In the paper, it is introduced the experimental study on heat treatment at a series of temperatures of 1 000~1 250 ℃ was carried out by taking the Fe-Mn-Al-C high manganese austenitic test steel as object of study. The surface oxide layer, microstructure and grain size of test steel were detected and analyzed separately. The results showed that the thickness of surface oxide layer increased with heating temperature increased, there was grain boundary oxidation when heating temperature was above 1 150 ℃; the grain size of test steel increased with heating temperature increased, there was mixed crystal at 1 150 ℃ and the grain size increased obviously at 1 250 ℃.

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.

In this paper, the effect laws of adding a certain proportion of high silicon Brazilian coarse powder ore into sintering on its technical indicators and quality of sinter with current raw material conditions of Baotou Steel are studied. The experiment showed that the complementary ore proportioning could be realized by adding a certain proportion of high silicon Brazilian coarse powder ore taking the ore proportioning structure that the self-produced iron ore concentrate by Baotou Steel adding Australian limonite and semi limonite as the main framework, which was conducive to improving the quality of sinter. The industrial experiment showed that the rate of sintering finished products, drum strength of sinter and size composition were improved after add the high silicon Brazilian coarse powder ore into sintering of Baotou Steel.

The basic pellet with limestone and low reduction expansion rate added 75% Bayan Obo iron concentrate is researched and developed aiming at the special nature of Bayan Obo iron concentrate. It is suggested that the proportion of bentonite is 1.5%~1.8%, alkalinity is 1.15±0.05 and proportion of limestone is 3.5%~3.8% for producing basic pellet with the process of chain grate machine-rotary kiln-ring cooler of Baotou Steel as well as explored the basic pellet is with such process system as good compressive strength, mineral composition and metallurgical properties, which could provide the technical supports for producing it with chain grate machine-rotary kiln-ring cooler of Baotou Steel.

In this paper, the influences of super-thick material layer on sintering process indexes as well as productivity and quality of sinter based on the iron material configuration condition that high proportion of iron concentrate of sintering of Baotou Steel are mainly elaborated. The study results showed that the FeO content of sinter could be significantly reduced by increasing thickness of sintering material layer, the thickness of material layer was increased from 700 mm to 1 000 mm and the FeO content of sinter was decreased by 1.39 percentage points, or 14.2%. The solid fuel consumption of sintering could be effectively reduced, yield and drum strength of sinter could be improved by increasing the thickness of sintering material layer. In this paper, such indexes as the fuel consumption, yield, drum strength, RI and RDI_{+3.15 mm} of sinter tend to be increased then decreased with the thickness of material layer increases as well as they are optimal when the thickness of material layer is 800 mm, which shows that the suitable thickness of material layer is 800 mm with the iron material configuration condition of 20% Barun iron concentrate+20% Mongolian iron concentrate+60% imported iron ore powder.

There are such problems as the temperature at gas inlet of burner for Kalugin top combustion stove is too high, package is red as well as weld joint of gas pipeline cracks and leaks. After soldering and surface air cooling, the effects are not obvious. It is found that the internal refractory bricks collapse through opening pore on the pipeline. Thus, the special measures are taken as well as the area is sprayed and with lining making to repair so that the hot air temperature returns to normal, blast temperature of blast furnace keeps at 1 200 ℃ for normal production and the effects are obvious.

The liquid steel could be purified, inclusions could be modified and steel could be microalloyed by adding rare earth into steel, which could reduce the harmful effects of inclusions on steel so that the plasticity, toughness and resistance to low temperature impact of steel could be improved. In order to study the effects of different rare earth contents on properties of steel, the smelting of low alloy high strength steel with manganese and different quantities of rare earth added and without rare earth are carried out using the 25 kg vacuum medium frequency induction furnace as well as the rolling with production process on site is simulated. Moreover, the chemical composition, mechanical properties, fracture and metallographic structure of rolled products are analyzed. The results showed that the grain size of microstructure for steel could be refined by adding rare earth into steel; with the increase of rare earth content in steel, refined grain size of microstructure makes the resistance to crack formation and propagation between grain boundaries increased so that the plasticity, impact toughness and mechanical properties of steel are improved.

In the paper, it is found that the hardness and wear resistance of working layer for cast iron roll are improved as well as the labor costs are reduced by developing continuous rolling concave roll with the metal spraying process through optimizing such key control points as the chemical composition and production process of continuous rolling roll as well as comparing and analyzing its mechanical properties and microstructure before and after optimization, which provide the technical basis for developing large grooved roll and roll collar in future.

Based on the investigation of technical requirements and production process for like products of pressure vessel steel, the chemical composition design, rolling and research of normalizing process for Q370R are carried out as well as the effects of normalizing temperature on the microstructure and properties of test steel are studied. After normalizing, the strength of steel plate added microalloying elements Nb, V and Ti is decreased, elongation and impact energy are increased significantly. With the increase of normalizing temperature, strength of test steel is decreased gradually. The strengths of steel plate with rolled state and the same normalizing process added a small amount of Cr are both higher than those of the steel plate without Cr, while the elongation and impact energy are lower than those of the steel plate without Cr. The cost of per ton of steel will be increased by adding a small amount of Cr. After normalizing, the microstructure is fine grained ferrite and pearlite. Based on the comprehensive consideration, test steel with the composition system of adding microalloying elements Nb, V and Ti as well as the properties of steel plate with controlled rolling and normalizing at 840~880 ℃ could meet the standard requirements.

