High-cleanness soft magnetic steel with excellent welding performance and production method thereof
1. A high-cleanness soft magnetic steel with excellent welding performance is characterized in that the soft magnetic steel comprises the following mass fractionsThe chemical composition of (A): c: 0.005-0.020%, Si: 1.82-2.05%, Mn: 0.26-0.45%, P < 0.0010%, S < 0.0005%, Cr: 0.10 to 0.42%, Ni: 0.45-0.65%, Ti: 0.006-0.012%, Ca: 0.0005-0.0017%, Nb < 0.0010%, V < 0.0010%, Als < 0.0010%, As < 0.0010%, Sn < 0.0010%, [ N ]]：12～15×10-4%，[O]＜10×10-4%，[H]＜0.2×10-4Percent, the balance being Fe and unavoidable impurities, and the chemical components also have to satisfy: (1) nb + V + Als is less than 0.0015%, and (2) C + Mn/6+ Cr/5+ Ni/15 is less than or equal to 0.18%.
2. The high cleanliness soft magnetic steel with excellent weldability according to claim 1, characterized in that: the Cr: 0.14 to 0.38%, Ti: 0.007-0.011%, Ca: 0.0007 to 0.0015 percent.
3. The high cleanliness soft magnetic steel with excellent weldability according to claim 1, characterized in that: the elongation A of the soft magnetic steel is more than or equal to 34.5%, and the impact toughness of the base material at the temperature of minus 25 ℃ is 157-182J; HAZ impact toughness of welding at-25 ℃ of 112-127J, B3≥0.89T，B40≥1.60T，B50≥1.69T。
4. A method for producing a high-cleanness soft magnetic steel excellent in weldability as claimed in claim 1, 2 or 3, comprising: molten iron desulfurization, converter smelting, external refining, vacuum treatment, full-flow protection pouring, casting blank heating, normalizing rolling and cooling; the method is characterized in that:
(1) smelting by adopting a converter double-slag method, performing external refining, vacuum treatment and full-flow protection, and pouring into a casting blank with the thickness of 200-250 mm, wherein N is ensured in the process] 12～15×10-4Percent, wherein: the converter top-bottom composite converting requires that the As content of the incoming molten iron is less than 0.0010%, the Sn content is less than 0.0010%, the S content is less than 0.0010% and the P content is less than 0.010%, and the P content is controlled to be less than 0.0010% before tapping; refining for 45-60 min outside the furnace; the vacuum treatment time is more than or equal to 18min, the vacuum degree is less than or equal to 0.10kPa, and the soft argon blowing time is 5-6 min; controlling the superheat degree to be 12-15 ℃ and the drawing speed to be 0.77-0.78 m/min during pouring;
(2) the heating temperature of the casting blank is 1280-1300 ℃, the heating rate is 8-12 min/mm, the soaking temperature is 1230-1250 ℃, and the soaking time is 50-60 min;
(3) normalizing and rolling: the rough rolling and final rolling temperature in the stage I is 1100-1120 ℃; the finishing temperature (T +/-5) DEG C in the II stage of finish rolling, wherein T = (910-1/2+4470Si-1520Ni) DEG C, wherein C, Si and Ni are chemical components in percentage by weight;
(4) and (4) naturally cooling the rolled steel plate to room temperature in the air for later use.
Background
The soft magnetic steel is mainly used for key components of a lateral guide plate of a magnetic suspension train, an automobile generator, an electromagnetic valve, a magnetic pole section or claw level and the like which realize the functions by means of electromagnetic force. In order to realize high performance of key components, the performance requirements on soft magnetic steel materials are higher and higher, and besides high magnetic permeability, high magnetic flux density and low iron loss, the soft magnetic steel is required to have good obdurability matching, steel purity, excellent welding performance and the like, so that the existing common soft magnetic steel cannot meet the requirements of safe, reliable, energy-saving, environment-friendly and the like for operation of equipment such as a magnetic suspension train and the like.
Before the invention, the Patent US Patent4350525 elaborates the component range and the production process in detail, and sets requirements on magnetic induction performance and 0 ℃ impact toughness, wherein the magnetic induction performance B3 and B40 are only 0.60T and 1.58T, and the longitudinal and transverse 0 ℃ impact toughness is 58J and 32J respectively, so that the magnetic induction performance and the impact toughness of the soft magnetic steel are not ideal, and the welding performance is not required.
