不同冶炼工艺对硫化物形态及尺寸分布的影响

利用扫描电镜和能谱分析等检测手段研究了"真空感应 真空自耗重熔"和"电弧炉 VOD 真空自耗重熔"两种工艺冶炼的G50超高强度钢中夹杂物形态和尺寸分布,结果表明 "真空感应 真空自耗重熔"冶炼的钢中硫化物夹杂物尺寸较小、平均间距较小,纵横比较大,尤其是细夹杂物较多,相应的细夹杂物密集区域较多,而"电弧炉 VOD 真空自耗重熔"冶炼的钢中MnS夹杂物均匀弥散分布,复合夹杂物中Ca含量较高,MnS变形困难,纵横比较小,导致夹杂物尺寸与平均间距较大.     

MnS形态对超高强度钢韧性的影响

 利用扫描电镜和能谱分析等检测手段研究了2种不同冶炼工艺生产的G50钢中夹杂物类型和尺寸分布。结果表明：随MnS复合夹杂物中钙含量的降低,MnS变形程度逐渐加重,纵横比随之增大。“电弧炉+VOD+真空自耗重熔”冶炼钢的韧性(冲击韧性和断裂韧性)明显得到改善。由于“电弧炉+VOD+真空自耗重熔”冶炼钢中夹杂物的钙含量均较高,纵横比小于“真空感应炉熔炼+真空自耗重熔”冶炼钢,因而有利于改善G50超高强度钢的韧性。     

EAF-VOD-VAR和VIM-VAR冶炼工艺对G50超高强度钢韧性的影响

研究了真空感应熔炼+真空自耗重熔(VIM-VAR)和电弧炉+真空-氧脱碳+真空自耗重熔(EAF- VOD-VAR)法两种工艺冶炼的超高强度钢G50%:0.28～0.29C、1.88～1.98Si、4.45～4.49Ni、1.04～1.05Cr、0.57～0.61Mo、0.031～0.034Nb)的夹杂物和机械性能。结果表明,EAF-VOD-VAR法冶炼的G50钢夹杂物级别低于VIM-VAR法冶炼的G50钢的夹杂物级别;EAF-VOD-VAR法冶炼的1350钢的韧性(A_KU2 86～88 J,K_IC130～132 MPa·m^1/2)明显高于VIM-VAR法冶炼的G50钢的韧性(A_KU270～74 J,K_IC 112～118 MPa·m^1/2)。     

非金属夹杂物对钢材疲劳性能的影响

详细地论述了非金属夹杂物的变形率、数量、尺寸、形状及分布对高强度钢疲劳性能的影响。     

拉伸载荷作用下AlN夹杂物对航空用超高强度钢中裂纹萌生的影响

 采用扫描电镜原位观测法,跟踪观察了航空用超高强度钢中长方型夹杂物导致裂纹萌生与扩展的微观行为。结果表明,拉伸载荷作用下,航空用超高强度钢中裂纹萌生的方式与夹杂物尺寸及夹杂物周围孔洞的大小有关。当夹杂物面积小于一定值时,无论夹杂物周围有无孔洞,裂纹均以夹杂物/基体界面开裂的方式萌生;当夹杂物面积大于一定值后,若夹杂物/基体界面基本完好,则裂纹易以夹杂物自身开裂的方式萌生;若夹杂物周围孔洞面积较大,则裂纹易以夹杂物/基体界面开裂的方式萌生。     

拉伸载荷作用下AIN夹杂物对航空用超高强度钢中裂纹萌生的影响

采用扫描电镜原位观测法,跟踪观察了航空用超高强度钢中长方型夹杂物导致裂纹萌生与扩展的微观行为。结果表明,拉伸载荷作用下,航空用超高强度钢中裂纹萌生的方式与夹杂物尺寸及夹杂物周围孔洞的大小有关。当夹杂物面积小于一定值时,无论夹杂物周围有无孔洞,裂纹均以夹杂物／基体界面开裂的方式萌生;当夹杂物面积大于一定值后,若夹杂物／基体界面基本完好,则裂纹易以夹杂物自身开裂的方式萌生;若夹杂物周围孔洞面积较大,则裂纹易以夹杂物／基体界面开裂的方式萌生。     

低合金高强度钢焊缝金属夹杂物与针状铁素体形核的研究

针对５００～６００ＭＰａ级低合金高强度钢的韧性问题，研究了针对状铁素体的形成的机理，并对夹杂物的类型，成分对针状铁素体形成的影响进行了分析，探讨，指出Ｔｉ，Ｍｎ，Ａｌ，Ｓｉ等的复合氧化物夹杂可有效地促进针状铁素体形核，而ＭｎＯ．ＳｉＯ２夹杂和ＭｎＳ夹杂不能促进针状铁素体形核。     

夹杂物对超高强度钢应力应变场的影响

非金属夹杂物对钢性能的影响与夹杂物的特征参数密切相关.首先分析拉伸和疲劳载荷下超高强度钢中TiN夹杂物导致裂纹萌生的扫描电镜原位观察结果,采用MSC Marc有限元分析软件对夹杂物及周围基体的应力场进行计算,然后对拉伸载荷下不同特征参数的TiN夹杂物及周围基体的应力应变场进行模拟.结果表明,有限元法能够解释并预测夹杂物及周围基体的力学行为.三角形夹杂物尖角附近的应力集中最严重.矩形夹杂物内部高应力区的位置受夹杂物与外载荷方向夹角的影响.随邻近夹杂物间距的增大,基体内的最大应力由夹杂物外侧移至夹杂物之间.近表面夹杂物使得基体自由表面附近出现高应力区,基体内最大应力的位置受夹杂物与自由表面距离和尺寸的影响.     

