氩气在炼钢生产中的应用

<正>近年来,鞍钢“吹氩精炼工艺”得到广泛推广。实践有力的证明,无论是采用顶吹、底吹、还是用于平炉、转炉,吹氩对于提高钢的质量,发展品种,降低消耗等都是行之有效的手段。当前主要用于炉外精炼:1．往“钢包”(钢水罐)内吹氩其目的在于调节钢水温度,均匀钢水化学成分以及去掉钢中气体,排除部分非金属夹杂物。同时为了避免钢液浇注过程中的二次氧化,也需采用氩气来保护浇注。总之,吹氩被作为进一步精炼金属、净化钢水的一种必要手段。     

新形势下炉外炼钢技术研究探讨

随着现代科学技术的发展和工农业对钢材质量要求的提高，钢厂普遍采用了炉外精炼工艺流程，它已成为现代炼钢工艺中不可缺少的重要环节。笔者结合自身工作实践，在本文中分析了炉外炼钢技术的主要特点，探讨了当前炉外炼钢技术在生产中的应用方法，并提出了下一步炉外精炼技术的发展方向，供业内同行借鉴参考。     

管线钢环焊缝的侧膨胀值测定方法

以不同管线钢为研究对象，比较了图像分析法、游标卡尺法、侧膨胀仪法测量侧膨胀值的差异，验证了用侧膨胀值测定韧-脆转变温度的准确性及稳定性，并对X80钢实心焊丝自动焊环焊缝进行不同温度的夏比冲击试验。结果表明：对于韧性较差、韧性不均匀的材料，以及冲击断裂后发生扭曲的试样，宜采用侧膨胀仪法测量其侧膨胀值；对于管线钢，采用侧膨胀值测定其韧-脆转变温度结果的准确性和稳定性较好；X80钢实心焊丝自动焊环焊缝韧-脆转变温度对应的侧膨胀值为0.90 mm。     

冲击试样顶针孔及其深度对冲击吸收能量的影响

HGCJ-20型棒材拉伸-冲击试样加工中心可实现冲击试样的一步加工成型,为保持冲击试样的对中性和固定性,需要在其一端钻顶针孔。通过对不同钻孔后的冲击标准试样以及42CrMo钢和Q235H钢的冲击加工试样进行冲击试验,对比研究了顶针孔及其深度对冲击试样冲击吸收能量测试值的影响以及采用HGCJ-20型棒材拉伸-冲击试样加工中心与传统加工工艺对冲击试样冲击吸收能量测试值的影响。结果表明:对于42CrMo钢和Q235H钢,采用新型加工中心加工的顶针孔深度为5mm的冲击试样的冲击吸收能量实测平均值和采用传统工艺加工的冲击试样的一致;对于冲击标准试样和Q235H钢冲击加工试样,当冲击试样一端无顶针孔或顶针孔深度不大于8mm时,冲击试样的冲击吸收能量实测平均值较稳定,在正常范围(110～120J)波动;当顶针孔深度达到9mm并高于该数值时,冲击试样冲击吸收能量实测平均值普遍低于正常范围。     

起落架用超高强度钢冲击值的意义——兼论贝氏体组织的低缺口敏感性EI

通过对飞机起落架用40CrMnSiMoVA超高强度钢的电子示波冲击试验研究和分析,证实采用300℃等温淬火工艺获得以贝氏体为主的组织是提高40CrMnSiMoV钢冲击值的有效手段。     

RH精炼开发冷轧用超低碳钢的技术革新

对于精炼能力不足的炼钢厂，采用RH真空单重精炼工艺替代双重精炼工艺，具有积极意义。但是和RH＋LF或LF＋RH双重精炼工艺不同，采用RH真空单重精炼工艺开发冶炼冷轧超低碳钢，主要难点在于钢中夹杂物控制，控制不恰当会严重影响浇铸性能。使用适量铝渣作为顶渣改质剂和优化RH真空炉的过程控制．取得较好效果。     

45号钢生产实践

重点介绍了采用转炉-LF精炼-连铸生产45号钢的生产实践，根据45号钢的钢种特点重点在转炉控碳、连铸容易发生粘结漏钢方面采取了相应措施．保证了45号钢的成功生产。     

