奥氏体化温度对La脱氧16Mn钢组织的影响

采用光学显微镜、扫描电子显微镜等分析技术观察了La脱氧钢组织及其夹杂物的变化,研究了不同奥氏体化温度对La处理16Mn钢组织的影响。结果表明,经La处理后钢中夹杂物由原来的MnS夹杂及Si-Mn-Al复合氧化物夹杂转变为LaAlO3、La2O2S及MnS的复合夹杂物。当La含量为0.013wt%时,钢中夹杂物分布的最为细小弥散,晶内铁素体形核效果较好,钢的组织最细小。当奥氏体化温度为1200℃并保温20 min时,钢中可形成大量晶内铁素体,有利于晶内铁素体形核的最佳奥氏体晶粒尺寸约为100μm。     

Ti-Mg复合脱氧对低碳钢中夹杂物及组织的影响

在高温钼丝炉内对实验钢采用Ti-Mg单独及复合脱氧处理,利用带有能谱仪的扫描电镜和光学显微镜研究脱氧产物的成分、大小分布及铸态微观组织的变化,分析夹杂物对晶内铁素体形核以及实验钢奥氏体晶粒大小的影响.结果表明,Ti-Mg复合脱氧后的产物可以作为TiN和MnS的析出核心,形成复合夹杂物;复合夹杂物在冷却过程中可以有效的促进晶内铁素体形核,同时抑制加热过程中奥氏体晶粒的粗化.     

钛脱氧低碳钢液凝固过程中氧化物的析出和长大

通过试验,研究了低碳钢加钛脱氧后钢液中夹杂物的形态、组成、尺寸和类型,并研究了加钛前后钢的组织变化。结果表明：加钛后,钢的组织明显细化,钛的脱氧产物可成为硫化锰夹杂的形核核心,也可以附着在Al2O3夹杂周围,此类夹杂物呈细小弥散析出;这些细小的夹杂物可以在奥氏体晶粒内部诱导针状铁素体析出,从而产生细化组织的效果。     

管线钢亚微米级夹杂物的控制及对抗HIC性能的影响

通过添加Ti和Ti-Mg改性剂,试制了不同夹杂物组态的X70酸性环境用管线钢。利用OM和SEM分析试验钢中夹杂物的形态、尺寸、分布与成分;根据均质形核临界形核半径讨论了钢中夹杂物的形核和长大;测试了试验钢的氢致开裂(HIC)敏感性,并讨论了夹杂物对HIC敏感性的影响。结果表明:加Ti和加Ti-Mg均可以有效的在钢中产生大量细小、弥散的氧化物核心,其中加Ti试验钢中夹杂物以Al-Ti氧化物为核心,主要为大量亚微米级夹杂物和少量大尺寸不规则氧化物;而Ti-Mg试验钢中夹杂物以Al-Mg-Ti氧化物为核心,析出MnS,不易长大,夹杂物具有细小、弥散分布的特征。两种试验钢抗HIC性能均达到欧标要求,且Ti-Mg试验钢中完全没有发现氢致裂纹,这对提升试验钢抗HIC性能的效果明显。     

Zr-Ti复合脱氧对低合金高强度钢CGHAZ组织和韧性的影响

对Zr-Ti复合脱氧低合金高强度30mm厚钢板采用气体保护焊进行多层多道焊接,利用光学显微镜,扫描电子显微镜及能谱分析对焊接热影响区组织进行了观察与分析．结果表明,该区域存在大量微米、亚微米级的复合铬、钛氧化物夹杂,呈细小弥散分布,没有发现条状MnS夹杂物的存在．夹杂物粒子在晶界和晶内析出,钉扎奥氏体品界,有效抑制了奥氏体晶粒长大,晶粒粗化不明显．在粗晶区奥氏体晶粒内部优先形成的针状铁素体,能有效分割奥氏体晶粒,细化组织．焊接热影响区粗晶区的力学性能测试表明,Zr-Ti复合脱氧技术使焊件具有良好的低温冲击韧性．     

金属铁熔融过程中镁脱氧产物的特性

在高温钼丝炉内向铁液中分别加入NiMg和SiMg合金进行脱氧,分析过程中溶解氧、全氧、残镁量及夹杂物随时间的变化,并与铝脱氧进行对比。结果表明:加入0.05%的SiMg合金处理后,铁液中溶解氧含量(质量分数)为1.5×10-6,全氧含量为1.9×10-5;经SiMg与NiMg合金处理的试样中夹杂物变化基本相同;加入镁合金并保温15min后凝固试样中夹杂物尺寸明显减小,约为2μm,其成分由Mn-Si-Al复合氧化物转变为Mg-Al尖晶石类夹杂物;加入Al并保温15min后,凝固试样中夹杂物尺寸较大,约为5μm,成分为纯Al2O3夹杂物;SiMg合金处理的试样中单位面积上夹杂物数量最少,钢中夹杂物最为细小、分散。     

