CA1237921A - Abrasive resistant white cast iron - Google Patents
Abrasive resistant white cast ironInfo
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- CA1237921A CA1237921A CA000451185A CA451185A CA1237921A CA 1237921 A CA1237921 A CA 1237921A CA 000451185 A CA000451185 A CA 000451185A CA 451185 A CA451185 A CA 451185A CA 1237921 A CA1237921 A CA 1237921A
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Abstract
ABSTRACT
A white cast iron having toughness, high tensile strength and abrasion resistance containing .01% to 4.0%
boron in an iron-carbon alloy with the carbides in the form of globules and of an average size less than 4 microns. This white cast iron is produced by incorporating the boron in the composition to form a melt, super cooling the melt while liquid to at least 5°F below the equilibrium solidification temperature between 2200°F to 2400°F and then solidifying the melt to produce the globules of carbides uniformly dispersed and having a size much smaller than the size of the carbide particles of conventional cast iron.
A white cast iron having toughness, high tensile strength and abrasion resistance containing .01% to 4.0%
boron in an iron-carbon alloy with the carbides in the form of globules and of an average size less than 4 microns. This white cast iron is produced by incorporating the boron in the composition to form a melt, super cooling the melt while liquid to at least 5°F below the equilibrium solidification temperature between 2200°F to 2400°F and then solidifying the melt to produce the globules of carbides uniformly dispersed and having a size much smaller than the size of the carbide particles of conventional cast iron.
Description
~;~37~
I ABRASIVE RESISTANT WHITE CAST IRON
INTRODUCTION
This invention relates to cast iron and more particularly to thy improvement in the toughness and abrasive resistance of white cast iron along with a significant increase in tensile strength. More specifically, the present invention relates to a new white cast iron composition and a process for producing such cast iron having improved toughness, ductility and tensile strength while retaining : desirable abrasive resistance through modification of the carbide morphology.
Unless otherwise indicated, all references in the disclosure and claims herein to proportions or relative amounts in the alloy compositions by way of percent are to percent (~) by weight.
:
I
I ABRASIVE RESISTANT WHITE CAST IRON
INTRODUCTION
This invention relates to cast iron and more particularly to thy improvement in the toughness and abrasive resistance of white cast iron along with a significant increase in tensile strength. More specifically, the present invention relates to a new white cast iron composition and a process for producing such cast iron having improved toughness, ductility and tensile strength while retaining : desirable abrasive resistance through modification of the carbide morphology.
Unless otherwise indicated, all references in the disclosure and claims herein to proportions or relative amounts in the alloy compositions by way of percent are to percent (~) by weight.
:
I
2--Alloy white cast iron it well known to be a highly wear-resistant material formed with a carbon content generally recognized to be in excess of 1 1/2% and the capability of being alloyed with other metals, usually chromium, to combine with the carbon to form a compound of iron-chromium carbide such as McCoy. In many instances, the inherent abrasive resistance of unalloyed cast iron is adequate to meet its intended use and therefore does not pose a problem to the user. However, when the cast iron forming an industrial apparatus is subjected to particular kinds of wear the inherent mechanical properties of cast iron leave much to be desired.
It is well recognized that there are several classifications of wear to which the cast iron material may be subjected In the first, a gouging or grooving wear, coarse abrasive particles penetrate the working surface of the cast iron to induce a high rate of metal removal. In the typical industrial experience of this type of wear, such as in earth moving equipment, hammer mill operations and jaw crushers, there is associated with the metal removal severe shock loading that has been found to have a detrimental effect upon the cast iron.
In another type of wear often referred to as high stress abrasion, abrasive particles, such as may be encountered in a mining operation, are crushed under grinding influence of moving metal surfaces. Stress levels involved in this operative wear process as occur typically in castings used for grinding, crushing rolls or mill liners often exceed the stress capabilities of the conventional cast iron leading to equipment failure.
In the third category of wear, a low stress abrasion or erosion, the abrasive operation to which the cast iron surfaces of the equipment are subjected are not severe ~37~32~
It is well recognized that there are several classifications of wear to which the cast iron material may be subjected In the first, a gouging or grooving wear, coarse abrasive particles penetrate the working surface of the cast iron to induce a high rate of metal removal. In the typical industrial experience of this type of wear, such as in earth moving equipment, hammer mill operations and jaw crushers, there is associated with the metal removal severe shock loading that has been found to have a detrimental effect upon the cast iron.
In another type of wear often referred to as high stress abrasion, abrasive particles, such as may be encountered in a mining operation, are crushed under grinding influence of moving metal surfaces. Stress levels involved in this operative wear process as occur typically in castings used for grinding, crushing rolls or mill liners often exceed the stress capabilities of the conventional cast iron leading to equipment failure.
In the third category of wear, a low stress abrasion or erosion, the abrasive operation to which the cast iron surfaces of the equipment are subjected are not severe ~37~32~
3--1 stressful conditions, but yet, require high abrasive resistance.
The gouging or grooving wear that is associated with a severe shock load requires a toughness that cast iron typically has not characteristically possessed in the past.
A manganese steel with high plasticity and toughness has been able to meet the severe shock resistant requirements for material subjected to this type of wear. However, the hardness and abrasive resistance is usually found to be inadequate to prevent an extremely high rate of wear in the high stress abrasion operation typical in a wide range of pulverizing processes such as a rotary ball mill. In this high stress operation both chrome molybdenum steel and lo alloyed white iron may be used in various types of apparatus depending upon the requirement of toughness and the combination of abrasion resistance required. In the last category of wear involving low stress operations chromium alloyed irons with or without molybdenum or nickel additions may be used with a desirable high martensitic matrix having a carbide embedment.
A consideration of the categories of wear and the knowledge of the industry concerning the types of metals available to meet the requirements in these wear categories has led to a dilemma to those skilled in the art. To operate apparatus subjected to at least the first two categories of wear there is a clear requirement or combination of optimum wear resistance and sufficient toughness to resist the severe impact and stress conditions characteristic to these types of wear. Hardness and toughness are generally recognized to typically stand at the opposite ends of the spectrum so that those compositions possessing more of one characteristic lose some of the other and yet both hardness and toughness are required.
The industry that supplies abrasion resistant castings has long sought to improve the useful life of the apparatus utilizing the casting in the wear applications described.
