Effect of RE Elements on the Morphology of Carbides and the Impact Fatigue Properties of the Low Cr White Cast Iron

An apparatus of zone melting unidirectional solidification with a steep temperature gradient andan impact fatigue tester were used.The effect of RE elements on the morphology of carbides and the impactfatigue properties of the low Cr white cast iron were investigated.Experimental results showed that the modi-fying effect of RE elements was remarkable on the M3C carbides.With the addition of RE elements in thelow Cr iron,a lot of plate-like carbides were transformed into lath-like and rod-like ones.The higher thecontent of RE elements was,the more was the fraction of the lath-like and rod-like carbides.In the low Crwhite cast iron,the RE modifying agent can efficiently increase the impact fatigue resistance and decrease thecrack growth rate and delay the time of incipient cracking.With the increase of the content of RE elements inthe low Cr cast iron,the impact fatigue resistance increased greatly and the crack growth rate decreased rap-idly.     

二元铝硅合金激光处理显微组织特征

探讨了不同成分的Al-Si二元合金经激光处理后,激光熔区的显微组织特征.讨论了激光熔区的凝固特征及成分与激光熔区的平均显微硬度的关系。     

球墨铸铁激光表面改性的研究

文中探讨了激光对球墨铸铁表面熔化处理,以及表面合金化对其钝化性能和耐腐蚀性能的影响。实验结果表明,激光处理后球铁表面产生的渗碳体和奥氏体细晶区,可大幅度降低球铁的腐蚀速度,使合金具有很好的钝化倾向(在5％H_2SO_4和5％HNO_3溶液中)。在激光合金化条件下,合金元素Cr和Si的作用不同,Cr可促进球铁钝化提高耐腐蚀性,而Si的作用则相反。     

30CrNi2MoVA钢激光相变硬化技术

研究了30CrNi2MoVA钢激光淬火后淬硬层微观结构特征及工艺参数对硬化层深度和硬度的影响。结果表明,激光淬火硬化层依其组织特征,分为完全淬硬层、过渡层和热影响层;硬化层深度随着激光功率的升高和扫描速度的减小而逐渐增加,表面硬度则存在一个极大值。