高硼奥氏体钢硼化物形态及分布优化  

Optimum Morphology and Distribution of Borides in High-boron Austenitic Steel

作　　者：陈祥[1,2] 王孟鑫[1] 刘仲礼 CHEN Xiang;WANG Mengxin;LIU Zhongli(School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;Key Laboratory for Advanced Materials Processing Technology,Ministry of Education of China,Beijing 100084,China;School of Nuclear Equipment and Nuclear Engineering,Yantai University,Yantai 264005,China)

机构地区：[1]清华大学材料学院,北京100084 [2]先进成形制造教育部重点实验室,北京100084 [3]烟台大学核装备与核工程学院,山东烟台264005

出　　处：《铸造技术》2023年第4期338-344,共7页Foundry Technology

基　　金：国家自然科学基金(50974080)。

摘　　要：传统高硼铁基合金中硼化物一般位于晶界位置,沿晶界呈网状或鱼骨状分布,具有尖锐边角,破坏了基体连续性,大大降低材料的力学性能。本文采用光学金相显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、飞行时间二次离子质谱仪(TOF-SIMS)和X射线衍射(XRD)研究了碳含量对高硼奥氏体钢组织的影响。采用热力学模拟试验机分析了碳含量对实验钢850℃高温力学性能的影响。结果表明,高硼奥氏体钢的碳含量较高(0.37%~0.42%,质量分数)时,可稳定得到形态圆整的硼化物,且硼化物在基体内呈粒状离散化均匀分布,无网状、鱼骨状沿晶界连结贯通的分布状态。粒状离散化硼化物为Fe_(1.1)Cr_(0.9)B_(0.9)、Mn_(2)B_(0.98)、Cr_(2)B的络合产物,硼化物中Cr、Mn的加入,以及基体C含量的提高,促进了硼化物形态圆整、分布粒状离散化。锻造工艺同样对硼化物的粒状离散分布起到直接促进作用。锻造的始锻温度达到1 150℃是硼化物实现粒状离散分布的基本条件。Borides in traditional high-boron-based alloys are generally located at the grain boundaries and distributed along the grain boundaries in a network or fish-bone shape with sharp edges and angles,which destroy the matrix continuity and greatly reduce the mechanical properties of the materials.The effect of carbon content on the microstructure of high boron austenitic steel was investigated by using optical microscope(OM),scanning electron microscope(SEM),transmission electron microscope(TEM),time-of-flight secondary ion mass spectrometer(TOF-SJMS)and X-ray diffraction(XRD).The eflect of carbon content on the mechanical properties of experimental steel at 850℃ was analysed by using a thennal mechanical simulation testing machine.The experimental results show that when the carbon content of high boron austenitic steel is high(0.37%~0.42%>mass fraction),the boride with round shape can be stably obtained,and the boride is evenly distributed in the matrix with granular dispersion,instead of network and fish-bone distribution along grain boundaries.The granular discrete boride is the complex compounds of Fe_(1.1)Cr_(0.9)B_(0.9)、Mn_(2)B_(0.98) and Cr_(2)B according to the XRD analysis.The addition of Cr and Mn in boride and the increase in matrix carbon content promote the roundness and granular dispersion of boride.The forging process also plays a direct role in promoting the granular dispersion of boride.The initial forging temperature of 1150°C is the basic condition for the granular dispersion of boride.

关 键 词：硼化物 高硼钢 形貌 分布 高温力学性能 

分 类 号：TG142.1[一般工业技术—材料科学与工程]