Chinese patent No. 01126937.5 discloses a high performance soft magnetic steel for magnetic suspension train, which comprises the following chemical components by weight percent: 0.010-0.070%, Si: 1.0-2.0%, Mn: 0.30-0.80%, P is less than or equal to 0.02%, S is less than or equal to 0.010%, and AlT: 0.020-0.090%, Cr: 0.60-1.0%, Cu: 0.20-0.60 percent of Ti, less than or equal to 0.0080 percent of Ti, less than or equal to 0.01 percent of N, less than or equal to 0.80 percent of Ni, and less than or equal to 100ppm of Ca. The steel has high strength and high toughness, high magnetic induction, high resistivity and excellent diamagnetism, but does not require welding performance, contains more Cr elements, is produced by adopting a normalizing process, increases the manufacturing cost, contains more Al alloy elements, and is easy to form coarse Al2O3Particles of inclusions, thereby causingThe pouring gate is clogged and deteriorates fracture toughness, causing a production accident.
The Chinese patent with the patent number 94105234.6 discloses a soft magnetic steel and a manufacturing method thereof, wherein the chemical components and the weight percentage are that C is less than or equal to 0.007%, Mn is less than or equal to 0.50%, P is less than or equal to 0.20%, S is less than or equal to 0.010%, N is less than or equal to 0.01%, O is less than or equal to 0.005%, Si +1.4 xAl is more than or equal to 0.5% and less than or equal to 3.5%, the grain size is required to be at least 0.2mm, and B25= 1.35-1.58T.
The Chinese invention patent with patent number 97197182.X discloses a high-energy weldable soft magnetic steel and application thereof to magnetic suspension rail components, wherein the chemical components and weight percentage are that C is less than or equal to 0.15%, Si: more than 1.0-2.0%, Mn: 0.15 to less than 0.6 percent, P is less than or equal to 0.045 percent, Cu: 0.25-0.55%, Cr: 0.65 to < 1.0%, Als: 0.02 to 0.07%, Ti: 0.01-0.02%, N: 0.003-0.008% and Ti/N = 2.0-4.0. The invention has high resistivity, good ageing resistance and atmospheric corrosion resistance. The invention adopts the heat treatment process for production, has high Cr alloy content, is easy to form Cr-containing large-scale inclusion types, has higher manufacturing cost, has the toughness of a welding heat affected zone below 50J at the temperature of minus 25 ℃, and has poorer welding performance.
The invention patents in China with patent numbers of 201510925592.2 and 201510966905.9 respectively disclose a soft magnetic steel material and a soft magnetic steel part with excellent electromagnetic property and a manufacturing method thereof, and a soft magnetic steel material and a soft magnetic steel part with excellent forgeability and a manufacturing method thereof, wherein the two products both belong to the shapes of wires or bars, are produced by adopting a hot rolling or hot forging + 560-790 ℃ heat treatment process, and have good electromagnetic property or low iron loss, but the two invention patents have complex process routes and do not have requirements on toughness and welding performance.
Disclosure of Invention
The invention aims to provide high-cleanness soft magnetic steel with excellent welding performance and a production method thereof aiming at the defects in the prior art. The invention does not need to carry out complex heat treatment procedures, has the advantages of low cost, simple procedures, short period and the like, and can be implemented in various metallurgical enterprises. The steel produced by the method has the characteristics of high cleanliness, good toughness, excellent magnetic induction performance, excellent welding performance and the like, and can be used for key components of a lateral guide plate of a magnetic suspension train, an automobile generator, an electromagnetic valve, a magnetic pole section or a claw stage and the like which realize the functions by relying on electromagnetic force.
The high-cleanness soft magnetic steel with excellent welding performance comprises the following chemical components in percentage by mass: c: 0.005-0.020%, Si: 1.82-2.05%, Mn: 0.26-0.45%, P < 0.0010%, S < 0.0005%, Cr: 0.10 to 0.42%, Ni: 0.45-0.65%, Ti: 0.006-0.012%, Ca: 0.0005-0.0017%, Nb < 0.0010%, V < 0.0010%, Als < 0.0010%, As < 0.0010%, Sn < 0.0010%, [ N ]]：12～15×10-4%，[O]＜10×10-4%，[H]＜0.2×10-4Percent, the balance being Fe and unavoidable impurities, and the chemical components also have to satisfy: (1) nb + V + Als is less than 0.0015%, and (2) C + Mn/6+ Cr/5+ Ni/15 is less than or equal to 0.18%.
