Effects of Strain Ratio on Fatigue Behavior of G20Mn5QT Cast Steel

Due to traffic and wave actions, cast steel joints are subjected to variable-amplitude fatigue loading, which may cause fatigue problems. The ratio of the minimum strain to the maximum strain(strain ratio)can be employed to analyze the influence of variable-amplitude fatigue both in the elastic and plastic ranges. To evaluate the effect of the strain ratio on G20Mn5 QT cast steel, the fatigue tests of smooth specimens were carried out at the strain ratio of 0.1. The cyclic deformation and the relationships between the strain amplitude, the stress amplitude, the Smith, Watson and Topper(SWT)parameter and fatigue life were studied and compared with those at the strain ratio of-1. Compared with other methods, Basquin formula and Solonberg formula provide reliable and appropriate ranges of S-N curve and fatigue limit at different strain ratios respectively. The SWT parameter can be used to predict the fatigue life at other strain ratios accurately.

20g钢高温高压水蒸汽氧化行为研究

通过20 g钢在360℃,18.67 MPa水蒸汽条件下的氧化试验,用静态增重法测定了20 g钢的氧化动力学曲线,其氧化动力学遵循抛物线规律;对氧化膜进行扫描电镜、X射线衍射和能谱分析,结果表明,氧化膜的氧化物类型为Fe3O4,呈颗粒状,而且,Fe3O4中富Fe;氧化物晶粒是通过形核和长大形成的;氧化初期,氧化速度较快,且随后的氧化反应一直在氧化膜的外表层进行,即发生外氧化.

20g品种钢工艺开发与研究

介绍了锅炉钢20g钢种转炉、连铸生产工艺及产品开发情况,试验表明其工艺是可行的。

流化床锅炉水冷壁20 G钢管泄漏的原因分析

某流化床锅炉水冷壁在水压加压过程中,发生钢管泄漏破裂,材料为20 G。文章对钢管进行了化学成分分析和金相组织检验,确定了钢管泄漏的原因。由于20 G钢管表面存在纵向裂纹源,位于缩口时的缩径处,而二次缩口时未进行消应力热处理,造成应力集中,与扁钢焊接时的焊接应力共同导致裂纹扩展,产生穿透性裂纹。此外,20 G钢管的外表面存在微裂纹,并且在裂纹附近有夹杂物存在,这也为裂纹扩展提供了条件。

炼钢厂Φ200mm20#g钢的生产实践

介绍了炼钢厂生产Ф200mm20#g钢的试验工艺，对影响铸坯质量的因素，如钢水质量、钢水温度、拉坯速度、冷却制度等进行了分析，提出了炼钢厂流程基础上的20#g钢的生产技术路线和措施，为下一步的生产提供了依据。