. .
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1 Various iron carbon compositions alloyed and non-alloyed do not have a high toughness in the martensitic state with the carbon starting as low as .04~. Hypereutectoid steels and white irons exhibit insufficient toughness because of the morphology of the cementite (Fake). Alloying the iron-carbon composition produces carbides (McCoy) with increased hardness thus meeting some requirements for greater abrasion resistance. However, while abrasion resistance increases the toughness or resistance to fracture decreases as the carbide volume increases, unless at any given carbide volume the carbide size is decreased. Metallurgists have long recognized the complexity of white cast iron because the two main micro-constituents, the carbide and the matrix act essentially independent of each other. Nevertheless, the ultimate characteristics of the material result from the interdependence between the two components if the white iron is subjected to abrasive and shock conditions. When impact takes place upon such material, the carbides shatter and if the carbides are continuous and of relatively large size the cracks will propagate throughout the structure often leading to failure or at least accelerated wear of the material.
There is thus to date no recognized iron-carbon alloy whose carbon content exceeds 1.7~ by weight that meets the requirements of high abrasive resistance and good shock stress absorption ~Z~7~
SUMMARY OX THE PRESENT INVENTION
Accordingly the present invention seeks to provide a white cast iron having characteristics of high hardness or wear resistance and improved toughness.
Further the present invention seeks to provide a white cast iron possessing not only desirable wear resistance and toughness characteristics but also having improved tensile strength.
The invention in one broad aspect pertains to an alloy cast iron composition comprising a base of the element iron, and one or more of the following alloying elements: 0.001% to 30% ,1 vanadium, titanium, niobium, tantalum, molybdenum, nickel, copper , our chromium, or mixtures thereof, and 2.0~ to 4.5~ carbon, the composition of the foregoing having a solidification point within 15F of the eutectic temperature of the cast iron formed with the selected alloying elements, and further containing 0.001~ to 4.0 boron whereby the cast iron possesses desirable wear resistance, toughness and tensile strength properties.
Another aspect of the invention pertains to the process of forming globular shaped carbides in cast iron comprising adding 0~001~ to 4.0% boron to an alloy cast iron comprising 0.001% to 30~ vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or chromium ox mixtures thereof and 2.0% to 4.5% carbon to form a molten cast iron composition, and cooling the molten alloy cast iron composition below equilibrium solidification temperature to a super cooled temperature, solidifying the molten cast iron composition to produce globular shaped carbides having an average size less than the average conventional cast iron carbide particle.
still further aspect of the invention pertains to the process of super cooling molten cast iron to improve the ~l~3~7~
-pa-toughness and abrasion resistance and tensile strength of cast iron comprising increasing the entropy of a molten cast iron mixture of carbon, iron and vanadium, titanium, molybdenum, nickel, copper, tantalum or chromium or mixtures thereof, to form a molten cast iron composition, super cooling the molten cast iron composition to a temperature below the equilibrium solidification temperature of the molten cast iron composition, and solidifying the molten cast iron composition while producing globular shaped carbides having an average size less than the average size of the conventional cast iron carbide.
The invention also pertains to a super cooled alloy cast iron composition consisting of a balance of iron, and one or more of the following alloying elements: .001% to 30% vanadium, titanium, niobium, tantalum, molybdenum, nickel, copper or mixtures thereof, 18% to 28% chromium, 1.5% to 3.0~ carbon, and further containing .001~ to 1.0~ boron, the composition of the foregoing having a solidification point within 15F of the eutectic temperature of the cast iron formed with the selected alloying elements. The composition when molten is capable of being super cooled below the equilibrium solidification temperature, a substantial portion of the carbon being present in the form of globular carbides, whereby the cast iron possesses desirable wear resistance, toughness and tensile strength properties and when solidified having a matrix essentially free of graphite.
Another broad aspect also comprehends the process ox forming globular shaped carbides in cast iron comprising adding 0.001% to 4.0% boron to an alloy cast iron comprising 0.001~ to 30% vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or mixtures thereof, 18% to 28% chromium, and 2.0% to 4.5% carbon to form a molten cast iron composition, and cooling the molten alloy cast iron composition below equilibrium solidification temperature to a super cooled temperature, solidifying the molten cast iron composition to produce globular shaped carbides having an average size less than the average conventional cast iron carbide particle.
The present invention also seeks to provide a cast iron composition having high abrasive resistance and toughness wherein ., , ~2~7~
the carbides are in the form of globules that approach spherical form and particularly a cast iron that is tough and wear resistant in which the carbides are of smaller than conventional average size and substantially evenly distributed throughout the matrix.
More particularly the present invention is a unique discovery of an alloy cast iron composition comprising as a base the element iron, with or without 0.001% to 30% by weight singly or cumulatively vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or chromium or mixtures thereof, 2.0 to 4.5% by weight carbon forming an alloy composition and introducing 0.001%
to 4.0% by weight boron to improve wear-resistance, toughness and tensile strength properties. The alloy has a solidification point between 2200F and 2400F and generally is in a range between 2260F to 2300F. This solidification point is within 15F of the eutectic temperature of the cast iron with the selected alloying elements. The carbides present in the form of globules that are approaching spherical form and are of a size that average less than 4 microns which is considerably less than I the average particle size of carbides in conventional cast iron.
In the process of the present invention an alloy white cast iron containing 0.001% to 30~ vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or chromium or mixtures thereof and 2.0% to 4.5% carbon forming a molten cast iron composition is provided with an entropy increasing additive such as 0.001~ to 4.0% boron then cooling the molten cast iron composition at least 5F below the equilibrium solidification temperature of between 2200F and 2400F to a super cooled temperature and thereafter solidifying the molten cast iron composition to produce globular shaped carbides having an average size less than the average conventional cast iron or carbide particle and, on the average, less than 4 microns.
, I, -- .
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It has long been recognized that white cast iron inherently possesses the wear-resistant characteristics desirable to meet the various wear conditions to which the apparatus composed of cast iron is subjected. It now has been discovered that the carbide morphology of the alloyed cast iron can be altered to retain the characteristic wear-resistance and not only increases the tensile strength but more importantly provides measurable plastic deformation and significant toughness improvement. It has been well known that in the prior cast irons either the free (in excess of that found in the matrix of austenite, puerility or marten site) carbon was in the form of graphite that takes a three-dimensional form somewhat similar to a corn flake or in the form of a carbide in a plate or rod-like shape. In either form the particles are microscopic in size but usually would be larger than lo microns or an average particle size assuming normal heat abstraction from a sand mold and a metal section size in excess ox loom.
