中国激光, 2007, 34 (s1): 66, 网络出版: 2009-05-25
球墨铸铁表面激光点状合金化组织及热疲劳性能研究
Microstructure and Thermal Fatigue Behavior of Spot Array Laser Alloying for Nodular Cast Iron
激光技术 激光点状合金化 球墨铸铁 显微组织 热疲劳性能 laser technique spot array laser alloying nodular cast iron microstructure thermal fatigue
摘要
采用CO2激光器对珠光体基体的球墨铸铁表面进行了点状合金化处理。设计了激光合金化点的分布方案，研究了强化层的组织和性能，对激光处理后的试样进行了热疲劳实验。结果表明，预置TH-2A型C-Si-B-RE合金化涂层，选择适当的激光辐照参数，可以获得表面光洁、硬度高、无裂纹的合金化层。热疲劳实验的循环温度为700 ℃至25 ℃，加热90 s，冷却10 s，共循环90次。实验发现，激光合金化点及其热影响区(HAZ)以外表面区域的热疲劳裂纹萌生主要与石墨球的存在及其圆整度有关，基体中裂纹的扩展在点状合金化区周围受到阻滞。合金化区内热疲劳裂纹同样在合金化区与热影响区的宏观界面被阻滞。热影响区内裂纹萌生主要与热循环过程中产生的氧化物有关，热影响区内极为细化的珠光体团有效地阻滞了裂纹并迫使其只能沿晶界缓慢扩展。
Abstract
Spot array laser alloying of C-Si-B-RE on nodular cast iron using CO2 laser has been made. The microstructure and characteristics of the alloying layer and HAZ have been analyzed and thermal fatigue tests on the laser treated samples have been done. The results demonstrate that laser alloying of C-Si-B-RE on nodular cast iron is able to achieve satisfying layers with high hardness and smooth surface which are free of cracks. The laser treated specimens were tested under the specified thermo-cyclic condition: 700 ℃～25 ℃, heating 90 s, cooling 10 s, 90 times. The results show that the initiation of the crack in the substrate is relevant to graphite nodular and its morphology. The thermal fatigue cracks in substrate and alloying area are retarded by the HAZ. The initiation of the crack in the HAZ is relevant to the oxide formed during thermal fatigue test. The refining pearlite colonies in heat affected zone (HAZ) compel the crack to develop slowly along the grain boundaries.
王海龙, 李正阳, 王秉毅, 刘文今, 钟敏霖, 杜志毅, 冯晓星, 梁德礼, 刘建国. 球墨铸铁表面激光点状合金化组织及热疲劳性能研究[J]. 中国激光, 2007, 34(s1): 66. 王海龙, 李正阳, 王秉毅, 刘文今, 钟敏霖, 杜志毅, 冯晓星, 梁德礼, 刘建国. Microstructure and Thermal Fatigue Behavior of Spot Array Laser Alloying for Nodular Cast Iron[J]. Chinese Journal of Lasers, 2007, 34(s1): 66.
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