CA2061765A1 - Martensitic stainless steel article and method for producing the same - Google Patents
Martensitic stainless steel article and method for producing the sameInfo
- Publication number
- CA2061765A1 CA2061765A1 CA 2061765 CA2061765A CA2061765A1 CA 2061765 A1 CA2061765 A1 CA 2061765A1 CA 2061765 CA2061765 CA 2061765 CA 2061765 A CA2061765 A CA 2061765A CA 2061765 A1 CA2061765 A1 CA 2061765A1
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- Canada
- Prior art keywords
- article
- sulfur
- carbon
- nitrogen
- hrc
- Prior art date
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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
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
ABSTRACT
A martensitic stainless steel article having an improved combination of strength, toughness, corrosion resistance and machinability. The article is particularly adapted for use in the manufacture of holder blocks, frames, backers and similar articles for anchoring molds and dies. The carbon and nitrogen content of the article are controlled to achieve the desired hardness. Sulfur is controlled in accordance with carbon plus nitrogen to maintain the required machinability of the article. Chromium and nickel are present for maintaining corrosion resistance, along with molybdenum, which also counteracts any adverse effects of increased sulfur content. The article may be austenitized at a temperature within the of 1500 to 1750°F for about 1 hour per inch of thickness and either oil quenched or air cooled to achieve a martensitic structure. Thereafter, the article may be tempered or stress-relieved at a temperature between 500 and 850°F for about 1 hour per inch of thickness and for a minimum of 2 hours. After these heat treatments, the article will exhibit a hardness within the range of 30 to 40 HRC, preferably 35 to 40 HRC for higher strength applications, along with a drill machinability rating equal to or greater than 100.
A martensitic stainless steel article having an improved combination of strength, toughness, corrosion resistance and machinability. The article is particularly adapted for use in the manufacture of holder blocks, frames, backers and similar articles for anchoring molds and dies. The carbon and nitrogen content of the article are controlled to achieve the desired hardness. Sulfur is controlled in accordance with carbon plus nitrogen to maintain the required machinability of the article. Chromium and nickel are present for maintaining corrosion resistance, along with molybdenum, which also counteracts any adverse effects of increased sulfur content. The article may be austenitized at a temperature within the of 1500 to 1750°F for about 1 hour per inch of thickness and either oil quenched or air cooled to achieve a martensitic structure. Thereafter, the article may be tempered or stress-relieved at a temperature between 500 and 850°F for about 1 hour per inch of thickness and for a minimum of 2 hours. After these heat treatments, the article will exhibit a hardness within the range of 30 to 40 HRC, preferably 35 to 40 HRC for higher strength applications, along with a drill machinability rating equal to or greater than 100.
Description
--\
2~76~
BAC~GROUND OF TH~ INVBNTION
FIELD OF THE INVENTION
The invention relate~ to a marten~itic stainless ~teel article u~sd for anchoring molds and dies and to a method for producing the ~ame.
DESCRIPTION OF THE PRIOR ART
Molds and dies used to produce part~ made from materials such a~ pla~tic are anchored in place during operation by frame~, holder blocks, backer~, and similar articles. The~e articles are usually made from steel of a composition exhibiting hlgh strength and toughness to withstand the ~tre~e~ incident to these applications and to provide sufficient service life. The steel must al~o have good machinability to facilitate manufacture of these articles and must be ea~ily heat-treatable in relatively large section sizes to the necessary hardnes~ limits.
Typical steel~ used in the manufacture of frames and holder bloc~ are prehardened within the hardness range of about 30 to 40 Rockwell C (HRC). Thi~ eliminates the need for heat-treatment by the user, and avoids the distortion normally encountered in heat-treating of machined article~.
The hardne~ range of 30 to 40 HRC i~ ~ignificant, because 2~17~
the machinability of most steels st hardnesses above 40 HRC
is reduced to a level that makes the required machinLng too expensive for most applications. Although lowering the hardness of the steel improves machinability, at hardnesses below about 30 HRC the steel lacks sufficient mechanical strength for these intended applications.
The low-alloy carbon steel~ conventionally used for the production of holder blocks, such as the ~ulfur-bearing modifications of AISI 4140 and AISI 5150, provide an excellent combination of mechanical properties, in combination with good machinability. They, however, lack sufficient corrosion resistance to resist rusting and other forms of corro~ion during both service and storage. This corrosive attack reduces the operating safety, efficiency and service life and moreover requires that the holder blocks and frames be covered with a protective coating when they are not in use.
A number of corrosion resistant steels have been evaluated as replacements for the conventional low-alloy carbon steels used in holder block applications. High quality stainless mold steels, such as AISI Type 414, AISI
~ype 420, and tho~e disclosed in U.S. Patent No. 3,720,545 have been considered; however, they are not widely used for holder block applications because of their cost, properties, 2~6176~
and comparatively poor machinability. To overcome the machinabillty problem, a number of sulfur-bearing modifications of AISI Type 420 and AISI Type 430 have been developed. While these ~ulfur-bearing steels have relatively good machinability, they are not well ~u$ted for this application becau~e their inherent hardening and tempering characteri~tics make it difficult to produce them in the broad hardness range of 30 to 40 HRC required for holder blocks snd especially in the narrower hardness range of 35 to 40 HRC required for high strength holder block~. In sddition, the relatively high austenitizing temperstures used to harden these steels, typically 1825 to 1900F, re~ult in increased cost and contribute to con~iderable distortion of the articles during the hardening heat-treatment. Further, at hardnesses within the range of about 30 to 40 HRC, these stainle~s steels exhibit a characteristic drop in toughness and corrosion resistance that significantly detract~ from their usefulness in these applications.
OBJECTS OF TEE INVENTION
It is a primary ob~ect of the present invention to provide a martensitic stainless steel article which may be used for holder blocks, frames, backers, and simllar articles for anchoring molds and dies, having an improved combination 20~176~
of strength, toughness, corrosion resistance, and machinability.
Another related ob~ect of the invention i8 to provide a method for producing a martensitic stainless steel article having these characteristics by the use of a simple hardening and tempering heat-treatment.
SUMMARY OF THF INVENTION
It has been determined in accordance with the invention that a martensitic stainle~s ~teel article having an improved combination of strength, toughne~s, corrosion resistance, and machinability may be produced by controlling carbon and nitrogen to achieve the desired hardness. Sulfur is controlled in accordance with carbon plu~ nitrogen to maintain a drill machinability rating equal to or greater *L~\Css ~, than 100 (when compared to a commercial ~ronbe-- hold0r block ~ 4;~\
steel). For this purpose, sulfur must be increased with increases in the carbon and nitrogen content. Chromium, and also nickel, are present for maintaining corroslon resistance. Molybdenum is also added for corro~ion resistance and specifically to counteract the adverse effects of increased sulfur in this regard. Consequently, molybdenum is increased with increased sulfur contents.
In accordance with the invention, a martensitic stainless steel article, which may be used for holder blocks, 2~176~
frames, backers, and similar articles for anchoring mold~ and dies, is of a composition within the limits set forth in Table 1.
_ g ~t ~ 2 ~ ~ ~0~76~i 9 ~11 9 9 8 ~ S
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20S176~
The article is characterized by a hardness within the range of 30 to 40 HRC, preferably 35 to 40 HRC for higher strength application~.
In accordance with the method of the invention, stsel in accordance with the compoqition limits set forth in Table I
is austenitized at a temperature within the range of 1500 to 1750F for about l hour per inch of thickness and either oil quenched or air cooled to achieve a martensitic structure.
Thereafter, the article can be tempered or stress-relieved at a te~perature between about 500 and 850F for about 1 hour per inch of thickness and for a minimum of 2 hours. After these heat treatments, the articles will exhibit a hardness within the range of 30 to 40 HRC, preferably 35 to 40 HRC for high strength application~, and a drill machinability rating equal to or greater than 100.
Preferably, the article after tempering in addition exhibits a corrosion rate in inches per year of less than 9 when tested in accordance with the procedure disclosed hereinafter.