Preferably, the ratio of Cr: 0.14 to 0.38%, Ti: 0.007-0.011%, Ca: 0.0007 to 0.0015 percent.
The elongation A of the soft magnetic steel is more than or equal to 34.5%, and the impact toughness of a base material at the temperature of minus 25 ℃ is 157-182J; HAZ impact toughness of welding at-25 ℃ of 112-127J, B3≥0.89T，B40≥1.60T，B50≥1.69T。
The invention relates to a production method of high-cleanness soft magnetic steel with excellent welding performance, which comprises the following steps: molten iron desulfurization, converter smelting, external refining, vacuum treatment, full-flow protection pouring, casting blank heating, normalizing rolling and cooling; wherein:
(1) smelting by adopting a converter double-slag method, performing external refining, vacuum treatment and full-flow protection, and pouring into a casting blank with the thickness of 200-250 mm, wherein N is ensured in the process] 12～15×10-4Percent, wherein: the converter top-bottom composite converting requires that the As content of the incoming molten iron is less than 0.0010%, the Sn content is less than 0.0010%, the S content is less than 0.0010% and the P content is less than 0.010%, and the P content is controlled to be less than 0.0010% before tapping; refining for 45-60 min outside the furnace; the vacuum treatment time is more than or equal to 18min, the vacuum degree is less than or equal to 0.10kPa, and the soft argon blowing time is 5-6 min; controlling degree of superheat during pouringThe temperature is 12-15 ℃, and the pulling speed is 0.77-0.78 m/min;
(2) the heating temperature of the casting blank is 1280-1300 ℃, the heating rate is 8-12 min/mm, the soaking temperature is 1230-1250 ℃, and the soaking time is 50-60 min;
(3) normalizing and rolling: the rough rolling and final rolling temperature in the stage I is 1100-1120 ℃; the finishing temperature (T +/-5) DEG C in the II stage of finish rolling, wherein T = (910-1/2+4470Si-1520Ni) DEG C, wherein C, Si and Ni are chemical components in percentage by weight;
(4) and (4) naturally cooling the rolled steel plate to room temperature in the air for later use.
The reasons for the limited amounts of the chemical components in the present invention are detailed below:
the content of C is selected to be 0.005-0.020%, and the strength is improved by solid solution strengthening but the low-temperature toughness is damaged by C. C expands the austenite phase region, lowers the phase transition temperature, and is not favorable for the magnetic induction performance. However, if the C content is too low, the strength cannot be ensured, and if the C content is too high, Fe is easily formed3C, increasing the pearlite structure proportion in the steel is not beneficial to the welding performance and the magnetic induction performance, and considering the performance factors comprehensively, the content of C is limited to 0.005-0.020%.
The Si content of the invention is selected to be 1.82-2.05%, the Si has a decisive effect on the magnetic induction performance, the Si improves the phase transition temperature, promotes the growth of the structure and improves the magnetic induction performance. However, since too high Si content causes rapid deterioration of low-temperature toughness and weldability, the Si content is limited to 1.82 to 2.05% in view of the balance.
The Mn content of the invention is selected to be 0.26-0.45%, Mn can improve the strength, but Mn is easy to form strip-shaped MnS inclusion with S, prevents the crystal grain from growing, and is not beneficial to the magnetic induction performance. In order to ensure the magnetic induction performance and the strength of the steel, the content of Mn is limited to 0.26-0.45%.
P is less than 0.0010 percent, S is less than 0.0005 percent, P, S is easy to deviate to grain boundaries to block the movement of the grain boundaries, and S is also easy to form strip MnS inclusions to reduce steel cleanliness, is not beneficial to magnetic induction performance and low-temperature toughness and damages welding performance, so that P and S are harmful impurity elements and the content of P, S is reduced as far as possible.
The Cr content of the invention is selected to be 0.10-0.42%, and Cr is improved by solid solution strengtheningStrength, but too high a Cr content tends to be formed2C3The series of compounds and various types of Cr-containing inclusions reduce the magnetic induction performance and steel cleanliness, and are not beneficial to the welding performance, so that the Cr content is limited to 0.10-0.42%, preferably 0.14-0.38% in comprehensive consideration.
