this terminal must be led out of the furnace. It has also been found that the temperature at this point terminal is partially lower than the temperature inside the furnace, which is extremely undesirable as it sometimes falls into the temperature range of 650℃, which is the embrittlement temperature of this type of material. It is something. Therefore, the purpose of this invention is to solve all of the drawbacks or difficulties in applying the above-mentioned extremely favorable attributes of Al-containing austenitic heat-resistant steel to the maximum extent possible for this type of application. In addition to being extremely effective at removing residual stress and thermal embrittlement that occur during molding, it also has excellent workability, and the entire electric heating element is oxidation-resistant even when actually installed in an electric furnace. An object of the present invention is to provide an electric heating element for an electric furnace that has excellent properties, excellent toughness, extremely strong strength, and a long life, and a method for manufacturing the same. [Means for Solving the Problems] To achieve the above object, the present invention first uses an Al-containing austenitic heat-resistant steel containing 4 to 10 wt% of Al as an electric heating material, heat-treats it, It forms homogeneous Al 2 O 3 on the surface to increase oxidation resistance and high-temperature strength, and has the extremely favorable attributes of both ferritic and austenitic systems. For electrical terminals that do not contain aluminum, the above-mentioned aluminum-containing austenitic heat-resistant steel is not used, but a non-aluminum-containing austenitic heat-resistant steel that does not cause embrittlement in the temperature range that occurs during use is used. In addition, this invention has the advantage that the thermal embrittlement temperature of Al-containing austenitic heat-resistant steel is
650℃, and since we recognize that a considerable amount of residual stress is generated during the molding of electric heating elements, which affects the durability of this type of heating element, an annealing treatment of at least 800℃ is applied after molding. It has been found that the above-mentioned residual stress and brittleness can be removed as much as possible, and at the same time, a homogeneous Al 2 O 3 film can be formed. Furthermore, the present invention applies cutting and bending to an electrically heated material made of Al-containing austenitic heat-resistant steel, taking into particular consideration the workability in this type of application as well as the aforementioned brittleness removal and residual stress removal. to form a heating element having a predetermined resistance value, electrical terminals made of aluminum-free austenitic heat-resistant steel are welded or crimped to both ends of this heating element, and then the whole is heated to at least 800°C or higher. This method employs annealing treatment in a high-temperature oxidizing atmosphere. [Example] Fig. 1 is a perspective view showing an example of a plate-shaped electric heating element, in which numeral 1 is a heating element made of Al-containing austenitic heat-resistant steel. Gas cutting is performed by numerical control, and a plurality of slits 2 are provided alternately and facing each other in the longitudinal direction. 3 is an electrical terminal welded by TIG welding in the right angle direction at the end of this heating element 1;
SUS310S is used as the material. The reason for using SUS310S as the terminal material here is that, as mentioned above, if Al-containing austenitic heat-resistant steel is used, the electrical terminal 3 led out of the furnace will be exposed to the embrittlement region at 650℃. , there is a good chance that the wire will break during use, and this is to prevent this. In theory, the terminal material is not limited to SUS310S; in short, considering that the terminal itself has a temperature gradient due to the mounting structure peculiar to this type of electric heating element that penetrates the furnace wall, There is no problem as long as it is an Al-free austenitic heat-resistant steel that does not cause embrittlement. Further, although the electrical terminals 3 are welded as described above in this embodiment, the present invention is not limited to this. For example, screwing or crimping may be used, but in the case of screwing, there is a risk of loosening when used at high temperatures, so in this type of invention,
Welding and crimping are preferred. Note that 4 is a heating element support, and like the electric terminal 3, it is installed perpendicular to the surface of the heating element, but the installation direction, number of installations, and installation position may be selected as appropriate depending on the structure of the furnace. . Furthermore, it goes without saying that the application of the present invention is not limited to the so-called plate-shaped electric heating element for electric furnaces shown in FIG. 1. For example, as shown in FIG. There is no problem if the heating element 5 is made of steel strip, and electrical terminals 6 made of non-Al-containing austenitic heat-resistant steel are welded to the ends of the heating element 5, as in the above example, and then annealed at 800°C or higher. do not have. As shown in FIG.