BRIFP D~SCRIPTION OF THF DRAMINGS
Figure 1 is a graph showing the relationship between tempering temperature and hardness for a commercial stainless 2~617~
holder block steel of the composition, in weight percont, 0.32% carbon, 1.33% mangane~e, 0.32% ~ilicon, 0.097% sulfur, 0.50% nickel, 16.8% chromium, 0.04% molybdenum, Q.034%
nitrogen and balance iron and incidental impurities;
Figure 2 is a graph showing the relationship between tempering temperature and hardness for the two indicated holder block steels in accordance with the invention;
Figure 3 is a graph showing the relation~hip between the hardness of holder block steel~ in accordance with the invention in the a~-hardened condition in relation to the carbon plu8 nitrogen content thereof;
Figure 4 is a graph showing the relationship between the drill machinability of holder block steels in accordance with the invention with re~pect to a parameter relating to the hardness and sulfur contents thereof; and Figure 5 is a ~eries of photograph~ comparing the corrosion resi~tance of three holder block ~teel~ in accordance with the invention with two holder block steels of compositions outside the scope of the invention.
DBTAI~BD DESCRIPTION OF TH~ PXBFERRED EM~ODI~ENTS
Stainles~ steel holder blocks are generally made by hot rolling or forging an ingot to slab or billet that i~
subsequently heat-treated to the desired final hardne~ and 2~76a then sawed and machined into blocks of the required shapes and dimensions. Less commonly, the holder blocks are cut and rough machined from fully annealed slabs or billets, heat-treated separately to the desired hardnes~, ~nd then machined to f~nal shape. The hardness typical of ~tandard holder block applicatLons ranges from about 30 to 35 HRC, wheress that for high strength holder block applications ranges from about 35 to 40 HRC. In order to attain these hardnesses without undue cost or difficulty, it is essential that the steel used in the holder block be readily heat-treatable to the required hardnesa levels. With stainless steels typical of those now used in corrosion resistant holder blocks, such as that tested to obtain the data presented in Figure 1, the tempering temperatures required to produce hardnesses in the range of about 30 to 40 HRC and especially in the range of about 35 to 40 HRC are quite critical in that s1ight differences in temperature result in a larqe difference in hardness. Thus, very close control of the tempering operstion is needed with these steels to obtain the hardnesse~ requ~red for holder block applications. Further, such steel~ when tempered to hardnesses in the range of about 30 to 40 HRC exhibit relatively low notch toughness and corrosion resistance.
In comparison, with the holder block steels of this invention it is possible to obtain an improved combination of 2~6~76~
corrosion resistance and toughne~ and the hardnesse~ needed for this application with a simple heat-treatment. Figure 2 shows that steel holder blocks produced in accordance with the invention and within the composition limit~ g$ven in Table I provide the desired hardnesse- in both the as-hardened condition and when tempered or ~tress-relieved over a broad range of temperatures. For example, a ~teel holder block made from Heat V1056 containing 0.043% carbon plu8 nitrogen schieve~ a hardness well within the range needed for standard holder blocks (30 to 35 HRC) in the as-hardened condition and also when tempered or stress relieved at temperatures up to about 850F. Similarly, a holder block made from Heat V1020 with 0.0~9~ carbon plu8 nitrogen achieves a hardness well within the range 35 to 40 HRC needed for high strength holder blocks in the as-hardened condition and also when tempered or stress relieved over a wide range of temperaturea. Also, in contrast to ~t~inle~s ~teel~ of the type now used in corrosion res$stant holder blocks, which are normally austenitized from temperatures between about 1825 to 1900F, steel holder blocks produced within the scope of the invention can be austeniti2ed from temperatures as low as about 1550F, which achieves considerable energy savings in heat-treatment.
With respect to the chemical composition of the steels used in the holder blocks of this invention, it is necessary _ 10 --within the composition ranges given in Table I to control their overall composition so that the holder block~ will be substantially fully martensitic in the as-hardened condition.
To obtain a substantially fully martensitic structure in the as-hardened condition, it is necessary that the composition of the steelY be balanced with respect to the austQnite forming elements, such as carbon, nitrogen, nickel, and manganese, and the ferrite forming elements, such as chromium, molybdenum, and ~ilicon, to minimize the formation of delta ferrite. Large amount-q of delt~ ferrite are detrimental in the steel from the ~tandpoint of reducing the hardne6s and toughness of holder blocks made therefrom.
The hardness of the ~teels used in the holder blocks of the invention in the as-hsrdened condition i8 primarily a function of the carbon plus nitrogen content. To obtain the desired hardnesses within the range of 30 to 40 HRC, it is therefore necessary to control the carbon and nitrogen contents within the rangeq indicated in Table I. With a carbon plu8 nitrogen content that is too low, the holder blocks will not achieve the minimum desired strength and hardness; with a carbon plu~ nitrogen content that is too high, the holder blocks will exceed the de~ired maximum hardness and exhibit unacceptable machinab$1ity.
Manganese is a desirable element in the steels used in the holder blocks. Manganese imparts hardenability and, in 2~1765 combination with sulfur, is al~o present for purposes of improvinq machinability through the formation of manganese sulfide. Also, manganese is an austenite forming element and can be used to partially replace nickel in the ~teel for composition balance and to thereby redùce steel costs.
Silicon is used in steelmaking for deoxidation and increasing chromium recovery. It al80 slightly improves corrosion resistance, but is a ferrite forming element and thus increases the amount of costly nickel or manganese needed to obtain a fully martensitic structure.
Nickel is required within the indicsted ranges to obtain the desired austenite-ferrite balance and to thereby obtain a substantially fully martensitic structure in the holder blocks. It also improves corrosion resi~tance; but ~8 a costly element, and for this reason is not desirable above the indicated ranges.
Chromium is essential for corro~ion re~istance, but above the indicated amounts increases the amount of nickel, manganese, and other austenite forming elements that are required to be present to avoid the formation of delta ferrite and to obtain a substantially fully martensitic structure ln the holder blocks.
Molybdenum is an expensive alloying element, but in small amounts and together with chromium has a very 2 ~ ~ ~ 7 6 ~
beneficial affect on the corro~ion resistance of the holder block~, and a minimum of about 0.25~ is neces~ary for reducing the adverse effect~ of ~ulfur on this property.
Consequently, molybdenum generally should be increased in the pre~ence of increa~ed ~ulfur for this purpo~e.
Sulfur i~ used for improving machinability, but decreases notch toughness and corrosion resistance. When high toughne~s and corrosion resistance are required in the holder blocks of the invention, ~ulfur should be limited to about 0.10~; but when greater machinability is desired, it can be increased to about 0.25% without lowering toughnesg and corrosion resi~tance to unacceptable levels. Molybdenum should be incres~ed w$th increased sulfur to maintain corrosion resistance at the desired level.
Copper is a common re~idual element in stainle~s steel melting, and i~ useful for controlling the austenite-ferrite balance. However, in amount~ greater than about 1.0~ it can have an undesirable hardening effect during tempering of the holder blocks.
To demonstrate the principle~ of the invention, a serie~
of experiment~l holder block steels were made and sub~ected to a variety of mechan~cal and corrosion tests. The chemical compositions of the experimental holder block steels and of a commercial ~tainless holder block steel (Alloy 90-45) included for comparison are given in Table II.
206176~
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jNN~ 2 ~ ~ N~oo 2 _ _ N~oN~NN~s .~ ~ NNNNNNNNN~
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_ O O O O O O O O
__ 2i S ~ I a!; ¢l . _o~NO~N~o~
_ ~ _ o 8 o o o 2~6~6~
Ingots of the experimental holder block steels were hot worked from a reheating temperature of about 2150F to bar stock from which samples were taken for metallographic evaluation and testing. Except for those samples used to determine attainable hardne~s, all the test ~ample~ were austenitized at 1550F, air cooled to room temperature, and then tempered for two hour~ at 550F. None of the experLmental holder block steels were found to contain any delta ferrite after this heat-treatment. The samples of the commercial stainless holder block steel were received in the prehardened condition at a hardness of 33 HRC. In order to test this material at a higher hardness of 38 ERC, samples of the commercial holder block steel were austenitized at 1850F, oil quenched to room temperature and then tempered for 2 hours at 975F.
