Poor permeability and low sintering productivity restrict the development of high-bed sintering.An efficient method of the double-layer sintering process(DLSP)was proposed to achieve high-bed sintering and solve the a...Poor permeability and low sintering productivity restrict the development of high-bed sintering.An efficient method of the double-layer sintering process(DLSP)was proposed to achieve high-bed sintering and solve the aforementioned problems.Theoretical calculation and sintering pot experiments were implemented to investigate the double-layer sintering process.Traditional sintering process and DLSP were compared in terms of sintering indices,metallurgical properties and morphology characterization.Under the condition of traditional sintering process,DLSP successfully realized fast velocity and highly productive sintering of 1000-mm high bed.After the sintering bed is charged and ignited twice,the air permeability of the bed has been greatly improved.Sintering time is shortened significantly by simultaneous sintering of the upper and lower feed layers.Under the condition of bed height proportion of 350/650 mm and pre-sintering time of 20 min,the yield,tumbler strength,productivity and solid fuel consumption are 69.96%,65.87%,1.71 t(m^(2)h)^(-1)and 56.71 kg/t,respectively.Magnetite,hematite,calcium ferrite and complex calcium ferrite are the main phases of DLSP products.The metallurgical properties of DSLP products meet the requirement of ironmaking.It indicates that DLSP is an effective method to solve the disadvantages of bad permeability and low sintering productivity in high-bed sintering.展开更多
M2高速钢是制备高性能精密切削刀具的重要材料之一。基于激光粉末床熔融(laser powder bed fusion,L-PBF)技术在300℃较高基板预热温度下成型了无层间裂纹的M2钢,并研究了扫描参数对致密度、微观组织、硬度及磨损性能的影响。结果表明:...M2高速钢是制备高性能精密切削刀具的重要材料之一。基于激光粉末床熔融(laser powder bed fusion,L-PBF)技术在300℃较高基板预热温度下成型了无层间裂纹的M2钢,并研究了扫描参数对致密度、微观组织、硬度及磨损性能的影响。结果表明:激光功率与扫描速度分别为260 W和0.8 m·s^(-1)时,M2钢的致密度在99.4%以上;微观组织主要由细小等轴状铁素体与大量条片状(长度约10μm)马氏体、下贝氏体构成,未见常规网状粗大共晶碳化物,下贝氏体形成的主要原因是高基板预热温度使得试样在快速冷却过程中能在一定时间内维持马氏体转变点(<200℃)以上温度,且热输入增加会提高下贝氏体的含量;高致密度M2钢的硬度(813.2HV0.3)稍低于淬回火锻造母材,但抗压强度(3.51 GPa)和压缩延展性(32%)与母材相当,同时还呈现出优异的耐磨损性能,其磨损率(3.98×10^(5)mm^(3)·N^(-1)·m^(-1))较母材降低了36.1%。展开更多
基金the National Key Research and Development Program of China(2017YFB0304301)the Fundamental Research Funds for the Central Universities of Central South University(No.202044016).
文摘Poor permeability and low sintering productivity restrict the development of high-bed sintering.An efficient method of the double-layer sintering process(DLSP)was proposed to achieve high-bed sintering and solve the aforementioned problems.Theoretical calculation and sintering pot experiments were implemented to investigate the double-layer sintering process.Traditional sintering process and DLSP were compared in terms of sintering indices,metallurgical properties and morphology characterization.Under the condition of traditional sintering process,DLSP successfully realized fast velocity and highly productive sintering of 1000-mm high bed.After the sintering bed is charged and ignited twice,the air permeability of the bed has been greatly improved.Sintering time is shortened significantly by simultaneous sintering of the upper and lower feed layers.Under the condition of bed height proportion of 350/650 mm and pre-sintering time of 20 min,the yield,tumbler strength,productivity and solid fuel consumption are 69.96%,65.87%,1.71 t(m^(2)h)^(-1)and 56.71 kg/t,respectively.Magnetite,hematite,calcium ferrite and complex calcium ferrite are the main phases of DLSP products.The metallurgical properties of DSLP products meet the requirement of ironmaking.It indicates that DLSP is an effective method to solve the disadvantages of bad permeability and low sintering productivity in high-bed sintering.