The same applies to the conventional linear electric heating body 8 as shown in the figure. In short, the present invention can be applied to any type of electric heating element for electric furnaces. By the way, tests conducted on a heating element related to an electric heating element for an electric furnace obtained using the method according to the present invention will be described in detail below. (a) Resistance temperature increase coefficient and specific resistance value Al-containing austenitic heat-resistant steel with an outer diameter of φ1.0
mm, length 400cm, heat treated at 1200℃ for 10 hours, and then heated at 20℃ using a Wheatstone bridge.
And the resistance value at 1200℃ was measured. The composition of the Al-containing austenitic heat-resistant steel used here is:
In weight%, C: 0.028, Si: 0.59, Mn: 0.32,
P: 0.001, Ni: 23.9, Cr: 16.6, Al: 4.93,
Fe: Consists of the remainder. As a result, the resistance value is 5.29Ω at 20℃, 1200℃
It was 7.47Ω. In addition, when calculating the specific resistance ρ value based on JIS C 2524 “Method for testing conductor resistance and volume resistivity of metal resistance materials”, ρ=R/L・A (μΩm) R: resistance value (Ω), L : length (m), A: cross-sectional area (cm 2 ), so ρ 1200 = 146.7 (μΩcm) ρ 20 = 103.9 (μΩcm), which are good values that can be used practically as a heating element. Ta. Note that the ρ value was found to fall within the range of 70 to 200 μΩcm. Also, the resistance temperature increase coefficient is approximately 1.41,
Compared to NCH's coefficient of approximately 1.09, we obtained a nearly equivalent value. (b) Lifespan test Based on JIS C 2524 "Method for lifespan testing of heating wires and bands" I method, lifespan values were determined by a test similar to this. In other words, (a) contains the same composition as that used in the test.
Al austenitic heat-resistant steel was used as a wire rod with a diameter of 1.0 mm, which was heat treated at 1200°C for 10 hours, and then a 40 gf wire was attached to the lower terminal. As a result, it was found that the product of the present invention had a lifespan of 1027 times, whereas NCH1 had a lifespan of 500 times and NCH2 had a lifespan of about 350 times, which was about 2 to 3 times longer. (c) Brittleness test A non-heat treated heating wire made of the same material as (a) was tested according to JIS
When energization was repeated under the conditions specified in 5.1.1(3) of C.2524, the wire broke near the connection between the terminal and the heating wire after 48 times. According to Thermo Paint, this area was assumed to be in the range of 600 to 700 degrees Celsius. On the other hand, since no breakage was observed in heating wires made of the same material as in (a) that were annealed at temperatures of 800°C or higher, it was found that annealing at temperatures of 800°C or higher is necessary for practical purposes. . (d) Oxidation weight gain test Based on JIS C 2520 “Oxidation weight gain test”, (a)
A heating wire made of austenitic heat-resistant steel with the same composition as
The test piece was 200 m (6.28 cm 2 ) and annealed at 1200°C for 10 hours. At this time, for comparison, Incoloy 800, FCH2,
This was also done for SUS301S. The results are shown in Table 1.