Several tests were conducted to compare the advantages of the holder block steels of the invention with those of a commercial stainle~s holder block steel and to demonstrate the significance of their composition. Tests were conducted to illustrate the effects of steel composition on attainable hardnes~, notch toughness, tensile strength, machinability, and corrosion re~istance.
The attainable hardnesses of the experimental holder block steels in the as-hardened condition are plotted in 2~176~
Figure 3 as a function of their carbon plus nitrogen contents. The specimens for these tests were austenitized for 15 minutes at 1600F and then air cooled to room temperature. Allowing for some normal scatter in the results of the hardness tests, Figure 3 shows that the attainable hardnes~ of the steels used in the holder blocks of the invention has a strong relationship with their carbon plus nitrogen contents. To obtain the hardnesses needed for holder block applications (30 ~o 40 HRC), Figure 3 shows that the carbon plus nitrogen contents of the holder blocks of the invention must be controlled in a range between about 0.02 to O.09%. Further, to obtain the hardness typical of standard holder blocks (30 to 35 HRC) and of high strength holder blocks (35 to 40 HRC), the carbon plu8 nitrogen content of the steels used in the holder blocks of the invention must be controlled from about 0.02 to 0.06% and from about 0.06 to 0.09%, respectively.
The results of the notch toughness and tension tests conducted on the experimental holder block steels and on the commercial stainless holder block steel are given in Table III.
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2 ~ ~ n 0 ~ ~ ~ J
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c ~ V o o ~ o 4 o o o ~n e ,.
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__ _ _ ~ - ~
~ 8~ ~0 0~ 0~ o ~, æ o . ~ -_ _ _ 2~176a These test results show that the notch impact toughness of the ~teels u~ed in the holder blocks of this invention, as measured in the Charpy V-notch impact test, are clearly superior to those of a commercial stainles~ steel typically used in this application (Alloy 90-45). The advantage in toughnes~ i8 particularly great for those experimental steels containing les~ than about 0.10~ sulfur, as can be qeen by comparing the notch toughnes~ values of Alloy V1033 (30.6 ft-lb) with those of the commercial stainless holder block steel (5.0 ft-lb). Above sulfur levels of about 0.10%, the impact properties of the steels u~ed in the holder blocks of the invention are still ~ignificantly better than that of the commercial stainle~s holder block steel. For example, the notch toughness of Alloy V1055 with 0.20% sulfur i8 15.0 ft-lb in the longitudinal direction; whereas, that of the commercial stainless holder block steel (Alloy 90-45) with 0.09% sulfur is only 5.0 ft-lb.
The tensile properties of the steels used in the holder blocks of this invention are largely a function of their hardness and are at least comparable to tho~e of the commercial stainless holder block steel at the same hardneqs.
About the ~ame mechanical properties and notch toughne~s are obtained for the higher manganese and lower nickel containing experimental holder block steels ~Alloys V1022 and V1055) a~
206176~
for the comparable steels with higher nickel and lower manganese (Alloys V1020 and V1056). Thus, when it i9 de~irable to reduce cost, manganese csn be used to replace psrt of the nickel in the steels used in the holder blocks of this invention.
The re~ult~ of drill machinability tests conducted on the experiment~l steel~ used in the holder blocks of the invention and on a commercial st~inless holder block steel are given in Table IV and in Figure 4. The machinability indexes given in this table and figure were obtained by comparing the times re~uired to drill holes of the same size and depth in the experimental steels and in the commercial stainless holder block steel at a hardness of 33.0 HRC and by multiplying the ratios of these time~ by 100. Indexes greater than 100 indicate that the drill machinability of the test specimen i~ greater than that of the commercial stainless holder block steel. Because the hardness and sulfur content of these steels are known to influence machinability, a parameter based on these factors [Rockwell C
hardnes~ -100 (% S)] wa~ derived and used to compare the drill machinability of the test materials.
2~176~
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BAC~GROUND OF TH~ INVBNTION
FIELD OF THE INVENTION
The invention relate~ to a marten~itic stainless ~teel article u~sd for anchoring molds and dies and to a method for producing the ~ame.
DESCRIPTION OF THE PRIOR ART
Molds and dies used to produce part~ made from materials such a~ pla~tic are anchored in place during operation by frame~, holder blocks, backer~, and similar articles. The~e articles are usually made from steel of a composition exhibiting hlgh strength and toughness to withstand the ~tre~e~ incident to these applications and to provide sufficient service life. The steel must al~o have good machinability to facilitate manufacture of these articles and must be ea~ily heat-treatable in relatively large section sizes to the necessary hardnes~ limits.
Typical steel~ used in the manufacture of frames and holder bloc~ are prehardened within the hardness range of about 30 to 40 Rockwell C (HRC). Thi~ eliminates the need for heat-treatment by the user, and avoids the distortion normally encountered in heat-treating of machined article~.
The hardne~ range of 30 to 40 HRC i~ ~ignificant, because 2~17~
the machinability of most steels st hardnesses above 40 HRC
is reduced to a level that makes the required machinLng too expensive for most applications. Although lowering the hardness of the steel improves machinability, at hardnesses below about 30 HRC the steel lacks sufficient mechanical strength for these intended applications.
The low-alloy carbon steel~ conventionally used for the production of holder blocks, such as the ~ulfur-bearing modifications of AISI 4140 and AISI 5150, provide an excellent combination of mechanical properties, in combination with good machinability. They, however, lack sufficient corrosion resistance to resist rusting and other forms of corro~ion during both service and storage. This corrosive attack reduces the operating safety, efficiency and service life and moreover requires that the holder blocks and frames be covered with a protective coating when they are not in use.
A number of corrosion resistant steels have been evaluated as replacements for the conventional low-alloy carbon steels used in holder block applications. High quality stainless mold steels, such as AISI Type 414, AISI
~ype 420, and tho~e disclosed in U.S. Patent No. 3,720,545 have been considered; however, they are not widely used for holder block applications because of their cost, properties, 2~6176~
and comparatively poor machinability. To overcome the machinabillty problem, a number of sulfur-bearing modifications of AISI Type 420 and AISI Type 430 have been developed. While these ~ulfur-bearing steels have relatively good machinability, they are not well ~u$ted for this application becau~e their inherent hardening and tempering characteri~tics make it difficult to produce them in the broad hardness range of 30 to 40 HRC required for holder blocks snd especially in the narrower hardness range of 35 to 40 HRC required for high strength holder block~. In sddition, the relatively high austenitizing temperstures used to harden these steels, typically 1825 to 1900F, re~ult in increased cost and contribute to con~iderable distortion of the articles during the hardening heat-treatment. Further, at hardnesses within the range of about 30 to 40 HRC, these stainle~s steels exhibit a characteristic drop in toughness and corrosion resistance that significantly detract~ from their usefulness in these applications.
OBJECTS OF TEE INVENTION
It is a primary ob~ect of the present invention to provide a martensitic stainless steel article which may be used for holder blocks, frames, backers, and simllar articles for anchoring molds and dies, having an improved combination 20~176~
of strength, toughness, corrosion resistance, and machinability.
Another related ob~ect of the invention i8 to provide a method for producing a martensitic stainless steel article having these characteristics by the use of a simple hardening and tempering heat-treatment.
SUMMARY OF THF INVENTION
It has been determined in accordance with the invention that a martensitic stainle~s ~teel article having an improved combination of strength, toughne~s, corrosion resistance, and machinability may be produced by controlling carbon and nitrogen to achieve the desired hardness. Sulfur is controlled in accordance with carbon plu~ nitrogen to maintain a drill machinability rating equal to or greater *L~\Css ~, than 100 (when compared to a commercial ~ronbe-- hold0r block ~ 4;~\
steel). For this purpose, sulfur must be increased with increases in the carbon and nitrogen content. Chromium, and also nickel, are present for maintaining corroslon resistance. Molybdenum is also added for corro~ion resistance and specifically to counteract the adverse effects of increased sulfur in this regard. Consequently, molybdenum is increased with increased sulfur contents.
In accordance with the invention, a martensitic stainless steel article, which may be used for holder blocks, 2~176~
frames, backers, and similar articles for anchoring mold~ and dies, is of a composition within the limits set forth in Table 1.
