The composition and production process of hot rolled steel strip for CT70 grade corrosion resistant coiled tubing are independently designed and formulated as well as small batch industrial trial production is carried out. For the trial product, the yield strength is 520~522 MPa, tensile strength is 575~584 MPa, elongation is 33%~34%, microstructure is mainly ferrite +pearlite with a small quantity of bainite, banded structure is grade 1.0 and total of inclusions is grade 1.0 so that non-metallic inclusions are well controlled. The mechanical properties, resistance to hydrogen induced cracking (HIC) and welding performance indexes of steel strip for CT70 as well as the mechanical properties and hardness of coiled tubing manufactured with steel strip for CT70 could all meet the user requirements.

There is alarm signal in the ultrasonic flaw detection of PZ100 grade expansion pipe. The detected defects those trigger alarm signal are found through cutting open the area where there is alarm on pipe body. The defects of alarm of flaw detection are determined to be big inclusions of aluminium oxides with main components of O, Al, Mg and Ca through such methods as microstructure observation and scanning electron microscope energy spectrum analysis. The continuity of matrix for PZ100 grade expansion pipe is destroyed by cinder inclusions under surface of pipe and interlayer is formed, so cracks are formed under the action of rolling force so that flaw detector is alarmed. The product quality of PZ100 grade expansion pipe is ensured by strictly implementing technological operation regulation as well as strengthening macroscopic examination of steel billet and detection of inclusions of finished product.

The integrated control platform system of special steel requires to adopt industrial private cloud architecture. The upper monitoring system needs to establish virtual machines in the private cloud as well as install the Windows 7 operating system and WinCC7.0 SCADA. The private cloud server and switch in central control room are connected to the two core switches separately to establish redundant network structure in core layer. The systems in control layer and switch in central control room form ring network through respective switches, which takes into account the economical efficiency and security of network.

The effects of heat treatment process on the microstructure and properties of 60Cr2MnMoNi steel are studied as well as the changes of microstructure and properties of samples at different states are compared and analyzed with TV-4X metallographic microscope, R(D)-150A1 material hardness tester, N1500C material impact testing machine and INSTRON5989 electronic universal material testing machine. The results showed that the as-cast microstructure of 60Cr2MnMoNi steel was P+B+A(residual)+carbide, average hardness was 28.1 HRC, average impact toughness was 15.4 J/cm², tensile strength was 795.9 MPa, yield strength was 458.1 MPa, elongation was 2.6% and reduction of area was 1.1%; the annealed microstructure was F(a little)+P+carbide, average hardness was 24.5 HRC, average impact toughness was 193.4 J/cm², tensile strength was 846.6 MPa, yield strength was 443.1 MPa, elongation was 17.5% and reduction of area was 25.3%; the quenched microstructure was B+M+A(residual)+carbide, average hardness was 58.1 HRC, average impact toughness was 14.5 J/cm², tensile strength was 1 442.6 MPa, yield strength was 1 186.4 MPa, elongation was 2.7% and reduction of area was 1.8%; the tempered microstructure was S(temper)+B+carbide, average hardness was 45.1 HRC, average impact toughness was 64.9 J/cm², tensile strength was 1 389.5 MPa, yield strength was 1 004.4 MPa, elongation was 7.4% and reduction of area was 10.9%. The microstructure and properties of 60Cr2MnMoNi steel are changed through different heat treatment processes so that the performance requirements of spare parts for equipment in service under different operating conditions could be met.

In this article, it is introduced the nitrogen content and oxygen concentration in heating furnace are reduced to inhibit NO_x to be generated through taking such specific measures as strictly implementing cooling system for rolling delay, improving hot charging rate and strengthening furnace body maintenance from the aspect of strengthening management of heating furnace as well as such means as taking minimum coefficient of excess air, refining air-fuel ratio, reasonably distributing thermal load, accurately controlling combustion temperature, prohibit negative pressure operations and increasing preheating temperature through analyzing the generation mechanism and influencing factors of NO_x based on current thought and methods of treatment for NO_x combining with working principle and characteristics of regenerative heating furnace. As a result, the accuracy of production operation is improved, generation of NO_x is reduced so that ultra low emission of NO_x is achieved.

In the paper, the simultaneous determination for elements of vanadium, manganese, phosphorus and silicon in vanadium-carbon alloy is carried out with inductively coupled plasma-atomic emission spectrometry (ICP-AES), calibration curve is drawn with matrix matching method to eliminate the effects of matrix effects as well as instrument parameters are optimized. The precision experiment results showed that relative standard deviation (RSD, n = 11) for elements of vanadium, manganese, phosphorous and silicon was 0.5%~3.0%. The recovery rate experiment results showed that recovery rate was 95%~110% through adding standard solutions of different concentrations. The accuracy experiment results showed that the experimental results of each determination element were consistent with standard values, which could meet the requirements of detection method so that rapid and accurate determination for elements of vanadium, manganese phosphorus and silicon in vanadium-carbon alloy is realized.

The rare earth inclusions in rare earth steel sample are separated from the matrix by electrolysis. The separations of rare earth sulfides, rare earth sulfur oxides and rare earth oxides are studied through different solvents, water bath time and chemical tests so that the scientific and reliable analytical method is established. The verification tests indicated that the results of precision for sample detection were good and relative standard deviation was less than 10%; for the comparative experiment of inductively coupled plasma mass spectrometry and spectrophotometry, detection results of the two methods were consistent. The analytical method could provide important technical supports for mechanism studies of rare earths in steel.

The stable operation of heavy duty mining truck is beneficial to safe production of mines. The failure rate of heavy duty mining truck in a mine is high and it is even higher in winter. It is found through analysis that the main causes are structural designs of accumulator and steering pump themselves for hydraulic system are not reasonable as well as control of mixture ratio of fuel to oil for engine is not accurate. The seal wear is reduced through changing single-point support to oriented multi-point support for piston of accumulator and adding unload groove; such problems as high pressure and temperature rise are solved as well as loss of parts is reduced through adding unloading valve on steering pump; temperatures of solidification point for different mixing ratios of 0^# and -35^# diesel are determined through experiments as well as auxiliary fuel tank is installed to choose different mixture ratios of fuel to oil and oil supply modes based on weather conditions. The failure rate of heavy duty mining truck is reduced through implementing the above measures.

The defect with morphology of rolling skin is found on the internal surface of Φ406 mm×8.8 mm seamless tube for gas cylinder, but longitudinal ultrasonic testing does not give an alarm, so probe of transverse flaw detector is started to detect defects and the proportion of alarm is found to be higher. The cause of transverse defect on internal surface is that the lubrication effect in rolling process of continuous mill is not good through the macro analysis, chemical composition analysis, metallographic analysis and energy spectrum analysis of defective products as well as the improvement measures for rolling method of reducing arresting force are proposed.

In this paper, the process flow and problems in process of production and operation for desulfurization and denitrification system of flue gas of coke oven are introduced in detail. The operation of the system is stable, emission indexes of flue gas are acceptable, repair cycle of the system is extended so that repair frequency is reduced and hourly qualified rate per month of emission for flue gas of coke oven is guaranteed to be over 95% through taking such measures as adjusting the heating schedule of coke oven, grouting of coke oven, sealing desulfurization and denitrification system, reforming denitrification system, strengthening heat preservation of gas pipeline as well as reducing impurities in gas.