It is known that these graphite flakes are the origin of the fractures along the plane of the flakes. Typically a good grade of cast iron would have a tensile strength of about 50,000 psi with 0% elongation producing a very brittle or non-tough material with no capability of deformation whatsoever. When properly alloyed, the free carbon partitions to an inter metallic metal carbide usually chromium carbide shaped generally in the form of the plates or rods and may be continuous or discontinuous within the matrix but again are of an average size greater than 10 microns The carbide particles may also take the form of needles but whatever appearance they may have microscopically, their long dimension on the average is still at least lo microns which increases the propensity for crack initiation under stress which often leads to an ultimate apparatus failure.
I
1 In the present invention it has been found that this normal rod or plate geometry of the carbides can be changed into a globular form that approximates a spherical shape producing not only the desired toughness but a significant tensile strength increase. This change in the morphology of the carbides of cast iron has altered the non-ductile, brittle, non deformable cast iron of the past to one that has the capability of plastic deformation, higher tensile strength with retention of the superior wear-resistant characteristics.
It has been found for instance, that the cast iron of the present invention will bend prior to breaking and the stress level to which it is subjected is significantly higher without fracture as compared to prior known cast irons. The cast iron of the present invention is preferably alloyed with chromium but depending upon various additions of vanadium, titanium, niobium, tantalum, nickel, molybdenum or copper from .001% to 30% to substitute for the chromium, the properties of the resultant cast iron vary.
In general, the cast iron of the present invention has been found to have a tensile strength as high as 120,000 psi compared to the traditional 50,000 to 60,000 psi tensile strength of prior known cast irons. Typical cast irons have had a I elongation characteristic while the present cast iron has a I elongation capability. Those skilled in the art would immediately recognize the significant advantages of an increase in elongation or plastic deformation as providing a toughness capability so important in those apparatuses subjected to great wear and shock loading such as, for instance, crushers and pulverizers for the mining industry and also in pumps for the transpiration of fluids containing abrasive solids. To achieve only the change in the shape of the carbides in the cast iron would be desirable but not nearly as effective as if the shape of the carbides would change to globules and the particle size was reduced substantially below the typical average 10 to 14 micron size I
g 1 of the particles of prior cast irons down to a size less than
The gouging or grooving wear that is associated with a severe shock load requires a toughness that cast iron typically has not characteristically possessed in the past.
A manganese steel with high plasticity and toughness has been able to meet the severe shock resistant requirements for material subjected to this type of wear. However, the hardness and abrasive resistance is usually found to be inadequate to prevent an extremely high rate of wear in the high stress abrasion operation typical in a wide range of pulverizing processes such as a rotary ball mill. In this high stress operation both chrome molybdenum steel and lo alloyed white iron may be used in various types of apparatus depending upon the requirement of toughness and the combination of abrasion resistance required. In the last category of wear involving low stress operations chromium alloyed irons with or without molybdenum or nickel additions may be used with a desirable high martensitic matrix having a carbide embedment.
A consideration of the categories of wear and the knowledge of the industry concerning the types of metals available to meet the requirements in these wear categories has led to a dilemma to those skilled in the art. To operate apparatus subjected to at least the first two categories of wear there is a clear requirement or combination of optimum wear resistance and sufficient toughness to resist the severe impact and stress conditions characteristic to these types of wear. Hardness and toughness are generally recognized to typically stand at the opposite ends of the spectrum so that those compositions possessing more of one characteristic lose some of the other and yet both hardness and toughness are required.
The industry that supplies abrasion resistant castings has long sought to improve the useful life of the apparatus utilizing the casting in the wear applications described.
. .
~3~7~
Jo .
1 Various iron carbon compositions alloyed and non-alloyed do not have a high toughness in the martensitic state with the carbon starting as low as .04~. Hypereutectoid steels and white irons exhibit insufficient toughness because of the morphology of the cementite (Fake). Alloying the iron-carbon composition produces carbides (McCoy) with increased hardness thus meeting some requirements for greater abrasion resistance. However, while abrasion resistance increases the toughness or resistance to fracture decreases as the carbide volume increases, unless at any given carbide volume the carbide size is decreased. Metallurgists have long recognized the complexity of white cast iron because the two main micro-constituents, the carbide and the matrix act essentially independent of each other. Nevertheless, the ultimate characteristics of the material result from the interdependence between the two components if the white iron is subjected to abrasive and shock conditions. When impact takes place upon such material, the carbides shatter and if the carbides are continuous and of relatively large size the cracks will propagate throughout the structure often leading to failure or at least accelerated wear of the material.
There is thus to date no recognized iron-carbon alloy whose carbon content exceeds 1.7~ by weight that meets the requirements of high abrasive resistance and good shock stress absorption ~Z~7~
SUMMARY OX THE PRESENT INVENTION
Accordingly the present invention seeks to provide a white cast iron having characteristics of high hardness or wear resistance and improved toughness.
Further the present invention seeks to provide a white cast iron possessing not only desirable wear resistance and toughness characteristics but also having improved tensile strength.
The invention in one broad aspect pertains to an alloy cast iron composition comprising a base of the element iron, and one or more of the following alloying elements: 0.001% to 30% ,1 vanadium, titanium, niobium, tantalum, molybdenum, nickel, copper , our chromium, or mixtures thereof, and 2.0~ to 4.5~ carbon, the composition of the foregoing having a solidification point within 15F of the eutectic temperature of the cast iron formed with the selected alloying elements, and further containing 0.001~ to 4.0 boron whereby the cast iron possesses desirable wear resistance, toughness and tensile strength properties.