The Ni content of the invention is selected to be 0.45-0.65%, Ni is a ferromagnetic material, the magnetic induction performance, low-temperature toughness and welding performance of the product can be improved, but too high Ni content increases cost, and surface iron scale is easy to generate, so that the Ni content is limited to be 0.45-0.65%.
The Ti content is selected to be 0.006-0.012%, the Ti and N, C are combined to form fine nitride or carbonitride particles, the crystal grain refining effect is achieved, the toughness of a base material and the toughness of a welding heat affected zone are improved, and excellent welding performance of a steel plate is ensured, but if the Ti content is too high, a large number of nitride or carbonitride particles are easily formed to block the movement of a magnetic domain wall and be not beneficial to the magnetic induction performance, so that the Ti content is limited to be 0.006-0.012%, preferably 0.007-0.011% by comprehensively considering the performance requirements of the product.
The content of Ca is selected to be 0.0005-0.0017%, the Ca can spheroidize and deteriorate sulfide inclusions, the impact toughness and the toughness of a welding heat affected zone of the base material are improved, the movement of a crystal boundary and a magnetic domain wall is hindered, the magnetic induction performance is not facilitated, and too high Ca is easy to form large-scale composite inclusions, so that the impact toughness and the magnetic induction performance of the base material and the heat affected zone are reduced, and the cleanliness of steel is poor. Therefore, in accordance with the requirements of the steel of the present invention, Ca is limited to 0.0005 to 0.0017%, preferably 0.0007 to 0.0015%.
The content of Nb is less than 0.0010%, and the content of V is less than 0.0010%. Nb, V and C, N are combined to form fine carbonitride particles, the strength is obviously improved and the low-temperature toughness is improved by refining grains, but the low-temperature toughness is extremely unfavorable for the magnetic induction performance, so the product performance requirement is comprehensively considered, the Nb content is limited to be less than 0.0010 percent, and the V content is limited to be less than 0.0010 percent.
The Als is selected to be less than 0.0010%, and the Als and N in the steel are combined to form AlN particles, so that the growth of crystal grains is hindered, the Als has the effects of refining the crystal grains and improving the impact toughness, but the Als is not beneficial to magnetic sensitivityCan, and excessive Als easily form Al2O3The inclusion is also not beneficial to the magnetic induction performance and the steel cleanliness is reduced, so the content of Als is limited to be less than 0.0010 percent to ensure the magnetic induction performance and the steel cleanliness of the product.
As is less than 0.0010 percent and Sn is less than 0.0010 percent, As and Sn in the steel are easy to segregate in crystal boundaries, the low-temperature impact toughness and the welding performance of the steel are seriously deteriorated due to the excessively high content of As and Sn, and the magnetic induction performance and the steel cleanliness are extremely adversely affected, so that the content of As and Sn in the steel is reduced As far As possible.
[ N ] of the invention]Is selected to be (12-15) × 10-4N, Ti and C are combined to form fine nitride or carbonitride particles so as to improve the toughness of a base material and the toughness of a welding heat affected zone, but if the content of N is too high, a large number of TiN or carbonitride particles are easily formed to block the movement of a magnetic domain wall and reduce the magnetic induction performance, so that the content of N is limited to (12-15) multiplied by 10 by taking the product performance requirements into consideration comprehensively-4%。
[ O ] of the invention]＜10×10-4The% of the iron-based alloy can form oxide particles or inclusions with elements such as Ti, Als and the like in steel, so that the growth of crystal grains is inhibited, the magnetic induction performance or the toughness of a welding heat affected zone is damaged, and the cleanliness of the steel is reduced, so that the content of O in the steel is reduced as much as possible.
[ H ] of the invention]＜0.2×10-4% and H content in steel is controlled to be 0.2 x 10-4% or less.
Meanwhile, the chemical components also need to meet the requirements that (1) Nb + V + Als is less than 0.0015 percent, and (2) C + Mn/6+ Cr/5+ Ni/15 is less than or equal to 0.18 percent. When Nb + V + Al is more than or equal to 0.0015%, more nitride or carbide or carbonitride or inclusion particles are easily formed, the movement of a crystal boundary and a magnetic domain wall is hindered, and the magnetic induction performance, the welding performance and the steel cleanliness are reduced; when C + Mn/6+ Cr/5+ (Cu + Ni) > 0.18%, impact toughness and weldability are impaired, and production cost increases. Therefore, in order to ensure that the product has excellent magnetic induction performance and welding performance and steel cleanliness, the Nb + V + Al content is strictly limited to be less than 0.0015 percent and the C + Mn/6+ Cr/5+ Ni/15 content is strictly limited to be less than or equal to 0.18 percent.