弹性材料受杆形射弹冲击的实验研究

采用实验方法,研究了长杆形钢射弹冲击钢、铝和尼龙6弹性材料时,射弹中应力随时间的变化规律。分析了冲击初速度、被冲击物材料特性对射弹中应力变化的影响。实验结果表明:弹性范围内,冲击初速度不改变射弹中应力变化规律,仅改变其幅值,应力波形中包含了被冲击物材料特性信息和几何信息。     

AF1410与300M钢的腐蚀冲击疲劳行为

根据舰载飞机起落的服务条件提出了腐蚀冲击概念和试验方法，考察了两种起落架材料在盐水中的腐蚀冲击疲劳行为，包括冲击疲劳寿命，裂纹萌生与扩展速率。尽管两种材料在空气中的冲击疲劳寿命几乎相等。但300M钢在盐水中的冲击疲劳寿命下降幅度较大。在盐水介质中，氢脆加速300M钢冲击疲劳裂纹的萌生和扩展。局部塑性变形区优先腐蚀促使AF1410钢的裂纹萌生，盐水对AF1410钢的裂纹扩展速率没有影响。     

钢液炉外精炼设备真空系统的设计分析

本文综合一些国内外有关资料，讨论了钢液炉外精炼设备真空系统设计中的一些技术问题，对放气量的确定、真空系统的气体负荷的等效换算以及真空泵容量的选择和能源消耗等进行了分析。给出蒸汽喷射泵的抽气能力与真空度的关系，可作为钢液炉外精炼设备的真空系统设计时参考。（注：1 Torr=133Pa）     

系列奥氏体锰钢耐磨性研究

测定了系列锰钢的冲击磨粒磨损性能，发现在低冲击功下锰钢的耐磨性与磨面硬度近似线性关系，而在高冲击功下耐磨性几乎与磨面硬度无关。对冲击功、冲击韧性及耐磨性三者之间关系研究得出：当冲击韧性与冲击功比值在３０—７０范围内时锰钢具有较高耐磨性     

钢结构厚板的冲击韧性研究

随着钢材在我国大跨度桥梁工程中广泛应用,钢材板厚也日益增加。对于厚板钢材,厚度增大使钢板的应力应变状态发生变化,中心偏析现象严重,更容易降低钢板厚度方向的韧性,且在低温环境下,这种现象表现尤为突出。而现行相关规范缺乏对厚钢板冲击试验规定。根据厚板低温冲击韧性试验数据,对钢板厚度变化对冲击韧性影响进行了探讨,并且利用Boltzmann函数对试验结果进行拟合,为钢结构厚板工程中冲击韧性取值提供参考作用。     

Tensile and Impact Properties of Shielded Metal Arc Welded AISI 409M Ferritic Stainless Steel Joints

The present study is concerned with the effect of filler metals such as austenitic stainless steel, ferritic stainless steel and duplex stainless steel on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure and fracture surface morphology of the joints fabricated by austenitic stainless steel, ferritic stainless steel and duplex stainless steel filler metals were evaluated and the results were reported. From this investigation, it is found that the joints fabricated by duplex stainless steel filler metal showed higher tensile strength and hardness compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Joints fabricated by austenitic stainless steel filler metal exhibited higher ductility and impact toughness compared with the joints fabricated by ferritic stainless steel and duplex stainless steel filler metals.     

Comparison of Impact Properties for Carbon and Low Alloy Steels

The impact properties of hot rolled carbon steel(used for the manufacture of reinforcement steel bars) and the quenched & tempered(Q&T) low alloy steel(used in the pressure vessel industry) were determined.The microstructure of the hot rolled carbon steel contained ferrite/pearlite phases,while that of the quenched and tempered low alloy steel contained bainite structure.Impact properties were determined for both steels by instrumented impact testing at temperatures between-150 and 200 C.The impact properties comprised total impact energy,ductile to brittle transition temperature,crack initiation and propagation energy,brittleness transition temperature and cleavage fracture stress.The Q&T low alloy steel displayed much higher resistance to ductile fracture at high test temperatures,while its resistance to brittle fracture at low test temperatures was a little higher than that of the hot rolled carbon steel.The results were discussed in relation to the difference in the chemical composition and microstructure for the two steels.     

