Abstract: Steel for coiled tubing with a low yield ratio and ultra-high strength and a preparation method thereof, wherein the chemical composition of the steel in mass percentage is: C: 0.05-0.16%, Si: 0.1-0.9%, Mn: 1.25-2.5%, P?0.015%, S?0.005%, Cr: 0.51-1.30%, Nb: 0.005-0.019%, V: 0.010-0.079%, Ti: 0.01-0.03%, Mo: 0.10-0.55%, Cu: 0.31-0.60%, Ni: 0.31-0.60%, Ca: 0.0010-0.0040%, Al: 0.01-0.05%, N?0.008%, and the rest being Fe and inevitable impurity elements. The chemical composition combines the technologies of low temperature finishing rolling and low temperature coiling to obtain an MA constituent+bainite+ferrite multiphase structure. The steel has a low yield ratio and ultra-high strength with the following specific properties: yield strength?620 MPa, tensile strength?750 MPa, elongation?11%, and yield ratio?0.83, and is suitable for manufacturing coiled tubing with ultra-high strength having a grade of 110 ksi or higher.

Abstract: Disclosed is a Grade 550 MPa high temperature-resistant pipeline steel, the chemical elements, in mass percentage, being: 0.061%?C?0.120%, 1.70%?Mn?2.20%, 0.15%?Mo?0.39%, 0.15%?Cu?0.30%, 0.15%?Ni?0.50%, 0.035%?Nb?0.080%, 0.005%?V?0.054%, 0.005%?Ti?0.030%, 0.015%?Al?0.040%, 0.005%?Ca?0.035%, and the balance being Fe and unavoidable impurities. Also disclosed is a manufacturing method of the Grade 550 MPa high temperature-resistant pipeline steel, comprising the steps of: smelting, casting, slab heating, rough rolling, finish rolling, controlled cooling, and air cooling to room temperature. The pipeline steel has an excellent mechanical property under a high temperature.

Abstract: Steel for coiled tubing with a low yield ratio and ultra-high strength and a preparation method thereof, wherein the chemical composition of the steel in mass percentage is: C: 0.05-0.16%, Si: 0.1-0.9%, Mn: 1.25-2.5%, P?0.015%, S?0.005%, Cr: 0.51-1.30%, Nb: 0.005-0.019%, V: 0.010-0.079%, Ti: 0.01-0.03%, Mo: 0.10-0.55%, Cu: 0.31-0.60%, Ni: 0.31-0.60%, Ca: 0.0010-0.0040%, Al: 0.01-0.05%, N?0.008%, and the rest being Fe and inevitable impurity elements. The chemical composition combines the technologies of low temperature finishing rolling and low temperature coiling to obtain an MA constituent+bainite+ferrite multiphase structure. The steel has a low yield ratio and ultra-high strength with the following specific properties: yield strength?620 MPa, tensile strength?750 MPa, elongation?11%, and yield ratio?0.83, and is suitable for manufacturing coiled tubing with ultra-high strength having a grade of 110 ksi or higher.

Abstract: The present invention relates to a method for producing hot rolled strip steel, especially the producing method of hot rolled strip steel with multiple target thicknesses in the longitudinal direction. It is a method to produce the strip steel with different target thicknesses in the longitudinal direction by using a hot continuous rolling mill. In this method, the first equal-thickness section of the strip steel is controlled with the conventional thickness control strategy, while other equal-thickness sections and the transition section between equal-thickness sections are controlled with the variable-thickness control strategy.

Abstract: Disclosed is a Grade 550 MPa high temperature-resistant pipeline steel, the chemical elements, in mass percentage, being: 0.061%?C?0.120%, 1.70%?Mn?2.20%, 0.15%?Mo?0.39%, 0.15%?Cu?0.30%, 0.15%?Ni?0.50%, 0.035%?Nb?0.080%, 0.005%?V?0.054%, 0.005%?Ti?0.030%, 0.015%?Al?0.040%, 0.005%?Ca?0.035%, and the balance being Fe and unavoidable impurities. Also disclosed is a manufacturing method of the Grade 550 MPa high temperature-resistant pipeline steel, comprising the steps of: smelting, casting, slab heating, rough rolling, finish rolling, controlled cooling, and air cooling to room temperature. The pipeline steel has an excellent mechanical property under a high temperature.

Abstract: The present invention relates to a method for producing hot rolled strip steel, especially the producing method of hot rolled strip steel with multiple target thicknesses in the longitudinal direction. It is a method to produce the strip steel with different target thicknesses in the longitudinal direction by using a hot continuous rolling mill. In this method, the first equal-thickness section of the strip steel is controlled with the conventional thickness control strategy, while other equal-thickness sections and the transition section between equal-thickness sections are controlled with the variable-thickness control strategy.

Abstract: The present invention relates to an automatic testing apparatus, which comprises a device under test and a testing module. The device under test has a testing program and includes a plurality of functional modules. The testing module is coupled to the device under test. The device under test executes a testing program and communicates with the testing module so that the testing module can test the plurality of functional modules of the device under test. By adopting automatic testing, no tester is needed for performing testing. Thereby, the personnel cost can be reduced and the total testing time can be shortened.

Abstract: The present invention relates to an automatic testing apparatus, which comprises a device under test and a testing module. The device under test has a testing program and includes a plurality of functional modules. The testing module is coupled to the device under test. The device under test executes a testing program and communicates with the testing module so that the testing module can test the plurality of functional modules of the device under test. By adopting automatic testing, no tester is needed for performing testing. Thereby, the personnel cost can be reduced and the total testing time can be shortened.