铁素体抗菌不锈钢的铜析出机理与性能控制

发布时间：2018-05-24 10:53

  本文选题：铁素体不锈钢 + 富铜相　； 参考：《北京科技大学》2016年博士论文

【摘要】：抗菌不锈钢兼具结构材料和抗菌功能材料的双重特点,极大地拓宽了抗菌材料的应用领域。尤其是低成本的铁素体抗菌不锈钢,可广泛用于家电厨具、卫生洁具等金属抗菌产品。开发和应用具有优良抗菌性能的抗菌不锈钢既可带来巨大的经济效益,又可产生广泛的社会价值。本文运用铌钛双稳定超纯化设计思路,采用高铬低镍设计思想,添加1.5wt%左右的铜,采用真空感应炉冶炼和抗菌处理,成功开发出抗菌性能、力学性能、成形性能和耐蚀性能良好配合的超纯铁素体抗菌不锈钢。通过高温拉伸试验研究了加热温度和时间、变形温度和速率对试验钢高温热脆行为的影响。结果表明,试验钢分别在加热温度1150℃、加热时间60min、变形温度1150℃和中等变形速率10-2 s-1时,其热脆敏感性达到最大值。分析认为是铜元素偏聚引起的。通过热压缩实验,获得试验钢的热变形方程：ε=81×1013sinh(ασ)4.6825 exp(-(323000)/RT)。通过耦合能量耗散图与流变失稳图,获得试验钢热加工图。退火工艺对试验钢析出行为具有显著影响。随抗菌退火温度的升高和抗菌退火时间的延长,析出相形状由球状向杆状转变,析出相尺寸和平均间距均增大。富铜相与基体存在K-S关系,即(111)ε-Cu//(110)α-Fe,[110]ε-Cu//[111]α-Fe。试验钢宜采用固溶+抗菌退火的制备工艺。抗菌退火温度为800℃时,抗菌性能最佳。随退火时间的延长,抗菌率不断增加,退火时间为1h后,抗菌率超过99%。析出相数量和尺寸达到获得良好抗菌性能的临界值,分别为(54.1±2.0)nm和173/100μm。铜析出相体积分数需超过0.77%。析出相尺寸和单位面积内析出相数量也是达到良好抗菌效果的重要因素。通过热力学计算软件Themo-calc模拟试验钢沉淀开始析出温度为926℃；800℃时,铜析出相体积分数约为0.775%。根据错配位错理论,对铜析出相在试验钢基体中沉淀析出过程进行理论计算,得到形核率-温度曲线(NrT曲线)和相变动力学曲线(PTT曲线)。对铜析出相Ostwald熟化过程进行了表征。熟化速率为m=((8σVpDCo)/(9CpRT))1/3,800℃时,实测析出相平均颗粒尺寸为rt=2.46t1/3。通过原子探针层析技术(APT)测试了不同时效时间试验钢中富铜相的演化规律。随着时效时间的延长,纳米富铜相的尺寸逐渐增大,数量密度降低。长大过程中,Mn和Ni原子在富铜相表面发生偏聚从宏观和微观两方面探讨了析出相的抗菌机理。通过拉伸试验测定试验钢的平均塑性应变比rm和各向异性指数△r,探讨其与抗菌退火温度和时间,以及微观织构的关系。通过动电位极化曲线测定试验钢耐点蚀性能。随着退火温度的升高和退火时间的延长,试验钢的点蚀电位均下降。富铜相尺寸越大,越不利于材料的耐蚀性能。
[Abstract]:Antibacterial stainless steel has the dual characteristics of structural materials and antibacterial functional materials, which greatly broadens the application field of antibacterial materials. Especially low-cost ferrite antibacterial stainless steel, can be widely used in household appliances kitchen utensils, sanitary ware and other metal antibacterial products. The development and application of antibacterial stainless steel with excellent antibacterial properties not only bring great economic benefits, but also produce a wide range of social values. In this paper, using the design idea of niobium and titanium double stable super-purification, adopting the design idea of high chromium and low nickel, adding about 1.5 wt% copper, using vacuum induction furnace smelting and antibacterial treatment, the antibacterial and mechanical properties have been developed successfully. Ultra-pure ferrite antibacterial stainless steel with good formability and corrosion resistance. The effects of heating temperature, time, deformation temperature and rate on the high temperature embrittlement behavior of the steel were studied by high temperature tensile test. The results show that the thermal embrittlement sensitivity of the test steel reaches the maximum at 1150 鈩，

本文编号：1928791