轧钢铁皮制备多孔不锈钢化学成分及孔隙控制

 为了充分发挥氧化铁皮含铁品位高、杂质元素含量低、产生量大的优势和特点,并开发高附加值的金属制品,采用真空还原烧结的方法制备了316多孔不锈钢,并确定了适宜的制备工艺以及孔隙率的影响因素。研究过程中采用高温真空管式炉对试样进行还原烧结制备;采用直读光谱、氧氢氮联合检测仪、X射线衍射分析仪、扫描电镜等设备对试样的化学成分、物相组成和微观形貌进行了分析。研究结果表明,以轧钢铁皮为主要原料,配入还原剂及其他合金粉末,通过高温真空还原可以得到成分合格的316多孔不锈钢,确定最佳制备工艺为10-3Pa真空度、1 200 ℃下保温3 h;还原烧结过程中,锰合金的收得率仅为61%。制备出的试样为单一的奥氏体组织,同时有Cr₇C₃在晶内析出,晶界附近存在σ相析出。保温0~3 h内,试样的孔隙率由37.26%增加至40.27%,延长保温时间至4 h,金属颗粒之间的烧结更加完全,孔隙率降低至35.16%;将制坯压力由76.43增加至152.87 MPa,多孔不锈钢的孔隙率由42.07%降低至34.44%,呈现逐渐降低趋势。当制样压力大于152.87 MPa时,发生了造孔剂偏聚的现象,导致孔隙率略微增加至35.76%。造孔剂碳酸氢铵每多增加10%,多孔不锈钢的孔隙率增加9.3%。通过对正交试验分析发现造孔剂加入量对多孔不锈钢孔隙率的影响最为显著,制样压力次之,保温时间对孔隙率的影响最小。

Chemical composition and pore control of porous stainless steel prepared by rolling steel skin

In order to give full play to the advantages and characteristics of high iron grade,low content of impurity elements and large amount of iron oxide scale,and to develop high value-added metal products,this paper adopts vacuum reduction sintering method to prepare 316 porous stainless steel,and determines the appropriate factors affecting the preparation process and porosity. In the research process,a high-temperature vacuum tube furnace was used to reduce and sinter the samples;direct-reading spectroscopy,combined oxygen,hydrogen and nitrogen detectors,X-ray diffraction analyzers,scanning electron microscopes and other equipment were used to determine the chemical composition,phase composition and microstructure of the samples. The morphology was analyzed. The research results show that using rolled steel skin as the main raw material,with reducing agent and other alloy powders,qualified 316 porous stainless steel can be obtained through high-temperature vacuum reduction. The best preparation process is determined to be 10-3Pa vacuum and heat preservation at 1 200 ℃ for 3 h. During the reduction and sintering process,the yield of Mn alloy is only 61%. The prepared sample is a single austenite structure,and at the same time,Cr₇C₃ is precipitated in the grain,and there is a σ phase precipitation near the grain boundary. The porosity of the sample was increased from 37.26% to 40.27% within 0-3 h of holding time,and the holding time was extended to 4 h,the sintering between the metal particles was more complete,and the porosity was reduced to 35.16%.The billet pressure was increased from 76.43 to 152.87 MPa,the porosity of porous stainless steel decreased from 42.07% to 34.44%,showing a gradual decrease trend. When the sample preparation pressure was greater than 152.87 MPa,segregation of the pore former occurred,causing the porosity to slightly increase to 35.76%. The porosity of porous stainless steel increases by 9.3% for every 10% increase in pore-forming agent ammonium bicarbonate. Through orthogonal test analysis,it is found that the amount of pore former has the most significant effect on the porosity of porous stainless steel,followed by sample preparation pressure,and holding time has the least effect on porosity.