45钢硼-稀土（铬）共渗工艺与组织性能的研究

【作者】 杨志兵；

【导师】 彭志辉；

【作者基本信息】 中南大学 ， 材料物理与化学， 2004， 硕士

【摘要】 本论文旨在通过硼的多元共渗的方法，来降低渗硼温度和改善渗硼层的组织和性能，共渗元素选用稀土和铬。运用正交实验法来确定渗硼工艺的参数（渗硼温度、渗硼时间、稀土加入量和铬加入量）对渗硼层厚度的影响，从而确定合理的渗硼工艺。用光学显微镜、金相显微镜、扫描电镜（SEM）、X射线衍射仪、显微硬度计、磨损试验机等仪器和设备来观察渗层的组织和测试渗层的性能。 通过实验得出如下结论： 渗层厚度随着温度的升高而增加，时间与渗层厚度的关系满足抛物线的规律，稀土对渗层有催渗作用，但加入量有最佳范围；合理的渗硼工艺：温度：880—920℃；时间：4—6小时；稀土的加入量：4—6％；铬的加入量：1—3％。 渗层组织都是由单相的Fe₂B组成，呈现出强烈的织构生长，渗层以齿状楔入基体，从表至里组织是Fe₂B→过渡区→基体；渗硼层提高了45钢的高温抗氧化性和在15％硫酸溶液中的耐蚀性。 与单渗硼渗层相比，共渗层组织得到改善，最外层疏松程度减轻；稀土和铬已经渗入共渗层，但在共渗层的分布不太均匀；加入稀土的共渗层的显微硬度梯度和共渗层的脆性得到改善；共渗层的耐磨性优于单渗硼渗层，尤其是加了稀土的共渗层的耐磨性更为优良。更多还原

【Abstract】 To reduce the boronizing temperature and improve the structure and properties of boride layer was the purpose of this paper. The method of multi-boronizing was used. The elements of multi-boronizing were Rare Earth element and Chromium element as well as Boron element. The method of orthogonal experiment was used to investigate the effect of parameter of boronizing process on the thickness of the boride layer. The parameter of boronizing process included boronizing temperature, boronizing time, the addition of Rare Earth and the addition of Chromium. Then the proper parameters of boronizing process were determined. Devices and equipments such as optical microscope, metallographic microscope, scanning electron microscope (SEM), X-ray diffractometer, microhardness tester, wear tester and so on, were used to observe the structure of boride layer and test properties of boride layer.The conclusions as follows:The higher boronizing temperature, the more the thickness of the boride layer. The relation between the thickness of the boride layer and boronizing time obeyed the parabolic law. Rare Earth could accelerate the growth of the boride layer. But there was optimal range for the addition of Rare Earth. The rational boronizing process as follows: Boronizing temperature: 880-920. Boronizing time: 4-6h. The addition of Rare Earth: 4-6%. The addition of Chromium: 1-3%.The structures of all boride layers consisted of simple Fe2B phase. The tooth-like structure of the boride layer inserted the matrix. The growth of the boride layer appeared sharp texture. From the surface of the boride layer to the matrix, the structures were Fe2B phase, the transition zone, the matrix, respectively. The high temperature oxidation resistance and the corrosion resistance in sulfuric acid solution(15%) of the boride layer were better than these of 45 steel.Comparing with the case of boronizing, the structure of the boride layer of multi-boronizing was improved. The degree of outermost rarefaction of the boride layer of multi-boronizing was relieved. Rare Earth element and Chromium element existed in the boride layer, buttheir distributions in the boride layer were non-uniform. Themicrohardness gradient of the boride layer contained Rare Earth elementwas improved. The brittleness and the wear resistance of the boride layerof multi-boronizing were better. Particularly, the wear resistance of boridelayer contained Rare Earth element was best.更多还原