CA2087389C - Heater sheath alloy - Google Patents
Heater sheath alloyInfo
- Publication number
- CA2087389C CA2087389C CA002087389A CA2087389A CA2087389C CA 2087389 C CA2087389 C CA 2087389C CA 002087389 A CA002087389 A CA 002087389A CA 2087389 A CA2087389 A CA 2087389A CA 2087389 C CA2087389 C CA 2087389C
- Authority
- CA
- Canada
- Prior art keywords
- alloy
- nickel
- present
- chromium
- phosphorus
- 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 - Fee Related
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C1/00—Details
- H01C1/02—Housing; Enclosing; Embedding; Filling the housing or enclosure
- H01C1/028—Housing; Enclosing; Embedding; Filling the housing or enclosure the resistive element being embedded in insulation with outer enclosing sheath
Abstract
A material for electric heater element sheathing, which has good weldability, is oxidation- and corrosion-resistant, and forms an eye-pleasing dark gray or black surface oxide, consists essentially of, by weight, from about 8.75-15.5% nickel, about 19.5-21.0% chromium, about 0.30-0.50 manganese, about 0.50-2.0% silicon, about 0.25-0.60% aluminum, about 0.25-1.0% titanium, up to about 0.05% carbon, up to about 0.005% sulfur, up to about 0.75% copper, up to about 1.0% cobalt, up toabout 1.0% molybdenum, up to about 0.02% phosphorus, about 0.001-0.015% calcium plus magnesium and remainder essentially iron, wherein the Ferrite Number is between 1 and 15.
Description
~ 2~87389 HEATER SHEATH ALLOY
BACKGROUND OF THE INVENTION
This invention is directed towards an improved oxidation and corrosion resistant, low cost, iron-base alloy range which forms an eye-appealing, protective dark 5 oxide coating, is highly compatible with high speed autogenous welding practice, and is particularly suitable for use as electric heater element shPathing Electric heater elements currently available usually comprise a resistance conductor enclosed in a tubular metal sheath with the resistance conductor embedded in and supported in spaced relation to the sheath by a densely compacted layer of 10 refractory, heat-conducting, electrically in~ul~ting material. The resistance conductor may be a helically wound wire member and the refractory material may be granularmagnesium oxide.
The material used for the heater sheath must be low-cost, have excellent resistance to oxidation at elevated temperatures, e.g. 850-900C, have resistance to 15 stress corrosion cracking, and exhibit good weldability. In addition, it has now become an important requirement that the material used for the heater sheath possess a desirable appearance. Since electric heater elements are usually exposed and are often ~~ -2- 2Q8~389 PC-2272/1 present in household items such as range tops and dish washers, consumers prefer that the heater element have an eye-pleasing color, such as black or dark gray.
Presently, a large percentage of heater element sheaths are made from INCOLOY~ alloy 840 tINCOLOY is a trademark of the Inco family of companies).
This alloy, disclosed in U.S. Patent No. 3,719,308, possesses all the necessary properties for use as heater element sheaths. Additionally, its surface oxidizes to a dark gray color. However, the high cost of this alloy, due in large part to its nominal nickel content of about 20%, has prompted a search for a more economical substitute.
Possible lower-cost alternatives are being contemplated, but they all suffer from drawbacks which make them less than ideal. Type 309 stainless steel and Nippon Yakin's NAS H-22 form undesirable greenish oxides. While Type 321 stainless steel oxidizes to a black color and Type 304 oxidizes to dark gray, they are two-phase alloys, and therefore lack adequate strength, and under certain circumstances, can be difficult to autogenously weld.
It is thus an object of the present invention to provide a material to be used as heater element sh~ ~hing which exhibits excellent resistance to oxidation at elevated temperatures, and good weldability characteristics through the formation of a critical amount of ~-ferrite upon solidification, as defined by a ferrite number of 1 to 15.
It is an additional object of the present invention to provide a heater element sheathing material which forms an eye-pleasing dark gray or black surface oxide layer.
It is a still further object of the present invention to provide a heater element sheathing at low cost.
SUMMARY OF THE INVENTION
In accordance with the above objectives, it has now been found that a novel alloy of the following composition is ideal for the required purpose:
Element Weight Percent Carbon 0.05 max.
Manganese 0.30-0.50 Iron Balance Sulfur 0.005 max.
Slllcon 0.50-2.0 Copper 0.75 max.
Nlckel 8.75-15.5 Chromlum 19.5-21.0 Alumlnum 0.25-0.60 Tltanlum 0.25-1.0 Cobalt 1.0 max.
Molybdenum 1.0 max.
Phosphorus 0.02 max.
Calclum + Magneslum 0.001-0.015 All composltlons throughout the speclflcatlon are glven ln welght percent. The alloy, on oxldatlon, obtains a protectlve oxlde layer ranglng ln colour from dark gray to black, and has a Ferrlte Number between 1 and 15.
