铁尾矿对混凝土性能的影响

为实现铁尾矿的无害化大宗利用,研究了鞍山地区铁尾矿的组成、结构和性能,探讨了用铁尾矿替代河砂配制混凝土对其性能的影响.结果表明:通过掺入粉煤灰、矿渣粉、硅灰等活性矿物掺合料和高效减水剂,可以弥补铁尾矿细度模数小的缺陷,生产出符合工程需要的混凝土.     

配加贾家堡铁矿对烧结矿性能的影响

为降低烧结矿成本,对烧结原料中配加一定比例的贾家堡铁矿进行了研究。烧结杯试验结果表明,随着烧结铁料中贾家堡铁矿配比增加,烧结矿成品率呈现逐渐降低趋势,转鼓指数也逐渐降低。贾家堡铁矿配比由0增加到4.48%时,烧结矿低温还原粉化率由76.7%降低到71.9%,而当贾家堡铁矿配比继续增加时,低温还原粉化率却有所上升。     

Effect of carbon on the surface properties of liquid iron

Conclusions A study was made of the effects of temperature and composition on of Fe-C melts. It was found that, in the hypoeutectic range of compositions, the polytherms of of the melts investigated are not straight lines and are characterized by a positive temperature coefficient of . Carbon exhibits surface activity in liquid iron. A hypothesis is advanced in explanation of this phenomenon. The wetting of alumina by Fe-C melts was investigated at various carbon concentrations and temperatures. Raising the carbon content improves wetting in the system (Fe-C)_L-A1₂O₃.Translated from Poroshkovaya Metallurgiya, No. 10 (118), pp. 57–61, October, 1972.     

Effect of copper additions on the mechanical properties of iron

The effect of copper alloying on the mechanical properties of iron is studied. Alloying of a model material (armco-iron) with 0.2–2.0% Cu is shown to increase the strength characteristics by a factor of 1.5–2.5 and to decrease the ductility by 8–60%.     

炭化工艺参数对铁焦冶金性能的影响

复合铁焦被认为是实现低碳高炉炼铁的革新技术之一。为了获得高质量的铁焦,需要采用适宜的炭化工艺条件。研究了炭化工艺参数对铁焦机械强度、反应性和反应后强度等冶金性能的影响,并对炭化后铁焦的金属化率、微观结构和碳微晶结构进行了解析。结果表明,炭化温度的升高可以提高铁焦的抗压强度和反应性。当温度为900～1 000℃时,铁焦的抗压强度和反应性较优。炭化时间的延长可以使铁焦的抗压强度提高,反应性降低。当炭化时间为3～4 h时,铁焦抗压强度和反应性较优。升温速度越快,铁焦的机械强度越低。适宜的升温速度为:Ⅰ段(室温至550℃)小于7℃/min,Ⅱ段(550℃至1 000℃)小于5℃/min。为防止铁焦冶金性能因碳气化溶损反应而劣化,在CO和CO₂混合炭化气氛中,CO₂与CO体积比(V(CO₂)/V(CO))应控制在0.11以下。在优化的炭化工艺条件下,制备的铁焦抗压强度大于3 500 N,反应性大于60%,反应后强度在16%左右。     

Effect of hydrostatic pressure on plastic-flow properties of iron single crystals

Hydrostatic pressure increases the yield strength and work-hardening rate of steel. The effect has been found to be greater than that predicted by current theories of plastic flow in metals. To aid in developing more representative plasticity theory that will improve our ability to predict the behavior of steel during complex working and forming operations, and to improve our understanding of the phenomena, critical experiments have been conducted on polycrystalline steels and on iron single crystals. In the present work, the effect of superimposed hydrostatic pressures up to 1104 MPa (160 ksi) on the deformation behavior of iron single crystals of three different orientations has been studied at room temperature. The three orientations investigated were chosen so that slip occurred on (110) planes or on (112) planes in both the twinning and anti-twinning directions.The results showed that both the critical resolved shear stress (crss) and the initial work-hardening rate were increased by hydrostatic pressure. However, the predominant effect of hydrostatic pressure was to increase the initial work-hardening rate, which suggests that the normal stress on the slip plane had a larger effect on dislocation interactions than on the initial movement of dislocations. Analysis of the slip systems and the dislocation structures present after deformation under hydrostatic pressure indicated that the same slip systems operated and the same kinds of dislocation distributions were formed as observed after deformation at 1 atmosphere. These results suggest that the predominant effect of hydrostatic pressure was to retard the generation of mobile dislocations resulting from cross-slip or other dislocation interactions because of the increase in volume associated with an increase in dislocation density, thereby resulting in a greater work-hardening rate under hydrostatic pressure than at atmospheric pressure.The increase in crss with increasing pressure was independent of orientation and was about twice the amount and can be accounted for by the change in shear modulus or the added effect of pressure on the dislocation volume. If the assumption is made that the increase in crss over that which can be accounted for was due to an activated process that controls deformation, then the activation volume for that process is about 0.1 atomic volume.