METHOD FOR PRODUCING LIGHT GAUGE STEEL

Abstract

The method is for use with a strip or plate of steel, the steel being of a composition and temperature suitable for heat treatment, and comprising the following steps: ustenizing the strip or plate to produce austenitized material; quenching the austenized material to produce hardened steel; thermally tempering the hardened steel to produce tempered steel; and stretching and leveling the tempered steel to produce heat treated steel.

Claims

1. A method for use with a strip or plate of steel, the steel being of a composition and temperature suitable for heat treatment, the method comprising the following steps: austenizing the strip or plate to produce austenitized material; quenching the austenized material to produce hardened steel; thermally tempering the hardened steel to produce tempered steel; and stretching and leveling the tempered steel to produce heat treated steel.

2. The method according to claim 1, wherein the stretching and leveling of the hardened steel is carried out using a stretcher leveler.

3. The method according to claim 2, wherein the strip plate is austenized in a reheat furnace.

4. The method according to claim 3, wherein the austenized material is quenched using a water quench process.

5. The method according to claim 4, wherein the tempered steel is cooled prior to the stretching and leveling process that results in the heat treated steel.

6. The method according to claim 2, wherein the heat treated steel is cut into blanks.

7. The method according to claim 1, wherein the stretcher leveler is a T4 stretcher leveler.

8. The method according to claim 7, wherein the strip or plate is produced by rolling a slab through a hot reduction mill.

9. The method according to claim 2, wherein the hardened steel, prior to stretching and leveling, has a yield strength of about 163,000 psi, tensile strength of about 198,000 psi and elongation of about 11%.

10. The method according to claim 2, wherein the strip or plate of steel is grade 387-418 BHN.

Description

DETAILED DESCRIPTION OF A NON-LIMITING EMBODIMENT

[0019] A method for producing light gauge steel according to a non-limiting embodiment of the invention consists of the following steps: [0020] liquid steel, having a chemistry suitable for heat treatment, is cast into a slab; [0021] the slab is rolled through a hot reduction mill into a master coil or master discrete plate and allowed to cool; [0022] the cooled master coil or master discrete plate is cut into specified daughter lengths; [0023] the daughter lengths are austenized in a reheat furnace and then quenched in water; and [0024] the now-hardened daughter lengths are passed through a T4 stretch leveller and cut into blanks for further forming, profiling, or otherwise fabrication into finished parts.

[0025] Examples of suitable steel materials that may be used in the processes as provided herein include but are not limited to those sold by Algoma Steel, Inc., Ontario. Canada. Illustratively a steel is Algoma 100 steel as provided in Table 1:

TABLE-US-00001 TABLE 1 Chemical Composition-Heat Analysis (% maximum) Thickness C Mn P S Si Cr Mo B 0.188″ (5 mm) 0.17 1.5 0.03 0.015 0.45  0.25 0.2 0.003 to 0.250″ (6.35 mm) Over 0.250″ 0.21 1.5 0.03 0.015 0.45 0.2 0.2 0.003 (6.35 mm) to 1.00″ (25.4 mm) Over 1.00″ 0.21 1.5 0.03 0.015 0.45  0.65 0.4 0.003 (25.4 mm) to 2.75″ (70 mm)
The steel of Table 1 has a minimum tensile strength of 110 ksi, a maximum tensile strength of 130 ksi, a yield strength of 100 ksi, and an elongation (percent) minimum in 2 inches of 16.
Illustratively a steel is Algoma 130 steel as provided in Table 2:

TABLE-US-00002 TABLE 2 Chemical Composition-Heat Analysis (% maximum) Thickness C Mn P S Si Cr Mo B 0.188″ (5 mm) to 0.17 1.5 0.025 0.015 0.45 0.2 0.2 0.003 0.250″ (6.35 mm) Over 0.250″ 0.21 1.5 0.025 0.015 0.45  0.65 0.4 0.003 (6.35mm) to 1.375″ (35 mm) Over 1.375″ 0.26 1.5 0.025 0.015 0.45 0.6  0.45 0.003 (35 mm) to 2.5″ (65 mm)
The steel of Table 2 has a minimum tensile strength of 136 ksi, a yield strength of 130 ksi, and an elongation (percent) minimum in 2 inches of 12.
Illustratively a steel is AlgoTuf 400F steel as provided in Table 3:

TABLE-US-00003 TABLE 3 Chemical Composition-Heat Analysis (% maximum) Thickness C Mn P S Si Cr Mo B 0.188″ (5 mm)  0.17 1.5 0.025 0.015 0.45 0.2 0.2 0.003 to less than 0.472″ (12 mm) 0.472″ (12 mm)  0.17 1.5 0.025 0.015 0.45  0.25 0.2 0.003 to 0.787″ (20 mm) Over 0.787″ 0.2 1.5 0.025 0.015 0.45 0.6  0.35 0.003 (20 mm) to 1.00″ (25.4 mm) Over 1.00″  0.26 1.5 0.025 0.015 0.45 0.6  0.45 0.003 (25.4 mm) to 2.75″ (70 mm)
The steel of Table 3 has a minimum tensile strength of 175 ksi, a yield strength of 145 ksi, and an elongation (percent) minimum in 2 inches of 15.
Illustratively a steel is AlgoTuf 450F steel as provided in Table 4:

TABLE-US-00004 TABLE 4 Chemical Composition-Heat Analysis (% maximum) Thickness C Mn P S Si Cr Mo B 0.188″ (5 mm) to 0.21 1.5 0.025 0.015 0.45 0.2 0.2 0.003 0.394″ (10 mm) Over 0.394″ (10 mm) 0.23 1.5 0.025 0.015 0.45 0.2  0.35 0.003 to 0.787″ (20 mm) Over 0.787″ (20 mm) 0.26 1.5 0.025 0.015 0.45 0.6  0.45 0.003 to 2.5″ (65 mm)
The steel of Table 4 has a minimum tensile strength of 200 ksi and an elongation (percent) minimum in 2 inches of 14.
Illustratively a steel is AlgoTuf 450F steel as provided in Table 5:

TABLE-US-00005 TABLE 5 Chemical Composition-Heat Analysis (% maximum) Thickness C Mn P S Si Cr Mo Ni B 0.236″ (6 mm) 0.33 1.5 0.025 0.015 0.5 0.7 0..5 0.7 0.003 to 1.25″ (31.75 mm)
The steel of Table 5 has a typical tensile strength of 255 ksi and an elongation (percent) typical in 2 inches of 14.
Illustratively, a steel is Armour steel with the following characteristics at a thickness of 6 mm to 31.75 mm:

TABLE-US-00006 Chemical composition (%) unless a range is specified individual values are maximums Carbon 0.22-0.32 Maganese 0.60-0.90 Phosphorous 0.02 Sulfur 0.01 Silicon 0.2-0.4 Chromium 0.4-0.7 Nickel 0.35-0.85 Molybdenum  0.2-0.35 Copper 0.25 Boron 0.003 Hardness (HBW) (average) 477-534 CVNL full size min. avg. impact (ft-lbs) @ −40 degrees F. 14 CVNT full size min. avg. impact (ft-lbs) @ −40 degrees F. 12 Heat Treatment Requires Q&T

EXPERIMENTAL

[0026] A slab was cast for 387-418 BHN grade and was passed through the hot rolling mill at Algoma, Ontario. The coil was later cut to length into master plates at Algoma's CTL facility. A resultant plate of dimensions 0.1891″×72″×240″ was austenized in a reheat furnace and then sprayed with water so as to get quenched. The quenched plate had a 0.5″ wave every 28″ and had a yield strength of about 163,000 psi, tensile strength of about 198,000 psi and elongation of about 11%. The wave is attributed to uneven cooling rate across the three dimensions. The plate was levelled on a T4 stretcher leveler of a type sold by RedBud Industries for a total of 3.7″. The resultant plate surprisingly turned out to be quite flat.

[0027] Persons of ordinary skill will also readily appreciate the process is advantageous in that, inter alia, it: [0028] permits the production of AHSS and HTP without the expense associated with a a discrete plate leveler; and [0029] is relatively easily replicated in comparison to known processes for production of AHSS and HTP given that the operator is largely required merely to ensure that the strip/plate is pulled to a definite stroke length.

[0030] Whereas a single example is herein described, persons of ordinary will appreciate that the process can be varied widely. For example, any conventional steel alloy used in the production of AHSS and HTP can be used, material of varying size can be used and greater or lesser amounts of stretching will be employed, based upon the starting shape. Accordingly, the invention should be understood to be limited only by the accompanying claims, purposively construed.