According to the characteristics of CSP production line of Baotou Steel, the trial production of 450 MPa grade weather resistant steel strip is carried out through adopting reasonable component design and formulating the process plan from processes of smelting to hot rolling. The good corrosion resistance is obtained with such alloy elements as Cu, Cr and Ni as well as grain refinement and precipitation strengthening are realized through microalloying of Ti and controlled rolling and controlled cooling. The microstructure and mechanical properties of optimized weather resistant steel strip Q450NQR1 are tested and analyzed. The results showed that the microstructure, grain size and mechanical properties of Q450NQR1 steel strip could meet the requirements of standard for railway steel Q450NQR1 as well as relative corrosion rate was 47.4%.

In this paper, the development process of SS105 grade rare earth microalloying seamless tube for drill pipe body resistant to H₂S stress corrosion is introduced. The designs of its chemical composition system and key production process are carried out according to the requirements of technical specification of a company and the API Spec 5DP 2020 Drill Pipe Specification as well as trial production of the product is carried out at the same time. The quality of continuous casting billet as well as chemical compositions, mechanical performances, metallographic structure and non-metallic inclusions of finished product are tested, all the indexes could meet design requirements. The effects of rare earth Ce on resistance to H₂S stress corrosion of SS105 grade seamless tube for drill pipe body are evaluated based on its service environment of the oil and gas drilling environment with high content of H₂S and low temperature. The results showed that the resistance to H₂S stress corrosion of the product was significantly improved after add rare earth into it.

The purpose of testing water pressure of steel pipe is to confirm whether there is any water leakage with authorised pressure so as to ensure its performances to meet user requirements. In order to manage the test data for water pressure of steel pipes more effectively and improve flexibility of reports, the test data sheet for water pressure of steel pipes is established with Access database. The archiving and extraction of test data for water pressure of steel pipes are realized by using codes of WinCC VBScript and adopting mode of instruction programming so that the analytical capability for water pressure of steel pipes is improved. As a result, the archiving management of data is more user-friendly, which wins user’s recognition.

With the development of digital and intelligent technologies in each field, they are widely applied due to the high efficiency and accuracy they brought. The digital and intelligent technologies for detection and routing inspection of industrial buildings (structures) are increasingly developed. In this paper, the important roles of intelligent detection technologies in safe operations of structure for industrial buildings (structures) are compared and explained through the specific analysis on applications of such three common intelligent detection technologies in detection of industrial buildings (structures) as unmanned aerial vehicle platform technology, digital image recognition technology and network technology of intelligent sensor for Internet of things.

The flotation process is the main method for removing impurity element fluorine in magnetic iron ore of Bayan Obo. The indicators and productivity of flotation operation can be effectively improved by reasonably selecting process flow of flotation. The existing flotation process is analyzed aiming at such problems as high iron grade and low productivity of flotation tailings as well as high consumption of reagent for flotation operation of magnetic iron ore of Bayan Obo. It is found that the gap between iron grades of foam in the first and second stages of rougher flotation is great, the iron grade of foam in the first stage is lower than that of flotation tailings, and then it is mixed with foam in the second stage to enter operation of scavenging so that the iron grade of flotation tailings is high and productivity of flotation is low. The foam in the first stage of roughing for flotation is directly with discarding tailings and conditions of flotation operation are reoptimized. In actual production, the iron grade of flotation tailings is decreased by 5.34 percentage points and productivity of flotation concentrate is increased by 6.16 percentage points after improving the process.

The research on the defect of cold-lap on surface of DC04 cold rolled plate is carried out. The defect parts of the sample taken from defective cold rolled plate are analyzed by the metalloscope, scanning electron microscope and energy spectrometer. The results showed that the defect of cold-lap on surface of cold rolled plate was caused by inclusions containing such elements as C, O, Na, Mg, Al, Si and Ca as well as the inclusions are resulting from the compounds of casting powder in continuous casting process and inclusions in molten steel. The defect of cold-lap can be reduced by improving the cleanliness of molten steel, ensuring good conditions of continuous casting machine and constant casting speed as far as possible as well as reducing level fluctuation of crystallizer.

In the paper, the chromite as well as external phlogopite and ferrodolomite are analyzed with such means as the point analysis with EPMA(electron probe micro-analyzer), map scanning and correlation analysis from the perspective of geochemistry. It is found from the analysis results that three annuluses can be seen inside and out of chromite, the contents of Al, Mn and Zn in the center are higher than those in outer ring as well as content of Fe in outermost ring is high, that is, the contents of Mn, Al and Zn are gradually decreased as well as content of Fe is gradually increased inside and out of the chromite. This indicates that the magnesium aluminate spinel should be formed firstly in this region, then it is replaced by fluorine-rich magma to chromite in later period, the fluorine-containing and silica-containing magma upwells into carbonatite dykes along channel as well as it is condensed into fluorine-containing phlogopite at the same time. The conclusion consistent with the above could be obtained with the Pearson correlation analysis, that is, there are negative correlations between FeO and Cr₂O₃, MnO, ZnO and Al₂O₃, which shows that there is isomorphic substitution among them.

With the gradual development of rail transit system, bridges and building engineering to large scale and span, the strength of steel used is required to be continuously improved. As the union piece, working stress of bolt products is obviously improved and its working environment is worse so that the requirements of its strength and corrosion resistance are higher. The corrosion resistance of material is improved by adding elements of Cu and Ni as well as austenite structure of steel is finer by adding such elements of refining grain as V and Nb. As a result, the hardenability of steel is reduced and its good cold heading performance is ensured so that the cold heading steel with high strength and corrosion resistance is successfully researched and developed.

The methods of manual dynamic regulation of bottom blowing of converter with steel grade of smelting and dynamic maintenance of furnace profile are proposed aiming at such problems as low gas supply intensity of bottom blowing, short service life of breathable element for bottom blowing and lower combined blowing rate for 150 t top bottom combined blowing converter in Steel-making Plant. Different gas supply intensity models are established and gas supply intensity of bottom blowing is optimized based on the requirements for end point carbon content of steel grade in actual production. As a result, the dynamic control of gas supply intensity of bottom blowing for smelting different steel grades is realized, iron oxide content of final slag of converter and end point product of carbon concentration and oxygen concentration are effectively reduced as well as metallurgical effects of bottom blowing system and quality of molten steel are improved.

The effects of double calcium treatment mode (Ca treatment-RH-Ca treatment) and single calcium treatment mode (RH-Ca treatment) on removing inclusions are studied with the process route of BOF-LF-RH-CC. The study results showed that the size and number of inclusions in molten steel with single calcium treatment mode when RH left were smaller than those with double calcium treatment mode so that single calcium treatment mode was better than double calcium treatment mode.