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Oxide Accelerating Primary Ferrite Nucleation of Austenitic Stainless Steel Weldment

奥氏体不锈钢焊件的氧化物加速初生铁素体形核

基本信息

批准号：
22K14510
负责人：
HOU YUYANG
金额：
$ 2.91万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Early-Career Scientists
财政年份：
2022
资助国家：
日本
起止时间：
2022-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-22K14510/
关键词：
Stainless steel Weld metal Nucleation Oxide TiN δ-ferrite Austenite Welding Metallurgy Stainless Steel Equiaxed Solidification Microstructural Mechanical property

项目摘要

In this study, we evaluate the accelerating effect of Ti2O3, (Ti,Al)2O3, and MgAl2O4 on TiN formation to promote primary ferrite nucleation. Ti2O3, (Ti,Al)2O3, and MgAl2O4 could all accelerate TiN formation to nucleate δ-ferrite, the specimen with MgAl2O4 showed the optimal effect of δ-ferrite refinement. Ti2O3 and (Ti,Al)2O3 could act as heterogeneous nuclei for TiN because low lattice misfits of 0.6% and 0.6~8.1% could be reached as for Ti2O3 and (Ti,Al)2O3 with orientation relationship of {0001}oxide//{111}TiN and [10-10] oxide//[110]TiN. Spinel type MgAl2O4 was identified to have a fully paralleled orientation relationship with TiN and lead to a 4.8% misfit with TiN in each crystal plane. MgAl2O4 could significantly accelerate TiN formation to form MgAl2O4-TiN with a higher area density of above 250 counts/mm2 compared to 75 counts/mm2 regarding Ti2O3-TiN and (Ti,Al)2O3-TiN. Baker-Nutting (B-N) orientation relationship was confirmed between TiN and δ-ferrite. The formed TiN could nucleate δ-ferrite.The effect of primary ferrite refinement on austenite formation was investigated. When MgAl2O4-TiN was introduced, the primary ferrite was greatly refined with random and multiple orientations, having little relationship with the temperature gradient. The morphology of residual ferrite showed vermicular morphology with fine-dispersed character. The austenite shows columnar morphology because the formation temperature of austenite is higher than the solidus and the austenite nucleated and grew independently to primary ferrite.

在这项研究中，我们评估了Ti 2 O3，（Ti，Al）2 O3和MgAl 2 O 4对TiN形成的加速作用，以促进初级铁素体形核。Ti_2O_3、（Ti，Al）_2O_3和MgAl_2O_4均能促进TiN的形成，使δ-铁素体形核，其中添加MgAl_2O_4的试样细化效果最好。Ti_2O_3和（Ti，Al）_2O_3的晶格失配度分别为0.6%和0.6~8.1%，取向关系为{0001}氧化物//{111}TiN和[10-10]氧化物//[110]TiN，因此Ti_2O_3和（Ti，Al）_2O_3可以作为TiN的异质形核。尖晶石型MgAl_2O_4被确定为与TiN具有完全的取向关系，并导致在每个晶面中与TiN的4.8%错配。MgAl 2 O 4可以显著加速TiN的形成，以形成MgAl 2 O 4-TiN，其具有高于250计数/mm 2的更高的面密度，而对于Ti 2 O3-TiN和（Ti，Al）2 O3-TiN为75计数/mm 2。TiN与δ-铁素体之间存在B-N取向关系。研究了初生铁素体细化对奥氏体形成的影响。当引入MgAl 2 O 4-TiN时，初生铁素体被显著细化，且具有随机和多取向，与温度梯度关系不大。残余铁素体呈细小弥散的蠕虫状。由于奥氏体的形成温度高于固相线，且奥氏体独立形核长大为初生铁素体，因此奥氏体呈柱状形貌。