泡沫钢的制备及压缩吸能特性

Preparation process, compression and energy absorption properties of steel foams

为制备高强轻质泡沫钢吸能材料,本文以430L不锈钢粉为原料、CaCl2为造孔剂,采用粉末冶金烧结-溶解法制备了孔隙率为64%~80%,孔径1~4 mm的泡沫钢.利用SEM和XRD对试样进行微观组织结构分析,并对试样进行轴向准静态压缩测试,分析讨论了孔隙率和孔形对泡沫钢压缩变形行为和吸能特性的影响,以及变形过程中孔结构变形和坍塌机理.研究表明:泡沫钢孔结构呈近球形且分布均匀,孔之间通过孔壁上的微孔形成有效连通.在压缩变形过程中,变形区首先发生在孔形不规则且孔壁较薄处,后诱发周围孔变形并形成多个变形带.泡沫钢试样压缩屈服平台应力随着孔隙率的增加而减小,当孔隙率为64.81%~78.82%时,其对应的屈服平台应力为59.37~17.04 MPa.在孔隙率相同的条件下,孔形为近球形的泡沫试样,其屈服平台应力远高于孔形不规则的试样.当应变量为40%时,孔隙率为64.81%~78.82%的泡沫钢,其单位体积的能量吸收值为23.92~7.32 MJ/m^3,约为泡沫铝的5~7倍.4种不同孔隙率泡沫钢样品的理想吸能效率(I)均达0.85以上,表明泡沫钢可以作为一种理想的吸能材料.

To prepare high strength and lightweight steel foam materials for energy absorbing,430 L stainless steel powder was used as raw material and CaCl2 as pore forming agent.Steel foam with porosity ranging from 64%to 80%and cell size from 1 mm to 4 mm were fabricated by a sintering-dissolution process.The specimens were tested and analyzed by axial quasi-static compression,SEM,and XRD.The effects of porosity and cells′shape on the energy absorption property,the deformation mechanism,and collapse of cells during compressing were analyzed and discussed.The experimental results show that the cell structure of steel foams is nearly spherical and evenly distributed,and the cell can be connected effectively through microspores in the cell wall.In the process of compression deformation,the deformation started from the irregular and thin wall firstly,and then expanded to the heterogeneous deformation of multiple deformation bands.The plateau stress of samples decrease with increase of the porosity,and corresponding plateau stress was 59.37~17.04 MPa when the porosity was between 64.81%~78.82%.Under the same porosity,the yield stress of steel foams with spherical cells was higher than with irregular cells.When stain was 40%,the unit volume energy absorption of steel foam with porosity between 64.81%and 78.82%was in the range of 23.92~7.32 MJ/m^3 which is about 5 to 7 times that of the aluminum foam.The ideal absorption efficiency(I)of four foam samples with different porosity were all above 0.85.The results indicate that steel foam is a kind of excellent energy absorption material.