Another aspect of the invention pertains to the process of forming globular shaped carbides in cast iron comprising adding 0~001~ to 4.0% boron to an alloy cast iron comprising 0.001% to 30~ vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or chromium ox mixtures thereof and 2.0% to 4.5% carbon to form a molten cast iron composition, and cooling the molten alloy cast iron composition below equilibrium solidification temperature to a super cooled temperature, solidifying the molten cast iron composition to produce globular shaped carbides having an average size less than the average conventional cast iron carbide particle.
still further aspect of the invention pertains to the process of super cooling molten cast iron to improve the ~l~3~7~
-pa-toughness and abrasion resistance and tensile strength of cast iron comprising increasing the entropy of a molten cast iron mixture of carbon, iron and vanadium, titanium, molybdenum, nickel, copper, tantalum or chromium or mixtures thereof, to form a molten cast iron composition, super cooling the molten cast iron composition to a temperature below the equilibrium solidification temperature of the molten cast iron composition, and solidifying the molten cast iron composition while producing globular shaped carbides having an average size less than the average size of the conventional cast iron carbide.
The invention also pertains to a super cooled alloy cast iron composition consisting of a balance of iron, and one or more of the following alloying elements: .001% to 30% vanadium, titanium, niobium, tantalum, molybdenum, nickel, copper or mixtures thereof, 18% to 28% chromium, 1.5% to 3.0~ carbon, and further containing .001~ to 1.0~ boron, the composition of the foregoing having a solidification point within 15F of the eutectic temperature of the cast iron formed with the selected alloying elements. The composition when molten is capable of being super cooled below the equilibrium solidification temperature, a substantial portion of the carbon being present in the form of globular carbides, whereby the cast iron possesses desirable wear resistance, toughness and tensile strength properties and when solidified having a matrix essentially free of graphite.
Another broad aspect also comprehends the process ox forming globular shaped carbides in cast iron comprising adding 0.001% to 4.0% boron to an alloy cast iron comprising 0.001~ to 30% vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or mixtures thereof, 18% to 28% chromium, and 2.0% to 4.5% carbon to form a molten cast iron composition, and cooling the molten alloy cast iron composition below equilibrium solidification temperature to a super cooled temperature, solidifying the molten cast iron composition to produce globular shaped carbides having an average size less than the average conventional cast iron carbide particle.
The present invention also seeks to provide a cast iron composition having high abrasive resistance and toughness wherein ., , ~2~7~
the carbides are in the form of globules that approach spherical form and particularly a cast iron that is tough and wear resistant in which the carbides are of smaller than conventional average size and substantially evenly distributed throughout the matrix.
More particularly the present invention is a unique discovery of an alloy cast iron composition comprising as a base the element iron, with or without 0.001% to 30% by weight singly or cumulatively vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or chromium or mixtures thereof, 2.0 to 4.5% by weight carbon forming an alloy composition and introducing 0.001%
to 4.0% by weight boron to improve wear-resistance, toughness and tensile strength properties. The alloy has a solidification point between 2200F and 2400F and generally is in a range between 2260F to 2300F. This solidification point is within 15F of the eutectic temperature of the cast iron with the selected alloying elements. The carbides present in the form of globules that are approaching spherical form and are of a size that average less than 4 microns which is considerably less than I the average particle size of carbides in conventional cast iron.
In the process of the present invention an alloy white cast iron containing 0.001% to 30~ vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or chromium or mixtures thereof and 2.0% to 4.5% carbon forming a molten cast iron composition is provided with an entropy increasing additive such as 0.001~ to 4.0% boron then cooling the molten cast iron composition at least 5F below the equilibrium solidification temperature of between 2200F and 2400F to a super cooled temperature and thereafter solidifying the molten cast iron composition to produce globular shaped carbides having an average size less than the average conventional cast iron or carbide particle and, on the average, less than 4 microns.
, I, -- .
~;3'7~
It has long been recognized that white cast iron inherently possesses the wear-resistant characteristics desirable to meet the various wear conditions to which the apparatus composed of cast iron is subjected. It now has been discovered that the carbide morphology of the alloyed cast iron can be altered to retain the characteristic wear-resistance and not only increases the tensile strength but more importantly provides measurable plastic deformation and significant toughness improvement. It has been well known that in the prior cast irons either the free (in excess of that found in the matrix of austenite, puerility or marten site) carbon was in the form of graphite that takes a three-dimensional form somewhat similar to a corn flake or in the form of a carbide in a plate or rod-like shape. In either form the particles are microscopic in size but usually would be larger than lo microns or an average particle size assuming normal heat abstraction from a sand mold and a metal section size in excess ox loom.
It is known that these graphite flakes are the origin of the fractures along the plane of the flakes. Typically a good grade of cast iron would have a tensile strength of about 50,000 psi with 0% elongation producing a very brittle or non-tough material with no capability of deformation whatsoever. When properly alloyed, the free carbon partitions to an inter metallic metal carbide usually chromium carbide shaped generally in the form of the plates or rods and may be continuous or discontinuous within the matrix but again are of an average size greater than 10 microns The carbide particles may also take the form of needles but whatever appearance they may have microscopically, their long dimension on the average is still at least lo microns which increases the propensity for crack initiation under stress which often leads to an ultimate apparatus failure.
I
1 In the present invention it has been found that this normal rod or plate geometry of the carbides can be changed into a globular form that approximates a spherical shape producing not only the desired toughness but a significant tensile strength increase. This change in the morphology of the carbides of cast iron has altered the non-ductile, brittle, non deformable cast iron of the past to one that has the capability of plastic deformation, higher tensile strength with retention of the superior wear-resistant characteristics.
It has been found for instance, that the cast iron of the present invention will bend prior to breaking and the stress level to which it is subjected is significantly higher without fracture as compared to prior known cast irons. The cast iron of the present invention is preferably alloyed with chromium but depending upon various additions of vanadium, titanium, niobium, tantalum, nickel, molybdenum or copper from .001% to 30% to substitute for the chromium, the properties of the resultant cast iron vary.
In general, the cast iron of the present invention has been found to have a tensile strength as high as 120,000 psi compared to the traditional 50,000 to 60,000 psi tensile strength of prior known cast irons. Typical cast irons have had a I elongation characteristic while the present cast iron has a I elongation capability. Those skilled in the art would immediately recognize the significant advantages of an increase in elongation or plastic deformation as providing a toughness capability so important in those apparatuses subjected to great wear and shock loading such as, for instance, crushers and pulverizers for the mining industry and also in pumps for the transpiration of fluids containing abrasive solids. To achieve only the change in the shape of the carbides in the cast iron would be desirable but not nearly as effective as if the shape of the carbides would change to globules and the particle size was reduced substantially below the typical average 10 to 14 micron size I
g 1 of the particles of prior cast irons down to a size less than
4 microns. sty a reduction of this magnitude in the size of the particle of the carbide, it is possible to minimize the mean-free path between the smaller discrete globular shaped particles in order to contribute to higher strength levels, better wear-resistance and greater deformation, capability.