【表】
以上の結果からも明らかなように、耐酸化性に
最もすぐれていることが判明した。
(ホ) 引張特性試験
JIS・Ｚ・2241「金属材料引張試験方法」に基
づき、(イ)と同組成のオーステナイト系耐熱鋼か
らなる電熱線について、実際の発熱温度に対応
する800℃、900℃、1000℃のそれぞれの高温度
域において引張試験を行なつた。なお、NCH1
及びFCH1を素材とするものについて同条件下
で行なつた。
その結果を第２表に示す。
明らかに、本発明に係る電熱線の方が他のも
のより引張力が大きく、靭性に優れ、高温強度
を有することが判明した。[Table] As is clear from the above results, it was found to have the best oxidation resistance. (e) Tensile property test Based on JIS Z 2241 "Metallic materials tensile test method", heating wires made of austenitic heat-resistant steel with the same composition as (a) were tested at 800℃ and 900℃ corresponding to the actual heat generation temperature. Tensile tests were conducted at high temperature ranges of 1000℃ and 1000℃. In addition, NCH1
The test was conducted under the same conditions for those made of FCH1 and FCH1. The results are shown in Table 2. It was clearly found that the heating wire according to the present invention has a higher tensile strength, superior toughness, and high-temperature strength than the other wires.
以上述べてきた様に、この発明は4.5〜10wt％
のAlを含有する主としてオーステナイト系耐熱
鋼を発熱体に採用し、しかも、その製造方法にお
いて、切断及び曲げ加工を施して所定の抵抗値を
有する発熱体を形成し、この発熱体の両端部に電
気端子を溶着もしくは圧着した後、少なくとも
800℃以上の高温酸化性雰囲気下において焼きな
まし処理を行う方法を採用したことによつて、耐
高温酸化性並びに高温強度にすぐれ、しかも脆性
破壊を惹起し得ない長寿命の電気炉用電熱体が得
られたものである。
さらにまた電気端子には発熱体の電熱材とは異
なる非含Alオーステナイト系耐熱鋼を用いたこ
とにより、たとえ端子が炉外に導出され、温度低
下を招き、含Alオーステナイト系耐熱鋼の脆化
温度領域を部分的に生じるとしても、この点全く
問題が生じないもので、この種電気炉用電熱体の
取付形態を充分に考慮した固有の構成を採用した
ものであつて、その工業的価値はきわめて大であ
る。
As stated above, this invention has a 4.5 to 10 wt%
Mainly austenitic heat-resistant steel containing aluminum of After welding or crimping electrical terminals, at least
By adopting a method of annealing in a high-temperature oxidizing atmosphere of 800°C or higher, we have created an electric heating element for electric furnaces that has excellent high-temperature oxidation resistance and high-temperature strength, and has a long life without causing brittle fracture. This is what was obtained. Furthermore, since the electrical terminals are made of non-Al-containing austenitic heat-resistant steel, which is different from the heating material of the heating element, even if the terminals are led out of the furnace, the temperature will drop, causing embrittlement of the Al-containing austenitic heat-resistant steel. Even if a temperature range is partially generated, there is no problem at all in this respect, and this type of electric furnace adopts a unique configuration that fully considers the installation form of the electric heating element, and its industrial value is is extremely large.
第１図はこの発明に係る電気炉用電熱体の一実
施例を示す要部斜視図、第２図及び第３図は同他
実施例を示す斜視図、第４図は従来の電気炉用電
熱体の一例を示す斜視図である。
１，５……発熱体、３，６……電気端子、７…
…電熱体。
Fig. 1 is a perspective view of essential parts showing one embodiment of the electric heating body for electric furnaces according to the present invention, Figs. 2 and 3 are perspective views showing other embodiments, and Fig. 4 is a conventional electric heating body for electric furnaces. It is a perspective view showing an example of an electric heating body. 1, 5... Heating element, 3, 6... Electrical terminal, 7...
...Electric heating element.
