Research on Austenite Phase Transformation Kinetics and Nucleation Mechanisms in CF170 Maraging Stainless Steel

IF 3.3 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Metals and Materials International Pub Date : 2024-10-26 DOI:10.1007/s12540-024-01831-5

Chao Zhang, Chang Wang, Hui Wang, Geng Liu, Chuanbo Zheng, Zhenbao Liu, Qilu Ge, Jie Su

{"title":"Research on Austenite Phase Transformation Kinetics and Nucleation Mechanisms in CF170 Maraging Stainless Steel","authors":"Chao Zhang, Chang Wang, Hui Wang, Geng Liu, Chuanbo Zheng, Zhenbao Liu, Qilu Ge, Jie Su","doi":"10.1007/s12540-024-01831-5","DOIUrl":null,"url":null,"abstract":"<div><p>CF170 is an ultralow-carbon, cobalt-free maraging stainless steel with a tensile strength of 1700 MPa, making it an ideal material for high-load gears in aerospace robotic arms. However, these gears are subjected to a long ageing process during ion nitriding, resulting in remarkable variations in the austenite volume fraction (<i>V</i><sub>a</sub>), which strongly affects the dimensional accuracy of the product. Therefore, accurately predicting <i>V</i><sub>a</sub> is crucial for optimizing the chemical heat treatment process of CF170 steel. In this work, the nonisothermal and isothermal ageing process, combined with Kissinger analysis and the Johnson‒Mehl‒Avrami (JMA) model, proved that the nonisothermal kinetic model was applicable for the prediction of <i>V</i><sub>a</sub>. Moreover, models of the preexponential factor <i>K</i><sub>0</sub> and maximum austenite volume fraction (<i>V</i><sub>max</sub>) were proposed, and a kinetic model of austenite phase transformation after ageing at 482–593 °C for 0–6000 min was established, which predicted and controlled the microstructure within a large temperature and time range. The nucleation mechanism of austenite in CF170 steel was investigated by scanning electron microscopy (SEM), electron backscattering diffraction (EBSD), and transmission electron microscopy (TEM). Nucleation was regulated by a shear mechanism, with nucleation occurring primarily at the grain boundary, packet, block, and subblock interfaces. The nucleation was the reversion of γ → α → γ, and the austenite inherited the crystal orientation features of the prior austenite, demonstrating the “austenite memory” phenomenon.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":703,"journal":{"name":"Metals and Materials International","volume":"31 5","pages":"1254 - 1271"},"PeriodicalIF":3.3000,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Metals and Materials International","FirstCategoryId":"88","ListUrlMain":"https://link.springer.com/article/10.1007/s12540-024-01831-5","RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}

引用次数: 0

Abstract

CF170 is an ultralow-carbon, cobalt-free maraging stainless steel with a tensile strength of 1700 MPa, making it an ideal material for high-load gears in aerospace robotic arms. However, these gears are subjected to a long ageing process during ion nitriding, resulting in remarkable variations in the austenite volume fraction (V_a), which strongly affects the dimensional accuracy of the product. Therefore, accurately predicting V_a is crucial for optimizing the chemical heat treatment process of CF170 steel. In this work, the nonisothermal and isothermal ageing process, combined with Kissinger analysis and the Johnson‒Mehl‒Avrami (JMA) model, proved that the nonisothermal kinetic model was applicable for the prediction of V_a. Moreover, models of the preexponential factor K₀ and maximum austenite volume fraction (V_max) were proposed, and a kinetic model of austenite phase transformation after ageing at 482–593 °C for 0–6000 min was established, which predicted and controlled the microstructure within a large temperature and time range. The nucleation mechanism of austenite in CF170 steel was investigated by scanning electron microscopy (SEM), electron backscattering diffraction (EBSD), and transmission electron microscopy (TEM). Nucleation was regulated by a shear mechanism, with nucleation occurring primarily at the grain boundary, packet, block, and subblock interfaces. The nucleation was the reversion of γ → α → γ, and the austenite inherited the crystal orientation features of the prior austenite, demonstrating the “austenite memory” phenomenon.

Graphical Abstract

查看原文本刊更多论文

CF170马氏体时效不锈钢奥氏体相变动力学及成核机理研究

CF170是一种超低碳，无钴马氏体时效不锈钢，抗拉强度为1700 MPa，使其成为航空航天机械臂高负荷齿轮的理想材料。然而，这些齿轮在离子氮化过程中经历了漫长的老化过程，导致奥氏体体积分数（Va）的显著变化，这强烈影响了产品的尺寸精度。因此，准确预测Va值对于优化CF170钢的化学热处理工艺至关重要。本文结合Kissinger分析和Johnson-Mehl-Avrami （JMA）模型，对非等温和等温时效过程进行了分析，证明了非等温动力学模型适用于Va的预测，并提出了指前因子K0和最大奥氏体体积分数（Vmax）模型，建立了482 ~ 593℃时效0 ~ 6000 min后奥氏体相变动力学模型。在较大的温度和时间范围内预测和控制微观结构。采用扫描电镜（SEM）、电子背散射衍射（EBSD）和透射电镜（TEM）研究了CF170钢中奥氏体的形核机制。成核受剪切机制调控，主要发生在晶界、包状、块状和亚块状界面。成核过程为γ→α→γ的逆转，奥氏体继承了原有奥氏体的取向特征，表现出“奥氏体记忆”现象。图形抽象

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Metals and Materials International 工程技术-材料科学：综合

CiteScore

7.10

自引率

8.60%

发文量

197

审稿时长

3.7 months

期刊介绍： Metals and Materials International publishes original papers and occasional critical reviews on all aspects of research and technology in materials engineering: physical metallurgy, materials science, and processing of metals and other materials. Emphasis is placed on those aspects of the science of materials that are concerned with the relationships among the processing, structure and properties (mechanical, chemical, electrical, electrochemical, magnetic and optical) of materials. Aspects of processing include the melting, casting, and fabrication with the thermodynamics, kinetics and modeling.