Thus, in accordance with the present invention not only are the carbides changed in shape to spherical or near spherically shaped globules, but the globular particles have been reduced in average size to below 4 microns.
Cast iron is well recognized to be an iron-carbon coup-position that may be alloyed. It is generally recognized in the art that the dividing line between cast iron and steel is the volubility of carbon in iron in the solid state. At higher levels of carbon, the carbon would be in the form of free graphite unless it was alloyed. Typically, the alloying element used to form carbides in cast iron and to improve various properties is chromium. However, molybdenum, vane-drum, titanium, copper, nickel, niobium and tantalum in any combination may optionally be added to the chromium or sub-statute for the chromium. when used in conjunction with chromium these metal elements are usually present in an amount up to about I though preferably vanadium and niobium may range from .001~ to 5%, molybdenum and copper from .001%
to I nickel from oily to 7% and titanium and tantalum range from .001'~ to I with the total in combination with chromium or with chromium alone should be in the range of .001% to 30~. Preferably the chromium is in the range of 7%
to 29% and more preferably in the ranges of 25~ to 28~ or 14 to 226 or 7% to 12~ which ranges of chromium represent the three major groups of commercial alloy white irons The carbon content is preferably not less than 2.0% and no more than about 4.5~ and preferably in the range of 2.06 to 3% for cast iron with a content of 25~ to 28% chromium and 14~ to 22~ chromium or 2% to 3.5~ for 7% to 12~ chromium.
The typical cast iron compositions outlined above can achieve a changed carbide morphology by the addition of boron I I
1 generally in the range of .001% to I and preferably .01~ to lo and most preferably between .01~ to 0.4~. This addition of boron is found to produce globular carbide particles but is more pronounced when the alloyed iron-carbon composition selected is related to the eutectic temperature.
The solidification point of pure iron is about 2800F
and as carbon is added, the solidification point decreases.
As alloyed with or without the addition of boron, the solidification temperature varies between 2200F and nephew varying primarily in accordance with the amount of chromium present but also varying due to the selection of the particular alloying elements. More desirably it is found that the solidification temperature of the alloyed iron-carbon system should be in the range of 2260F to 2300F
or approximately 2280F plus or minus 10 to 20F. Any specific cast iron composition with the selected alloying elements present in amounts in accordance with this invention will solidify within 15F of the eutectic temperature for that system of cast irons formed with those particular alloying elements.
With this alloyed cast iron composition and the addition of boron, it has been found possible to modify the carbide morphology to produce globular carbide particles that are approximating spherical shape.
To achieve this important particle size modification and to attain a substantially uniform distribution of the globular carbide particles, it has been found that if the cast iron composition were cooled below the equilibrium solidification temperature by at least 5F, and preferably it is believed 8 to 10F or more, prior to solidification that the particle size of the carbide particles would be dramatically reduced from their usual average size of 10 microns or more to an average size of less than 4 microns.
This super cooling was found to be difficult to achieve and only upon a thermodynamic approach to the problem was it discovered that by increasing the entropy of the cast iron ~Z3'7~
melt, the disol-deL- of the system its increased to allow the melt to be under cooled. A higher entropy value decreases the Gibbs free energy value of a liquid-solid system, and the phase with the lowest free energy will be the most stable.
The relationship is Go = _ S where G is Gibbs free energy, T
is the absolute temperature and S the entropy. Additionally, the thermodynamic relationship OH = TO + UP reduces to OH = TO because UP = O for solids indicates that US = OH
where S is the entropy and the heat of fusion and T the absolute solidification point. An increase in entropy produces a decrease in the solidification point with a constant heat of fusion for the system.
It was discovered that boron will, when added to the cast iron composition, increase the entropy that produced the higher randomness within the system and allow the requisite under cooling. rho exact changes occurring are not completely understood and the explanation as set forth above should be considered to be theoretical.
As the alloy cast iron composition of this invention is cooled below the equilibrium solidification temperature into the super cooling range of at least 5F below the equilibrium solidification temperature, when the solidification does occur it is more instantaneous than when super cooling does not take place. Thus, the super cooling avoids the usual lengthy period of crystal or particle growth that conventionally occurs. Rather, the solidification is more rapid before the growth of the particles can be achieved.
Thus, the minute carbide particles instead of agglomerating into rods or plates as occurs in the conventional cast iron do not have the opportunity to agglomerate with the rapid solidification in the alloy cast iron composition of the present invention nor is there a migration of these particles to agglomerate to form a plate or rod so as to produce non-uniformity in the distribution of the carbides. Rather, the uniformity in the carbide distribution is inherent in the ; melt phase even during the super cooling phase of the alloy. .
~,~
1 cast iron composition so that the uniformity of the carbide distribution is retained during solidification. The result of solidification of the super cooled melt below the equilibrium solidification temperature is a substantial reduction in the size of the particle and a more uniform distribution of the carbides throughout the matrix of the cast iron which is the basis for the strength, toughness and abrasion resistance of the cast iron composition of the present invention.
Specific_Exam~le A typical cast iron composition containing 27.2 chromium, 2.04% carbon is an alloy composition with solidification in the range of 2280F which is above the eutectic temperature of about 2263F. With the addition ox 0.17~ boron the alloy can be super cooled to a temperature of
Thus, in accordance with the present invention not only are the carbides changed in shape to spherical or near spherically shaped globules, but the globular particles have been reduced in average size to below 4 microns.