The alloy preferably contalns 11.5-15.0% nlckel, .002% max. sulfur and .015% max. phosphorus. An advantageous composition of the alloy comprlses about 20.5% chromlum by welght and about 14% nlckel, as such maxlmlzes the potentlal for optlmum weldablllty whlle assurlng the formatlon of a black, oxlde durlng sheath manufacture.
The present lnvention provldes a low-cost, oxldatlon reslstant, stress-corroslon cracklng-reslstant, weldable, strong alloy whlch oxidlzes to a deslrable color for use as a heater element sheathlng ln products such as electrlc ranges, colled surface plates and dlshwashers, and elsewhere as a low-cost substltute for INCOLO ~ alloy 840.
- 3a -,, 4- 208 7 3 8 ~ PC-2272/1 The oxides discussed herein for both the present invention and those of the prior art were all formed by heating at 1078C (1970F) in an air-methane mixture of ratio 6:1. This method is typical of current industry practice.
BRIEF DESCRTPTION OF THE DRAVVING
The FIGURE is a nomogram for determining ferrite number.
DETAILED DESCRIPIION OF THE INVENTION
Various studies were undertaken to demonstrate the efficacy of the claimed alloy composition and the desirability thereof for use as heater element sheath as compared to known materials.
The chemical composition of the alloys included in the study are provided in Table 1.
Two heats of the claimed alloy were made containing 10.75 and 14.88 percent nickel, respectively (Examples A and B). Also, heats of Type 309 stainless steel and alloy NAS H-22 were made. These four alloys were hot and then cold worked down to n.o60 inch thick. In addition, Types 304 and 321 stainless steel,INCOLOY~ alloy 800, and three heats of INCOLOY'i9 alloy 840 were included in thetesting. The Type 304 stainless steel was cold rolled from 0.125 inch to 0.060 inch.
The INCOLOY0 alloy 800 was 0.05 inch thick in the hot rolled annealed condition.The three heats of INCOLOY~ alloy 840 were hot worked to 0.30 inch and then coldrolled to 0.018 inch and bright annealed.
One inch square specimens of the alloys were exposed in an electrically heated horizontal tube furnace at 1078C (1970F) in an air-methane mixture at an air:fuel ratio of 6:1. The time at temperature was five minutes, and the gas flow rate was 500 cm3 per minute. Most of the specimens were first given a 120 grit surface finish. The specimens were then laid flat on a cordierite boat. The mullite furnace tube was sealed at both ends and the boat was pushed into the hot zone with a push TABLE I
Alloy C Cr Ni Si Mn Mo Al Ti Cu Ca Mg Example A 0.03520.7110.750.57 0.30 0.280.39 0.41 0.28.0011 .0002 Example B 0.03720.6614.880.62 0.36 0.300.39 0.41 0.30.0018 .0002 Type 304 SS 0.0818-20 8-10.5 1.0 2.0 -- -- -- -- -- --(nominal) Type 309 SS 0.09823.2914.æ 0.45 0.77 0.006 -- 0.00010.0001.0017 .0003 Type 321 SS 0.0817-19 9-12 1.00 2.0 -- --0.40 min. c.001(nominal) INCOLOY~ alloy 840 0.03 19.68 21.35 0.620.36 0.47 0.300.32 0.24 .0008 .0006 (specimen 1) INCOLOYG alloy 840 0.03 19.80 18.78 0.600.35 0.22 0.460.38 0.29 .0014 .0005 (specimen 2) O
INCOLOY~ alloy 840 0.03 21.32 18.63 0.570.36 0.44 0.420.37 0.17 .0027 .0008 _~
(specimen 3) Cl:~
Alloy NAS H-220.022 23.6220.74 0.69 0.360.021 0.13 0.210.019 .0021 .0002 rod which passed through a gas tight O-ring seal. After exposure, the specimens were examined. The results are set forth in Table 2.
Material D~ tion and R~ . lti-~ Color after Exposure in S Air-Methane Mixture (AFR=6) for 5 Minutes at 1078C (1970F) Alloy Surface Finish Color Example A 120 grit dark gray Example B 120 grit dark gray Type 304 SS 120 grit dark gray 10Type 309 SS 120 grit green Type 321 SS 120 grit black (1) INCOLOY6~ alloy 840as-rolled + bright annealmedium gray (1) INCOLOY8\ alloy 840120 grit dark gray (2) INCOLOY0 alloy 840as-rolled + bright anneal dark gray 15(2) INCOLOY'9 alloy 840120 grit dark gray (3) INCOLOY6' alloy 840as-rolled + bright anneal dark gray Alloy NAS H-22 120 grit greenish dark gray The compositional range was arrived at with a view towards the unique characteristics required for heater element sheath. In pursuing this invention, it was necessary to balance the conflicting metallurgical phenomena affecting weldability on the one hand and black oxide formation on the other.
