节点文献
耐磨钢在湿磨和空蚀条件下的腐蚀磨损性能与机制
【作者】 邢文静；
【作者基本信息】 合肥工业大学 ， 材料学， 2007， 博士
【摘要】 本论文研究了几种耐磨钢在不同介质中湿磨和空蚀实验条件下的腐蚀磨损性能和机制。应用了失重法、扫描电镜、显微硬度、电化学及表面粗糙度测量等方法，探索研究了不同介质和实验条件对耐磨钢冲击腐蚀磨损机理和空蚀机理的影响。针对低碳高合金钢和两种湿式研磨机衬板常用材料高锰钢和中碳高合金钢在酸性条件下、不同颗粒中冲击腐蚀磨损的研究表明，试样硬度和颗粒硬度的比值小于0.85时，颗粒硬度对磨损起决定作用。低碳高合金钢和高锰钢在腐蚀介质中不同冲击功的作用下，高锰钢由于耐腐蚀性差，大大降低了它的使用性能，腐蚀对材料流失的促进很大。而低碳高合金钢因为其耐腐蚀性能好，加之板条马氏体硬度高，阻碍裂纹扩展，使得它具有较好的耐冲击腐蚀性能。采用电化学手段，通过极化曲线、交流阻抗谱和线性电阻的测量，对两种钢在不同腐蚀介质中的纯耐腐蚀性能作了一系列的研究。结果表明，在酸性和中性介质中，由于低碳高合金钢成分中含有Ni、Cr、Mo等元素，因此在试样的表面形成钝化膜，使得试样的耐腐蚀性增加。但低碳高合金钢在碱性介质中一直处于活性溶解状态，耐腐蚀性较之在酸性和中性介质中差。高锰钢在中性介质和酸性介质中一直处于活性溶解状态，腐蚀速率较大，但由于高锰钢阴极极化阻碍了阳极腐蚀，使得它在碱性中的耐腐蚀性相对中性和酸性介质中的耐腐蚀性大大增加。在空蚀实验的动态条件下，通过引进电化学手段，系统地研究了在不同介质中，冲击、腐蚀、磨损三因素在实验过程中对试样破坏的影响及其交互作用。研究结果表明，在酸性和中性介质中，腐蚀因素不是影响低碳高合金钢的空蚀性能的主要因素，通过低碳高合金钢在中性介质中的腐蚀磨损交互作用的各个分量所占的份额来看，低碳高合金钢腐蚀引起的力学破坏增量W_CE和力学破坏引起的腐蚀增量W_EC大致相同，分别占有总量的7.8％和7.2％。高锰钢在空蚀条件下，腐蚀引起的力学破坏增量W_CE和力学破坏引起的腐蚀增量W_EC分别占总量的29.3％和11.2％，说明腐蚀是影响高锰钢的主要因素。在碱性介质中，高锰钢的耐腐蚀性能尤其优越，从而使得高锰钢在这种介质中的抗空蚀性能远比低碳高合金钢好。低碳高合金钢在空蚀条件下，铁素体相区率先产生裂纹、脱落，最终导致试样破坏。高锰钢在空蚀的初期，通过滑移和加工硬化等塑性变形，使得它具有很好的抗空蚀能力，但在空蚀后期，位错冲破塞积，致使试样破坏。
【Abstract】 The impact-corrosion properties and the corresponding mechanism of kinds of wear -resistance steels under wet-grinding and cavitation in different medium are studied by means of mass loss, SEM, micro-hardness , electrochemistry and surface roughness measurement et al.During the tests on wear-resistant properties in acid circumstance with impact particals of different sizes, it is found that the wear-resistant properties of carbon high alloy steel, high manganese steel and medium carbon alloy steel are controlled by the hardness of impacting grain when the ratio of sample hardness to impacting partical hardness is less than 0.85.Low carbon high alloy steel and high manganese steel are impacted in corrosive slurry with different impact stress. It is showed that the material mass loss of high manganese steel is accelerated by the corrosion circumstance due to its poor corrosive-resistant properties. On the other hand, low carbon high alloy steel showed excellent corrosive - erosion resistance to corrosion circumstance due to the excellent corrosion-resistant and cracking-blocking lathy martensite microstructure of high hardness blocking crack spreading.To comparatively study the mechanism of corrosive - erosion resistance of low carbon high alloy steel, different kinds of electrochemistry experiments were conducted, including Potentiodynamic polarization curves, Nyquist plots and Rp measured. It is showed that low carbon high alloy steel exhibit excellent corrosive-wear-resistance properties in acid and neuter circumstances, due to the existence of easy-sample-surface-form passivation elements, Ni, Cr, Mo and the quick -passivation-mending ability of Mo. However, in alkalescent circumstance, low carbon high alloy steel is in active dissolving conditions, resulting in lower corrosion-resistance properties than in acid and neuter circumstance. On the contrary, high manganese steel is in active dissolving states in both acid and neuter circumstances, resulting in the large corrosive current. In alkalescent slurry, due to the anode corrosion-blocking effect of cathode polarization, corrosion-resistant properties of high manganese steel are superior to in acid and in neuter circumstances.Cavitative resistances of low carbon high alloy steel and high manganese steel are also studied. To identify the influence of impact, corrosion and wear corrosive - erosion process and the interaction among these three factors, a systemic electrochemistry exoeriments in dynamic condition are conducted with cavitation experimental equipment. Research results show that the ratio of the corrosion caused erosion increment (7.8%) and that of erosion caused corrosion increment (7.2%) in gross are similar, indicating that corrosive medium has little influence on the cavitation-erosion-resistance properties of low carbon high alloy steel in acid and neutral circumstances. However, as to high manganese steel, the corresponding ratios changed to 29.3% and 11.2%, respectively, indicating that corrosion plays primary role on the resistance properties of high manganese steel to cavitation erosion. But in alkalescent circumstance, high manganese steel exhibit more excellent cavitation corrosion resistance property than that of low carbon high alloy steel. Under cavitative condition, crackles produce and break off easily in the ferrite phase of low carbon high alloy steel, finally resulting in the sample damage. On the contray, in early cavitation test, high manganese steel has very excellent cavitative resistance by dislocations slippage and work-harding ; while in late cavitation test, dislocations crash and damage the samples.