Cast iron is well recognized to be an iron-carbon coup-position that may be alloyed. It is generally recognized in the art that the dividing line between cast iron and steel is the volubility of carbon in iron in the solid state. At higher levels of carbon, the carbon would be in the form of free graphite unless it was alloyed. Typically, the alloying element used to form carbides in cast iron and to improve various properties is chromium. However, molybdenum, vane-drum, titanium, copper, nickel, niobium and tantalum in any combination may optionally be added to the chromium or sub-statute for the chromium. when used in conjunction with chromium these metal elements are usually present in an amount up to about I though preferably vanadium and niobium may range from .001~ to 5%, molybdenum and copper from .001%
to I nickel from oily to 7% and titanium and tantalum range from .001'~ to I with the total in combination with chromium or with chromium alone should be in the range of .001% to 30~. Preferably the chromium is in the range of 7%
to 29% and more preferably in the ranges of 25~ to 28~ or 14 to 226 or 7% to 12~ which ranges of chromium represent the three major groups of commercial alloy white irons The carbon content is preferably not less than 2.0% and no more than about 4.5~ and preferably in the range of 2.06 to 3% for cast iron with a content of 25~ to 28% chromium and 14~ to 22~ chromium or 2% to 3.5~ for 7% to 12~ chromium.
The typical cast iron compositions outlined above can achieve a changed carbide morphology by the addition of boron I I
1 generally in the range of .001% to I and preferably .01~ to lo and most preferably between .01~ to 0.4~. This addition of boron is found to produce globular carbide particles but is more pronounced when the alloyed iron-carbon composition selected is related to the eutectic temperature.
The solidification point of pure iron is about 2800F
and as carbon is added, the solidification point decreases.
As alloyed with or without the addition of boron, the solidification temperature varies between 2200F and nephew varying primarily in accordance with the amount of chromium present but also varying due to the selection of the particular alloying elements. More desirably it is found that the solidification temperature of the alloyed iron-carbon system should be in the range of 2260F to 2300F
or approximately 2280F plus or minus 10 to 20F. Any specific cast iron composition with the selected alloying elements present in amounts in accordance with this invention will solidify within 15F of the eutectic temperature for that system of cast irons formed with those particular alloying elements.
With this alloyed cast iron composition and the addition of boron, it has been found possible to modify the carbide morphology to produce globular carbide particles that are approximating spherical shape.
To achieve this important particle size modification and to attain a substantially uniform distribution of the globular carbide particles, it has been found that if the cast iron composition were cooled below the equilibrium solidification temperature by at least 5F, and preferably it is believed 8 to 10F or more, prior to solidification that the particle size of the carbide particles would be dramatically reduced from their usual average size of 10 microns or more to an average size of less than 4 microns.
This super cooling was found to be difficult to achieve and only upon a thermodynamic approach to the problem was it discovered that by increasing the entropy of the cast iron ~Z3'7~
melt, the disol-deL- of the system its increased to allow the melt to be under cooled. A higher entropy value decreases the Gibbs free energy value of a liquid-solid system, and the phase with the lowest free energy will be the most stable.
The relationship is Go = _ S where G is Gibbs free energy, T
is the absolute temperature and S the entropy. Additionally, the thermodynamic relationship OH = TO + UP reduces to OH = TO because UP = O for solids indicates that US = OH
where S is the entropy and the heat of fusion and T the absolute solidification point. An increase in entropy produces a decrease in the solidification point with a constant heat of fusion for the system.
It was discovered that boron will, when added to the cast iron composition, increase the entropy that produced the higher randomness within the system and allow the requisite under cooling. rho exact changes occurring are not completely understood and the explanation as set forth above should be considered to be theoretical.
As the alloy cast iron composition of this invention is cooled below the equilibrium solidification temperature into the super cooling range of at least 5F below the equilibrium solidification temperature, when the solidification does occur it is more instantaneous than when super cooling does not take place. Thus, the super cooling avoids the usual lengthy period of crystal or particle growth that conventionally occurs. Rather, the solidification is more rapid before the growth of the particles can be achieved.
Thus, the minute carbide particles instead of agglomerating into rods or plates as occurs in the conventional cast iron do not have the opportunity to agglomerate with the rapid solidification in the alloy cast iron composition of the present invention nor is there a migration of these particles to agglomerate to form a plate or rod so as to produce non-uniformity in the distribution of the carbides. Rather, the uniformity in the carbide distribution is inherent in the ; melt phase even during the super cooling phase of the alloy. .
~,~
1 cast iron composition so that the uniformity of the carbide distribution is retained during solidification. The result of solidification of the super cooled melt below the equilibrium solidification temperature is a substantial reduction in the size of the particle and a more uniform distribution of the carbides throughout the matrix of the cast iron which is the basis for the strength, toughness and abrasion resistance of the cast iron composition of the present invention.
Specific_Exam~le A typical cast iron composition containing 27.2 chromium, 2.04% carbon is an alloy composition with solidification in the range of 2280F which is above the eutectic temperature of about 2263F. With the addition ox 0.17~ boron the alloy can be super cooled to a temperature of
5 degrees below that equilibrium solidification temperature and to about slightly below 2275F. Between this temperature point and below the equilibrium solidification temperature the melt is super cooled and remains liquid.
Further cooling produces carbides having a globular shape that is nearly spherical and of an average particle size of less than 4 microns. The tensile strength of the resulting cast iron is in the range of 120,000 psi with approximately I elongation permitted. Such a white cast iron is quite wear-resistant and additionally has improved tensile strength and toughness characteristics that make it particularly useful in high wear and stress operations.
Similar results are obtained with a composition of 3.32%
carbon, 9.12% chromium, 5.18~ nickel and 0.17~ boron having an equilibrium solidification temperature at about the eutectic temperature of 2287F. Supercooling then takes place down to 2280F before solidification occurs.
It is believed that the objects of the present invention have been met by the invention as described above and it is ~;Z379~
1 believed that the invention should only be restricted in accordance with the following claims in which
Further cooling produces carbides having a globular shape that is nearly spherical and of an average particle size of less than 4 microns. The tensile strength of the resulting cast iron is in the range of 120,000 psi with approximately I elongation permitted. Such a white cast iron is quite wear-resistant and additionally has improved tensile strength and toughness characteristics that make it particularly useful in high wear and stress operations.
Similar results are obtained with a composition of 3.32%
carbon, 9.12% chromium, 5.18~ nickel and 0.17~ boron having an equilibrium solidification temperature at about the eutectic temperature of 2287F. Supercooling then takes place down to 2280F before solidification occurs.