Thus, it was desirable to maintain the highest possible chromium level for ferrite formation without forming green oxide scale. In turn, setting the chromium limit imposes limits on the nickel content. Moreover, the nickel content is in turn limited by cost considerations. A chromium range of 19.5 to 21% (preferably about 20.5%) and a nickel range of 8.75 to 15.5% (preferably about 11.0 to 15.0%) ~ -7- 2Q87389 PC-2272/1 m~imi7es the potential for optimum weldability while assuring the formation of a dark oxide during sheath manufacture.
To successfully compete as a sheathing alloy, the alloy must be compatible with high speed autogenous welding techniques. This can only be achieved 5 if the alloy composition is carefully balanced such that the percentage of ~-ferrite as defined by its Ferrite Number is between 1 and 15. The Ferrite Number in this invention is defined as in the technical paper, "Ferrite Number Prediction to 100 FN in Stainless Steel Weld Metal," by T.~ Sievart, C.N. McCowen and D.L. Olson in the American Welding Society publication, Welding Research Supplement. pp. 289-s to 298-s, December, 1988. These authors define two equations, which the inventors of this invention have modified to be pertinent to the alloys described herein. These equations in combination with the nomogram, shown in the Figure, determine the critical relationship between chromium plus molybdenum and nickel plus carbon which will yield the amount of ~-ferrite essential for high speed autogenous welding techniques. The two equations are:
(1) Creq = % Cr + % Mo (2) Nieq = % Ni + 35 x (% C) The nomogram plots Creq versus Nieq~ with values for the third variable, FerriteNumber, present as diagonal isograms across the grid.
Since the maximum cLlullliulll content which will always result in a dark oxide is 20.5%, the maximum permissible Creq becomes 21.5 if up to 1.0%
molybdenum is present in the alloy. Thus, by locating the isogram for 1, the minimum desired Ferrite Number, it can be seen at point P that the maximum Nieq becomes about 17.25 at zero percent carbon and the nickel content becomes 15.5% maximum if the carbon is 0.05%. The minimum desirable chromium from a corrosion viewpoint is deemed to be 19.5%; thus, the Creq is 19.5 at zero percent molybdenum and 20.5 at 1.0% molybdenum. Consequently, by locating the isogram at Ferrite Number 15, themaximum desirable value, it can be seen at point R that the minimum Nieq becomesabout 10 at zero percent carbon and the nickel level becomes a minimum of 8.75% at 0.05% carbon. The required values for Creq and Nieq must fall within the quadrilateral f -8- 2 0 8 7 3 8 9 PC-2272/1 PQRS of the FIGURE to achieve desired characteristics of color, corrosion-resistance and weldability.
Further, the highest quality welds will occur when the phosphorus content is less than 0.02% (preferably 0.015%), the sulfur content is less than 0.005%
5 . (preferably .002%) and the residual calcium plus magnesium after deoxidation is from 0.001% to 0.015%.
While the lower limit of 8.75% nickel assures transformation of the ~-ferrite formed during solidification of the weld bead to austenite, it was quiteunexpected that the relatively low nickel content would result in a desirable dark gray 10 oxide formation, and would also possess tensile properties similar to INCOLOY alloy 840. Tensile properties for two versions of the claimed alloy and INCOLOY alloy 840 are compared below in Table 3.
TENSILE DATA FOR EXPERIMENTAL ALLOYS vs. INCOLOY0 ALLOY 840 Yield Strength Ultimate Tensile Strength Elongation (ksi) (ksi) (~) ROOM TEMPERATURE TENSILE DATA
Example A 36.5 88.6 41.0 Example B 26.1 76.1 46.0 INCOLOY~ alloy 840 30.8 82.8 40.0 800 Ctl472F TENSILE DATA
20Example A 15.5 23.6 66.5 Example B 13.9 29.8 66.0 INCOLOY0 alloy 840 15.0 26.6 81.5 Aluminum and titanium are integral components of the alloy. Aluminum, at 0.25-O.~O~o, contributes to oxidation- and corrosion-r~cict~nce; and titanium, at 0.25-25 1.0%, in conjunction with the carbon as titanium carbide, contributes to grain sizestability.
~ , -9- 2 08~38g PC-2272/1 The particular ~nri~ ing atmosphere utilized, i.e., air-methane 6:1, was chosen because it is simple, inexpensive and in general use throughout the industry. It is contemplated that other known ~lritli7ing atmospheres or methods may be used to achieve similar results.
S Although the present invention has been described in conjunction with the preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.
BACKGROUND OF THE INVENTION
This invention is directed towards an improved oxidation and corrosion resistant, low cost, iron-base alloy range which forms an eye-appealing, protective dark 5 oxide coating, is highly compatible with high speed autogenous welding practice, and is particularly suitable for use as electric heater element shPathing Electric heater elements currently available usually comprise a resistance conductor enclosed in a tubular metal sheath with the resistance conductor embedded in and supported in spaced relation to the sheath by a densely compacted layer of 10 refractory, heat-conducting, electrically in~ul~ting material. The resistance conductor may be a helically wound wire member and the refractory material may be granularmagnesium oxide.
