Establishing the Principles of Compositional Design for Long Life Rail Steels

铁路轨道是一个复杂的互联网络系统，其枢纽是车轮和钢轨之间的接触。因此，钢轨的退化也是许多系统变量的函数，并且该关键部件的组成设计和微观结构属性的优化需要基于对整个铁路网络所经历的应力状态范围的透彻理解和明确定义。正是在这种背景下，拟议项目的重点是以下任务，其综合结果将使轨道钢的成分和微观结构设计的优化，以提供所需的寿命和较低的生命周期成本。1.冶金属性的表征：这将在各种钢轨钢上进行，包括原始钢轨钢和受控试验后的钢轨钢。微观结构表征将包括评估，如测量层间距，板条厚度，体积分数和溶解度。建立全方位的轮轨接触条件：铁路所需的功能高度依赖于轨道和交通特性，因此即使在单一网络中，轮轨接触条件也可能变化很大，从高速平线到客运和货运混合线的紧凑曲线。将整理大量过去的研究结果，以确定在混合交通网络3上可能遇到的接触条件的范围。受控实验室检查：一台大直径双圆盘试验机已经升级，以便能够开发类似于轨道中遇到的各种接触条件。一种新的方法将被用来从商业上可用的轧制钢轨中提取样品。如有必要，还将补充定制成分的轧制板材。在严格控制的条件下，将为各种可用的和新型的钢轨钢建立耐磨性和滚动接触疲劳的比较。上述分析的结果将经过神经网络分析，以确定各种组成元素对受控试验下建立的退化率的影响。预期的产出是优化钢轨钢成分的冶金设计规则，然后可以形成钢轨规范（如EN 13674 -1 2017）中包含的成分合理化的基础。

Railway track is a complex web of interconnected systems whose hub is the contact between wheel and rail. Consequently, degradation of rail is also a function of many system variables and the optimisation of the compositional design and microstructural attributes of this key component needs to be based on a thorough understanding and clear definition of the range of stress states experienced throughout a rail network. It is within this context that the proposed project is focused on the following tasks, the combined results of which will enable the optimisation of the compositional and microstructural design of rail steels to deliver the desired longevity and lower life cycle costs.1. Characterisation of metallurgical attributes: This will be undertaken on a wide range of rail steels both in the virgin and after controlled testing. Microstructural characterisation will include assessments such as measurement of interlamellar spacing, lath thickness, volume fraction cementite, and cementite dissolution.2. Establishing full range of wheel-rail contact conditions: The functionality required of the rail is highly dependent on the track and traffic characteristics and hence the wheel-rail contact conditions even within a single network can vary widely, from those for high-speed plain line to tight curves on mixed passenger and freight lines. Extensive past research results will be collated to define the range of contact conditions that could be encountered on a mixed traffic network3. Controlled laboratory tests: A large diameter twin disc test machine has been upgraded to enable development of a wide range of contact conditions that resemble those that are encountered in track. A novel methodology will be used to extract samples from commercially available rolled rails. These will be supplemented, if necessary, with rolled plates of bespoke compositions. Comparative resistance to wear and rolling contact fatigue will be established for the wide range of available and novel rail steels under closely controlled conditions.The results from the above analysis will be subjected to neural network analysis to establish the influence of the various compositional elements on the rate of degradation established under controlled testing. The expected output is a metallurgical design rule for the optimisation of rail steel compositions that could then form the basis for the rationalisation of compositions included in rail specifications, such as EN13674-1 2017.