The experiment with 14MnCrMoNiNb steel was for studying quenching + quenching in two-phase region + tempering process (QQ'T). The experimental results showed that the multiphase microstructure of tempered sorbite + a small amount of ferrite could be obtained with the QQ'T process. On the premise of without losing the strength and toughness of material, the yield ratio of material could be reduced to about 0.80 so that the serviceability safety performance of material could be improved greatly.

The metallographic structure of hot-rolled TC4 titanium alloy seamless tubes with different specifications was studied with the light microscope and scanning electron microscope as well as the mechanical properties of titanium alloy tube were tested. Moreover, the effects of different heat treatment and pickling processes on the microstructure and properties of tube were also studied. It was found that the differences of as-hot-rolled microstructure of titanium alloy tubes with different specifications were significant as well as the outer diameter and wall thickness of the head of tubular billet after perforation were larger than those of the tail. The annealed microstructure obtained by the two-phase region annealing process at different temperatures did not change significantly. Although the oxidation products on the surface of titanium tube could be effectively removed with the pickling process, the time parameters of pickling process were very important, otherwise, the surface quality of titanium tube would be deteriorated.

In the paper, the effects of reheating temperature in the on-line normalizing process on yield strength and impact energy of steel tube were explored with industrial experiments based on the indexes of yield strength and impact toughness for Φ139.7 mm × 7.72 mm N80-1 casing in the Q/YS 1572.1 standard. The results showed that the yield strength of steel tube could reach 570~620 MPa and the half-size longitudinal impact energy at 0 ℃ is ≥40 J if the temperature of steel tube before entering reheating furnace was≤550 ℃ and reheating temperature was controlled at 870~900 ℃, which could meet the requirements of the Q/YS 1572.1 standard.

The instrument of production in Steel Tube Co. of Baotou Steel, mandrel, is damaged during use, so different repair plans are put forward based on the different forms and degrees of damages. The effects are remarkable through practical applications so that its repair problems are solved fundamentally, its service life is prolonged and the production costs are reduced.

In this paper, the design for key technological parameters of hot continuous rolling process of producing TA2 seamless titanium tube with MPM unit is introduced. The trial production showed that the plastic deformation was better and the surface of hot tool was not sticky when the heating temperature was controlled at 1 010~1 020 ℃, the surfaces of top and guide plate were coated with the self-developed viscous resistance agent as well as the initial rolling temperature was controlled at 940~960 ℃. The inspection results of TA2 seamless titanium tube produced with the hot continuous rolling process showed that its internal and external surface quality was good as well as the outer diameter and wall thickness were controlled within the dimensional deviations so that the process could be used for producing the titanium tube and titanium alloy tube.

With the change of application environment for tubular products, the requirements for impact energy and grain size of J55 casing are continuously increased. The growth of grain size during heating is controlled through the micro Ti processing during steel making. The shape of precipitation of ferrite is changed through applying the controlled rolling and controlled cooling technology with tandem mill of hot-rolling seamless pipe so that the product performances are improved.

The service environment of high-pressure boiler tube is harsh, so the requirements for inclusions of tube bloom are very strict. In the actual production process of 12Cr1MoVG, the inclusions are often over proof, which is solved by such measures as improving the control target of end-point carbon content in converter, optimizing refining slag system and narrow component control.

The defect of infolding is one of the main problems during hot perforation of 1Cr5Mo alloy steel tube blank, which could not only influence the qualified products ratio, but also the yield of steel tube. In the paper, it is mainly introduced the heating schedule of circular furnace, rolling pace, perforation technology and application of hot tools are optimized as well as analyzed the defects of infolding in the production of 1Cr5Mo alloy steel tube of our company so that the effects are good.

The stress concentration is generated in the processes of cooling, stretching and straightening for continuous casting tube bloom with large diameter as well as the stress cracks are formed on the interior and surface of continuous casting tube bloom when the stress is too large. In this paper, it is analyzed their causes and mechanisms as well as summarized the types of defects for steel pipe caused by them in the process of hot rolling seamless steel tubes. Moreover, the guiding suggestions for controlling and solving stress cracks of continuous casting tube bloom and defects of seamless steel pipe are proposed by analyzing their relevance, which conduce to controlling the related elements pointedly in practices and reduce the defects in the process of rolling seamless steel pipe.

In the production process of round billet with Φ430 mm section, the original current direction ("single direction rotation") of electromagnetic stirring of mould was adjusted to "alternate rotation with positive and negative rotation" mode. The experimental results showed the equiaxial crystal ratio of section center was increased and the carbon segregation was obviously improved.

The process of rolling the TC4 titanium alloy tube blank with the PQF rolling mill, Accu rolling mill and Assel rolling mill was simulated by ABAQUS simulation software as well as the changes of section form, temperature, stress and strain in rolling process were analyzed. The results showed that the change of section form in the process of rolling TC4 seamless tube with PQF rolling mill was smaller than that in the process of rolling TC4 seamless tube with Accu and Assel rolling mills as well as the dimension precision was higher; the stress distribution in the rolling process with Accu and Assel rolling mills was more complicated than that in the rolling process with PQF rolling mill; the metal strain of inside wall thickness was larger than that of outside wall thickness when the three rolling routes were adopted; the temperature reduction with Accu and Assel rolling mills was smaller than that with PQF rolling mill because of the short rolling time.

In the paper, the influencing factors and control main points of resistance to hydrogen sulfide corrosion are mainly described. The hydrogen sulfide stress corrosion resistant casing with independent intellectual property rights is produced combining with the production practices of Baotou Steel, which is with good resistance to H₂S corrosion. It is proved after being used that the product performances are good and can reach the level of domestic like products.

In this paper, the phase transition points of test steel and continuous cooling transformation (CCT) curve of supercooled austenite were determined with the FORMASTOR-F full automatic phase transformation instrument as well as the microstructure of specimen processed at different cooling rates was analyzed with the Zeiss microscope by taking the 3Cr corrosion resistant oil well pipe steel as the object of study. The experimental results showed that the phase transition points of 3Cr corrosion resistant oil well pipe steel A_c1 was 730 ℃ and A_c3 was 830 ℃. When the cooling rate was at 0.1~0.5 ℃/s, the microstructure at room temperature was proeutectoid ferrite + bainite, when the cooling rate was at 0.5~0.8 ℃/s, the microstructure at room temperature was ferrite + bainite + martensite, when the cooling rate was at 1~3 ℃/s, the microstructure was mixed martensite + bainite and the martensite structure was obtained when the cooling rate was greater than 3 ℃/s.

In the paper, it is introduced the special properties of S135 grade petroleum drill pipe body steel produced by Baotou Steel have been studied in the laboratory. The results showed that it was with good low temperature impact toughness and the average impact energy could reach above 80 J when the temperature was-70 ℃; its average torsional strength was 920 MPa, fatigue limit stress of rotating bending was 462 MPa, average spreading rates of fatigue crack were 8.4 ×10^-6 mm/cycle and 19. 7 × 10^-6 mm/cycle as well as the opening displacement of crack tip was 0.181 mm.

In the paper, the high-strength and high-toughness perforating barrel produced with quenching and tempering by Baotou Steel is introduced. Its development and effects are summarized through the design of steel grade, heat treatment process test and actual productions. The results show that its strength can reach 150KSI level, transverse impact toughness is good so that it is with high-strength and high-toughness performance after the appropriate heat treatment process.

The traditional manual accounting mode has been adopted in the point inspection work of Steel Tube Co. for a long time. Based on this, the R&D for intelligent information point inspection platform has been put forward by Steel Tube Co.. The overall goals are to promote enterprise management innovation, optimize management mode, implement business process reengineering and establish a modern equipment operation management system by means of the advanced information technology with informatization so that the equipment operations are transmitted timely and accurately through the network as well as duplicate entry of the same data source is reduced. As a result, the equipment operation data are accurate, timely and sharable.

In the paper, it is introduced the information sharing platform for factory through field constructed with the MES-ERP system of Steel Tube Co. of Baotou Steel, based on operating the VMI vendor management system in oilfield and the cloud services are as medium, with which the wastes of manpower and material resources caused by manual data input for updating quality parameters of oilfield are reduced as well as the manufacturer, Steel Tube Co. can also obtain the feedback information of product use first time. Moreover, the use ratio of information resources is improved, information transfer is accelerated, waste of resources in collecting, storing and transferring information is avoided so that the efficiency is greatly improved.

The servo valve is the core control element of hydraulic cylinder control system (HCCS), the computer system implemented the closed-loop control is the main control mechanism of HCCS and the D791 servo valve itself used for rolling mill is the control valve with closed-loop control. In the paper, the working principles of MOOG D791 servo valve are introduced as well as the control characteristics of its flow and its dynamic properties are analyzed. The feedback signals of spool displacement for servo valve could be seen with the simulated program as well as the superiority and inferiority for its working performances could be judged through the following features curve of feedback values and set values in the whole motion process of servo valve.

In the paper, the problems of short service life for support stand of mandril as well as the abnormal steel tube wall thickness quality accuracy and surface abrasion of mandril caused by misalignment of mandril are solved with such measures as adjustable pull rod and bent axle of roller based on the working principles of support stand for mandril of PQF rolling mill. As a result, the service life of thermal deformation tool is increased and the consumption of mandril is reduced greatly, which is with certain guiding function for actual productions.

The ABB ACS6000SD medium-inverter control system is used in Φ460 mm production line of Steel Tube Co. of Baotou Steel. The system is equipped with two sets of water cooling units to dissipate heat of electrical elements in the cabinet through heat exchange. Parameters such as the inner ring water temperature and conductivity of water cooling system as well as water pressure are very important to the normal operations of the whole system. In this paper, the key maintenance points as well as the faults and solutions in operations are discussed and summarized through analyzing the control principles of water cooling system.

In the paper, the difficulties and current situations of traditional equipment maintenance system are analyzed based on the economical efficiency of equipment maintenance as well as the relatedness between its subsystems is discussed to try to establish a maintenance system which could realize the control and optimization of cost economics with structural, random and economic connections.

In the paper, the experimental study for comparing the Mn removal methods of lime-base process and oxidation to select the optimal technological conditions is introduced. The experimental results showed that the efficiency of Mn removal with oxidation for Mn-phosphatizing waste water could reach up to 99.96%, the content of Mn in the water after treatment was less than 2 mg/L, which could meet the first class emission standard of the related national standard.

In this article, the corrosion reasons of water supply pipeline are analyzed in detail from such aspects as its corrosion mechanism, corrosion types, materials of pipeline and buried environment. Moreover, some countermeasures for corrosion prevention of water supply pipeline are put forward combining with the working practices so that the safe operations of water supply pipeline could be better guaranteed.

The tensile to failure experiment was carried out with the sleeve joint of API round thread and the tensile load did not reach the minimum connection strength so that the joints slipped. In the paper, the effects of changes of outer diameter, wall thickness and inner diameter of steel tube as well as taper of thread on connection strength of joints were compared with the finite element method. The calculation results showed that the effects of geometric parameters of steel tube were greater and the control principle for geometric parameters of plain-end tube for processing round thread was put forward.

In this paper, the uncertainties for yield strength R_t0.5, tensile strength R_m and elongation after fracture A₅0 mm of L80-1 pipe with specification of Φ114. 3 mm × 7. 37 mm manufactured by a Tube Co. are evaluated. The expanded uncertainties of each detected value are U (R_t0.5)=20 N/mm², U (R_m)=5 N/mm², U (A)=0.8% as well as their relative expanded uncertainties are U_rel (R_t0.5)=3%, U_rel (R_m)=1%, U_rel (A)=3%, which are obtained through establishing model, analyzing sources of uncertainties, evaluating each component and calculating combined standard uncertainties.