Claims (1)
イト系耐熱鋼の電熱材に、切断及び曲げ加工を施
して所定の抵抗値を有する発熱体を形成し、この
発熱体の両端部に非含Alオーステナイト系耐熱
鋼を素材とする電気端子を溶着もしくは圧着し、
しかる後全体を少なくとも800℃以上の高温酸化
性雰囲気下において焼きなまし処理を施すことを
特徴とする電気炉用電熱体の製造方法。 ２ 電熱材を切断及び曲げ加工して形成してなる
発熱体の両端部に、電気端子をそれぞれ接続した
電気炉用電熱体において、上記電熱材として４〜
10wt％のAlを含有する含Alオーステナイト系耐
熱鋼を用い、端子素材には非含Alオーステナイ
ト系耐熱鋼を用いて、全体に少なくとも800℃以
上の高温酸化性雰囲気下において焼きなまし処理
を施したことを特徴とする電気炉用電熱体。 ３ 含Alオーステナイト系耐熱鋼が、Ｃ：0.4wt
％以下、Si：2.0wt％以下、Mn：10wt％以下、
Ni：12〜50wt％、Cr：５〜30wt％、Al：４〜
10wt％含有し、その他必要に応じてCo、Mo、Ｗ
のうちの１種または２種以上を5wt％以下、Ti、
Zr、Nb、Td等のうちの１種または２種以上を
2.0wt％以下、希土類元素のＹ、Ce、La等の１種
以上を1wt％以下含有し、残部Feより主としてな
り、かつ高温酸化性雰囲気中でオーステナイト相
中に10wt％未満のδ−フエライト相が析出する
ように成分調整された特許請求の範囲第２項記載
の電気炉用電熱体。[Claims] 1. A heating element having a predetermined resistance value is formed by cutting and bending an electric heating material made of aluminum-containing austenitic heat-resistant steel containing 4 to 10 wt% of Al. Electrical terminals made of aluminum-free austenitic heat-resistant steel are welded or crimped to both ends.
1. A method for manufacturing an electric heating element for an electric furnace, characterized in that the entire body is then annealed in a high-temperature oxidizing atmosphere at a temperature of at least 800°C or higher. 2. In an electric heating element for an electric furnace, in which electric terminals are connected to both ends of the heating element formed by cutting and bending an electric heating material, 4 to 4 are used as the electric heating material.
Al-containing austenitic heat-resistant steel containing 10wt% Al is used, and non-Al-containing austenitic heat-resistant steel is used for the terminal material, and the entire product is annealed in a high-temperature oxidizing atmosphere of at least 800℃ or higher. An electric heating element for electric furnaces characterized by: 3 Al-containing austenitic heat-resistant steel, C: 0.4wt
% or less, Si: 2.0wt% or less, Mn: 10wt% or less,
Ni: 12~50wt%, Cr: 5~30wt%, Al: 4~
Contains 10wt% and other Co, Mo, W as necessary
5wt% or less of one or more of the following, Ti,
One or more of Zr, Nb, Td, etc.
2.0wt% or less, containing 1wt% or less of one or more rare earth elements such as Y, Ce, La, etc., with the balance mainly consisting of Fe, and less than 10wt% of δ-ferrite phase in the austenite phase in a high-temperature oxidizing atmosphere. The electric heating element for an electric furnace according to claim 2, wherein the components are adjusted so that the precipitates of .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9945784A JPS60243991A (en) | 1984-05-16 | 1984-05-16 | Electric heater for electric furnace and method of producingsame |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9945784A JPS60243991A (en) | 1984-05-16 | 1984-05-16 | Electric heater for electric furnace and method of producingsame |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60243991A JPS60243991A (en) | 1985-12-03 |
| JPH0421995B2 true JPH0421995B2 (en) | 1992-04-14 |
Family
ID=14247844
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9945784A Granted JPS60243991A (en) | 1984-05-16 | 1984-05-16 | Electric heater for electric furnace and method of producingsame |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60243991A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003017229A (en) * | 2001-06-28 | 2003-01-17 | Akashi Denki Kk | Manufacturing method of heater element |
| DE102007029400B4 (en) * | 2007-06-26 | 2014-05-15 | Outokumpu Vdm Gmbh | Iron-nickel-chromium-silicon alloy |
-
1984
- 1984-05-16 JP JP9945784A patent/JPS60243991A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60243991A (en) | 1985-12-03 |
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