Q195热轧带钢凝固冷却过程非金属夹杂物生成热力学及工业实践

为了控制Q195钢中非金属夹杂物在凝固冷却过程的转变,采用ASPEX自动扫描电镜研究了实际生产凝固冷却过程夹杂物的转变,并用FactSage软件理论计算了这一过程夹杂物转变的热力学原理。研究结果表明:Si-Mn-Al复合脱氧Q195热轧带钢中间包内夹杂物主要成分为SiO2-MnO-Al2O3,连铸坯中硫化物夹杂质量分数急剧升高,氧化物夹杂中SiO2质量分数升高,MnO质量分数下降。钢中夹杂物成分与尺寸有明显对应关系,中间包内夹杂物尺寸越大,Al2O3质量分数越多,SiO2质量分数越低;铸坯中夹杂物尺寸越小,MnS质量分数越高,氧化物夹杂尺寸越小,SiO2质量分数越高。FactSage热力学计算表明,在钢凝固冷却过程,钢中会析出SiO2相、Mn2Al4Si5O18相和MnS相,析出相尺寸一般较小,使小尺寸夹杂物中SiO2和MnS质量分数升高,热力学理论计算可以较好地解释夹杂物成分在凝固冷却过程的转变。     

18Cr2Ni4WA钢过热和石状断口的观察

比较了三种不同冶炼工艺(平炉与电炉混合炼钢经RH真空循环脱气处理、碱性电炉冶炼及电炉冶炼加电渣重熔)和两种不同脱氧方法(并用铝、钛或仅用铝脱氧)生产的五炉18Cr2Ni4WA钢的过热敏感性并观察了断口.实验表明,这种钢产生严重过热井出现石状断口的条件是:(1)钢在高温加热时原始奥氏体晶粒充分长大;(2)钢中含有MnS夹杂物以细小的颗粒沉淀在原始奥氏体晶界上,并用铝、钛脱氧使钢中含有微量残留钛可以在高温加热过程中阻止奥氏体晶粒长大同时改善MnS夹杂物的形态和分布状况,从而有效地降低了这种钢的过热敏感性。最后,讨论了这种钢形成石状断口的机构。     

AN INVESTIGATION OF ROCK-LIKE FRACTURE OF 18Cr2Ni4WA

比较了三种不同冶炼工艺(平炉与电炉混合炼钢经RH真空循环脱气处理、碱性电炉冶炼及电炉冶炼加电渣重熔)和两种不同脱氧方法(并用铝、钛或仅用铝脱氧)生产的五炉18Cr2Ni4WA钢的过热敏感性并观察了断口.实验表明,这种钢产生严重过热井出现石状断口的条件是:(1)钢在高温加热时原始奥氏体晶粒充分长大;(2)钢中含有MnS夹杂物以细小的颗粒沉淀在原始奥氏体晶界上,并用铝、钛脱氧使钢中含有微量残留钛可以在高温加热过程中阻止奥氏体晶粒长大同时改善MnS夹杂物的形态和分布状况,从而有效地降低了这种钢的过热敏感性。最后,讨论了这种钢形成石状断口的机构。     

Zr对高强度钢热影响区第二相粒子及韧性影响

研究了0.012 4%锆对低合金高强度钢焊接热影响区粗晶区第二相粒子和冲击韧性的影响.结果表明,模拟20 kJ/cm焊接线能量下无锆钢焊接热影响区粗晶区中第二相粒子为Al-Ti复合氧化物和（Ti,Nb） N析出物.而含锆钢则是Zr-Al-Ti复合氧化物及（Al,Ti,Nb） N和（Ti,Nb） N析出物.同时,定量数据分析表明含锆钢中氧化物和氮化物粒子密度更高且尺寸更加细小.这些高密度的细小的第二相粒子在焊接过程中能有效钉扎晶界移动,抑制奥氏体晶粒粗化,在焊接热影响区粗晶区中得到尺寸相对细小均匀的原奥氏体晶粒,使得含锆钢焊接热影响区粗晶区呈现韧性断裂和极好的低温冲击韧性.     