The material used for the heater sheath must be low-cost, have excellent resistance to oxidation at elevated temperatures, e.g. 850-900C, have resistance to 15 stress corrosion cracking, and exhibit good weldability. In addition, it has now become an important requirement that the material used for the heater sheath possess a desirable appearance. Since electric heater elements are usually exposed and are often ~~ -2- 2Q8~389 PC-2272/1 present in household items such as range tops and dish washers, consumers prefer that the heater element have an eye-pleasing color, such as black or dark gray.
Presently, a large percentage of heater element sheaths are made from INCOLOY~ alloy 840 tINCOLOY is a trademark of the Inco family of companies).
This alloy, disclosed in U.S. Patent No. 3,719,308, possesses all the necessary properties for use as heater element sheaths. Additionally, its surface oxidizes to a dark gray color. However, the high cost of this alloy, due in large part to its nominal nickel content of about 20%, has prompted a search for a more economical substitute.
Possible lower-cost alternatives are being contemplated, but they all suffer from drawbacks which make them less than ideal. Type 309 stainless steel and Nippon Yakin's NAS H-22 form undesirable greenish oxides. While Type 321 stainless steel oxidizes to a black color and Type 304 oxidizes to dark gray, they are two-phase alloys, and therefore lack adequate strength, and under certain circumstances, can be difficult to autogenously weld.
It is thus an object of the present invention to provide a material to be used as heater element sh~ ~hing which exhibits excellent resistance to oxidation at elevated temperatures, and good weldability characteristics through the formation of a critical amount of ~-ferrite upon solidification, as defined by a ferrite number of 1 to 15.
It is an additional object of the present invention to provide a heater element sheathing material which forms an eye-pleasing dark gray or black surface oxide layer.
It is a still further object of the present invention to provide a heater element sheathing at low cost.
SUMMARY OF THE INVENTION
In accordance with the above objectives, it has now been found that a novel alloy of the following composition is ideal for the required purpose:
Element Weight Percent Carbon 0.05 max.
Manganese 0.30-0.50 Iron Balance Sulfur 0.005 max.
Slllcon 0.50-2.0 Copper 0.75 max.
Nlckel 8.75-15.5 Chromlum 19.5-21.0 Alumlnum 0.25-0.60 Tltanlum 0.25-1.0 Cobalt 1.0 max.
Molybdenum 1.0 max.
Phosphorus 0.02 max.
Calclum + Magneslum 0.001-0.015 All composltlons throughout the speclflcatlon are glven ln welght percent. The alloy, on oxldatlon, obtains a protectlve oxlde layer ranglng ln colour from dark gray to black, and has a Ferrlte Number between 1 and 15.
The alloy preferably contalns 11.5-15.0% nlckel, .002% max. sulfur and .015% max. phosphorus. An advantageous composition of the alloy comprlses about 20.5% chromlum by welght and about 14% nlckel, as such maxlmlzes the potentlal for optlmum weldablllty whlle assurlng the formatlon of a black, oxlde durlng sheath manufacture.
The present lnvention provldes a low-cost, oxldatlon reslstant, stress-corroslon cracklng-reslstant, weldable, strong alloy whlch oxidlzes to a deslrable color for use as a heater element sheathlng ln products such as electrlc ranges, colled surface plates and dlshwashers, and elsewhere as a low-cost substltute for INCOLO ~ alloy 840.
- 3a -,, 4- 208 7 3 8 ~ PC-2272/1 The oxides discussed herein for both the present invention and those of the prior art were all formed by heating at 1078C (1970F) in an air-methane mixture of ratio 6:1. This method is typical of current industry practice.
BRIEF DESCRTPTION OF THE DRAVVING
The FIGURE is a nomogram for determining ferrite number.
DETAILED DESCRIPIION OF THE INVENTION
Various studies were undertaken to demonstrate the efficacy of the claimed alloy composition and the desirability thereof for use as heater element sheath as compared to known materials.
The chemical composition of the alloys included in the study are provided in Table 1.
Two heats of the claimed alloy were made containing 10.75 and 14.88 percent nickel, respectively (Examples A and B). Also, heats of Type 309 stainless steel and alloy NAS H-22 were made. These four alloys were hot and then cold worked down to n.o60 inch thick. In addition, Types 304 and 321 stainless steel,INCOLOY~ alloy 800, and three heats of INCOLOY'i9 alloy 840 were included in thetesting. The Type 304 stainless steel was cold rolled from 0.125 inch to 0.060 inch.
The INCOLOY0 alloy 800 was 0.05 inch thick in the hot rolled annealed condition.The three heats of INCOLOY~ alloy 840 were hot worked to 0.30 inch and then coldrolled to 0.018 inch and bright annealed.
