大尺寸K465镍基高温合金母合金铸锭表面缺陷形成机理  

Formation Mechanisms of Surface Defects in Large-Sized K465 NickelBased Superalloy Casting-Ingot

作　　者：王树森 舒德龙 王振江[2] 谢君[2] 梁军 荀淑玲 侯桂臣[2] 于金江[2] WANG Shu-sen;SHU De-long;WANG Zhen-jiang;XIE Jun;LIANG Jun;XUN Shu-ling;HOU Gui-chen;YU Jin-jiang(Anshan Military Representative office of Shenyang Military Representative Bureau,Naval Equipment Department of the Chinese People's Liberation Army,Anshan 114001,Liaoning,China;Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,Liaoning,China;Sino-Foundry Refractory(Jiangsu)Co.,Ltd.,Zhenjiang 212114,Jiangsu,China)

机构地区：[1]中国人民解放军海军装备部驻沈阳地区军事代表局驻鞍山地区军事代表室,辽宁鞍山114001 [2]中国科学院金属研究所,师昌绪先进材料创新中心,辽宁沈阳110016 [3]中铸新材工业(江苏)有限公司,江苏镇江212114

出　　处：《铸造》2021年第5期547-553,共7页Foundry

基　　金：国家自然科学基金(51701212,51771191,51971214);辽宁省自然基金项目(2019-MS-336);中国科学院科技服务网络计划区域重点项目(KFJSTS-QYZX-079);2018年度泰州市高层次创新创业人才引进计划项目(2018-21);2020年度中国科学院青年创新促进会项目(2020198)。

摘　　要：通过对大尺寸K465镍基高温合金母合金锭表面缺陷进行组织观察和缺陷附近的元素浓度分布测量,研究了表面气孔、细小裂纹及蛛网状裂纹的形成机理。结果表面,浇注期间,金属锭模内壁放气或内壁上附着的少量气体在钢液浇注瞬间体积增大,并延铸锭薄弱区域向合金锭内膨胀,是导致母合金锭表面产生孔洞的主要原因。锭模预热期间内壁形成的碳层被钢液卷入并与熔体中的Ti反应形成脆性较大的TiC,并在合金锭冷却收缩期间断裂,是表面产生细小裂纹的主要原因。而原料中通过精炼处理未完全消除的N元素杂质,以及由真空炉漏气产生的“过堂风”可促进熔体中形成的大量TiN颗粒,随合金液注入锭模后,局部TiN颗粒聚集引起该区域液相流动受阻,阻碍与周围区域的浓度交换,导致形成α-W;另一方面,TiN颗粒促进大量MC碳化物析出,使该区域与周围的组织差异性较大,导致该区域在合金锭冷却期间发生热裂,从而产生蛛网状裂纹。The formation mechanisms of the defects,such as blowhole,fine-cracks and arachnoid cracks,on the surface of K465 nickel-based superalloy casting-ingot with large size have been studied by observing the microstructure and measuring the concentration distributions of elements near the defects.The results show that the volume of small amount of air from or on the inner surface of the ingot mold increases instantly during pouring the melt into the ingot mold,and expands along the weak regions into the ingot,which is the main reason of the blowholes occurrence on the ingot surface.The carbon layer on the inner surface formed during the ingot mold preheating is drawn into the ingot mold by steel melt,and reacts with Ti in the melt to form TiC with high brittleness.Thereforce,the fracture of TiC due to the ingot shrinkage during the cooling should be main reason of the fine-cracks occurrence.The N-element impurities in raw materials that have not been completely eliminated by high-temperature refining,as well as the"overwind"by the leakage of gas from the vacuum furnace,can promote the formation of a large number of TiN particles in the melt.When the melt with TiN particles is poured into the ingot mold,the accumulation of the TiN particles in the local regions hinders the liquid phase flowing and the concentration exchange with the around regions.As a result,α-W phase will precipitate in the region.On another hand,the TiN particles can promote the precipitation of MC.Amounts of the MC precipitation will make a great microstructure difference between the local region and its around,which results in the hot tearing to occur easily and the arachnoid cracks to form during the ingot cooling.

关 键 词：K465镍基高温合金 大尺寸铸锭 表面缺陷 组织 

分 类 号：TG27[金属学及工艺—铸造]