_ g ~t ~ 2 ~ ~ ~0~76~i 9 ~11 9 9 8 ~ S
o 8 o _ 8 8 N 8 ¦ O O O N O O _ _ _ O
8 ~n _ 8.
~ ~ - x ~j ~ 8 ~
8 8 o o o o 8 0 8 ~ 8 O O O N O O _ _ _ O
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1~1 ~ ~ N 8 ~ ~
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o 9 ~ O ~ o _ j;
_ o o o 8 o o 8 g 8 N g a o 1~ O O O N O O _ _ _ O _ ~3 2c~ ~ g C~ V~ O ~N 8 ~ r~
~ 9 ~ 9 ~ 9 ~ g ~ ~ Ue i~ ~ o o o 8 o _ 8 8 j N 8 o _ 8, ~ r~
~ ~i 9 9 o 9 ~ o ~
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_ g N 8 ~ 8 ~ 9 9 ~ 9 9 0 o m 8 g o ~ o o 8 8 . N g O O O ~ O O -- _ -- O
_ 1~
.
20S176~
The article is characterized by a hardness within the range of 30 to 40 HRC, preferably 35 to 40 HRC for higher strength application~.
In accordance with the method of the invention, stsel in accordance with the compoqition limits set forth in Table I
is austenitized at a temperature within the range of 1500 to 1750F for about l hour per inch of thickness and either oil quenched or air cooled to achieve a martensitic structure.
Thereafter, the article can be tempered or stress-relieved at a te~perature between about 500 and 850F for about 1 hour per inch of thickness and for a minimum of 2 hours. After these heat treatments, the articles will exhibit a hardness within the range of 30 to 40 HRC, preferably 35 to 40 HRC for high strength application~, and a drill machinability rating equal to or greater than 100.
Preferably, the article after tempering in addition exhibits a corrosion rate in inches per year of less than 9 when tested in accordance with the procedure disclosed hereinafter.
BRIFP D~SCRIPTION OF THF DRAMINGS
Figure 1 is a graph showing the relationship between tempering temperature and hardness for a commercial stainless 2~617~
holder block steel of the composition, in weight percont, 0.32% carbon, 1.33% mangane~e, 0.32% ~ilicon, 0.097% sulfur, 0.50% nickel, 16.8% chromium, 0.04% molybdenum, Q.034%
nitrogen and balance iron and incidental impurities;
Figure 2 is a graph showing the relationship between tempering temperature and hardness for the two indicated holder block steels in accordance with the invention;
Figure 3 is a graph showing the relation~hip between the hardness of holder block steel~ in accordance with the invention in the a~-hardened condition in relation to the carbon plu8 nitrogen content thereof;
Figure 4 is a graph showing the relationship between the drill machinability of holder block steels in accordance with the invention with re~pect to a parameter relating to the hardness and sulfur contents thereof; and Figure 5 is a ~eries of photograph~ comparing the corrosion resi~tance of three holder block ~teel~ in accordance with the invention with two holder block steels of compositions outside the scope of the invention.
DBTAI~BD DESCRIPTION OF TH~ PXBFERRED EM~ODI~ENTS
Stainles~ steel holder blocks are generally made by hot rolling or forging an ingot to slab or billet that i~
subsequently heat-treated to the desired final hardne~ and 2~76a then sawed and machined into blocks of the required shapes and dimensions. Less commonly, the holder blocks are cut and rough machined from fully annealed slabs or billets, heat-treated separately to the desired hardnes~, ~nd then machined to f~nal shape. The hardness typical of ~tandard holder block applicatLons ranges from about 30 to 35 HRC, wheress that for high strength holder block applications ranges from about 35 to 40 HRC. In order to attain these hardnesses without undue cost or difficulty, it is essential that the steel used in the holder block be readily heat-treatable to the required hardnesa levels. With stainless steels typical of those now used in corrosion resistant holder blocks, such as that tested to obtain the data presented in Figure 1, the tempering temperatures required to produce hardnesses in the range of about 30 to 40 HRC and especially in the range of about 35 to 40 HRC are quite critical in that s1ight differences in temperature result in a larqe difference in hardness. Thus, very close control of the tempering operstion is needed with these steels to obtain the hardnesse~ requ~red for holder block applications. Further, such steel~ when tempered to hardnesses in the range of about 30 to 40 HRC exhibit relatively low notch toughness and corrosion resistance.
In comparison, with the holder block steels of this invention it is possible to obtain an improved combination of 2~6~76~
corrosion resistance and toughne~ and the hardnesse~ needed for this application with a simple heat-treatment. Figure 2 shows that steel holder blocks produced in accordance with the invention and within the composition limit~ g$ven in Table I provide the desired hardnesse- in both the as-hardened condition and when tempered or ~tress-relieved over a broad range of temperatures. For example, a ~teel holder block made from Heat V1056 containing 0.043% carbon plu8 nitrogen schieve~ a hardness well within the range needed for standard holder blocks (30 to 35 HRC) in the as-hardened condition and also when tempered or stress relieved at temperatures up to about 850F. Similarly, a holder block made from Heat V1020 with 0.0~9~ carbon plu8 nitrogen achieves a hardness well within the range 35 to 40 HRC needed for high strength holder blocks in the as-hardened condition and also when tempered or stress relieved over a wide range of temperaturea. Also, in contrast to ~t~inle~s ~teel~ of the type now used in corrosion res$stant holder blocks, which are normally austenitized from temperatures between about 1825 to 1900F, steel holder blocks produced within the scope of the invention can be austeniti2ed from temperatures as low as about 1550F, which achieves considerable energy savings in heat-treatment.
With respect to the chemical composition of the steels used in the holder blocks of this invention, it is necessary _ 10 --within the composition ranges given in Table I to control their overall composition so that the holder block~ will be substantially fully martensitic in the as-hardened condition.
To obtain a substantially fully martensitic structure in the as-hardened condition, it is necessary that the composition of the steelY be balanced with respect to the austQnite forming elements, such as carbon, nitrogen, nickel, and manganese, and the ferrite forming elements, such as chromium, molybdenum, and ~ilicon, to minimize the formation of delta ferrite. Large amount-q of delt~ ferrite are detrimental in the steel from the ~tandpoint of reducing the hardne6s and toughness of holder blocks made therefrom.
The hardness of the ~teels used in the holder blocks of the invention in the as-hsrdened condition i8 primarily a function of the carbon plus nitrogen content. To obtain the desired hardnesses within the range of 30 to 40 HRC, it is therefore necessary to control the carbon and nitrogen contents within the rangeq indicated in Table I. With a carbon plu8 nitrogen content that is too low, the holder blocks will not achieve the minimum desired strength and hardness; with a carbon plu~ nitrogen content that is too high, the holder blocks will exceed the de~ired maximum hardness and exhibit unacceptable machinab$1ity.
Manganese is a desirable element in the steels used in the holder blocks. Manganese imparts hardenability and, in 2~1765 combination with sulfur, is al~o present for purposes of improvinq machinability through the formation of manganese sulfide. Also, manganese is an austenite forming element and can be used to partially replace nickel in the ~teel for composition balance and to thereby redùce steel costs.
Silicon is used in steelmaking for deoxidation and increasing chromium recovery. It al80 slightly improves corrosion resistance, but is a ferrite forming element and thus increases the amount of costly nickel or manganese needed to obtain a fully martensitic structure.
Nickel is required within the indicsted ranges to obtain the desired austenite-ferrite balance and to thereby obtain a substantially fully martensitic structure in the holder blocks. It also improves corrosion resi~tance; but ~8 a costly element, and for this reason is not desirable above the indicated ranges.
Chromium is essential for corro~ion re~istance, but above the indicated amounts increases the amount of nickel, manganese, and other austenite forming elements that are required to be present to avoid the formation of delta ferrite and to obtain a substantially fully martensitic structure ln the holder blocks.
Molybdenum is an expensive alloying element, but in small amounts and together with chromium has a very 2 ~ ~ ~ 7 6 ~
beneficial affect on the corro~ion resistance of the holder block~, and a minimum of about 0.25~ is neces~ary for reducing the adverse effect~ of ~ulfur on this property.
Consequently, molybdenum generally should be increased in the pre~ence of increa~ed ~ulfur for this purpo~e.