One inch square specimens of the alloys were exposed in an electrically heated horizontal tube furnace at 1078C (1970F) in an air-methane mixture at an air:fuel ratio of 6:1. The time at temperature was five minutes, and the gas flow rate was 500 cm3 per minute. Most of the specimens were first given a 120 grit surface finish. The specimens were then laid flat on a cordierite boat. The mullite furnace tube was sealed at both ends and the boat was pushed into the hot zone with a push TABLE I
Alloy C Cr Ni Si Mn Mo Al Ti Cu Ca Mg Example A 0.03520.7110.750.57 0.30 0.280.39 0.41 0.28.0011 .0002 Example B 0.03720.6614.880.62 0.36 0.300.39 0.41 0.30.0018 .0002 Type 304 SS 0.0818-20 8-10.5 1.0 2.0 -- -- -- -- -- --(nominal) Type 309 SS 0.09823.2914.æ 0.45 0.77 0.006 -- 0.00010.0001.0017 .0003 Type 321 SS 0.0817-19 9-12 1.00 2.0 -- --0.40 min. c.001(nominal) INCOLOY~ alloy 840 0.03 19.68 21.35 0.620.36 0.47 0.300.32 0.24 .0008 .0006 (specimen 1) INCOLOYG alloy 840 0.03 19.80 18.78 0.600.35 0.22 0.460.38 0.29 .0014 .0005 (specimen 2) O
INCOLOY~ alloy 840 0.03 21.32 18.63 0.570.36 0.44 0.420.37 0.17 .0027 .0008 _~
(specimen 3) Cl:~
Alloy NAS H-220.022 23.6220.74 0.69 0.360.021 0.13 0.210.019 .0021 .0002 rod which passed through a gas tight O-ring seal. After exposure, the specimens were examined. The results are set forth in Table 2.
Material D~ tion and R~ . lti-~ Color after Exposure in S Air-Methane Mixture (AFR=6) for 5 Minutes at 1078C (1970F) Alloy Surface Finish Color Example A 120 grit dark gray Example B 120 grit dark gray Type 304 SS 120 grit dark gray 10Type 309 SS 120 grit green Type 321 SS 120 grit black (1) INCOLOY6~ alloy 840as-rolled + bright annealmedium gray (1) INCOLOY8\ alloy 840120 grit dark gray (2) INCOLOY0 alloy 840as-rolled + bright anneal dark gray 15(2) INCOLOY'9 alloy 840120 grit dark gray (3) INCOLOY6' alloy 840as-rolled + bright anneal dark gray Alloy NAS H-22 120 grit greenish dark gray The compositional range was arrived at with a view towards the unique characteristics required for heater element sheath. In pursuing this invention, it was necessary to balance the conflicting metallurgical phenomena affecting weldability on the one hand and black oxide formation on the other.
Thus, it was desirable to maintain the highest possible chromium level for ferrite formation without forming green oxide scale. In turn, setting the chromium limit imposes limits on the nickel content. Moreover, the nickel content is in turn limited by cost considerations. A chromium range of 19.5 to 21% (preferably about 20.5%) and a nickel range of 8.75 to 15.5% (preferably about 11.0 to 15.0%) ~ -7- 2Q87389 PC-2272/1 m~imi7es the potential for optimum weldability while assuring the formation of a dark oxide during sheath manufacture.
To successfully compete as a sheathing alloy, the alloy must be compatible with high speed autogenous welding techniques. This can only be achieved 5 if the alloy composition is carefully balanced such that the percentage of ~-ferrite as defined by its Ferrite Number is between 1 and 15. The Ferrite Number in this invention is defined as in the technical paper, "Ferrite Number Prediction to 100 FN in Stainless Steel Weld Metal," by T.~ Sievart, C.N. McCowen and D.L. Olson in the American Welding Society publication, Welding Research Supplement. pp. 289-s to 298-s, December, 1988. These authors define two equations, which the inventors of this invention have modified to be pertinent to the alloys described herein. These equations in combination with the nomogram, shown in the Figure, determine the critical relationship between chromium plus molybdenum and nickel plus carbon which will yield the amount of ~-ferrite essential for high speed autogenous welding techniques. The two equations are:
(1) Creq = % Cr + % Mo (2) Nieq = % Ni + 35 x (% C) The nomogram plots Creq versus Nieq~ with values for the third variable, FerriteNumber, present as diagonal isograms across the grid.
Since the maximum cLlullliulll content which will always result in a dark oxide is 20.5%, the maximum permissible Creq becomes 21.5 if up to 1.0%
molybdenum is present in the alloy. Thus, by locating the isogram for 1, the minimum desired Ferrite Number, it can be seen at point P that the maximum Nieq becomes about 17.25 at zero percent carbon and the nickel content becomes 15.5% maximum if the carbon is 0.05%. The minimum desirable chromium from a corrosion viewpoint is deemed to be 19.5%; thus, the Creq is 19.5 at zero percent molybdenum and 20.5 at 1.0% molybdenum. Consequently, by locating the isogram at Ferrite Number 15, themaximum desirable value, it can be seen at point R that the minimum Nieq becomesabout 10 at zero percent carbon and the nickel level becomes a minimum of 8.75% at 0.05% carbon. The required values for Creq and Nieq must fall within the quadrilateral f -8- 2 0 8 7 3 8 9 PC-2272/1 PQRS of the FIGURE to achieve desired characteristics of color, corrosion-resistance and weldability.
