形变热处理对NHS15钢微观组织和高周疲劳性能的影响  

Effect of Modified-Ausformed on Microstructure and High-Cycle Fatigue Properties of NHS15 Steel

作　　者：张永健[1] 惠卫军[1] 董瀚[1] 翁宇庆[2] 

机构地区：[1]钢铁研究总院先进钢铁材料技术国家工程研究中心,北京100081 [2]中国金属学会,北京100711

出　　处：《热加工工艺》2015年第24期45-48,共4页Hot Working Technology

基　　金：国家重点基础研究发展规划资助项目(2004CB619104)

摘　　要：研究了经形变热处理和常规热处理后NHS15高强度钢的微观组织结构和高周疲劳性能。结果表明,经形变热处理后,实验钢的屈服强度提高,试样的原奥氏体晶粒被细化,晶粒在轧制方向上被轻微拉长,且晶界被扭曲成锯齿状;形变热处理试样的马氏体束变细,回火后析出的碳化物更加细小、弥散;在107循环周次内,与常规热处理相比,形变热处理提高了试样的疲劳断裂抗力和疲劳寿命;常规热处理试样的疲劳断裂多起源于表面和内部基体,而形变热处理试样的断裂多源于内部夹杂物;疲劳断口裂纹源GBF处的应力场强度因子幅ΔK_(GBF)不随疲劳寿命N_f变化而变化。The fatigue tests were conducted for modified-ausformed and oil-quenched versions of spring steel （NHS 15） with the chemical composition of 0.45C-2.04Si-0.77Mn （in mass pct）. The results showthat the yield strength ofthe tested steel improves. The prior-austenite grain size decreases and the grains were lengthened by modified ausforming A fairly better fatigue property can be obtained at the modified-ausformed test steel. The SEM observations of the fatigue fracture surface reveal that the most of fatigue crack initiates from matrix in oil-quenched test steel and most of fatigue cracks initiate from internal inclusions in modified-ausformed test steel. The further investigation shows that the stress intensity factor ranges at GBF boundary △KGBF keeps almost constant with varying Nf It can conclude that the fatigue properties can be improved by modified ausforming

关 键 词：形变热处理 微观组织 高强度钢 高周疲劳 疲劳源 

分 类 号：TG111.8[金属学及工艺—物理冶金] TG142[金属学及工艺—金属学]