Effect of rare earth cerium on the impact toughness,corrosion and wear resistance of CrNiMnMo alloyed lining steel

The effects of the addition of rare earth cerium on the impact corrosion and wear resistance of CrNiMnMo alloyed lining steel were studied using metallurgical microscopy, scanning electron microscope, x-ray powder diffraction, a hardness tester, an impact tester, and an impact corrosion abrasion tester. The properties of CrNiMnMo alloyed lining steel with the addition of cerium were compared with that of CrNiMnMo steel without the addition of cerium after being heat treated by same processes. The results show that CrNiMnMo alloyed lining steel with the addition of rare earth cerium consisted of lath martensite with a low residual austenite phase after being quenched and tempered. The lath of the martensite was fine and uniform. The impact toughness and the corrosion resistance of the steel lining board improved greatly with the addition of cerium and the impact toughness increased by 22 % with the fracture mode of being ductile. The CrNiMnMo alloyed lining steel with cerium showed the highest resistance to impact corrosion abrasion compared with the alloy without cerium.     

Relationship between stress-induced martensitic transformation and impact toughness in low carbon austenitic steels

The effect of test temperature, which controls the stability of austenite, on the impact toughness of a low carbon Fe-Ni-Mn-C austenitic steel and 304 stainless steel, has been investigated. Under impact conditions, stress-induced martensitic transformation occurred, in a region near the fracture surface, at test temperatures below 80°C for the Fe-Ni-Mn-C steel and below –25°C for 304 stainless steel. The former shows significant transformation toughening and the highest impact toughness was obtained at 10°C, which corresponds to the maximum amount of martensite formed by stress-induced transformation above the Ms temperature. The stress-induced martensitic transformation contributes negatively to the impact toughness in the 304 stainless steel. Increasing the amount of stress-induced transformation to martensite, lowered the impact toughness. The experimental results can be well explained by the Antolovich theory through the analysis of metallography and fractography. The different effect of stress-induced transformation on the impact toughness in Fe-Ni-Mn-C steel and 304 stainless steel has been further understood by applying the crystallographic model for stress-induced martensitic transformation to these two steels.     

12CrNi5MoV锻钢的回火脆特性研究

研究了系列温度回火处理的12CrNi5MoV锻钢的夏比冲击试验,并采用扫描电镜对冲击断口形貌进行了分析。结果表明,12CrNi5MoV锻钢存在两个回火脆温度,分别为400℃和570℃。与原始调质态相比,400℃回火和570℃回火分别使-20℃冲击功下降了52%和47%。     

应变时效对ADB610钢冲击韧性的影响

采用最小二乘法、相关系数检验法和K-S检验法分别对ADB610钢42 mm厚度钢板在5%应变时效处理前后冲击韧性进行正态分布拟合检验分析,认为两种情况下的冲击韧性值都服从正态分布。采用F检验法和t检验法对应变时效处理前后的冲击韧性进行标准差和均值的检验研究,认为5%应变时效处理对ADB610钢42 mm厚度钢板冲击韧性值的标准差和均值都无显著性差异,即ADB610钢42 mm厚度钢板的冲击韧性对5%内的应变时效处理不敏感。     

外包不锈钢圆中空夹层钢管混凝土柱抗撞计算方法研究

目前钢筋混凝土和实心钢管混凝土构件已广泛应用于实际工程,在抗冲击性能方面已形成相关设计方法,而针对外包不锈钢圆中空夹层钢管混凝土(CFDST)柱的耐撞性能研究较少。为此,该文在前期试验研究的基础上,采用ABAQUS建立了该类构件在轴力与侧向撞击耦合作用下的有限元模型。分析了轴力-撞击共同作用下该类构件的抗撞机理;重点研究了轴压比、名义含钢率等对构件抗撞性能的影响;给出了该类构件在轴力-撞击耦合作用下撞击力平台值动力放大系数(DIF)的计算公式。结果表明:外钢管的塑性变形是构件耐撞的主要耗能机制;轴压比对构件抗撞性能起削弱作用,且当轴压比大于0.5时,削弱程度更加明显;名义含钢率、外钢管与混凝土强度、撞击速度和截面外径对构件抗撞性能影响较大;建议的计算公式能够较好预测该类构件侧向撞击下的撞击力平台值。