The steel of the present invention contains the above chemical components, and the balance of Fe and inevitable impurities.
The invention aims to provide high-cleanness soft magnetic steel with excellent welding performance and a production method thereof, wherein the related steel finished product does not need to be subjected to a complex heat treatment process, has the advantages of low cost, simple process, short period and the like, can be implemented in various metallurgical enterprises, ensures the product performance and also aims at accurately controlling the process parameters, and the specific measures are as follows:
smelting by a converter double-slag method, performing external refining, vacuum treatment and full-flow protection casting to form a casting blank, and ensuring N]Is (12-15) × 10-4% is to ensure that N, Ti and C are combined to form fine nitride or carbonitride particles, improve the toughness of the base material and the toughness of a welding heat affected zone, and simultaneously avoid forming a large amount of TiN or carbonitride particles due to overhigh content of N, thereby hindering the movement of a magnetic domain wall and reducing the magnetic induction performance; in addition, the P, S, N, O, H content can be reduced as much as possible by adopting the steps, and the formation of various types of inclusions caused by the high content of the P, S, N, O, H can be avoided, so that the cleanliness of the steel is reduced, and the magnetic induction performance and the toughness of the base material and the welding heat affected zone are damaged.
The converter top-bottom composite blowing adopts a double-slag method for smelting, and requires that the As content of incoming molten iron is less than 0.0010%, the Sn content is less than 0.0010%, the S content is less than 0.0010% and the P content is less than 0.010%, so that the contents of As, Sn, S and P in a finished product are reduced As far As possible, the purity of steel is improved, and the P content before tapping is ensured to be less than 0.0010%; blowing is forbidden in the tapping process, and the slag thickness is ensured to be less than or equal to 100mm so as to avoid nitrogen increase. Controlling the refining time outside the furnace for 45-60 min so as to desulfurize and deoxidize as far as possible, avoiding the magnetic induction performance and impact toughness from being damaged due to the high S and O content, promoting the components and temperature of the molten steel to be uniform by soft argon blowing for 5-6 min, strictly prohibiting nitrogen increase during the period, and ensuring that the P content of a finished product is less than or equal to 0.0010%. In order to promote the inclusions to float sufficiently and ensure that the steel has high purity, low-temperature toughness, magnetic sensitivity and other properties, the vacuum process parameters required by the invention are required to be controlled. In order to avoid the increase of the content of the molten steel P and secondary oxidation caused by the contact of the molten steel and air and further improve the purity of steel, the whole-process protective pouring process is strictly executed, and the superheat degree is controlled to be 12-15 ℃ so as to reduce the internal defects of central porosity, segregation and the like of a casting blank.
The invention controls the heating temperature, the heating rate, the soaking temperature and the soaking time of the casting blank within the parameter range required by the invention, aims to ensure the sufficient austenitization and homogenization of the casting blank, reduce the internal defects of the casting blank such as center segregation and the like, control the austenite grain size within a proper range, prevent overheating and overburning and ensure the magnetic induction performance and the low-temperature toughness of a welding heat affected zone of the product. The rough rolling finishing temperature at the first stage of normalizing rolling, the finish rolling finishing temperature at the second stage of normalizing rolling and the cooling mode are controlled, so that mixed crystals are prevented from appearing, and proper grain size is obtained, so that the product provided by the invention with excellent welding performance and magnetic induction performance is obtained.
It is worth to be noted that, through the verification of repeated experiments by the inventor, the steel plate manufactured by strictly adopting the chemical components, converter smelting, external refining, RH vacuum treatment, normalizing rolling and cooling process parameters of the invention can meet the requirements of the steel of the invention. Compared with the prior art, the invention does not need to carry out complex heat treatment procedures, has the advantages of low cost, simple manufacturing procedures, short production period and the like, can be implemented in large scale in various metallurgical enterprises, and the product produced by the method has the characteristics of high cleanliness, good toughness, excellent magnetic induction performance, excellent welding performance and the like, and can be used for key parts depending on the functions of electromagnetic force, such as a side guide plate of a maglev train, an automobile generator, an electromagnetic valve, a magnetic pole section or a claw level and the like.
