SPECIES ASSESSMENT FOR WESTERN LONG -EARED MYOTIS (MYOTIS EVOTIS ) IN WYOMING

The primary object of the present invention is to provide a cold-rolled steel sheet with properties of high-strength, high-ductility, and a process for manufacturing it. The constituents of the cold-rolled steel sheet comprise: 0.08%-0.25% carbon by weight, 0.03%-2.0% silicon by weight, 0.6%-1.8% manganese by weight, 0.01%-0.10% niobium by weight, 0.01%-0.08% aluminium by weight, with the rest being substantially iron and unnoticed impurities. The process for manufacturing cold-rolled steel sheets of the present invention by using the molten steel material as described above includes the following steps: (a) preparing steel ingots by continuous casting the molten steel; (b) hot rolling the steel ingots into hot-rolled bands; (c) coiling the hot-rolled bands at a temperature below 600 DEG C.; (d) after cold-rolling, forming steel sheets from the hot-rolled bands and soaking the steel sheets at a temperature in the two-phase range (equal to AC1+10 DEG C.-AC3-10 DEG C. shown in FIG. 1) for a time duration ranging from 1 minute to 10 minutes; (e) cooling the steel sheets to a temperature ranging from 350 DEG C. to 500 DEG C. at a cooling rate greater than 50 DEG C./SEC; (f) soaking the steel sheets at a temperature ranging from 350 DEG C. to 500 DEG C. for a time duration from 1 minute to 10 minutes; (g) cooling the steel sheets by air so as to form the cold-rolled steel sheets having a microstructure of ferrite plus residual austenite plus bainite (or a small amount of martensite).