热处理对NiTi形状记忆合金冲蚀磨损性能的影响

采用自制浆罐式砂水冲蚀磨损试验装置研究了4种经不同条件热处理的NiTi合金与1Cr18Ni9Ti不锈钢的冲蚀磨损性能;采用XL-30型扫描电子显微镜观察试样的冲蚀磨损表面形貌;采用MH-6型显微硬度计测量NiTi合金硬度;采用自制拉伸装置测量NiTi合金的力学性能.结果表明:5种试样的冲蚀磨损量随着冲蚀时间、冲蚀速度、砂水比及砂粒度的增加而增大,4种NiTi合金的耐冲蚀性能相近,均明显优于1Cr18Ni9Ti不锈钢,其中试样NiTi-3和NiTi-1表现出较好的耐冲蚀性能;硬度并非NiTi合金冲蚀磨损性能的决定因素,超弹性和超塑性是NiTi合金具有较好耐冲蚀性的主要原因,热处理使得NiTi合金的超弹性变形量减小,但增加了NiTi合金的塑性变形量;合金丝磨损表面不同部位的磨损机理不同,中部为典型的变形磨损,侧面为微切削磨损,5种试样均表现为典型的韧性材料冲蚀磨损特征.

Effect of Heat Treatment on the Erosive Properties of NiTi Shape Memory Alloys

Slurry erosive properties of four NiTi alloys which are heat treated in different programs and 1Cr18Ni9Ti stainless steel have been systematically studied using a specially designed slurry-pot equipment. The erosive loss of five samples increase with the erosion time, velocity, mass ratio of sand to water and sand size. Four NiTi alloys exhibited very little difference in wear-resistance and they exhibited better wear-resistance than 1Cr18Ni9Ti stainless steel. NiTi-3 and NiTi-1 exhibited a little better erosive resistance than the others. The superelasticity and the superplasticity, not the hardness, are the key elements for the good anti-erosive properties of NiTi alloys. The heat treatments decrease the superelasticity but increase the plasticity greatly. Deformation occurred in the middle part of the NiTi-wire, and micro-cutting in the sides, which indicated that all the samples exhibit ductile material characteristics in the erosion.