It is believed that the objects of the present invention have been met by the invention as described above and it is ~;Z379~
1 believed that the invention should only be restricted in accordance with the following claims in which
Claims (53)
1. An alloy cast iron composition comprising:
a base of the element iron, and one or more of the following alloying elements: 0.001% to 30% vanadium, titanium, niobium, tantalum, molybdenum, nickel, copper or chromium, or mixtures thereof, and 2.0% to 4.5% carbon, the composition of the foregoing has a solidification point within 15°F of the eutectic temperature of the cast iron formed with the selected alloying elements, and further containing 0.001% to 4.0% boron whereby the cast iron possesses desirable wear resistance, toughness and tensile strength properties.
a base of the element iron, and one or more of the following alloying elements: 0.001% to 30% vanadium, titanium, niobium, tantalum, molybdenum, nickel, copper or chromium, or mixtures thereof, and 2.0% to 4.5% carbon, the composition of the foregoing has a solidification point within 15°F of the eutectic temperature of the cast iron formed with the selected alloying elements, and further containing 0.001% to 4.0% boron whereby the cast iron possesses desirable wear resistance, toughness and tensile strength properties.
2. The composition of Claim 1 including said alloy having a solidification point between 2200°F and 2400°F.
3. The composition of Claim 1 including said vanadium, titanium, niobium or tantalum being present in an amount up to 7%.
4. The composition of Claim 1 including said chromium being present in an amount from 0.1% to 30%.
5. The composition of Claim 1 including up to 7%
nickel, up to 4% molybdenum or up to 4% copper or combinations thereof being added.
nickel, up to 4% molybdenum or up to 4% copper or combinations thereof being added.
6. The composition of Claim 1, including said carbon being present at least in part in the form of globular carbides.
7. The composition of Claim 2 including said alloy solidification point being about 2260°F to 2300°F.
8. The composition of claim 7 including said alloy solidification point being about 2280°F.
9. The composition of Claim 1 including said carbon being present at least in part in the form of globular carbides, said vanadium, titanium, niobium, nickel. copper, molybdenum or tantalum being present in an amount up to 7%, and said alloy solidification point being about 2260°F to 2300°F.
10. The composition of Claim 1 including said carbon being present at least in part in the form of globular carbides, said alloy having a solidification point between 2200°F and 2400°F, and said vanadium, titanium, niobium, nickel, copper, molybdenum or tantalum being present in an amount up to 7%.
11. The composition of Claim 1 including said carbon being present at least in part in the form of globular carbides, said chromium being present in an amount from 0.1%
to 30%, and said alloy solidification point being about 2260°F to 2300°F.
to 30%, and said alloy solidification point being about 2260°F to 2300°F.
12. The composition of Claim 1 wherein the amount of said chromium is selected from the group consisting of 20% to 29%, 14% to 22%, and 7% to 12%, said carbon being 2.0% to 3.5%, and said boron being 0.01% to 1.0%.
13. The composition of Claim 1 including said chromium being 25% to 28%, said carbon being 2.0% to 3.0% and said boron being 0.1% to 0.4%.
14. The composition of Claim 1 or 6 including said carbon being present at least in part in the form of globular carbides having an average particle size of less than 4 microns.
15. The process of forming globular shaped carbides in cast iron comprising:
adding 0.001% to 4.0% boron to an alloy cast iron comprising 0.001% to 30% vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or chromium or mixtures thereof and 2.0% to 4.5% carbon to form a molten cast iron composition, and cooling said molten alloy cast iron composition below equilibrium solidification temperature to a super cooled temperature, solidifying said molten cast iron composition to produce globular shaped carbides having an average size less than the average conventional cast iron carbide particle.
adding 0.001% to 4.0% boron to an alloy cast iron comprising 0.001% to 30% vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or chromium or mixtures thereof and 2.0% to 4.5% carbon to form a molten cast iron composition, and cooling said molten alloy cast iron composition below equilibrium solidification temperature to a super cooled temperature, solidifying said molten cast iron composition to produce globular shaped carbides having an average size less than the average conventional cast iron carbide particle.
16. The process of Claim 15 including said alloy having a solidification point between 2200°F and 2400°F.
17. The process of Claim 15 including said vanadium, titanium, niobium, tantalum, molybdenum, copper or nickel being present in an amount up to 7%.
18. The process of Claim 15 including said chromium being present in an amount from 0.1% to 30%.
19. The process of Claim 15 including adding up to 7%
nickel, up to 4% molybdenum or up to 4% copper or combinations thereof.
nickel, up to 4% molybdenum or up to 4% copper or combinations thereof.
20. The process of Claim 15 including cooling said molten cast iron composition to a super cooled temperature at least about 5°F below the equilibrium solidification temperature.
21. The process of Claim 15 including solidifying said molten cast iron composition by continuing to cool said molten cast iron composition to a super cooled temperature to form globular shaped carbides having an average size of less than about 4 microns.
22. The process of Claim 15 including cooling said molten cast iron composition to a super cooled temperature at least about 5°F below the equilibrium solidification temperature, and solidifying said molten cast iron composition by continuing to cool said molten cast iron composition to a super cooled temperature to form globular shaped carbides having an average size of less than about 4 microns.
23. The process of Claim 20, 21 and 22 including said equilibrium solidification point being 2200°F to 2400°F.
24. The process of Claim 20, 21 and 22 including said equilibrium solidification point being 2260°F to 2300°F.
25. The process of super cooling molten cast iron to improve the toughness and abrasion resistance and tensile strength of cast iron comprising:
increasing the entropy of a molten cast iron mixture of carbon, iron and vanadium, titanium, molybdenum, nickel, copper, tantalum or chromium or mixtures thereof, to form a molten cast iron composition, super cooling the molten cast iron composition to a temperature below the equilibrium solidification temperature of the molten cast iron composition, and solidifying said molten cast iron composition while producing globular shaped carbides having an average size less than the average size of the conventional cast iron carbide.
increasing the entropy of a molten cast iron mixture of carbon, iron and vanadium, titanium, molybdenum, nickel, copper, tantalum or chromium or mixtures thereof, to form a molten cast iron composition, super cooling the molten cast iron composition to a temperature below the equilibrium solidification temperature of the molten cast iron composition, and solidifying said molten cast iron composition while producing globular shaped carbides having an average size less than the average size of the conventional cast iron carbide.
26. The process of Claim 25 including cooling said molten cast iron composition to a super cooled temperature at least about 5°F below the equilibrium solidification temperatures.
27. The process of Claim 25 including solidifying said molten cast iron composition by continuing to cool said molten cast iron composition to a super cooled temperature to form globular shaped carbides having an average size of less than about 4 microns.
