The effect of residual stress for rail on its fatigue performance is great. In this paper, the influences of different residual stress values on fatigue crack growth rate for U75V heat-treated rail are studied with tempering test and metallographic analysis method. The influences of different tempering times on the residual tension of rail are analyzed with the tempering test. It is concluded that the residual stress gradually decreases with increase of tempering time; the crack growth path at tip of fatigue crack is analyzed by testing the metallographic structure of rail treated with tempering process and observing the metallographic structure of rail with different tempering times, the influences of different tempering times on fatigue crack growth rate are analyzed according to the mode and length of crack growth; the residual stress and fatigue crack growth rate of rail can be effectively reduced so that the anti-fatigue performance of rail can be improved through tempering process control.

The process parameters of hot rolling and controlled rolling, pickling-rolling and continuous annealing for steel strip are determined through the composition system design based on the technical requirements of continuous annealing steel strip HG400 for slide rail. The mechanical properties of the product produced with industrial production line could meet technical requirements and its elongation after fracture is 21%~26%. The study on optimizing the production process of continuous annealing is carried out aiming at the problem that elongation after fracture is lower as well as continuous annealing temperature and elongation of temper mill are adjusted. After the optimization, elongation after fracture of product could be stably controlled at about 31%. At present, the product is produced stably and applied widely.

The phase transition law of continuous cooling for SWRCH35KM test steel is tested with Gleeble-1500 thermal simulated test machine. The phase transition law of spheroidization of pearlite after final rolling is studied by the thermal simulation test of online spheroidization. There are transformations of ferrite and pearlite at different cooling rates as well as the characteristics of microstructure for ferrite change with the increase of cooling rates. When the cooling rate is below 2 ℃/s, the metallographic structure of SWRCH35KM test steel is ferrite and pearlite. With the cooling rate gradually increases, the acicular ferrite along with Widmanstatten structure appear continuously in the metallographic structure. Meanwhile, the ferrite is more refined than before and its volume fraction is also gradually reduced. Based on the phase transition law of microstructure and with thermal simulation test data of SWRCH35KM test steel, rolling and cooling will be strictly controlled in industrial production in order to obtain ideal metallographic structure, especially the controlled cooling mode of Stelmor cooling line to ensure to obtain fine ferrite and spheroidized pearlite.

In the paper, it is discussed the research progress and protection measures of corrosion for rail at home and abroad, elaborated the mechanism of corrosion failure in service process of rail lines as well as listed the chemical composition, performance parameters and industrial applications of new materials for corrosion resistant rails currently researched and developed such as the corrosion resistant rails of India and Wuhan Iron and Steel (Group) Co.. The development direction of production technology for corrosion resistant rail is proposed combining with the research and development ideas of new materials for corrosion resistant rail as well as the effects of resisting corrosion for other steels. The countermeasures taken in the research and development of corrosion protection for rail of Baotou Steel are mainly introduced as well as the future research direction of this field is expected.

The process technology of “oxidation+chemical precipitation+coagulating sedimentation and heavy metal collector” is proposed through studying the treatment technology of thallium-containing desulfurization waste water as well as the optimal proportion meeting the requirements of removing thallium is determined by adjusting the concentration (set value) of oxidant (sodium hypochlorite), pH, polyaluminum chloride (PAC), heavy metal collector and polyacrylamide (PAM). The experimental results showed that the removal efficiency of thallium was 99.75% when the concentrations of oxidant (sodium hypochlorite), PAC, heavy metal collector and PAM were 1 500 mg/L, 200 mg/L, 1 300 mg/L, 4 mg/L respectively and pH value was 10, which could meet the requirements of discharge standard for thallium in desulfurization waste water.

