基于Maxwell方程建立含有相变过程的感应熔铸温度场模型并验证,以及以温度场模型为基础,引入流动控制方程,建立感应熔铸过程中熔池模型并分析。结果表明,熔池随电流增大而增大;频率增大并非一定使熔池增大,而存在一个极小值点;550 A时...基于Maxwell方程建立含有相变过程的感应熔铸温度场模型并验证,以及以温度场模型为基础,引入流动控制方程,建立感应熔铸过程中熔池模型并分析。结果表明,熔池随电流增大而增大;频率增大并非一定使熔池增大,而存在一个极小值点;550 A时极小值出现频率约为78.5 k Hz;熔池内流场呈涡旋状且沿顺时针分布,中心接近于静止;熔池的最大流速出现在靠近交界处涂层一侧;工艺参数对熔池内流速的影响规律与对熔池大小的基本一致。涂层中存在被稀释现象,随深度增加,涂层硬度先增大后减小;对比不同粒度的涂层硬度,目数越大硬度越大,被稀释现象越明显。展开更多
采用电渣熔铸技术,制备了以5Cr Ni Mo模具钢为基体,WC颗粒为硬质相的钢基复合材料。利用扫描电子显微镜、冲击试验机、摩擦磨损试验机等研究了复合材料的冲击韧度、断口形貌、摩擦系数、磨损量和磨损机制。结果表明,复合材料冲击韧度值...采用电渣熔铸技术,制备了以5Cr Ni Mo模具钢为基体,WC颗粒为硬质相的钢基复合材料。利用扫描电子显微镜、冲击试验机、摩擦磨损试验机等研究了复合材料的冲击韧度、断口形貌、摩擦系数、磨损量和磨损机制。结果表明,复合材料冲击韧度值较小,断裂方式均是脆性断裂。顶部和中部试样分布着沿晶或穿晶二次裂纹,为解理断裂。尾部试样部分区域具有一些韧性特征,断口为细韧窝和部分沿晶断口。热处理后试样的耐磨性得到很大提高,在干滑动磨损条件下,试样的磨损机制主要是粘着磨损引起的表面剥落及磨屑充当第三体引起的磨粒磨损。展开更多
The electromagnetic characteristics of cold wall crucible, especially its field strength and distribution, were evaluated experimentally, in which the effects of parameters as input power and position were also discus...The electromagnetic characteristics of cold wall crucible, especially its field strength and distribution, were evaluated experimentally, in which the effects of parameters as input power and position were also discussed. The results showed that the magnetic induction intensity （B） increased with the increase of the input power. Along the radial direction inside the cold crucible, B is the strongest at the edges, and gradually attenu- ated from the edges to the center. While along the axial direction, B is the strongest at the center, and gradually attenuated from the center to the edges. Corresponding with the calculation on electromagnetic field distribution inside the coil without cold crucible, the effects of cold crucible on the electromagnetic field have been reduced by comparing measured and calculated results. However, it was also found that the value of B strength will be decreased to about 50% of its original proposition without cold crucible due to the electromagnetic shielding effect, which will be the understanding for mehing turns in cold crucible.展开更多
文摘基于Maxwell方程建立含有相变过程的感应熔铸温度场模型并验证,以及以温度场模型为基础,引入流动控制方程,建立感应熔铸过程中熔池模型并分析。结果表明,熔池随电流增大而增大;频率增大并非一定使熔池增大,而存在一个极小值点;550 A时极小值出现频率约为78.5 k Hz;熔池内流场呈涡旋状且沿顺时针分布,中心接近于静止;熔池的最大流速出现在靠近交界处涂层一侧;工艺参数对熔池内流速的影响规律与对熔池大小的基本一致。涂层中存在被稀释现象,随深度增加,涂层硬度先增大后减小;对比不同粒度的涂层硬度,目数越大硬度越大,被稀释现象越明显。
文摘采用电渣熔铸技术,制备了以5Cr Ni Mo模具钢为基体,WC颗粒为硬质相的钢基复合材料。利用扫描电子显微镜、冲击试验机、摩擦磨损试验机等研究了复合材料的冲击韧度、断口形貌、摩擦系数、磨损量和磨损机制。结果表明,复合材料冲击韧度值较小,断裂方式均是脆性断裂。顶部和中部试样分布着沿晶或穿晶二次裂纹,为解理断裂。尾部试样部分区域具有一些韧性特征,断口为细韧窝和部分沿晶断口。热处理后试样的耐磨性得到很大提高,在干滑动磨损条件下,试样的磨损机制主要是粘着磨损引起的表面剥落及磨屑充当第三体引起的磨粒磨损。
文摘The electromagnetic characteristics of cold wall crucible, especially its field strength and distribution, were evaluated experimentally, in which the effects of parameters as input power and position were also discussed. The results showed that the magnetic induction intensity （B） increased with the increase of the input power. Along the radial direction inside the cold crucible, B is the strongest at the edges, and gradually attenu- ated from the edges to the center. While along the axial direction, B is the strongest at the center, and gradually attenuated from the center to the edges. Corresponding with the calculation on electromagnetic field distribution inside the coil without cold crucible, the effects of cold crucible on the electromagnetic field have been reduced by comparing measured and calculated results. However, it was also found that the value of B strength will be decreased to about 50% of its original proposition without cold crucible due to the electromagnetic shielding effect, which will be the understanding for mehing turns in cold crucible.
