The potential of domestic production and imports of oil and gas in China:an energy return on investment perspective

Concerns about China’s energy security have escalated because of the country’s high dependency on oil and gas imports, so it is necessary to calculate the availability of domestic oil and gas resources and China’s ability to obtain foreign energy through trade. In this work,the calculation was done by using the energy return on investment（EROI） method. The results showed that the EROIstnd（i.e., standard EROI） of China’s oil and gas extraction decreased from approximately 17.3：1 in 1986 to 8.4：1 in 2003, but it increased to 12.2：1 in 2013. From a company-level perspective, the EROIstnddiffered for different companies and was in the range of（8–12）：1. The EROI2,d（EROI considering energy outputs after processed and direct energy inputs） for different companies was in the range of（3–7）：1. The EROI of imported oil（EROIIO）declined from 14.8：1 in 1998 to approximately 4.8：1 in 2014, and the EROI of imported natural gas（EROIING）declined from 16.7：1 in 2009 to 8.6：1 in 2014. In 2015, the EROIIO and EROIING showed a slight increase due to decreasing import prices. In general, this paper suggests that from a net energy perspective, it has become more difficult for China to obtain oil and gas from both domestic production and imports. China is experiencing an EROI decline, which demonstrates the risk in the use of unsustainable fossil resources.

Numerical simulation on gradient cooling behavior of jumbo slab ingot

Shrinkage porosity defect is often found in an air cooled jumbo steel ingot, which will influence the quality of the final rolled plates. In practical production, some rolled plates are frequently rejected due to the serious shrinkage porosity of the ingot. To improve the quality of the ingot, a new cooling method, gradient cooling process (in which the upper part of the ingot is air cooled and the lower part is spray cooled) was put forward in this study. The solidification behaviors for a 60 t jumbo slab ingot under gradient cooling condition were simulated using the ProCast software, and the results were compared with those of an ingot by air cooling condition. The solidifying tendency, temperature field and distribution of shrinkage porosities in the ingot under different cooling conditions were analyzed. Simulation results show that under gradient cooling condition the solidification of the slab ingot progresses in an upward manner along the vertical z axis and in a centripetal manner along the horizontal x and y axes. Gradient cooling can efficiently reduce shrinkage porosity of the jumbo slab ingot by optimizing the solidification sequence, and making the position of shrinkage porosity move from near the middle height of the ingot (under air cooling condition) towards the head of the ingot; and the secondary shrinkage is eliminated. In addition, the solidification time of the ingot under gradient cooling is 7.3 h in this simulation, which is 2.7 h faster than that under air cooling. A 60 t jumbo slab ingot was successfully produced under gradient cooling condition. The ingot was rolled to a plate with a thickness of 100 mm and length of 18,000 mm, and ultrasonic flaw detection was performed. Some porosity was found along the axis of the plate at 4,900 - 6,000 mm from the head of the plate, indicating that the position of the defect is moved towards the head of the ingot. This distribution trend of the defect is consistent with the simulated result.

棒材热连轧力能参数的解析

采用三维流函数法对棒材热连轧时的椭圆 -圆孔型系统进行了力能参数的解析 ,其结果与实测结果符合很好。

Dynamic CCT Diagram of Automobile Beam Steel With High Strength Produced by FTSR Technology

The dynamic continuous cooling transformation（CCT）diagram and phase transformation rules of 510 MPa automobile beam steel,which is produced by a continuous casting of thin slab of FTSR technology in Tangshan Iron and Steel Co.Ltd.,are researched by thermal simulation experiment.The microstructure characteristics of the beam steel under different test conditions are studied by means of optical microscope and scanning electron microscope.The test results show that the critical temperatures of phase transformation Ar3 and Ar1 will all decrease with the increase of the cooling rate.When the cooling rate is lower than 20 ℃·s-1,the ferrite and pearlite phase transformations are the main parts;when the cooling rate is higher than 20 ℃·s-1,the bainite phase appears.Moreover,the microstructures of 510 MPa automobile beam steel produced by FTSR technology are also studied,and the results are basically in accordance with the CCT diagram gained from the test.

Formation of Phosphorous Surface Inverse Segregation in Twin-Roll Cast Strips of Low-Carbon Steels

The formation of phosphorous surface inverse segregation （SIS） in twin-roll cast strips of low-carbon steels was studied. High phosphorous strips were fabricated by using a pilot twin-roll strip caster and a melt/substrate contacting apparatus, respectively. Solidification structures of strips were observed and analyzed, and phosphorus distributions along longitudinal sections of strips were investigated and discussed. The results showed that solidification structures of all strips were columnar grains, either integrated or coarse in the strip made by the melt/substrate contacting apparatus or damaged in some degree in cast strips; and that during cast strip solidification, enrichment of phosphorus occurred between columnar grains, and the average phosphorus concentration near the surface in the strip with 0.15% of phosphorus was measured to be about 0.27% which was obviously higher than that in the bulk.