The accuracy of performance characterization for material has crucial influences on the numerical simulation results. In the software CAE, it generally contains the material cards of European mainstream material suppliers and a small number of domestic manufacturers, but due to different material characteristics of each manufacturer, the corresponding material card of material with the same grade shows different data distribution law as well as the criterion of yield and hardening. Thus, it is an indispensable link in such product applications as evaluation of stamping process as well as design and manufacture of mould to accurately characterize the characteristics of their own products and establish own material cards for material manufacturers. In the paper, the test scheme suitable for presenting cold stamping performance is established and data processing method is studied by taking the typical grade DC04 for cold stamping steel as the objective. Finally, the material data card for stamping simulation analysis which could accurately characterize product characteristics of Baotou Steel is developed. After adjust the working condition of stamping based on the calculation guidance of material data card, the stamping process suitable for performance characteristics of sheet matal of Baotou Steel is obtained to ensure the accuracy of simulation technology support and accurately improve the applicability of product.

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.

In this paper, it is introduced the CCT curve of 700 MPa grade high strength steel is measured with the Formastor-F full automatic phase change instrument and its microstructures at various cooling rates of 0.5~118 ℃/s are analyzed. The results showed that the transformation product was ferrite and pearlite when the cooling rate of test steel was 0.5 ℃/s; bainite structure began to form when the cooling rate was more than 1 ℃/s; bainite structure began to increase and perlite structure began to reduce with the cooling rate gradually increased; pearlite structure disappeared as well as the structure was ferrite and bainite when the cooling rate was 10 ℃/s; transformation products were mainly bainite when the cooling rate increased to 118 ℃/s. The analysis on the CCT curve and microstructure of 700 MPa grade high strength steel provide the theoretical basis for formulating heat treatment technology in actual production processes.

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 this paper, the industrial experiments of different heat treatment processes for X65Q seamless steel tube with medium thick wall are carried out as well as its microstructure and properties are tested and analyzed. The test results showed that the martensite content of X65Q seamless steel tube with specification of Ф406.4 mm×26.19 mm was gradually reduced from inner wall to center after quench with 3 300 m³/h inner and outer spraying as well as the microstructure of its internal surface was tempered sorbite+bainite, microstructure of its outer surface was bainite; after quenching, its grain size reached grade 8.5, transverse impact value at 0 ℃ reached over 200 J and yield strength reached over 500 MPa with tempering of 630 ℃ so that the strength and toughness of material matched well, which could meet the requirements of API 5L standard.

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.

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 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.

In the article, it is introduced the rail is deformed violently in rolling process and internal compactness is changed greatly due to the cross section size of ingot blank increases when rolling 60 kg/m rail using ingot blank with the cross section of 320 mm×415 mm instead of that with the cross section of 280 mm×380 mm in the production of rail. In order to ensure the product quality in rolling process, the roller of each rolling mill is adjusted to ensure stable as rolled state. After rolling the finished products, the macrostructure, microstructure, grain size and impact performance of rail are tested and analyzed with such equipment as the optical microscope, scanning electron microscope and impact testing apparatus. The results showed that the compression ratio of ingot blank was increased by rolling rail with large size ingot blank so that such mechanical properties as grain size and impact of rail could be improved.

Such elements that could refine grain as V, Nb, Ti, Al and rare earth (RE) are added into the medium carbon steel as well as the stable compound formed by N, C and elements that could refine grain is used to refine the austenite grain and increase the strength and toughness of non-quenched and tempered steel. The stable compound formed by N, C, V, Nb, Ti and Al are observed with metallographic microscope and transmission electron microscope so that the non-quenched and tempered ferrite-pearlite steel is successfully developed. Its yield strength is greater than 550 MPa, tensile strength is greater than 780 MPa, hardness (HB) is not less than 210, elongation is greater than 18%, reduction of area is greater than 45% and impact value of V-notch at room temperature is greater than 50 J. Compared with common non-quenched and tempered steel, the non-quenched and tempered steel F28MnSiVTiRE is with such advantages as high strength and toughness and free cutting so that it could be used for machining such components as vehicle crankshaft and engine connecting rod.

In the process of rolling wire rods with Φ5.5 mm and Φ6.5 mm in Long Products Plant, the accident of piling-up of steel is easily to happen at the water cooling section after finishing rolling so that the rhythm of production and output are affected. Its true causes are found out through analyzing its phenomena, morphology and microstructure of its samples with the scanning electron microscope so that the probability of repetitive accidents and its times of piling-up of steel at water cooling section after finishing rolling are reduced. After the rectify and reform, the ratio of piling-up of steel is reduced to 0.013%, cumulative failure time is reduced to 35.8 hours and rejection rate is reduced to 0.027%.

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.

Tower crane is the mechanical equipment playing a leading role in the construction of high rise buildings as well as it is widely used because it could achieve any work height and work range through installing and attaching. Its installation and disassembly are more dangerous projects, so construction organizations should pay high attention to the safety technology management of installing and disassembling tower crane. In the paper, it is introduced the construction process of demolition with tower crane, mainly discussed the problems need to be solved in the process as well as elaborated the construction preparation, order of demolition with tower crane, safety precautions and reinforcement measures of truck crane at different positions of roof for underground garage in detail, which could be as the reference for construction of demolition with tower crane.

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.