高铬白口铸铁半固态成形研究

【作者】 戴长泉；

【导师】 周荣；

【作者基本信息】 昆明理工大学 ， 材料加工工程， 2004， 硕士

【摘要】 半固态金属加工技术是近年来全世界范围内竟相开展研究与开发的一项金属加工技术，半固态成形技术发展至今已有30多年的历史，它以其诸多的优越性而被专家们称为21世纪新一代金属成形技术，在众多的研究中所使用的材料主要集中在低温合金，而对高温合金特别是铁基合金的研究却很少。而且非枝晶组织的制备也主要局限于搅拌和特殊的预处理(或后热处理)方法。针对这种现状，本研究以高熔点的铁基合金为研究对象，应用新的非枝晶组织制备方法，分别获得了具有细晶组织的亚共晶高铬白口铸铁和过共晶高铬白口铸铁的半固态铸锭。 寻找一个简便、可靠又经济的金属半固态成形工艺是本实验的目的。 对于亚共晶成分的合金，本研究采用低温浇注倾斜板冷却体法获得了理想的亚共晶高铬铸铁半固态非枝晶组织，并且从形状系数和等效直径(亚共晶合金)两个方面定量评价了所获得的非枝晶组织特征，得出形成理想颗粒状初生奥氏体的最佳工艺参数。采用低温浇注倾斜板冷却体法，在浇注过程中，液相线以上50℃左右浇注，是最佳的半固态成形工艺条件，所获得的初生奥氏体颗粒平均形状系数为0.792，平均等效直径为40.7μm。并对亚共晶高铬铸铁试样进行了冲击磨料磨损性能测试，性能测试结果表明半固态成形技术使材料的耐磨性有一定的提高。 对于过共晶成分的合金，采用低温浇注倾斜板冷却体法使过共晶高铬铸铁的初生碳化物明显细化，利用不同固定区域内碳化物的体积分数及其颗粒数来定量描述初生碳化物形态及分布，得出形成理想细晶初生碳化物的最佳工艺参数。即液相线以上50℃左右浇注，是最佳的半固态成形工艺条件。并进行了冲击磨料磨损性能测试，性能测试结果表明半固态成形技术使过共晶高铬铸铁耐磨性得到了一定的提高。 总之，采用倾斜板冷却体法制作半固态坯锭，工艺流程短、容易操作、过程稳定，是一种比较可行的工艺方法且适合批量生产。此课题的开展和研究丰富了半固态成形方法，扩展了半固态成形技术及半固态合金的研究领域。为进一步研究半固态铁基合会及其直接成形技术提供了理论和实验基础。加快了半固态成形技术在工业上的应用步伐。更多还原

【Abstract】 Semi-Solid Metal Process has actively been spread all around the world in recent years. Up to now Semi-Solid Metal Process has been developed for more than 30 years, it is called by experts as a new generation of metal formation technique in 21 century for the presence of a lot of advantages. Among many studies, the materials researched concentrate on nonferrous alloys. However, the alloys with high molting point especially Fe-base alloy, which had not much study in producing SSM. The methods of fabricating non-dendritic microstructure are confined to stirring and special pretreatment(pr post-treatment). In view of this situation, the hypo-eutectic Fe-Cr-C white cast iron,the hyper-eutectic Fe-Cr-C white cast iron with high melting point was choosen as a semi-solid alloy. A new method to form non-dendritic microstructure was used to fabricate semi-solid Fe-base alloy bellets.Looking for a good way which is simple, dependable and economical to produce semi-solid blocks is the experimental goal.In the experiment for the hypo-eutectic, non-dendretic microstructures were obtained by a cooling plate proessing technique. And the non-dendretic microstructures were characterized by equivalent diameter and shape factor. The best processing conditions to form ideal primary austenite were concouded. The temperature is 50 C above the liquidus is the best processing condition, average shape factor of primary austenite obtained is 0.792, average equivalent diameter is 40.7um. Abrasion resistance of hypo-eutectic high chromium white iron by normal casting and hypo-eutectic high chromium white iron by Semi-solid state forming has been investigated in this paper by means of impact abrasion test. The results show that the abrasion resistance of hypoeutectic high chromium white iron by Semi-solid state forming is higher than that of hypoeutectic high chromium white iron by normal casting.In the experiment for the hyper-eutectic, primary carbide phase was thinned by a cooling plate proessing technique. And the thinedmicrostructures were characterized by amount and volume fraction of carbide phase in different area. The best processing conditions to form ideal thinned Carbide phase were concouded. The temperature is 50C above the liquidus is the best processing condition., Abrasion, resistance of hyper-eutectic high chromium white iron by normal casting and hypoeutectic high chromium white iron by Semi-solid state forming has been investigated in this paper by means of impact abrasion test. The results show that the abrasion resistance of hyper-eutectic high chromium white iron by Semi-solid state forming is higher than that of hypoeutectic high chromium white iron by normal casting.In a word, To make semi-solid blocks by a cooling plate proessing technique, it has some advantages such as short technological process , easy-to-move , and the stable processing course and suit to industrilize. The method and metals field of the study Semi-solid state forming is expanded. It must lay a good theoretical and experimental foundation on studying ferro-based alloys by a cooling plate proessing technique. All of those must speed up industry application steps on direct formation technique of SSM.更多还原