Study On The Preparation And Compressive Properties Of 430L Stainless Steel Porous Material

As a new type of metal porous material developed in recent years,steel foam has the advantages of high specific strength?high specific modulus?high temperature resistance?light weight?porous filtration and so on.At the same time,steel foam is far toughness?impact energy absorption and so on higher than aluminum foam.Therefore,it has broad application prospects in safety engineering?automobile manufacturing?shipbuilding.In this paper,430L stainless steel powder was used as raw material and Ca Cl₂ as pore forming agent,steel foam and steel foam filled aluminum alloy tube with different porosity?different pore size and pore morphology were fabricated by sintering-dissolution process and physical bonding process.The specimens were tested and analyzed by axial quasi-static compression,SEM and XRD.The effects of porosity?pore structure?pore size?strain rate on the energy absorption property?plateau stress?the deformation and collapse mechanism of cells were analyzed and discussed during compressing.The main results of the study are as follows:?1?The experimental parameters of pressing pressure 300MPa and holding time5min?drying temperature 120?and holding time 120min?sintering temperature1100?and holding time 120min were adopted,steel foam and steel foam filled aluminum alloy tube with porosity ranging from 64%to 81%and cell size from 1 mm to 4 mm were fabricated by sintering-dissolution process and physical bonding process.Metal particles to form metallurgical bonding,matrix is?-Fe,cells formed due to removal of the pore forming agent,and the cells can be connected effectively through microspores in the cell wall by sintering temperature 1100?and holding time 120min.?2?Deformation mechanism and compressive properties of steel foam during quasi-static compression were studied by universal testing machine.The results show that,in the process of compression deformation,the deformation starts from the irregular and thin wall firstly,and then expands to the heterogeneous deformation of multiple deformation bands.The plateau stress of samples increase with the decrease of porosity,and the plateau stress of steel foams with spherical cells is higher than with irregular cells,and the pore size has little effect on the overall plateau stress.Corresponding plateau stress is 59.37MPa¹7.04MPa when the porosity is between64.81%⁷8.82%,the unit volume energy absorption of steel foam is in the range of23.92MJ·m^-37.32MJ·m^-3 which is 5 to 7 times that of the aluminum foam when stain is 40%.Modulus of steel foam is 1.63GPa⁵.84GPa with porosity of 66.37%⁸0.91%.The ideal absorption efficiency?I?of four foam samples with different porosity is above 0.85.The results indicate that steel foam is a kind of excellent energy absorption material.?3?When the compression strain rate are 10^-4s^-1?10^-3s^-1?10^-2s^-1?10^-1s^-1,the plateau stress are 10.63MPa?11.15MPa?11.58MPa?13.08MPa,and the unit volume energy absorption are 4.49MJ·m^-3?5.05MJ·m^-3?5.10MJ·m^-3?5.37MJ·m^-3,the energy absorption efficiency difference is 0.33⁰.36,the ideal energy absorption efficiency is0.84⁰.88.The maximum energy absorption value of the steel foam specimen with same parameter which is about 1.23 times that of the aluminum foam.Therefore,the strain rate has no significant influence on the mechanical properties and energy absorption performance of the steel foam?quasi-static?.?4?Deformation mechanism and compressive properties of steel foam filled aluminum alloy tube during quasi-static compression were studied by universal testing machine.The results show that steel foam filled aluminum alloy tube and aluminum alloy tube shows deformation model of axisymmetric ring.At the same porosity?66.32%⁸0.58%?,compared to the steel foam,the plateau stress of filled tube increased by 25.74MPa to 30.63MPa,and the compressive strength increased by55.56%to 287.88%,the energy absorption value of filled tube?strain of 40%?increased by 10.24MJ·m^-315.82 MJ·m^-3,the value increased by 79.97%to 216.50%.Meanwhile,the plateau stress of filled tube is 6.51MPa¹1.40MPa higher than the sum of the plateau stress of steel foam and aluminum alloy tube,the energy absorption value of filled tube is 3.65MJ·m^-39.13MJ·m^-3 higher than the sum of the steel foam and aluminum alloy tube.At the same porosity,the elastic modulus of the filled tube is 0.86GPa².88GPa higher than that of the steel foam,and the elastic modulus improvement is 14.73%¹76.69%.The ideal energy absorption efficiency is above 0.90 and the maximum is 0.98.This shows that the filled tube is a kind of energy absorbing material with better performance.