镁系易切削钢中夹杂物分析

为了探究Mg处理对易切削钢中夹杂物的影响,以1144高硫易切削钢为试验钢种,采用金相和能谱仪等手段研究了 Mg处理对1144易切削钢中夹杂物的形态、尺寸分布和夹杂物成分的影响.结果表明:在易切削钢铸坯中,Mg处理使得易切削钢铸坯硫化物夹杂由Ⅱ类向Ⅲ类、Ⅰ类转变,分布更为均匀,同时使得复合硫化锰夹杂物比例提升.在轧材中,...     

易切削钢AISI 1215铸态硫化物形貌尺寸分布特征研究

对易切削钢AISI 1215铸坯中的夹杂物形貌、尺寸进行观察和统计,结果显示铸坯边缘区域为Ⅰ类MnS,中心区域为Ⅱ类MnS.根据Uhlmann的凝固前沿夹杂物析出模型以及铸坯化学成分分析,认为冷却速度和硫元素偏析对MnS夹杂形貌和尺寸分布有着重要影响,冷却速度越快,越易形成Ⅰ类MnS,硫元素偏析越严重越有利于形成Ⅱ类MnS.     

MnS在Ti-Al复合脱氧氧化物上的析出研究

采用高温电阻炉,通过改变不同冷却条件和不同硫含量,系统研究了Ti-Al复合脱氧夹杂对MnS夹杂物析出量和形貌的影响。试验结果表明:冷却速率对MnS的析出有着重要的影响。当钢液中硫的质量分数从0.001%增加到0.01%时,在炉冷条件下,MnS析出量随着钢液中硫含量的增加而增加。但是在水冷条件下,MnS的析出量不随钢液中硫含量的增加而变化。当钢液中w([S])0.008%时,所有氧化物夹杂表面都会析出MnS夹杂;当0.002%≤w([S])0.008%时,复合氧化物夹杂中MnO+SiO2含量越高,MnS越容易在氧化物上面析出。复合夹杂物中Ti3O5和Al2O3对MnS的析出没有明显影响。当w([S])0.002%时,基本没有MnS夹杂析出。MnS在低熔点氧化物上呈镶嵌状析出,在高熔点上呈包裹状析出。     

Morphology and Precipitation Kinetics of MnS in Low-Carbon Steel During Thin Slab Continuous Casting Process

The morphology of manganese sulfide formed during thin slab continuous casting process in low-carbon steel produced by compact strip production （CSP） technique was investigated. Using transmission electron microscopy analysis, it was seen that a majority of manganese sulfides precipitated at austenite grain boundaries, the morphologies of which were spherical or close to the spherical shape and the size of MnS precipitates ranged from 30 nm to 100 nm. A mathematical model of the manganese sulfide precipitation in this process was developed based on classical nucleation theory. Under the given conditions, the starting and finishing precipitation temperatures of MnS in the continuous casting thin slab of the studied low-carbon steel are 1 189 ℃ and 1 171 ℃, respectively, and the average diameter of MnS precipitates is about 48 nm within this precipitation temperature range. The influences of chemical components and thermo-mechanical processing conditions on the precipitation behavior of MnS in the same process were also discussed.     

冶金过程中的时空多尺度结构及其效应

时空多尺度结构是众多物质转化过程的共同特征,冶金过程是一类典型的关于物质转化的过程工业。笔者以炼钢为例,说明冶金过程中存在着多尺度结构,简要地介绍了时空多尺度概念以及它在冶金领域的应用前景。     

Effect of MnS and Its Size on the Heterogeneous Nucleation and Precipitation of Bismuth in Steel

Transactions of the Indian Institute of Metals - The effect of MnS and its size on the heterogeneous nucleation and precipitation of Bismuth was investigated. The results show that bismuth...     

Effects of MnS Inclusions on the Banded Microstructure in Non-quenched and Tempered Steel

Metallurgical and Materials Transactions B - The effects of MnS inclusions in a non-quenched and tempered steel on banded ferrite/pearlite (F/P) microstructure have been studied in this...     

Effect of Boron on Morphology of Inclusions in Tire Cord Steel

B2O3 was added to tire cord steel during refining in a carbon tube furnace.The influence of boron on the deformability of oxide inclusions was studied by metallographic and scanning electron microscope（SEM） observations.The melting points of boron-bearing compound oxide inclusions were calculated using Factsage software.The results showed that the main inclusion was a boron-bearing compound oxide and the deformation properties of the inclusions were clearly improved by adding B2O3.As the boron content was increased from 0.0046% to 0.039%,the proportion of long strip type inclusions changed slightly and the number of inclusions decreased.The low-melting point areas of the MnO-SiO2-Al2O3 and CaO-SiO2-Al2O3 ternary system increased with the addition of B2O3.Moreover,the area increased with the increase of B2O3 content.Clear improvements in the deformation ability of the inclusions occurred when the B2O3 mass percent rose to 5% in the CaO-SiO2-Al2O3 inclusion system and to 10% in the MnO-SiO2-Al2O3 inclusion system