The phase transition temperature and static CCT curve at critical point of 800 MPa grade steel for hydropower project with low susceptivity to weld cracking are determined with phase change instrument Formast-F and the dilatation method combing with metallographic method as well as the effects of cooling rate on microstructure are studied. The results showed that the phase transition temperatures of test steel, Ac₁ was 675 ℃, Ac₃ was 875 ℃, Ar₁ was 615 ℃ and Ar₃ was 739 ℃; when the cooling rate was less than 0.25 ℃/s, the transformation products were ferrite (F) + pearlite (P) + a small amount of bainite (B); when the cooling rate was 0.25~1 ℃/s, the transformation products were ferrite (F)+ bainite (B); when the cooling rate was 1~5 ℃/s, the transformation product was bainite (B); when the cooling rate was 5~20 ℃/s, the transformation products were bainite (B)+ martensite (M); when the cooling rate was greater than 20 ℃/s, the transformation product was martensite (M).

In order to improve product quality and strengthen quality monitoring of high speed rail, the chemical composition of U71Mn rail is optimized, Mn content in steel is reduced and rolling process is controlled as well as the trial productions are carried out for such whole series of sections as 60 N, 60 kg/m, 50 kg/m, QU120, QU100 and QU80 of U71Mn. The results showed that the tensile strength was reduced by 7.2 MPa and mean value reached 950 MPa, tread hardness (HB) was reduced by 2.8 and mean value reached 269.2 as well as elongation is basically unchanged by comparing the performances of U71Mn rail with those before optimization. Moreover, the ideal perlite structure is obtained, performances of rail could all meet the standard requirements and is with enough margin so that the effects are better.

The aluminum is often used as the deoxidizer in production process of slab. In the theoretical thermodynamic calculation, the amount of aluminum deoxidizer could keep dynamic equilibrium of aluminum and oxygen in liquid steel within limits. If beyond the limit, the surplus aluminum forms non-metallic inclusions so that the cleanness of molten steel is deteriorated and the performances of steel are affected. In the paper, it is analyzed and studied the changes of amount and size for inclusions with different amounts of deoxidizer in converter through industrial tests by taking the L415M steel as an example, elaborated the effects of reducing the amount of deoxidizer on inclusions in the whole production process of high grade pipeline steel. The ratio of inclusions (Class B) less than grade 2 in rolled products is increased from 96.8% to 99.83% by proposing the optimization scheme for controlling the cleanness of molten steel.

The sample is dissolved by acid, residue is precipitated and filtered, the mixed flux of anhydrous sodium carbonate and boric acid is melted as well as it is mixed with acid dissolving test solution and the constant volume process is carried out. The contents of Si, Mn, P, Al and Cu in ferrotitanium are determined with the ICP-AES, the analytical spectral lines of elements to be determined and working parameters of instrument are optimized with this method as well as the disturbing effects of matrix elements Ti and Fe are investigated. The disturbing effects are eliminated with the mode of matrix matching and detection limit of the method is 0.000 3%~0.002 7%. The standard samples are determined with this method as well as measured values are consistent with certified values of all compositions, relative standard deviation (RSD, n=11) is 0.85%~9.03%, which could meet the analysis requirements of ferrotitanium.

The armco iron requires the manganese content in steel to be controlled within 0.005%. In order to study the smelting process for low manganese steel, the thermodynamic and dynamic conditions of demanganization reaction are analyzed. The study showed that the lower the temperature of liquid steel was, the higher the oxidizability of slag and oxygen content in steel were as well as the lower the manganese oxide content in slag was, the easier the oxidation reaction of manganese was. When the manganese content in liquid iron is 0.040%~0.055%, the end point carbon content of liquid steel in converter after bessemerizing is controlled at 0.025%~0.035% and final temperature is controlled below 1 620 ℃ so that residual manganese content in liquid steel could be reduced to 0.04%~0.08%. The demanganization rate of liquid steel increases with the quantity of converter slag increases. Without the deoxidation during tapping of converter, the liquid steel and slag in ladle would maintain higher oxidizability. During the refining process in ladle furnace(LF), the manganese content in steel could be reduced by 32% on average and decreasing amplitude is 0.01~0.04 percentage points. The manganese content in steel could be reduced steadily within 0.05% with the combined demanganization processes of converter and LF.