镁对GCr15轴承钢中夹杂物及奥氏体晶粒的影响  

Effect of magnesium on inclusions and austenite grain in a GCr15 bearing steel

作　　者：尉政 任英[1] 任强 张立峰 YU Zheng;REN Ying;REN Qiang;ZHANG Lifeng(School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China;College of Mechanical Engineering,Yanshan University,Qinhuangdao 066004,Hebei,China;School of Mechanical and Material Engineering,North China University of Technology,Beijing 100144,China)

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]燕山大学机械工程学院,河北秦皇岛066004 [3]北方工业大学机械与材料工程学院,北京100144

出　　处：《钢铁》2023年第7期133-143,共11页Iron and Steel

基　　金：国家自然科学基金资助项目(U22A20171,51874032)。

摘　　要：为了研究镁对轴承钢中夹杂物的改性效果及不同镁含量轴承钢中夹杂物对奥氏体晶粒尺寸的影响,通过实验室试验和热力学计算分析了不同镁含量轴承钢中的夹杂物和奥氏体晶粒尺寸。分析了总镁质量分数分别为0.0002%、0.0004%、0.0012%、0.0025%和0.0038%的轴承钢样品中夹杂物的成分、尺寸、形貌及含量的变化。镁处理轴承钢中夹杂物的改性顺序为Ca-Al-O、Al_(2)O_(3)→Ca-Al-Mg-O→MgAl_(2)O_(4)→MgO。总镁质量分数从0.0002%增加到0.0025%,钢中1~2μm夹杂物的数密度从6.04个/mm^(2)增加至22.99个/mm^(2);总镁质量分数为0.0038%时,钢中夹杂物数密度略有下降(17.59个/mm^(2)),夹杂物平均尺寸从总镁质量分数为0.0002%时的3.03μm降低至2.02μm。当奥氏体化保温时间从15 min增加至120 min或当奥氏体化温度从900℃增加至1050℃时,轴承钢的奥氏体晶粒尺寸呈增加趋势。热力学计算结果表明,升温会导致碳化物溶解,奥氏体晶界钉扎作用减弱,奥氏体晶粒长大,而镁处理形成的小尺寸夹杂物会钉扎晶界,阻碍奥氏体晶粒的长大。通过Zener钉扎力计算结果发现,夹杂物尺寸越小并且体积分数越大时,夹杂物对晶界的钉扎作用越强,晶界的迁移速度越小,奥氏体晶粒尺寸越小。因此,总镁质量分数为0.0012%和0.0025%的样品的奥氏体晶粒在保温期间或升温过程中呈现缓慢的增长趋势,当保温温度为1000℃、保温时间为120 min时,总镁质量分数为0.0012%时奥氏体晶粒尺寸最小,为26.4μm,总镁质量分数为0.0025%时,晶粒尺寸为28.4μm,其余镁含量轴承钢中奥氏体晶粒尺寸均大于35μm。基于Arrhenius奥氏体晶粒长大模型预测了镁处理轴承钢中奥氏体晶粒的长大过程,与奥氏体晶粒生长过程较为符合。In order to study the modification effect of inclusions in the bearing steel by magnesium and the influence of inclusions in the bearing steel on austenite grain size of different magnesium content conditions,the inclusion and austenite grain size in the bearing steel with different magnesium content were analyzed by laboratory experiments and thermodynamic calculations.The composition,size,morphology,and composition of inclusions in bearing steel samples with the mass percent of total magnesium of 0.0002%,0.0004%,0.0012%,0.0025%,and 0.0038%were analyzed.The modification sequence of inclusions in the magnesium-treated bearing steel was Ca-Al-O,Al_(2)O_(3)→Ca-Al-Mg-O→MgAl_(2)O_(4)→MgO.With the increase of the mass percent of total magnesium from 0.0002%to 0.0025%,the number density of 1-2μm inclusions in the steel increased from 6.04 piece/mm^(2) to 22.99 piece/mm^(2),when the mass percent of total magnesium was 0.0038%,the number density of inclusions in the steel decreased slightly(17.59 piece/mm^(2)),and the average size of inclusions decreased from 3.03μm(the mass percent of total magnesium was 0.0002%)to 2.02μm(the mass percent of total magnesium was 0.0038%).When the austenitizing time increased from 15 min to 120 min or when the austenitizing temperature increased from 900℃to 1050℃,the austenite grain size of a bearing steel showed an increasing trend.Thermodynamic calculation results showed that temperature rise led to the dissolution of carbides,the decrease of austenite grain boundary nailing,and the growth of austenite grains.The results of Zener nailing force calculation showed that when the size of inclusions was smaller and the volume percent of inclusions was larger,the inclusion had stronger nailing effect on the grain boundary,the migration rate of the grain boundary was smaller,and the austenite grain size was smaller.So the austenite grains of the samples with the mass percent of total magnesium of 0.0012%and 0.0025%showed a slow growth trend during the holding or heating process.Wh

关 键 词：GCR15轴承钢 镁处理 夹杂物 奥氏体晶粒 钉扎作用 长大模型 

分 类 号：TG142.1[一般工业技术—材料科学与工程]