In-situ observation of grain refinement in the simulated heat-affected zone of high-strength low-alloy steel by Zr-Ti combined deoxidation

The effect of Zr-Ti combined deoxidation on the grain refinement in the simulated coarse-grained heat-affected zone of a high-strength low-alloy steel was investigated by means of analytical characterization techniques such as in-situ microscopy, transmission electron microscopy, and electron backscattered diffraction analysis. Owing to the Zr-Ti combined deoxidation, a large amount of fine Zr-Ti oxide particles were formed in the steel and retarded the austenite grain growth during simulated welding thermal cycle. The austenite grains were small and uniform. The Mn can diffuse spontaneously from austenite to Zr-Ti oxide inclusion and MnS precipitated on ZrO₂, which can form Mn depleted zone in the vicinity of inclusion. The acicular ferrite grains nucleated on intragranular Zr-Ti oxide inclusions in austenite grains grew in different directions and effectively divided the austenite grain into several finer and separate regions at intermediate temperature. The crystallographic grain size became small in the simulated coarse-grained heat-affected zone of Zr-Ti-killed steel due to the effective pinning effect by Zr-Ti oxide particles and acicular ferrite formation.     

Morphology and chemistry of oxide inclusions after Al and Ti complex deoxidation

The morphology and chemistry of oxide inclusions after various Al and Ti complex deoxidation sequences were investigated at 1600°C. Depending on the addition sequence of Al and Ti deoxidants and the holding time, the morphology and the chemistry were changed. In particular, when Ti was added prior to Al, spherical Al₂O₃ oxide inclusions with hollow holes were frequently observed, which is reported for the first time. On the other hand, when Al was added prior to Ti, Al₂O₃ inclusion formed. When Al and Ti were added simultaneously, Al−Ti−O oxide inclusion formed in the beginning and was transformed to Al₂O₃ inclusion. Based on the experimental results, the formation mechanism of the oxide inclusions after Al−Ti deoxidation was proposed. The nozzle clogging of Ti bearing Al killed steel was also discussed based on the experimental results.     

硫质量分数对船体钢诱发点蚀行为的影响研究

采用腐蚀浸泡的方法研究了酸性氯离子环境下S质量分数对低合金船板钢耐蚀性的影响,探讨了非金属夹杂物诱发点蚀形核的机理。结果表明,杂质元素S对钢的耐蚀性具有不利影响。随着S质量分数的增加,钢的耐点蚀性能恶化。S元素损害耐蚀性主要与钢中的非金属夹杂物有关。不同种类夹杂物诱发点蚀的机理有显著差异。单一MnS夹杂物与基体间存在缝隙,其诱导点蚀形核包括缝隙腐蚀和夹杂物溶解两个过程,MnS夹杂物是最敏感的点蚀诱发源;MXS-Al2O3复合夹杂物同样能诱发低合金钢的点蚀形核,包裹在Al2O3外层的硫化物优先发生溶解,成为腐蚀介质的通道,从而引发局部腐蚀。MnS-Al2O3夹杂物的点蚀形核能力大于CaS-Al2O3夹杂物,CaS遇到水容易发生水解并在夹杂物周边形成OH-,阻碍了坑内部的酸化,有利于抑制钢的耐局部腐蚀性能。     

Al与Re脱氧对取向硅钢铸态组织的影响

在真空冶炼过程中,分别采用铝和稀土两种元素对取向硅钢进行脱氧,并对两种脱氧剂所冶炼的试验钢的铸态组织与夹杂物的类型、尺寸、形貌等方面进行分析.结果表明:与铝脱氧剂相比,稀土元素作为脱氧剂所冶炼的取向硅钢,其铸坯的宏观缺陷更少,夹杂物多为变质的硫化锰及少量的稀土铝酸盐,使得取向硅钢铸态组织和性能得到改善.     

Influence of inclusion and grain boundary on corrosion behaviour of low alloy steel in cargo oil tank bottom plate environment

Corrosion behaviours of low alloy steels with various alloying element contents were studied in simulated corrosion environment (pH?=?0·85, 10% NaCl solution) of cargo oil tank (COT) bottom plate corrosion environment. Corrosion rate was measured, and the surface morphology of test steels was characterised using scanning electron microscope (SEM). The electrochemical results were investigated using polarisation curves and electrochemical impedance spectroscopy (EIS). The corrosion behaviour of inclusion was investigated using in situ SEM images and energy disperse spectroscopy (EDS) analysis. The effect of misorientation distribution on corrosion resistance of steel was evaluated using electron backscattered diffraction microscopy. The results showed that MnS dissolved into the simulated COT corrosion solution before steel matrix, whereas TiO₂ would not be dissolved. A 10–20 μm area was formed as a circular cathode around inclusion centre. The corrosion was inclined to occur in the place where curvature radius of inclusion is small. An increase in the proportion of low energy grain boundaries was conducive to the improvement of corrosion resistance especially in the early stages of corrosion.     

