Jianzhong WANG
金属学报(英文版)
doi:10.1016/S1006-7191(08)60122-2
A new method for producing higher density PM parts, high velocity compaction (HVC), was presented in the paper. Using water atomized pure iron powder without lubricant admixed as the staring material, ring samples were compacted by the technique. Scanning electron microscopy (SEM) and a computer controlled universal testing machine were used to investigate the morphologies and the mechanical properties of samples, respectively. The relationships among the impact velocity, the green density, the sintered density, the bending strength and the tensile strength were discussed. The results show that with increasing impact velocity, the green density and the bending strength increase gradually, so the sintered density does. In addition, the tensile strength of sintered material is improved continuously with the sintered density enhancing. In the study, the sintered density of 7.545~g/cm3 and the tensile strength of 190~MPa are achieved at the optimal impact velocity of 9.8 m/s.
关键词:
Powder metallurgy
,
high velocity compaction
,
green properties
,
stress wave
,
bending strength
刘诗汉陈大融
金属学报
对由铁素体和渗碳体组成的低、中、高碳钢进行振动空蚀实验, 发现它们空蚀破坏的共同特点是铁素体的严重变形和破损. 但由于铁素体的含量及分布形态不同, 材料空蚀破坏的表现形式大不相同: 铁素体含量高的低碳钢以大面积均匀塑性变形为主; 铁素体含量与珠光体含量大致相等并呈网状分布的中碳(亚共析)钢是由于铁素体隆起脱落而破坏; 以珠光体为主的高碳钢是由于铁素体从渗碳体的夹缝中向外挤出、两相分离而破坏. 微射流冲击形成的应力波使低强度相屈服是造成上述破坏的原因.
关键词:
双相钢
,
cavitation erosion
,
stress wave