Sulfur i~ used for improving machinability, but decreases notch toughness and corrosion resistance. When high toughne~s and corrosion resistance are required in the holder blocks of the invention, ~ulfur should be limited to about 0.10~; but when greater machinability is desired, it can be increased to about 0.25% without lowering toughnesg and corrosion resi~tance to unacceptable levels. Molybdenum should be incres~ed w$th increased sulfur to maintain corrosion resistance at the desired level.
Copper is a common re~idual element in stainle~s steel melting, and i~ useful for controlling the austenite-ferrite balance. However, in amount~ greater than about 1.0~ it can have an undesirable hardening effect during tempering of the holder blocks.
To demonstrate the principle~ of the invention, a serie~
of experiment~l holder block steels were made and sub~ected to a variety of mechan~cal and corrosion tests. The chemical compositions of the experimental holder block steels and of a commercial ~tainless holder block steel (Alloy 90-45) included for comparison are given in Table II.
206176~
_ ~
_ O N~O~O~gg~
jNN~ 2 ~ ~ N~oo 2 _ _ N~oN~NN~s .~ ~ NNNNNNNNN~
O ._ ~ n ~ NNNN_NNN_O
_ ,0 _ O ` O O ~~ O ~ - æ. 8.
_ O O O O O O O O
__ 2i S ~ I a!; ¢l . _o~NO~N~o~
_ ~ _ o 8 o o o 2~6~6~
Ingots of the experimental holder block steels were hot worked from a reheating temperature of about 2150F to bar stock from which samples were taken for metallographic evaluation and testing. Except for those samples used to determine attainable hardne~s, all the test ~ample~ were austenitized at 1550F, air cooled to room temperature, and then tempered for two hour~ at 550F. None of the experLmental holder block steels were found to contain any delta ferrite after this heat-treatment. The samples of the commercial stainless holder block steel were received in the prehardened condition at a hardness of 33 HRC. In order to test this material at a higher hardness of 38 ERC, samples of the commercial holder block steel were austenitized at 1850F, oil quenched to room temperature and then tempered for 2 hours at 975F.
Several tests were conducted to compare the advantages of the holder block steels of the invention with those of a commercial stainle~s holder block steel and to demonstrate the significance of their composition. Tests were conducted to illustrate the effects of steel composition on attainable hardnes~, notch toughness, tensile strength, machinability, and corrosion re~istance.
The attainable hardnesses of the experimental holder block steels in the as-hardened condition are plotted in 2~176~
Figure 3 as a function of their carbon plus nitrogen contents. The specimens for these tests were austenitized for 15 minutes at 1600F and then air cooled to room temperature. Allowing for some normal scatter in the results of the hardness tests, Figure 3 shows that the attainable hardnes~ of the steels used in the holder blocks of the invention has a strong relationship with their carbon plus nitrogen contents. To obtain the hardnesses needed for holder block applications (30 ~o 40 HRC), Figure 3 shows that the carbon plus nitrogen contents of the holder blocks of the invention must be controlled in a range between about 0.02 to O.09%. Further, to obtain the hardness typical of standard holder blocks (30 to 35 HRC) and of high strength holder blocks (35 to 40 HRC), the carbon plu8 nitrogen content of the steels used in the holder blocks of the invention must be controlled from about 0.02 to 0.06% and from about 0.06 to 0.09%, respectively.
The results of the notch toughness and tension tests conducted on the experimental holder block steels and on the commercial stainless holder block steel are given in Table III.
2~76 o Q~
y U .~ ~ ~ ~ o ~ I ~ ~ ~
~ .... _ . o ~ _ _ _ ~ ~
V- V~ o~ ~ ` ~ ~
~ ~ C
.o ~ o ~ o o ~ o ' 2L
2 ~ ~ n 0 ~ ~ ~ J
o ~ 3 .
c ~ V o o ~ o 4 o o o ~n e ,.
~ ~ ~ 2 ~ O O ~ g g ~ a o ~C, ~ O
o o o o o o o o o O, 1"~
__ _ _ ~ - ~
~ 8~ ~0 0~ 0~ o ~, æ o . ~ -_ _ _ 2~176a These test results show that the notch impact toughness of the ~teels u~ed in the holder blocks of this invention, as measured in the Charpy V-notch impact test, are clearly superior to those of a commercial stainles~ steel typically used in this application (Alloy 90-45). The advantage in toughnes~ i8 particularly great for those experimental steels containing les~ than about 0.10~ sulfur, as can be qeen by comparing the notch toughnes~ values of Alloy V1033 (30.6 ft-lb) with those of the commercial stainless holder block steel (5.0 ft-lb). Above sulfur levels of about 0.10%, the impact properties of the steels u~ed in the holder blocks of the invention are still ~ignificantly better than that of the commercial stainle~s holder block steel. For example, the notch toughness of Alloy V1055 with 0.20% sulfur i8 15.0 ft-lb in the longitudinal direction; whereas, that of the commercial stainless holder block steel (Alloy 90-45) with 0.09% sulfur is only 5.0 ft-lb.
The tensile properties of the steels used in the holder blocks of this invention are largely a function of their hardness and are at least comparable to tho~e of the commercial stainless holder block steel at the same hardneqs.
About the ~ame mechanical properties and notch toughne~s are obtained for the higher manganese and lower nickel containing experimental holder block steels ~Alloys V1022 and V1055) a~
206176~
for the comparable steels with higher nickel and lower manganese (Alloys V1020 and V1056). Thus, when it i9 de~irable to reduce cost, manganese csn be used to replace psrt of the nickel in the steels used in the holder blocks of this invention.
The re~ult~ of drill machinability tests conducted on the experiment~l steel~ used in the holder blocks of the invention and on a commercial st~inless holder block steel are given in Table IV and in Figure 4. The machinability indexes given in this table and figure were obtained by comparing the times re~uired to drill holes of the same size and depth in the experimental steels and in the commercial stainless holder block steel at a hardness of 33.0 HRC and by multiplying the ratios of these time~ by 100. Indexes greater than 100 indicate that the drill machinability of the test specimen i~ greater than that of the commercial stainless holder block steel. Because the hardness and sulfur content of these steels are known to influence machinability, a parameter based on these factors [Rockwell C
hardnes~ -100 (% S)] wa~ derived and used to compare the drill machinability of the test materials.
2~176~
8 ?~
I - ~ ~ Z Z, ~ i ll L ~! C æ _ O o ". æ ~ ~ N 8 ~
~ ~ 1~ -- C
~ 0 ~ ~ ~ ~7 o, ~7 o. o, ~ 0 ~
1~ -- 0 N N æ N N Ir~ N _ _ N l!e ~ ~ ' ~ ~ ~ O. O. ~ ~ O. In 0. O, O. In ~
S~ ~i -- N ~ ~ O
~ ~ O ~ ~ o O O N _ ~ g ~ ~
_ O O O O O O O O O O O ~
O
'~ I ~ ~ O ~ O O O 0 50~ ~o ~N N
_ O O O O O O O O O O O
~ 1~ O~ ~ N O _ ~ tl ~ ~U
3 ~ 8 o ~ o o o ~ ~ ~ _ 20~7~
Analysis of the drill machinability test data using the rQlationship derived between the above parameter and the machinability index indicate~ that to provide machinability at lea~t equivalent to that of the commercial stainless holder block steel at a hardness of 33 HRC, the steels used in the holder blocks of this invention must contain at least 0.05% sulfur. Likewise, to provide machinability at least comparable to that of the commercial ~tainless holdor block steel at a hardness of 33 HRC, the holder block steels of the invention at a hardness of 38 HRC mu~t contain at least 0.10 sulfur. These result~, in combination with those of the notch toughness tests reported in Table III, indicate that at sulfur levels between about 0.05 and 0.10% the steels used in the holder blocks of the invention afford substantially better notch toughne~s and machinability superior to that provided by current stainles~ holder block ~teels. They also indicate that at sulfur contents between about 0.10 and 0.25~, the steels used in the holdor block~ of this invention provide substantially better machinability and notch toughness superior to that of current stainless holder block ~teel~.