�̺�����΢�Ͻ�����ܵ�Ӱ�켰������������̬

为了探讨高锰含量对微合金钢性能的影响及其夹杂物存在形态,采用低碳+钒铁微合金化工艺生产一种高强度热轧型钢,锰质量分数为1.50%~1.60%。结果表明:产品屈服强度为440~460 MPa,抗拉强度为600~620 MPa,金相组织为铁素体+团状珠光体,带状组织3~4级,晶粒度为7~8.5级,但是锰提高了团状珠光体的相对量,削弱了钢材的低温冲击韧性。锰除固溶于铁基体中外,多以含锰夹杂物的形式存在,主要包括片状硫化锰、球形复合型夹杂物和纺锤体形复合型夹杂物。     

钢液脱氧和氧化物夹杂控制的热力学模型

应用多元系亚正规溶液模型计算了CaO—MgO—Al2O3-SiO2和CaO-MnO—Al2O3-SiO2系各组元的活度，并以此为基础建立了钢液脱氧和氧化物夹杂控制的热力学模型，用于炼钢过程脱氧、渣金平衡和氧化物夹杂钢液平衡的热力学计算，以控制钢液脱氧和氧化物夹杂成分．在钢包精炼的渣金平衡条件下钢液硅脱氧和铝硅脱氧后钙处理的工业性实验，以及钢液凝固过程形成的钢中氧化物夹杂分析结果说明，该热力学模拟方法可用于钢包精炼中钢液的脱氧控制和钢中氧化物夹杂控制．     

Precipitation behavior of MnS on oxide inclusions in Si/Mn deoxidized steel

The precipitation behavior of the MnS phase of MnO-SiO₂ oxides in Si/Mn deoxidized steels was examined. MnS phase formation in the oxide phase was clearly identified, and the Mn content in both phases increased with isothermal holding at 1,200°C. With increased cooling rate, both the size of inclusions and the precipitation ratio of the MnS phase in the oxides decreased. More than 90% of MnO-SiO₂ oxides contain MnS phases and MnS precipitation is accompanied by an Mn-depleted zone around the oxides. This zone was created not just around the MnS, but around the whole oxide inclusion. One can tentatively conclude that the majority of the MnS islands after isothermal holding are formed by the diffusion of Mn and S from the matrix into the inclusions.     

ϡ����430�����岻�����ʴ�Ե�Ӱ��

 通过电化学方法测绘了不同稀土含量430铁素体不锈钢在35%中性氯化钠溶液中的极化曲线,采用金相、扫描电镜和能谱等分析手段,研究了微量稀土对430铁素体不锈钢耐蚀性的影响。研究结果表明：稀土通过将MnS、Al2O3 以及硅酸盐类等块状、链状及条带状夹杂物变质为细小弥散的圆形或椭圆形稀土硫氧化物及其复合夹杂物,有效地抑制了点蚀的发生。电化学试验数据显示：稀土含量0037%~0043%时钢的耐蚀性能最好。     

稀土Ce含量对4Cr5MoSiV1钢中夹杂物的变质作用

为探究Ce元素对热作模具钢中夹杂物的影响及其作用机理,用场发射扫描电镜(SEM/EDS)和附带的夹杂物自动分析系统对不同Ce含量的4Cr5MoSiV1钢中夹杂物的类型、形貌、数量、尺寸及其分布进行观察和统计分析。结果表明,不含Ce的试样中夹杂物不仅数量多、平均尺寸较大且形状不规则,主要类型为Mg-Al-O类、MnS和Mg-Al-O外覆盖MnS的夹杂物;随Ce含量的增加,试样中的夹杂物有数量和平均尺寸减小、并变质为球形稀土硫氧化物的趋势。当钢中Ce含量为0.0070%时,夹杂物的数量最少,平均尺寸最小;继续增加稀土Ce含量到0.0120%时,会形成更多的硫氧化物夹杂,且夹杂物有数量增多、平均尺寸增大的趋势。随着凝固过程的进行,Ce主要以稀土硫氧化物形式存在试验钢中,60%以上的夹杂物会被凝固前沿推动,且最终留在晶界附近。