1. A high-strength cold-rolled steel sheet, excellent in elongation and stretch flange formability, which comprises a steel including C: 0.05 to 0.13 mass %, Si: 0.5 to 2.5 mass %, Mn: 0.5 to 3.5 mass %, and at least one of Mo: 0.05 to 0.6 mass % and Cr: 0.05 to 1.0 mass %,
wherein
the steel is of composite structure of a ferrite + a second phase, the second phase having an area ratio of 30 to 70% and being combined approximately in a shape of a network, a circle-equivalent average ferrite grain size being not more than 10 \u03bcm, and a circle-equivalent diameter of ferrite grain aggregate that exists continuously in an area surrounded by the second phase being not more than 3 times of the average ferrite grain size.
2. The high-strength cold-rolled steel sheet according to claim 1, further including at least one element selected from a group composed of Ti: 0.005 to 0.05 mass %, Nb: 0.005 to 0.05 mass %, and V: 0.005 to 0.2 mass %.
3. The high-strength cold-rolled steel sheet according to claim 1, wherein the second phase is mainly of tempered martensite or of martensite.
4. The high-strength cold-rolled steel sheet according to claim 1, wherein a ratio (HvIIHv\u03b1) of an average hardness (HvII) of the second phase to an average hardness (Hv\u03b1) of the ferrite phase is not more than 3.0.
5. The high-strength cold-rolled steel sheet according to claim 1, wherein an elongation (El) is not less than 14%, and a stretch flange formability (\u03bb) is not less than 50%.
6. The high-strength cold-rolled steel sheet according to claim 1, wherein a tensile strength (Ts) is not less than 780 MPa.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of creating a dictionary for soil detection of a sheet, comprising:
dividing a sensible area in first and second adjustment images into a plurality of areas;
calculating a first characteristic amount of each divided area of the first adjustment image;
calculating a second characteristic amount of each divided area of the second adjustment image;
calculating a mean and a variance of the first and second characteristic amounts of each area;
setting weight data for each area based on the calculated mean and variance; and
storing the weight data together with threshold values for soil detection of a sheet, for said each area.
2. The method of creating a dictionary for soil detection of a sheet according to claim 1, further comprising:
calculating a within-class variance and a between-class variance based on the mean and variance of the first and second characteristic amounts; and
setting weight data for each area based on the ratio between the calculated within-class variance and between-class variance.
3. The method of creating a dictionary for soil detection of a sheet according to claim 2, further comprising:
determining the order of each area based on the ratio between the calculated within-class variance and between-class variance; and
setting weight data for each area based on the determined order.
4. The method of creating a dictionary for soil detection of a sheet according to claim 3, further comprising:
setting weight data in stages for each area based on the determined order.
5. The method of creating a dictionary for soil detection of a sheet according to claim 4, further comprising:
determining the order of each area in descending order of the values obtained by dividing the between-class variance by the within-class variance; and
setting the values of weight data in descending order.
6. The method of creating a dictionary for soil detection of a sheet according to claim 5, further comprising:
setting the weight data of an area without a watermark to a higher value.
7. A sheet processing apparatus comprising:
a dictionary storage configured to previously store a
dictionary containing weight data and threshold values for soil detection to determine whether each area is soiled or not;
a conveying system configured to convey a sheet;
an imaging unit configured to receive light from a sheet conveyed along the conveying system, and takes an image for evaluation;
a dividing unit configured to divide a sensible area in the image for evaluation taken by the imaging unit;
a calculation unit configured to calculate a characteristic amount for evaluation of each divided area of the image for evaluation;
a stain detection unit configured to detect stain in each area based on the characteristic amount for evaluation calculated by the calculation unit, and the threshold values for soil detection contained in the dictionary stored in the dictionary storage; and
a soil detection unit configured to detect soil of the sheet based on the result of stain detection for each area determined by the stain detection unit, and the weight data contained in the dictionary stored in the dictionary storage.
8. The sheet processing apparatus according to claim 7, wherein the soil detection unit previously stores threshold values for soil detection of the sheet, weights the result of stain detection for each area determined by the stain detection unit by weight data, and detects soil of the sheet based on the weighted result and the threshold values for soil detection.
9. A sheet processing method comprising:
conveying a sheet;
receiving light from the conveyed sheet, and taking an image for evaluation;
dividing a sensible area in the image for evaluation into a plurality of areas;
calculating a characteristic amount for evaluation of each divided area of the image for evaluation;
detecting stain in each area based on the calculated characteristic amount for evaluation, and previously stored threshold values for soil detection of each divided area; and
detecting soil of the sheet based on the result of stain detection for each area, and previously stored weight data.