Two tests were used to compare the corrosion re~istance of the steels used in the holder blocks of this invention to that of a typical commercial stainless holder block ~teel, 20~176a the composition of which iQ given in Table II. In one test, the weight 1088 and resulting corro-~ion rates were determined for specimenQ immerQed for three hours at ambient temperature in a dilute solution of aqua-regia containing 5% nitric acid and 1% hydrochloric acid by volume. This test is described in the literature (E. A. Oldfield, "Corrosion of Cutlery~, Corrosion Technology, June, 1958, pp. 187-189) and is particularly useful for comparing the effects of composition and heat treatment on the corroQion re~istance of marten~itic stainless steels. The term corrosion rate in inche~ per year~ as used herein rafer~ to the corrosion rate exhibited by an alloy article sub~ected to this test procedure. The~e tests were conducted on specimen that were passivated and not passivated prior to testing in a solution of 20% nitric acid containing 3% by weight of potas~ium chromate at 120F
for 1/2 hour. The other test was a salt spray test in which ~pecimens were exposed for three hours at 90F to vapors generated from an aqueous solution containing 2.5% by weight of sodium chloride. In this latter test, material performance was ran~ed visually by estimating the percentage of the surface area thst was affected by corrosion. The results of the corro~ion tests are summarized in Table V.
Photographs of five of the specimens sub~ected to the salt spray test are shown in Figure S.
206~7~5 ~ ~y _ } ~ SS ii ,, D 2 ~ o o o ~ o ~ ~o Y ~`
D N 1' ~ ~ N ~ ~
~:3 ~ _ 1~ 1~ ~ ~ ~ .-lô ~ 8 N -- ~E -- Y
O O O O O O O O O _ y O Y
.. ~ o ~ 8 ~ e ~
_ o ~ J 0 ~0 0 g 0~ 0 0 0 C O
_ ,, ~,,,,, æ ~ ~
_ _ 206~7~5 The result~ of the dilute aqua-regia and the salt spray tests clearly show that the steels used in holder blocks of this invention have substantially better corrosion resistance than a steel typical of that now uQed in stainless steel holder block~. This is evidenced by the great difference in the corrosion rates exhibited in the dilute aqua-regia te~t by Alloys V1033 (4.3 inches/year) and V1021 (5.5 inchesJ
year), whose compo~itionQ are within the scope of the invention, and Alloy 90-45 (14.1 inches/year) which is representative of the steel~ now used in stainless steel holder blocks. The great advantage of the s~eels used in the holder blocks of this invention is also exhibited in the salt spray test, a~ can be seen by comparing the percent affected area for these same alloys. The results of the corrosion tests also demonstrate the importance of maintaining the molybdenum content of the steels used in the holder blocks of this invention above about 0.25. In this regard, note, for example, the relatively poor performance of Alloy V1087, which except for a very low molybdenum content has a composition within the scope of the invention, a~ compared to the good performance of Alloys V1003 and V1009, which contain about 0.32~ molybdenum and whose compo~itions are within the scope of the invention.
The relative corrosion reQistance of three of the experimental holder block steel~ (Alloy~ Y1009, V1020, and 2~617~
Vl020) and of two steel~ (Alloy~ V1087 and 90-45) out~ide the ~cope of the invention is further illustrated in ~igure 5.
As can be ~een, Alloy~ V1009, V1020, and V1021, havinq compositions within the ~cope of the invention, ~how considerably better corro~ion re~i~tance in the salt spray te~t than do Alloy~ V1087 and 90-45. The composition of Alloy V1087 i9 similar to that of Alloy~ V1009 and V1020, except that it contain~ lesY than 0.01~ molybdenum. This again demonstrates the importance of maintaining a minimum of about 0.25% molybdenum in the steels used in the holder block~ of this invention. ~lloy 90-4S iQ typical of the steels currently used in stainless steel holder blocks, and its comparatively poor performance again demon~trates that the steels used in the holder blocks of thi~ invention have substantially better corro~ion resistance.
The re~ults of the corro~ion test~ together with those of the mechanical property tests in ~able III and of the machinability te~ts in Table IV clearly ~how that the corrosion re~istant holder block ~teel~ of the invention provide a substantially better combination of notch toughne~, m~chinability, and corrosion re~i~tance than afforded by conventional stainless steel holder blocks.
Further, the steel~ u~ed in the holder block~ of the invention have the advantaqe of being hardenable to the hardnesse~ needed for this application with a ~imple heat-tre~tment.
Analysis of the drill machinability test data using the rQlationship derived between the above parameter and the machinability index indicate~ that to provide machinability at lea~t equivalent to that of the commercial stainless holder block steel at a hardness of 33 HRC, the steels used in the holder blocks of this invention must contain at least 0.05% sulfur. Likewise, to provide machinability at least comparable to that of the commercial ~tainless holdor block steel at a hardness of 33 HRC, the holder block steels of the invention at a hardness of 38 HRC mu~t contain at least 0.10 sulfur. These result~, in combination with those of the notch toughness tests reported in Table III, indicate that at sulfur levels between about 0.05 and 0.10% the steels used in the holder blocks of the invention afford substantially better notch toughne~s and machinability superior to that provided by current stainles~ holder block ~teels. They also indicate that at sulfur contents between about 0.10 and 0.25~, the steels used in the holdor block~ of this invention provide substantially better machinability and notch toughness superior to that of current stainless holder block ~teel~.
Two tests were used to compare the corrosion re~istance of the steels used in the holder blocks of this invention to that of a typical commercial stainless holder block ~teel, 20~176a the composition of which iQ given in Table II. In one test, the weight 1088 and resulting corro-~ion rates were determined for specimenQ immerQed for three hours at ambient temperature in a dilute solution of aqua-regia containing 5% nitric acid and 1% hydrochloric acid by volume. This test is described in the literature (E. A. Oldfield, "Corrosion of Cutlery~, Corrosion Technology, June, 1958, pp. 187-189) and is particularly useful for comparing the effects of composition and heat treatment on the corroQion re~istance of marten~itic stainless steels. The term corrosion rate in inche~ per year~ as used herein rafer~ to the corrosion rate exhibited by an alloy article sub~ected to this test procedure. The~e tests were conducted on specimen that were passivated and not passivated prior to testing in a solution of 20% nitric acid containing 3% by weight of potas~ium chromate at 120F
for 1/2 hour. The other test was a salt spray test in which ~pecimens were exposed for three hours at 90F to vapors generated from an aqueous solution containing 2.5% by weight of sodium chloride. In this latter test, material performance was ran~ed visually by estimating the percentage of the surface area thst was affected by corrosion. The results of the corro~ion tests are summarized in Table V.
Photographs of five of the specimens sub~ected to the salt spray test are shown in Figure S.
206~7~5 ~ ~y _ } ~ SS ii ,, D 2 ~ o o o ~ o ~ ~o Y ~`
D N 1' ~ ~ N ~ ~
~:3 ~ _ 1~ 1~ ~ ~ ~ .-lô ~ 8 N -- ~E -- Y
O O O O O O O O O _ y O Y
.. ~ o ~ 8 ~ e ~
_ o ~ J 0 ~0 0 g 0~ 0 0 0 C O
_ ,, ~,,,,, æ ~ ~
_ _ 206~7~5 The result~ of the dilute aqua-regia and the salt spray tests clearly show that the steels used in holder blocks of this invention have substantially better corrosion resistance than a steel typical of that now uQed in stainless steel holder block~. This is evidenced by the great difference in the corrosion rates exhibited in the dilute aqua-regia te~t by Alloys V1033 (4.3 inches/year) and V1021 (5.5 inchesJ
year), whose compo~itionQ are within the scope of the invention, and Alloy 90-45 (14.1 inches/year) which is representative of the steel~ now used in stainless steel holder blocks. The great advantage of the s~eels used in the holder blocks of this invention is also exhibited in the salt spray test, a~ can be seen by comparing the percent affected area for these same alloys. The results of the corrosion tests also demonstrate the importance of maintaining the molybdenum content of the steels used in the holder blocks of this invention above about 0.25. In this regard, note, for example, the relatively poor performance of Alloy V1087, which except for a very low molybdenum content has a composition within the scope of the invention, a~ compared to the good performance of Alloys V1003 and V1009, which contain about 0.32~ molybdenum and whose compo~itions are within the scope of the invention.
