High speed steel has been widely used in various fields due to their excellent red hardness and good wear resistance. However, the influence of mischmetal （Ce-La） on the as-cast microstructures and mechanical proper...High speed steel has been widely used in various fields due to their excellent red hardness and good wear resistance. However, the influence of mischmetal （Ce-La） on the as-cast microstructures and mechanical properties of high speed steel has rarely been reported. Thus, the microstructure and mechanical properties of M2 high speed steel with addition of mischmetal （Ce-La） were investigated. The morphology and distribution of the eutectic carbides of the steel were observed by using optical microscopy and scanning electron microscopy, and the impact toughness and bending strength were tested. The results show that adding mischmetal has an obvious effect on the microstructure and mechanical properties of M2 high speed steel. The coarse eutectic structure is refined, the weak connection of the carbide networks is broken and the flake carbides become short and fine. More networks of eutectic carbides dissolve into the matrix. When a suitable adding content of mischmetal is selected, for example, 0.3 mass%, the impact strength and bending strength can increase by 27% and 10.76% compared with that without misehmetal, respectively.展开更多
The influence of mischmetal （Ce-La） addition on phase transformation and as-cast microstructure characteristics of M2 high-speed steel （HSS） was investigated using Thermo-Calc software, differential scanning calor...The influence of mischmetal （Ce-La） addition on phase transformation and as-cast microstructure characteristics of M2 high-speed steel （HSS） was investigated using Thermo-Calc software, differential scanning calorimetry, X-ray diffractometry and scanning electron microscopy with energy dispersive spectrometry. The results showed that the measured phase transition points of M2 HSS were broadly consistent with the theoretical results. After mischmetal addition, the liquidus peak temperature, the peak temperature of the eutectic precipitation of M6C and MC were all increased, especially for the M6C which was affected significantly and increased about 31 °C. The contents of Mo and V in the eutectic carbide decreased and that of Fe increased, while in the matrix, the Mo, V and Cr contents all increased slightly. Furthermore, the microstructure of as-cast dendrite and ledeburite were refined, the total eutectic carbide content decreased and distributed into a discontinuous network, the lamellar spacing of M2C was reduced and the lamellae became thinner.展开更多
在实验室条件下采用立式连铸的方法连铸φ100 mm M2钢,在扫描电镜下观察分析其碳化物的分布、形貌、尺寸和类型,研究了析出碳化物的演变规律,并对其在液相区、固-液两相区和固相区的析出规律进行了热力学计算。结果表明:φ100 mm M2钢...在实验室条件下采用立式连铸的方法连铸φ100 mm M2钢,在扫描电镜下观察分析其碳化物的分布、形貌、尺寸和类型,研究了析出碳化物的演变规律,并对其在液相区、固-液两相区和固相区的析出规律进行了热力学计算。结果表明:φ100 mm M2钢连铸坯碳化物呈网状分布,网状碳化物的厚度从铸坯边部的1.5μm增大到中心的30μm,增大约20倍。碳化物形貌包括:块状、片层状和棒状,其中块状碳化物为VC,而片层状和棒状碳化物为M_2C。在液相和固-液两相区δ铁素体析出过程中,各种碳化物均不具备析出的热力学条件;在固-液两相区中γ奥氏体转变过程中,W_2C在1504 K具有析出的热力学条件;当温度降到固相线以下时,碳化物的析出顺序为VC>Mo_2C>W_2C,其析出温度分别为1475 K、549 K和333 K。展开更多
用Y K Na对M2高速钢进行复合变质处理,研究了变质处理对M2高速钢组织和性能的影响。结果表明,M2铸造高速钢经Y K Na复合变质处理后,组织明显细化,共晶碳化物由网状分布变为块状和团球状,冲击韧性提高70 7%,耐磨性也明显提高,各项力学性...用Y K Na对M2高速钢进行复合变质处理,研究了变质处理对M2高速钢组织和性能的影响。结果表明,M2铸造高速钢经Y K Na复合变质处理后,组织明显细化,共晶碳化物由网状分布变为块状和团球状,冲击韧性提高70 7%,耐磨性也明显提高,各项力学性能接近锻造M2高速钢的水平。展开更多
基金Item Sponsored by Key Project of National Research Program of China(2011BAC10B04)National Natural Science Foundation of China(51201075)
文摘High speed steel has been widely used in various fields due to their excellent red hardness and good wear resistance. However, the influence of mischmetal （Ce-La） on the as-cast microstructures and mechanical properties of high speed steel has rarely been reported. Thus, the microstructure and mechanical properties of M2 high speed steel with addition of mischmetal （Ce-La） were investigated. The morphology and distribution of the eutectic carbides of the steel were observed by using optical microscopy and scanning electron microscopy, and the impact toughness and bending strength were tested. The results show that adding mischmetal has an obvious effect on the microstructure and mechanical properties of M2 high speed steel. The coarse eutectic structure is refined, the weak connection of the carbide networks is broken and the flake carbides become short and fine. More networks of eutectic carbides dissolve into the matrix. When a suitable adding content of mischmetal is selected, for example, 0.3 mass%, the impact strength and bending strength can increase by 27% and 10.76% compared with that without misehmetal, respectively.
基金supported by National Natural Science Foundation of China(51171161,51101137)the Major Projects of the State Nuclear Power(2011ZX06004-016)Science Fund for Distinguished Young Scholars in Hebei Province(E2011203131)
文摘The influence of mischmetal （Ce-La） addition on phase transformation and as-cast microstructure characteristics of M2 high-speed steel （HSS） was investigated using Thermo-Calc software, differential scanning calorimetry, X-ray diffractometry and scanning electron microscopy with energy dispersive spectrometry. The results showed that the measured phase transition points of M2 HSS were broadly consistent with the theoretical results. After mischmetal addition, the liquidus peak temperature, the peak temperature of the eutectic precipitation of M6C and MC were all increased, especially for the M6C which was affected significantly and increased about 31 °C. The contents of Mo and V in the eutectic carbide decreased and that of Fe increased, while in the matrix, the Mo, V and Cr contents all increased slightly. Furthermore, the microstructure of as-cast dendrite and ledeburite were refined, the total eutectic carbide content decreased and distributed into a discontinuous network, the lamellar spacing of M2C was reduced and the lamellae became thinner.
文摘在实验室条件下采用立式连铸的方法连铸φ100 mm M2钢,在扫描电镜下观察分析其碳化物的分布、形貌、尺寸和类型,研究了析出碳化物的演变规律,并对其在液相区、固-液两相区和固相区的析出规律进行了热力学计算。结果表明:φ100 mm M2钢连铸坯碳化物呈网状分布,网状碳化物的厚度从铸坯边部的1.5μm增大到中心的30μm,增大约20倍。碳化物形貌包括:块状、片层状和棒状,其中块状碳化物为VC,而片层状和棒状碳化物为M_2C。在液相和固-液两相区δ铁素体析出过程中,各种碳化物均不具备析出的热力学条件;在固-液两相区中γ奥氏体转变过程中,W_2C在1504 K具有析出的热力学条件;当温度降到固相线以下时,碳化物的析出顺序为VC>Mo_2C>W_2C,其析出温度分别为1475 K、549 K和333 K。