Further, the highest quality welds will occur when the phosphorus content is less than 0.02% (preferably 0.015%), the sulfur content is less than 0.005%
5 . (preferably .002%) and the residual calcium plus magnesium after deoxidation is from 0.001% to 0.015%.
While the lower limit of 8.75% nickel assures transformation of the ~-ferrite formed during solidification of the weld bead to austenite, it was quiteunexpected that the relatively low nickel content would result in a desirable dark gray 10 oxide formation, and would also possess tensile properties similar to INCOLOY alloy 840. Tensile properties for two versions of the claimed alloy and INCOLOY alloy 840 are compared below in Table 3.
TENSILE DATA FOR EXPERIMENTAL ALLOYS vs. INCOLOY0 ALLOY 840 Yield Strength Ultimate Tensile Strength Elongation (ksi) (ksi) (~) ROOM TEMPERATURE TENSILE DATA
Example A 36.5 88.6 41.0 Example B 26.1 76.1 46.0 INCOLOY~ alloy 840 30.8 82.8 40.0 800 Ctl472F TENSILE DATA
20Example A 15.5 23.6 66.5 Example B 13.9 29.8 66.0 INCOLOY0 alloy 840 15.0 26.6 81.5 Aluminum and titanium are integral components of the alloy. Aluminum, at 0.25-O.~O~o, contributes to oxidation- and corrosion-r~cict~nce; and titanium, at 0.25-25 1.0%, in conjunction with the carbon as titanium carbide, contributes to grain sizestability.
~ , -9- 2 08~38g PC-2272/1 The particular ~nri~ ing atmosphere utilized, i.e., air-methane 6:1, was chosen because it is simple, inexpensive and in general use throughout the industry. It is contemplated that other known ~lritli7ing atmospheres or methods may be used to achieve similar results.
S Although the present invention has been described in conjunction with the preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.
Claims (12)
1. A weldable, oxidation- and corrosion-resistant alloy which obtains, upon oxidation, a protective oxide layer ranging in color from dark gray to black, the alloy consisting essentially of, by weight, from about 8.75-15.5% nickel, about 19.5-21.0%
chromium, about 0.30-0.50 manganese, about 0.50-2.0% silicon, about 0.25-0.60%
aluminum, about 0.25-1.0% titanium, up to about 0.05% carbon, up to about 0.005%sulfur, up to about 0.75% copper, up to about 1.0% cobalt, up to about 1.0%
molybdenum, up to about 0.02% phosphorus, about 0.001-0.015% calcium plus magnesium and remainder essentially iron, wherein the Ferrite Number is between 1 and 15.
chromium, about 0.30-0.50 manganese, about 0.50-2.0% silicon, about 0.25-0.60%
aluminum, about 0.25-1.0% titanium, up to about 0.05% carbon, up to about 0.005%sulfur, up to about 0.75% copper, up to about 1.0% cobalt, up to about 1.0%
molybdenum, up to about 0.02% phosphorus, about 0.001-0.015% calcium plus magnesium and remainder essentially iron, wherein the Ferrite Number is between 1 and 15.
2. The alloy of claim 1, wherein nickel is present at about 11.5-15%.
3. The alloy of claim 2, wherein sulfur does not exceed about .002% and phosphorus does not exceed about .015%.
4. The alloy of claim 3, wherein nickel is present at about 14% and chromium is present at about 20.5%.
5. A weldable, oxidation- and corrosion-resistant alloy which obtains, upon oxidation, a protective oxide layer ranging in color from dark gray to black, the alloy consisting essentially of, by weight, from- about 8.75-15.5% nickel, about 19.5-21.0%
chromium, about 0.30-0.50 manganese, about 0.50-2.0% silicon, about 0.25-0.60%
aluminum, about 0.25-1.0% titanium, up to about 0.05% carbon, up to about 0.005%sulfur, up to about 0.75% copper, up to about 1.0% cobalt, up to about 1.0%
molybdenum, up to about 0.02% phosphorus, about 0.001-0.015% calcium plus magnesium and remainder essentially iron, wherein the amounts of chromium, molybdenum, nickel and carbon are determined according to the formulae:
(1) Creq = % Cr + % Mo (2) Nieq = % Ni + 35 (% C) and the permissible values of Creq and Nieq lie within the quadrilateral PQRS of the FIGURE.
chromium, about 0.30-0.50 manganese, about 0.50-2.0% silicon, about 0.25-0.60%
aluminum, about 0.25-1.0% titanium, up to about 0.05% carbon, up to about 0.005%sulfur, up to about 0.75% copper, up to about 1.0% cobalt, up to about 1.0%
molybdenum, up to about 0.02% phosphorus, about 0.001-0.015% calcium plus magnesium and remainder essentially iron, wherein the amounts of chromium, molybdenum, nickel and carbon are determined according to the formulae:
(1) Creq = % Cr + % Mo (2) Nieq = % Ni + 35 (% C) and the permissible values of Creq and Nieq lie within the quadrilateral PQRS of the FIGURE.
