The pelletizing process is the key link in pellet production. The quality of green pellets will directly affect quality of finished ball. The pelletization rate is increased from 75% to 81% and average drop strength of green pellets is increased by 0.3 times by taking such measures as improving drying effect of iron charge, intensifying high-pressure roller grinding process and optimizing parameters of pelletizer so that quality of green pellets is improved obviously.

In this paper, it is introduced the design scheme of nickel metal hydride battery pack in railway passenger cars as well as elaborated the necessities of replacing lead acid battery and nickel-cadmium battery with it from such aspects as safety, environmental protection and maintenance free. With the sealed nickel metal hydride battery system as redundant electrical power, there is no need to replenish it so that the workload of artificial maintenance for it is greatly reduced. It is with the management system of charging and discharging, which can monitor its such important parameters as the voltage, current, temperature and SOC in real time as well as monitor its usage status so that the safety of vehicle operation is improved.

With the development requirements of lightweight of automobile, the 590 MPa grade cold-rolled dual phase steel for structural parts is successfully researched and developed through the chemical composition design with C-Mn-Cr alloy system combining with reasonable hot rolling, pickling tandem cold rolling and continuous annealing processes based on the advanced equipment and technological characteristics of Baotou Steel in order to meet the requirements of car body safety and environmental protection. The mass production and application of users show that all the mechanical properties of cold-rolled dual phase steel HC340/590DP could meet the technical and user requirements.

The defect of transverse crack on surface is the folded mark vertical to rolling direction of steel belt and the defect of pickled SPHC product has been the main quality problem faced by production line since Rare Earth Steel Plate Co., Ltd. was put into production in commission, which seriously influences the yield and qualified rate. In the article, it is analyzed its mechanism, studied the effects of chemical components, coiling temperature, levelling process, decoiling temperature of pickling and deep bending roll on it as well as a series of related improvement measures are taken so that its occurrence rate is reduced significantly and the effects are better.

In the article, the principle of narrow lap welding and judgment methods for weld quality are clear and definite as well as the hardness impact of various martensite during rapid cooling for strip steel of this material and the CCT diagram of rapid cooling phase transformation for carbon steel are analyzed. The obtained drawing test results of weld are qualified and the fracture is not at weld in tensile test through adjusting welding parameters as well as increasing annealing process of weld so that the quality of weld seam is eligible in actual production.

The inclined Y-groove welding crack test, maximum hardness test in heat affected zone and rigid butt-joint cracking test for bridge steel Q345qDNH produced by Baotou Steel are carried out. The test results showed that the cold crack sensitivity of bridge steel Q345qDNH with thickness of 20 mm was not great and its cold cracks could be avoided without preheating or using the preheating temperature system of 50 ℃ in actual welding process.

The surface defects of DC04 steel are tested and analyzed by such testing methods as chemical composition analysis, metalloscope, tensile testing machine, scanning electron microscope and energy disperse spectroscopy. The results showed that there was a strip of 200 μm inclusion (type B) at defect and the inclusion of matrix exceeded the standard. The nonmetallic inclusions cause stress concentration, microcracks are generated during rolling so that surface defects are formed in punching process.

The N80 grade experimental steel for oil casing is developed with the microalloying composition design of C-Mn-Nb-Ti, smelting with low P and S as well as reasonable controlled rolling and cooling process so that the refined crystalline strengthening and precipitation strengthening are made full use of. Moreover, the continuous cooling transformation curve (CCT curve) of N80 grade ERW steel for oil casing is measured to study the effects of different cooling rates on products of phase change.

In this paper, such performances as drawing, impact, ductile-brittle transition temperature, torsional strength at room temperature and rotating bending fatigue of seamless steel pipe for V150 grade drill pipe body developed and produced by Baotou Steel are tested and studied. The results showed that such technical indexes as the conventional mechanical properties and grain size of as-heat-treated steel pipe could meet the requirements of DS-1^TM Standard Vol.1 Specification of Tubular Products for Drilling. At the same time, it is also with such excellent material characteristics as good transverse impact toughness, high low temperature impact toughness, low ductile-brittle transition temperature, high torsional strength at room temperature and good anti-rotating bending fatigue, which could meet the requirements of steel for V150 grade drill pipe body with super high strength.

The R320Cr steel is a heavy rail steel grade that can be used to produce heavy haul railway rail according to the European Railway Standards. Its main technical indexes include tensile strength ≥1 080 MPa, elongation ≥9%, range for hardness of tread center (HB) is 320~360. Its smelting composition range, production technology and operating points of each process are determined through the laboratory researches as well as its technical indexes in industrial production could meet the technical requirements of standard.