Detailed Description
In order to better explain the technical solution of the present invention, the technical solution of the present invention is further described below with reference to specific examples, which are only exemplary to illustrate the technical solution of the present invention and do not limit the present invention in any way.
The following table 1 is a list of values of chemical components of each example and comparative example of the present invention;
table 2 below is a list of values of the main process parameters of the examples and comparative examples of the present invention;
table 3 below shows the mechanical property test results of the examples of the present invention and the comparative examples.
Wherein the thicknesses of the products of examples 1 to 8 were 10mm, 20mm, 30mm, 40mm and 50mm, respectively, and the thicknesses of the products of comparative examples were 30mm, respectively.
The high-cleanness soft magnetic steel with excellent welding performance comprises the following chemical components in percentage by mass: c: 0.005-0.020%, Si: 1.82-2.05%, Mn: 0.26-0.45%, P < 0.0010%, S < 0.0005%, Cr: 0.10 to 0.42%, Ni: 0.45-0.65%, Ti: 0.006-0.012%, Ca: 0.0005-0.0017%, Nb < 0.0010%, V < 0.0010%, Als < 0.0010%, As < 0.0010%, Sn < 0.0010%, [ N ]]：12～15×10-4%，[O]＜10×10-4%，[H]＜0.2×10-4Percent, the balance being Fe and unavoidable impurities, and the chemical components also have to satisfy: (1) nb + V + Als is less than 0.0015%, and (2) C + Mn/6+ Cr/5+ Ni/15 is less than or equal to 0.18%.
The production method of the high-cleanness soft magnetic steel with excellent welding performance comprises the following steps: molten iron desulfurization, converter smelting, external refining, vacuum treatment, full-flow protection pouring, casting blank heating, normalizing rolling and cooling; wherein:
(1) smelting by adopting a converter double-slag method, performing external refining, vacuum treatment and full-flow protection, and pouring into a casting blank with the thickness of 200-250 mm, wherein N is ensured in the process] 12～15×10-4Percent, wherein: the converter top-bottom composite converting requires that the As content of the incoming molten iron is less than 0.0010%, the Sn content is less than 0.0010%, the S content is less than 0.0010% and the P content is less than 0.010%, and the P content is controlled to be less than 0.0010% before tapping; refining for 45-60 min outside the furnace; the vacuum treatment time is more than or equal to 18min, the vacuum degree is less than or equal to 0.10kPa, and the soft argon blowing time is 5-6 min; controlling the superheat degree to be 12-15 ℃ and the drawing speed to be 0.77-0.78 m/min during pouring;
(2) the heating temperature of the casting blank is 1280-1300 ℃, the heating rate is 8-12 min/mm, the soaking temperature is 1230-1250 ℃, and the soaking time is 50-60 min;
(3) normalizing and rolling: the rough rolling and final rolling temperature in the stage I is 1100-1120 ℃; II-stage finish rollingThe rolling temperature is (T +/-5) DEG C, wherein T = (910-1/2+4470Si-1520Ni) DEG C, wherein C, Si and Ni are chemical components in percentage by weight;
(4) and (4) naturally cooling the rolled steel plate to room temperature in the air for later use.
TABLE 1 tabulated (wt,%) list of chemical compositions for each example of the invention and comparative example
TABLE 2 tabulation of values of the main process parameters for each example of the invention and comparative example
TABLE 3 mechanical Property test results of inventive and comparative examples
The results of the tests on the magnetic induction characteristics of the conventional transverse tensile test at-25 ℃ and welding HAZ impact, the magnetic field strength of 300A/m, 4000A/m and 5000A/m in the embodiments and the comparative examples show that the product produced by the components and the process has high cleanliness, good toughness matching, excellent magnetic induction characteristics and welding performance, and the performances are far better than those of the comparative examples.
The embodiments described above are merely specific examples of the present invention exemplified for explaining the present invention, and do not limit the present invention in any way, and any insubstantial changes from the contents and forms described above, which do not depart from the scope of the claims of the present invention, should be construed as falling within the scope of the claims of the present invention. The invention is not limited to the specific embodiments described above.