6. The alloy of claim 5, wherein nickel is present from about 11.5-15%.
7. The alloy of claim 6, wherein sulfur does not exceed about .002% and phosphorus does not exceed about .015%.
8. The alloy of claim 7, wherein nickel is present at about 14% and chromium is present at about 20.5%.
9. A heater element comprising a sheathing having a protective oxide layer ranging in color from dark gray to black, said sheathing being formed from an alloy consisting essentially of, by weight, from about 8.75-15.5% nickel, about 19.5-21.0%
chromium, about 0.30-0.50% manganese, about 0.50-2.0% silicon, about 0.25-0.60%
aluminum, about 0.25-1.0% titanium, up to about 0.05% carbon, up to about 0.005%sulfur, up to about 0.75% copper, up to about 1.0% cobalt, up to about 1.0%
molybdenum, up to about 0.02% phosphorus, about 0.001-0.015% calcium plus magnesium, and remainder essentially iron, wherein the alloy has a Ferrite Number of between 1 and 15.
chromium, about 0.30-0.50% manganese, about 0.50-2.0% silicon, about 0.25-0.60%
aluminum, about 0.25-1.0% titanium, up to about 0.05% carbon, up to about 0.005%sulfur, up to about 0.75% copper, up to about 1.0% cobalt, up to about 1.0%
molybdenum, up to about 0.02% phosphorus, about 0.001-0.015% calcium plus magnesium, and remainder essentially iron, wherein the alloy has a Ferrite Number of between 1 and 15.
10. The heater element of claim 9, wherein nickel is present from about
11.5-15%.
11. The heater element of claim 10, wherein the sulfur does not exceed about .002% and phosphorus does not exceed about .015%.
11. The heater element of claim 10, wherein the sulfur does not exceed about .002% and phosphorus does not exceed about .015%.
12. The heater element of claim 11, wherein nickel is present at about 14%
and chromium is present at about 20.5%.
and chromium is present at about 20.5%.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/822,084 | 1992-01-17 | ||
| US07/822,084 US5160382A (en) | 1992-01-17 | 1992-01-17 | Heater sheath alloy |
| US07/889,556 US5217545A (en) | 1992-01-17 | 1992-05-27 | Heater sheath alloy |
| US07/889,556 | 1992-05-27 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2087389A1 CA2087389A1 (en) | 1993-07-18 |
| CA2087389C true CA2087389C (en) | 1997-04-08 |
Family
ID=27124612
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002087389A Expired - Fee Related CA2087389C (en) | 1992-01-17 | 1993-01-15 | Heater sheath alloy |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US5217545A (en) |
| EP (1) | EP0551711B1 (en) |
| JP (1) | JPH07103450B2 (en) |
| KR (1) | KR930016555A (en) |
| AU (1) | AU651783B2 (en) |
| CA (1) | CA2087389C (en) |
| DE (1) | DE69217901T2 (en) |
| NZ (1) | NZ245441A (en) |
| TW (1) | TW225557B (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030164225A1 (en) * | 1998-04-20 | 2003-09-04 | Tadashi Sawayama | Processing apparatus, exhaust processing process and plasma processing |
| US6201217B1 (en) * | 1999-04-12 | 2001-03-13 | Heartware Home Products, Inc. | Counter-top electric cooker |
| US6747250B1 (en) | 2003-01-10 | 2004-06-08 | Morning Electronics Co. Ltd. | Counter-top electric oven |
| SE529741C2 (en) * | 2005-01-17 | 2007-11-13 | Sandvik Intellectual Property | Procedure for thermal insulation of weld joint and sleeve therefor |
| US7964824B2 (en) * | 2007-11-30 | 2011-06-21 | Ibc-Hearthware, Inc. | System, method and computer program product for programmable counter-top electric oven |
| US8835810B2 (en) * | 2007-11-30 | 2014-09-16 | Nuwave LLC | System and method for a programmable counter-top electric dehydrator |
| US8330083B2 (en) | 2007-11-30 | 2012-12-11 | Hearthware, Inc. | Portable countertop electric oven |
| US8287403B2 (en) * | 2009-10-13 | 2012-10-16 | O-Ta Precision Industry Co., Ltd. | Iron-based alloy for a golf club head |
| USD693643S1 (en) | 2010-03-12 | 2013-11-19 | Hearthware Inc. | Power head for a portable countertop electric oven |
| JP2015155790A (en) * | 2014-01-15 | 2015-08-27 | 日本特殊陶業株式会社 | Sheath heater and glow plug |
