真空感应炉熔炼合金钢时用氮化物增氮的试验研究

分析了真空度、温度和氮化物成分对钢中氮溶解度影响,并在50 k真空感应炉对不同化学成分的合金钢(/%:0.06～0.36C、≤3.23Si、≤2.20Al、≤9.00Cr)进行3种氮化物-氮化硅、氮化锰和氮化铬的增氮试验。结果表明,气相中氮气分压对钢液中氮溶解度影响最大;钢中Ti、Cr提高氮溶解度和氮化物的收得率;增加C含量则降低氮溶解度和氮化物的收得率;钢中含有一定量的铝,可以显著提高氮化物的收得率。40 kPa氩气压力,1 600～1 650℃时在硅钢、结构钢和9%Cr钢中氮化硅、氮化锰、氮化铬的收得率分别为25%～30%、30%～50%、60%～100%。     

真空感应炉超纯净钢钢液取样技术的开发应用

文章试验了市面上钢液取样器在真空感应炉内的应用效果,深入分析了问题产生的原因。针对性的研究了真空感应炉内钢液取样的特殊性,开发出了适合真空感应炉超纯净钢钢液取样的技术和产品,效果好,与钢锭取样对比五大常规元素的分析误差全部控制在0.001%以内,而且安全适用,很适合真空感应炉超纯净钢钢液取样工艺。     

Ti-Nb微合金化高速护栏钢连续冷却组织转变规律研究

利用热模拟试验机、OM、TEM等试验设备,研究了Ti-Nb微合金化高速护栏钢的连续冷却组织转变规律,建立了试验钢的CCT曲线。研究结果表明：当冷速为0.5℃/s时,试验钢中的奥氏体发生铁素体-珠光体相变;当冷速大于1℃/s时,开始发生贝氏体相变;当冷速为10～20℃/s时,既发生铁素体-贝氏体相变又发生马氏体相变;当冷速≥30℃/s时,发生贝氏体-马氏体的相变。随着冷速的增加,试验钢的硬度也随之增大。在不同冷速下钢中均存在（Ti, Nb）C析出物,且在钢中呈弥散分布,在低冷速条件下,钢中析出物的体积分数较大,尺寸较小,具有一定的析出强化效果。     

薄板坯连铸连轧弹簧钢60Si2Mn的组织和性能

基于薄板坯连铸连轧产线低偏析、高洁净度、浅脱碳的特点,试制了最薄厚度为1.5 mm、宽度1250 mm的60Si2Mn热轧钢板,采用拉伸试验机、硬度计、金相显微镜、扫描电镜对试验钢进行了性能测试和组织分析。结果表明:热轧板力学性能满足切板、冲压下料的加工工艺要求,夹杂物为D0.5,组织为珠光体+少量铁素体,单面脱碳层为厚度的1.3%。加热温度840~920℃时淬火硬度61 HRC,200~280℃回火后硬度为57~60 HRC,满足制造产品的要求。     

Composition Optimization of Nb-Ti Microalloyed High Strength Steel

Four Nb-Ti microalloyed steels were refined and rolled to study the composition optimization of Nb-Ti microalloyed steels. The effects of Nb and Ti on the microstructures, precipitates and properties of Nb-Ti microalloyed steel were investigated. The results showed that an increase in Ti content resulted in the appearance of many fine precipitates leading to a strong precipitation strengthening effect. Hence, the yield strength increased. Besides, the increased strength by the combined increase of Nb and Ti was similar to that observed for the increase in Ti content alone. This increase in strength was attributed widely to the increase in the Ti content alone rather than Nb. Moreover, the increase in Nb content beyond 0.036 wt% exerted no significant effect on the strength of Ti-Nb microalloyed steels, in which more Ti could be added to further improve the strength of steels.     

Ti微合金化高强度热轧带钢组织性能及强化机理

The continuous cooling transformation behavior, the effect of coiling temperature on microstructure and mechanical properties, and strengthening mechanisms of Ti microalloyed high strength hot strip steel were systematically investigated by thermal simulation testing machine, laboratory rolling mill, SEM and HR-TEM. The dynamic CCT curve was established. The results show that the austenite to ferrite and pearlite transformation takes place when the cooling rate is less than 1??/s. The austenite to bainite transformation accompanied with austenite to ferrite and pearlite transformation takes place when the cooling rate is in the range of 5 ??/s to 10 ??/s. The bainitic transformation temperature is about 600??. The amount of granular bainite decreases, while the amount of lath bainite increases with the increase of cooling rate in the range of 20??/s to 50??/s. Furthermore, the study on the effect of coiling temperature on the microstructure and mechanical properties of experimental steel has shown that the strength and plasticity of tested steel are improved with decreasing the coiling temperature. When the coiling temperature is 550?棬the experimental steel possesses optimal mechanical properties owing to the grain refinement and precipitation of nano-scale TiC particles. And the tensile strength, yield strength and elongation of tested steel were 742MPa, 683MPa and 22??5%, respectively.     

金刚石锯片基体用钢75Cr1的连续冷却转变曲线研究

为充分发挥75Cr1钢种的性能优势,探索最佳的热处理工艺参数,采用相变仪、金相显微镜、维氏硬度计和扫描电镜对75Cr1钢进行研究。通过分析不同冷却速度下的相变组织和硬度,为优化热轧工艺及球化退火、淬火等提供理论指导。结果表明:75Cr1钢的相变点A_(c1)=705℃,A_(c3)=746℃,M_s=220℃。随冷却速度由0.1℃/s提高到30℃/s,组织逐渐由珠光体转变为贝氏体、马氏体,硬度由288 HV提高到772 HV。     

用氧化镁坩埚真空熔炼优质低碳低氧钢

为了降低氧化钙坩锅冶炼优质低碳低氧钢的生产成本,在50kg真空感应炉上开展氧化镁坩埚替代氧化钙坩锅冶炼优质低碳低氧钢的工艺试验。试验结果表明:随炉加入5g底碳可以用于钢液脱氧,不会造成钢液增碳;利用SiO挥发脱氧的特点,在真空度1Pa时,加入硅铁,抽气10min,成功用氧化镁坩埚冶炼出w(C)为9×10-6～14×10-6、w(O)为14×10-6～18×10-6的优质低碳低氧钢。     

差厚板轧制技术及其应用

介绍了差厚板的产生及其理论基础,阐述了差厚板的生产流程及其生产中的关键控制技术,通过国外大量应用实例说明差厚板的广阔前景,同时对我国差厚板的研究进程进行了分析,提出了我国差厚板的发展方向。     

加热温度对钛铌复合微合金化高强钢析出和性能的影响

在实验室冶炼了一种低碳高强度微合金钢,进行了轧制和回溶试验,对轧制试样进行了拉伸试验﹑检验了金相组织,并用TEM对比分析了不同加热温度下试样的析出物形貌、成分、尺寸。结果表明,1 280℃加热保温后轧制产品的性能优于1 180℃加热轧制后产品的性能;两种加热温度下轧制试样的组织都由铁素体和珠光体组成,晶粒尺寸基本相同;轧制试样的析出物均为(Ti,Nb)(C,N)复合析出,但1 280℃加热温度的试样析出更加细小、数量更多。析出强化理论计算表明,加热温度高的试样析出强化要比加热温度低的试样高131 MPa。回溶试验表明,铸坯在1 280℃保温1.5 h后,析出物基本回溶,而1 180℃保温1.5 h后,析出物不能充分溶解,证明了加热温度对钛铌微合金化高强钢析出强化有较大的影响。