28. The process of Claim 25 including cooling said molten cast iron composition to a super cooled temperature at least about 5°F below the equilibrium solidification temperature, and solidifying said molten cast iron composition by continuing to cool said molten cast iron composition to a super cooled temperature to form globular shaped carbides having an average size of less than about 4 microns.
29. The process of Claim 25, including increasing the entropy of said cast iron mixture by adding 0.001%
to 4.0% boron.
to 4.0% boron.
30. The process of Claim 29 including said boron being present in the amount of 0.1% to 0.4%.
31. The process of Claim 15 including said boron being present in the amount of 0.1% to 0.4%.
32. The composition of Claim 1 including said boron being present in the amount of 0.1% to 0.4%.
33. A supercooled alloy cast iron composition consisting of:
a balance of iron, and one or more of the following alloying elements: .001% to 30% vanadium, titanium, niobium, tantalum, molybdenum, nickel, copper or mixtures thereof, 18% to 28% chromium, 1.5% to 3.0% carbon, and further containing .001% to 1.0% boron, the composition of the foregoing having a solidification point within 15°F of the eutectic temperature of the cast iron formed with the selected alloying elements, said composition when molten being capable of being supercooled below the equilibrium solidification temperature, a substantial portion of said carbon being present in the form of globular carbides, whereby the cast iron possesses desirable wear resistance, toughness and tensile strength properties and when solidified having a matrix essentially free of graphite.
a balance of iron, and one or more of the following alloying elements: .001% to 30% vanadium, titanium, niobium, tantalum, molybdenum, nickel, copper or mixtures thereof, 18% to 28% chromium, 1.5% to 3.0% carbon, and further containing .001% to 1.0% boron, the composition of the foregoing having a solidification point within 15°F of the eutectic temperature of the cast iron formed with the selected alloying elements, said composition when molten being capable of being supercooled below the equilibrium solidification temperature, a substantial portion of said carbon being present in the form of globular carbides, whereby the cast iron possesses desirable wear resistance, toughness and tensile strength properties and when solidified having a matrix essentially free of graphite.
34. The composition of Claim 33 including said alloy having a solidification point between 2200°F and 2400°F.
35. The composition of Claim 33 including said vanadium, titanium, niobium or tantalum being present in an amount up to 7%.
36. The composition of Claim 33 including said chromium being present in an amount from 24% to 26%.
37. The composition of Claim 33 including up to 7%
nickel, up to 4% molybdenum or up to 4% copper or combinations thereof being added.
nickel, up to 4% molybdenum or up to 4% copper or combinations thereof being added.
38. The composition of Claim 34 including said alloy solidification point being about 2260°F to 2300°F.
39. The composition of Claim 38 including said alloy solidification point being about 2280°F.
40. The composition of Claim 33 including said vanadium, titanium, niobium, nickel, copper, molybdenum or tantalum being present in an amount up to 7%, and said alloy solidification point being about 2260°F to 2300°F.
41. The composition of Claim 33 including said alloy having a solidification point between 2200°F and 2400°F, and said vanadium, titanium, niobium, nickel, copper, molybdenum or tantalum being present in an amount up to 7%.
42. The composition of Claim 33 including said chromium being 25% to 28%, said carbon being 2.0% to 3.0% and said boron being 0.1% to 0.4%.
43. The composition of Claim 33 including said carbon being present at least in part in the form of globular carbides having an average particle size of less than 4 microns.
44. The process of forming globular shaped carbides in cast iron comprising:
adding 0.001% to 4.0% boron to an alloy cast iron comprising 0.001% to 30% vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or mixtures thereof, 18% to 28% chromium, and 2.0% to 4.5% carbon to form a molten cast iron composition, and cooling said molten alloy cast iron composition below equilibrium solidification temperature to a super cooled temperature, solidifying said molten cast iron composition to produce globular shaped carbides having an average size less than the average conventional cast iron carbide particle.
adding 0.001% to 4.0% boron to an alloy cast iron comprising 0.001% to 30% vanadium, titanium, niobium, molybdenum, nickel, copper, tantalum or mixtures thereof, 18% to 28% chromium, and 2.0% to 4.5% carbon to form a molten cast iron composition, and cooling said molten alloy cast iron composition below equilibrium solidification temperature to a super cooled temperature, solidifying said molten cast iron composition to produce globular shaped carbides having an average size less than the average conventional cast iron carbide particle.
45. The process of Claim 44 including said alloy having a solidification point between 2200°F and 2400°F.
46. The process of Claim 44 including said vanadium, titanium, niobium, tantalum, molybdenum, copper or nickel being present in an amount up to 7%.
47. The process of Claim 44 including said chromium being present in an amount from 24% to 28%.
48. The process of Claim 44 including adding up to 7% nickel, up to 4% molybdenum or up to 4% copper or combinations thereof.
49. The process of Claim 44 including cooling said molten cast iron composition to a super cooled temperature at least about 5°F below the equilibrium solidification temperature.
50. The process of Claim 44 including solidifying said molten cast iron composition by continuing to cool said molten cast iron composition to a super cooled temperature to form globular shaped carbides having an average size of less than about 4 microns.
51. The process of Claim 44 including cooling said molten cast iron composition to a super cooled temperature at least about 5°F below the equilibrium solidification temperature, and solidifying said molten cast iron composition by continuing to cool said molten cast iron composition to a super cooled temperature to form globular shaped carbides having an average size of less than about 4 microns.
52. The process of Claim 49, 50 and 51, including said equilibrium solidification point being 2200°F to 2400°F.
53. The process of Claim 49, 50 and 51 including said equilibrium solidification point being 2260°F to 2300°F.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000451185A CA1237921A (en) | 1984-04-03 | 1984-04-03 | Abrasive resistant white cast iron |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000451185A CA1237921A (en) | 1984-04-03 | 1984-04-03 | Abrasive resistant white cast iron |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1237921A true CA1237921A (en) | 1988-06-14 |
Family
ID=4127578
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000451185A Expired CA1237921A (en) | 1984-04-03 | 1984-04-03 | Abrasive resistant white cast iron |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1237921A (en) |
-
1984
- 1984-04-03 CA CA000451185A patent/CA1237921A/en not_active Expired
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