| JP6186043B1 (en) * | 2016-05-31 | 2017-08-23 | 日本冶金工業株式会社 | Fe-Ni-Cr alloy, Fe-Ni-Cr alloy strip, sheathed heater, method for producing Fe-Ni-Cr alloy, and method for producing sheathed heater |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3362813A (en) * | 1964-09-15 | 1968-01-09 | Carpenter Steel Co | Austenitic stainless steel alloy |
| US3729308A (en) * | 1970-07-21 | 1973-04-24 | Int Nickel Co | Iron nickel chromium alloys |
| SE7705578L (en) * | 1976-05-15 | 1977-11-16 | Nippon Steel Corp | TWO-PHASE STAINLESS STEEL |
| JPS6214628A (en) * | 1985-07-12 | 1987-01-23 | Minolta Camera Co Ltd | Camera with preview mechanism |
| JPS648695A (en) * | 1987-07-01 | 1989-01-12 | Hitachi Ltd | Printed circuit board processor |
| JP2760004B2 (en) * | 1989-01-30 | 1998-05-28 | 住友金属工業株式会社 | High-strength heat-resistant steel with excellent workability |
| US5087414A (en) * | 1989-11-03 | 1992-02-11 | Carpenter Technology Corporation | Free machining, mon-magnetic, stainless steel alloy |
-
1992
- 1992-05-27 US US07/889,556 patent/US5217545A/en not_active Expired - Lifetime
- 1992-08-13 TW TW081106413A patent/TW225557B/zh active
- 1992-09-21 DE DE69217901T patent/DE69217901T2/en not_active Expired - Fee Related
- 1992-09-21 EP EP92308587A patent/EP0551711B1/en not_active Expired - Lifetime
- 1992-10-28 JP JP4290503A patent/JPH07103450B2/en not_active Expired - Fee Related
- 1992-11-19 KR KR1019920021688A patent/KR930016555A/en not_active Application Discontinuation
- 1992-12-11 NZ NZ245441A patent/NZ245441A/en unknown
-
1993
- 1993-01-15 CA CA002087389A patent/CA2087389C/en not_active Expired - Fee Related
- 1993-01-15 AU AU31817/93A patent/AU651783B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05247598A (en) | 1993-09-24 |
| AU651783B2 (en) | 1994-07-28 |
| US5217545A (en) | 1993-06-08 |
| DE69217901D1 (en) | 1997-04-10 |
| TW225557B (en) | 1994-06-21 |
| JPH07103450B2 (en) | 1995-11-08 |
| KR930016555A (en) | 1993-08-26 |
| AU3181793A (en) | 1993-07-22 |
| EP0551711A1 (en) | 1993-07-21 |
| CA2087389A1 (en) | 1993-07-18 |
| NZ245441A (en) | 1993-12-23 |
| EP0551711B1 (en) | 1997-03-05 |
| DE69217901T2 (en) | 1997-10-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0016225B1 (en) | Use of an austenitic steel in oxidizing conditions at high temperature | |
| CA1070528A (en) | Oxidation and sulfidation resistant austenitic stainless steel | |
| CA2645596C (en) | Weldable oxidation resistant nickel-iron-chromium-aluminum alloy | |
| CA2087389C (en) | Heater sheath alloy | |
| JPS638176B2 (en) | ||
| US4882125A (en) | Sulfidation/oxidation resistant alloys | |
| CA1214667A (en) | Duplex alloy | |
| US2797162A (en) | Low alloy steel for sub-zero temperature application | |
| US5160382A (en) | Heater sheath alloy | |
| US4743318A (en) | Carburization/oxidation resistant worked alloy | |
| US5300751A (en) | Method for gas-shield arc welding of a pipe and weld wire for use in the welding method | |
| KR20030012799A (en) | Electric resistance material | |
| JPS63121641A (en) | External coating of sheathed heater made of austenitic stainless steel | |
| US5330705A (en) | Heat resistant alloys | |
| KR880001356B1 (en) | Low interstitial 29% chromium-48% molybdenun weldable ferrite stainless steel containing columbium or titanium | |
| WO2000075391A1 (en) | A welding electrode, a welded article, and a steel weldable with the welding electrode | |
| GB1581280A (en) | Fe-ni-cr alloys resistant to high temperature oxidation | |
| JPS5935424B2 (en) | heat resistant cast steel | |
| US4456483A (en) | Ferritic stainless steel | |
| JPH041046B2 (en) | ||
| JPS5935425B2 (en) | heat resistant cast steel | |
| US4662953A (en) | Creep resistant cold-rolled and annealed steel sheet and strip | |
| JPH02118053A (en) | Heat-resistant alloy | |
| JPH05195162A (en) | High temperature material excellent in weldability and oxidation resistance | |
| JPS596908B2 (en) | heat resistant cast steel |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |