It has been approached how to improve uniformity of mechanical property of the Al-killed steel produced on continuous annealing lines based on the consistent process. Measures such as adding boron, controlling manganese content, controlling the coiling temperature in U-shape and heating from edges are put forward to improve the uniformity of the steel's mechanical property. All those measures have proved to be effective with mass production in steel industry.

Key Words: Yield strength; Coiling temperature; AlN; Cementite

The failure of drill pipes mainly occurs in weld seams or inner upset transitional sections according to the experience accumulated by oil fields. Friction welding and proper post heat treatment of weld seams are common methods mainly adopted by major domestic and overseas drill pipe producers to improve weld seam’s safety.Baosteel’s quality guaranteeing ability for drill pipes has been evaluated on the basis of development of the two methods, in combination with fundamental requirements for mechanical properties of drill pipes by the API Standards, by contrast with China Oil and Gas Industry Standards, and through statistical analysis of mechanical properties of drill pipes produced by Baosteel. Ways of realizing the two methods have been proposed with focus on the problems that might occur in the process.

Keywords：drill pipe; friction welding; heat treatment

Tinned sheet is cold rolled sheet whose surface is electroplated with a layer of uniform and dense tin. Its properties can be controlled through adjusting its chemical composition(in steel making process),hot rolling temperature, cold rolling draught, annealing and leveling. At the low and high coiling temperatures, Baosteel T-4CA tinned sheets with similar chemical composition are chosen. The tendem cold strip mill has adopted three ways of annealing ageing,i.e. constant temperature ageing, inclined ageing and over ageing, to make experiments on fast cooling(1C) and ageing treatment(OA).Effects of different HR tapping temperatures, coiling temperatures and CR annealing systems on ageing properties of T- 4CA tinned sheets are studied. Chemical composition of low C and N and high Al, HR temperature system for low-temperature tapping and high-temperature coiling, and a better ageing treatment should be adopted.

Keywords：tinned sheet；tapping temperature；coiling temperature；constant temperature ageing；inclined ageing；over ageing; anti fluting

In consideration of lifting equipment manufacturing capacity for large-scale thermal power plants, and meeting pressing demand of sub-critical and supercritical boilers for power stations, Baosteel Branch Steel Tubing Plant began to develop T23 product in April of 2001,and designed a new manufacturing process based on characteristics of its own equipment and understanding of the product. Having undergone stages of development of steel grades, trial rolling of products, assessment of performance and production in batches, Baosteel T23 high pressure boiler tubes prove stable in performance, suitable for large-volume power station boilers with its technical indices and properties conforming to the ASME SA-213 standard. Now the Steel Tubing Plant has formed capacity of mass production and supply.T23 has been greatly welcomed by each large-scale boiler plant at home since it was put into production successfully.

Keywords：T23 high pressure boiler tube; property; standard; power station boiler

A measurement system for profile of hot-rolled sheet based on laser triangular principle is introduced in this paper. The measurement of the thickness of a single point of the sheet is realized and the profile is thus calculated accurately. With this method, the measurement accuracy is enhanced and the goal of environmental protection is achieved. Using top-and-bottom surface differential measurement structure with dual-triangular laser, the system greatly reduces disturbances like vibration and so on. The system can work smoothly under severe environmental conditions. A specially designed transducer not only improves the measurement accuracy, but makes some adjustment automatically to different surfaces of the sheet as well. The system has a wide application and is easy to use. Experimental results show that the system’s measurement accuracy has been up to 3μm, which can fully meet the requirement for high accuracy measurement.

Keywords：laser triangular measurement; hot-rolled sheet; profile;off-line

Common video interference phenomenon in CCTV is concluded. Ways and causes of producing interference are analyzed. Corresponding measures to solve this problem are introduced on the basis of different situations. These measures are as follows: to install an anti-interference filter in the system so as to suppress the interference from the supply source; to suppress the interference from the system itself by raising the videosignal source output level, matching the impedance, adopting the low noise amplifier and improving the construction quality; to suppress the interference from the earth potential by using single-end grounding and connecting a high-frequency transformer in the videosignal transmission circuit and to develop a video isolated equalization amplifier. All these are very helpful to improve the CCTV project quality and ensure the system's smooth operation.

Keywords：video interference; voltage; video isolated equalization amplifier

Among high strength sheets, extra low-carbon bakehardening steel sheet (BH ) is a new kind of automobile sheet with sound quality. To guarantee good deep-drawing property of BH steel sheet, it is required that the yield strength (YS) be effectively controlled in production. A method called Four Square Puzzle has been used to identify key factors that affect YS. They include chemical composition, hot rolling and cold rolling parameters, etc. A multi-variable analytical model has been built to study the effect of key input variables (KIV) on YS (KOV) through analysis of a great number of historical data on production with three different methods including regression analysis, neural network and decision tree. The model has been evaluated by taking neural network as an example. Based on this model, it is possible to predict finished BH steel product’s YS if certain KIV values are available. As a result, qualification rate has climbed by 7% and better economic benefits have been reaped.

Keywords：data mining; neural network; regression analysis