The relative corrosion reQistance of three of the experimental holder block steel~ (Alloy~ Y1009, V1020, and 2~617~
Vl020) and of two steel~ (Alloy~ V1087 and 90-45) out~ide the ~cope of the invention is further illustrated in ~igure 5.
As can be ~een, Alloy~ V1009, V1020, and V1021, havinq compositions within the ~cope of the invention, ~how considerably better corro~ion re~i~tance in the salt spray te~t than do Alloy~ V1087 and 90-45. The composition of Alloy V1087 i9 similar to that of Alloy~ V1009 and V1020, except that it contain~ lesY than 0.01~ molybdenum. This again demonstrates the importance of maintaining a minimum of about 0.25% molybdenum in the steels used in the holder block~ of this invention. ~lloy 90-4S iQ typical of the steels currently used in stainless steel holder blocks, and its comparatively poor performance again demon~trates that the steels used in the holder blocks of thi~ invention have substantially better corro~ion resistance.
The re~ults of the corro~ion test~ together with those of the mechanical property tests in ~able III and of the machinability te~ts in Table IV clearly ~how that the corrosion re~istant holder block ~teel~ of the invention provide a substantially better combination of notch toughne~, m~chinability, and corrosion re~i~tance than afforded by conventional stainless steel holder blocks.
Further, the steel~ u~ed in the holder block~ of the invention have the advantaqe of being hardenable to the hardnesse~ needed for this application with a ~imple heat-tre~tment.
Claims (29)
1. A martensitic stainless steel article, which may be used for holder blocks, frames, backers, and similar articles for anchoring molds and dies, said article having a hardness within the range of about 30 to 40 HRC and consisting essentially of, in weight percent, up to 0.09% carbon, up to 0.09% nitrogen, 0.02 to 0.09% carbon plus nitrogen, up to 4.50% manganese, up to 0.05% phosphorus, 0.05 to 0.25%
sulfur, up to 1.0% silicon, 1.00 to 4.00% nickel, 11.00 to 14.00% chromium, 0.25 to 1.00% molybdenum, up to 1.00%
copper, balance iron and incidental impurities.
sulfur, up to 1.0% silicon, 1.00 to 4.00% nickel, 11.00 to 14.00% chromium, 0.25 to 1.00% molybdenum, up to 1.00%
copper, balance iron and incidental impurities.
2. A martensitic stainless steel article, which may be used for holder blocks, frames, backers, and similar articles for anchoring molds and dies, said article having a hardness within the range of about 30 to 35 HRC and consisting essentially of, in weight percent, up to 0.06% carbon, up to 0.06% nitrogen, 0.02 to 0.06% carbon plus nitrogen, up to 2.00% manganese, up to 0.05% phosphorus, 0.05 to 0.25%
sulfur, up to 1.00% silicon, 2.00 to 4.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75% molybdenum, up to 1.0% copper, balance iron and incidental impurities.
sulfur, up to 1.00% silicon, 2.00 to 4.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75% molybdenum, up to 1.0% copper, balance iron and incidental impurities.
3. The article of claim 2 having 0.05 to 0.10% sulfur.
4. The article of claim 2 having 0.10 to 0.25% sulfur.
5. A martensitic stainless steel article, which may be used for holder blocks, frames, backers, and similar articles for anchoring molds and dies, said article having a hardness within the range of about 30 to 35 HRC and consisting essentially of, in weight percent, up to 0.06% carbon, up to 0.06% nitrogen, 0.02 to 0.06% carbon plus nitrogen, 2.00 to 4.50% manganese, up to 0.05% phosphorus, 0.05 to 0.25%
sulfur, up to 1.00% silicon, 1.00 to 2.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75% molybdenum, up to 1.00 copper, balance iron and incidental impurities.
sulfur, up to 1.00% silicon, 1.00 to 2.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75% molybdenum, up to 1.00 copper, balance iron and incidental impurities.
6. The article of claim 5 having 0.05 to 0.10% sulfur.
7. The article of claim 5 having 0.10 to 0.25% sulfur.
8. A martensitic stainless steel article, which may be used for omit holder blocks, frames, backers, and similar articles for anchoring molds and dies, said article having a hardness within the range of about 35 to 40 HRC and consisting essentially of, in weight percent, up to 0.09%
carbon, up to 0.09% nitrogen, 0.06 to 0.09% carbon plus nitrogen, up to 2.00% manganese, up to 0.05% phosphorus, 0.05 to 0.25% sulfur, up to 1.00% silicon, 2.00 to 4.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75% molybdenum, up to 1.00% copper, balance iron and incidental impurities.
carbon, up to 0.09% nitrogen, 0.06 to 0.09% carbon plus nitrogen, up to 2.00% manganese, up to 0.05% phosphorus, 0.05 to 0.25% sulfur, up to 1.00% silicon, 2.00 to 4.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75% molybdenum, up to 1.00% copper, balance iron and incidental impurities.
9. The article of claim 8 having 0.05 to 0.10% sulfur.
10. The article of claim 8 having 0.10 to 0.25% sulfur.
11. A martensitic stainless steel article, which may be used for holder blocks, frames, backers, and similar articles for anchoring molds and dies, said article having a hardness within the range of 35 to 40 HRC, and consisting essentially of, in weight percent, up to 0.09% carbon, up to 0.09%
nitrogen, 0.06 to 0.09% carbon plus nitrogen, 2.00 to 4.50% manganese, up to 0.05% phosphorus, 0.05 to 0.25%
sulfur, up to 1.00% silicon, 1.00 to 2.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75% molybdenum, up to 1.00%
copper, balance iron and incidental impurities.
nitrogen, 0.06 to 0.09% carbon plus nitrogen, 2.00 to 4.50% manganese, up to 0.05% phosphorus, 0.05 to 0.25%
sulfur, up to 1.00% silicon, 1.00 to 2.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75% molybdenum, up to 1.00%
copper, balance iron and incidental impurities.
12. The article of claim 11 having 0.05 to 0.10% sulfur.
13. The article of claim 11 having 0.10 to 0.25% sulfur.
14. A method for producing a martensitic stainless steel article, which may be used for holder blocks, frames, backers, and similar articles for anchoring molds and dies, said method comprising producing said article of an alloy composition consisting essentially of, in weight percent, up to 0 09% carbon, up to 0.09% nitrogen, 0.02 to 0.09% carbon plus nitrogen, up to 4.50% manganese, up to 0.05% phosphorus, 0.05 to 0.25% sulfur, up to 1.0% silicon, 1.00 to 4.00%
nickel, 11.00 to 14.00% chromium, 0.25 to 1.00% molybdenum, up to 1.00% copper, balance iron and incidental impurities;
austenitizing said article at a temperature of 1500 to 1750°F
for about 1 hour per inch of thickness and thereafter air cooling or oil quenching to achieve a martensitic structure and thereafter tempering or stress-relieving said article at a temperature of 500 to 850°F for about 1 hour per inch of thickness and for a minimum of 2 hours to achieve a combination of a hardness within the range of 30 to 40 HRC and a drill machinability rating equal to or greater than 100.
nickel, 11.00 to 14.00% chromium, 0.25 to 1.00% molybdenum, up to 1.00% copper, balance iron and incidental impurities;
austenitizing said article at a temperature of 1500 to 1750°F
for about 1 hour per inch of thickness and thereafter air cooling or oil quenching to achieve a martensitic structure and thereafter tempering or stress-relieving said article at a temperature of 500 to 850°F for about 1 hour per inch of thickness and for a minimum of 2 hours to achieve a combination of a hardness within the range of 30 to 40 HRC and a drill machinability rating equal to or greater than 100.
15. The method of claim 14 wherein said alloy composition has sulfur of 0.05 to 0.10%.
16. The method of claim 14 wherein said alloy composition has sulfur of 0.10 to 0.25%.
17. The method of claims 14, 15 or 16 wherein said article after said tempering exhibits a corrosion rate in inches per year of less than 9.
18. A method for producing a martensitic stainless steel article, which may be used for holder blocks, frames, backers, and similar articles for anchoring molds and dies, said method comprising producing said article of an alloy composition consisting essentially of, in weight percent, up to 0.06% carbon, up to 0.06% nitrogen, 0.02 to 0.06% carbon plus nitrogen, 2.00 to 4.50% manganese, up to 0.05%
phosphorus, 0.05 to 0.25% sulfur, up to 1.00% silicon, 1.00 to 2.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75%
molybdenum, up to 1.00% copper, balance iron and incidental impurities; austenitizing said article at a temperature of 1500 to 1750°F for about 1 hour per inch of thickness and thereafter air cooling or oil quenching to achieve a martensitic structure and thereafter tempering or stress-relieving said article at a temperature of 500 to 850°F for about 1 hour per inch of thickness and for a minimum of 2 hours to achieve a combination of a hardness within the range of 30 to 40 HRC and a drill machinability rating equal to or greater than 100.
phosphorus, 0.05 to 0.25% sulfur, up to 1.00% silicon, 1.00 to 2.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75%
molybdenum, up to 1.00% copper, balance iron and incidental impurities; austenitizing said article at a temperature of 1500 to 1750°F for about 1 hour per inch of thickness and thereafter air cooling or oil quenching to achieve a martensitic structure and thereafter tempering or stress-relieving said article at a temperature of 500 to 850°F for about 1 hour per inch of thickness and for a minimum of 2 hours to achieve a combination of a hardness within the range of 30 to 40 HRC and a drill machinability rating equal to or greater than 100.
19. The method of claim 18 wherein said alloy composition has sulfur of 0.05 to 0.10%.
20. The method of claim 18 wherein said alloy composition has sulfur of 0.10 to 0.25%.
21. The method of claims 18, 19 or 20 wherein said article after said tempering exhibits a corrosion rate in inches per year of less than 9.
22. A method for producing a martensitic stainless steel article, which may be used for holder blocks, frames, backers, and similar articles for anchoring molds and dies, said method comprising producing said article of an alloy composition consisting essentially of, in weight percent, up to 0.09% carbon, up to 0.094 nitrogen, 0.06 to 0.09% carbon plus nitrogen, up to 2.00% manganese, up to 0.054 phosphorus, 0.05 to 0.25% sulfur, up to 1.00% silicon, 2.00 to 4.00%
nickel, 11.00 to 13.00% chromium, 0.25 to 0.75% molybdenum, up to 1.00% copper, balance iron and incidental impurities;
austenitizing said article at a temperature of 1500 to 1750°F
for about 1 hour per inch of thickness and thereafter air cooling or oil quenching to achieve a martensitic structure and thereafter tempering or stress-relieving said article at a temperature of 500 to 850°F for about 1 hour per inch of thickness and for a minimum of 2 hours to achieve a combination of a hardness within the range of 30 to 40 HRC and a drill machinability rating equal to or greater than 100.
nickel, 11.00 to 13.00% chromium, 0.25 to 0.75% molybdenum, up to 1.00% copper, balance iron and incidental impurities;
austenitizing said article at a temperature of 1500 to 1750°F
for about 1 hour per inch of thickness and thereafter air cooling or oil quenching to achieve a martensitic structure and thereafter tempering or stress-relieving said article at a temperature of 500 to 850°F for about 1 hour per inch of thickness and for a minimum of 2 hours to achieve a combination of a hardness within the range of 30 to 40 HRC and a drill machinability rating equal to or greater than 100.
23. The method of claim 22 wherein said alloy composition has sulfur of 0.05 to 0.10%.
24. The method of claim 22 wherein said alloy composition has sulfur of 0.10 to 0.25%.
25. The method of claims 22, 23 or 24 wherein said article after said tempering exhibits a corrosion rate in inches per year of less than 9.
26. A method for producing a martensitic stainless steel article, which may be used for holder blocks, frames, backers, and similar articles for anchoring molds and dies, said method comprising producing said article of an alloy composition consisting essentially of, in weight percent, up to 0.09% carbon, up to 0.09% nitrogen, 0.06 to 0.09% carbon plus nitrogen, 2.00 to 4.50% manganese, up to 0.05% phosphorus, 0.05 to 0.25% sulfur, up to 1.00% silicon, 1.00 to 2.00% nickel, 11.00 to 13.00% chromium, 0.25 to 0.75%
molybdenum, up to 1.00% copper, balance iron and incidental impurities; austenitizing said article at a temperature of 1500 to 1750°F for about 1 hour per inch of thickness and thereafter air cooling or oil quenching to achieve a martensitic structure and thereafter tempering or stress-relieving said article at a temperature of 500 to 850°F for about 1 hour per inch of thickness and for a minimum of 2 hours to achieve a combination of a hardness within the range of 30 to 40 HRC and a drill machinability rating equal to or greater than 100.
molybdenum, up to 1.00% copper, balance iron and incidental impurities; austenitizing said article at a temperature of 1500 to 1750°F for about 1 hour per inch of thickness and thereafter air cooling or oil quenching to achieve a martensitic structure and thereafter tempering or stress-relieving said article at a temperature of 500 to 850°F for about 1 hour per inch of thickness and for a minimum of 2 hours to achieve a combination of a hardness within the range of 30 to 40 HRC and a drill machinability rating equal to or greater than 100.
27. The method of claim 26 wherein said alloy composition has sulfur of 0.05 to 0.10%.
28. The method of claim 26 wherein said alloy composition has sulfur of 0.10 to 0.25%.
29. The method of claims 26, 27 or 28 wherein said article after said tempering exhibits a corrosion rate in inches per year of less than 9.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US68382591A | 1991-04-11 | 1991-04-11 | |
| US07/683,825 | 1991-04-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2061765A1 true CA2061765A1 (en) | 1992-10-12 |
Family
ID=24745598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2061765 Abandoned CA2061765A1 (en) | 1991-04-11 | 1992-02-24 | Martensitic stainless steel article and method for producing the same |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0508574A1 (en) |
| JP (1) | JPH05171366A (en) |
| CA (1) | CA2061765A1 (en) |
| MX (1) | MX9201431A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5362337A (en) * | 1993-09-28 | 1994-11-08 | Crs Holdings, Inc. | Free-machining martensitic stainless steel |
| AT409636B9 (en) * | 2001-02-14 | 2002-12-27 | Boehler Edelstahl Gmbh & Co Kg | STEEL FOR PLASTIC MOLDS AND METHOD FOR HEAT TREATING THE SAME |
| FR2872825B1 (en) * | 2004-07-12 | 2007-04-27 | Industeel Creusot | MARTENSITIC STAINLESS STEEL FOR MOLDS AND CARCASES OF INJECTION MOLDS |
| CN100503871C (en) * | 2007-08-15 | 2009-06-24 | 金雹峰 | Ferroalloy |
| CN102719627B (en) * | 2012-07-04 | 2013-11-06 | 中原特钢股份有限公司 | Heat treatment method of high-chromium martensitic stainless steel |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1478469A (en) * | 1966-02-28 | 1967-04-28 | Crucible Steel Co America | Stainless steels easily suitable for machining |
| US3720545A (en) * | 1971-08-20 | 1973-03-13 | Crucible Inc | Steel mold and method for producing the same |
| US4406698A (en) * | 1980-04-28 | 1983-09-27 | Tokyo Shibaura Denki Kabushiki Kaisha | Martensitic stainless cast steel having high cavitation erosion resistance |
| FR2567151B1 (en) * | 1984-07-04 | 1986-11-21 | Ugine Aciers | METHOD FOR MANUFACTURING MARTENSITIC STAINLESS STEEL BARS OR MACHINE WIRE AND CORRESPONDING PRODUCTS |
-
1992
- 1992-02-21 EP EP92301473A patent/EP0508574A1/en not_active Withdrawn
- 1992-02-24 CA CA 2061765 patent/CA2061765A1/en not_active Abandoned
- 1992-03-30 MX MX9201431A patent/MX9201431A/en unknown
- 1992-04-10 JP JP11672392A patent/JPH05171366A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0508574A1 (en) | 1992-10-14 |
| JPH05171366A (en) | 1993-07-09 |
| MX9201431A (en) | 1992-10-01 |
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