Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： The heat-affected zone (HAZ) produced by welding in stainless steel has higher susceptibility to intergranular corrosion, which is attributed to the Cr depletion induced by grain-boundary carbide-precipitation. The grain boundary engineering can be used to control over the grain boundary structure, which has significant influence on the carbide precipitation and the associated Cr depletion and hence on the susceptibility to intergranular corrosion. The grain boundary network in a 304 austenite stainless steel can be controlled by grain boundary engineering (GBE) with 5% tensile deformation and subsequent annealing at 1100 ℃ for 30 min. The total length proportion of Σ3n coincidence site lattice (CSL) boundaries was increased to more than 75%, and the large-size highlytwinned grain-cluster microstructure was formed through the treatment of GBE. Specimens were welded by gas tungsten arc- welding. Then the microstructure and the corrosion resistance of HAZ were characterized. The result showed that the high proportion of low ΣCSL boundaries and the optimum grain boundary character distribution were stable in the HAZ of the grain boundary engineered stainless steel, and the grain size was nearly the same. The weld-decay region of GBE samples performed better intergranular corrosion resistance during the intergranular corrosion immersion experiment and electrochemical potentiokinetic reactivation (EPR) test. The reported results indicated that the grain boundary engineering can effectively improve the intergranular corrosion resistance of the heat-affected zone in 304 austenitic stainless steel.
Subjects: Geosciences >> Geology submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
In China, the county is not only an important contributor to carbon emissions and a major carbon sink zone but also a key administrative unit for the implementation of China’s national goals for carbon peak and carbon neutrality. Focusing on Qingcheng County as a typical county in the Loess Plateau, we investigate the carbon emission characteristics and spatiotemporal patterns, to raise awareness of the need for ecological protection of the Yellow River Basin, while achieving high- quality development and green and low carbon transformation. The key results of our study are as follows. (1) The change and structure of county carbon emission in underdeveloped areas have distinct characteristics. Industries below the designated size are the largest source of carbon emissions in Qingcheng County, having a low proportion of industrial carbon emissions but a relatively high proportion of service sector and household carbon emissions. (2) The spatial distribution of carbon emissions in Qingcheng County conforms to the Pareto Principle: 80% of carbon emissions are concentrated in 20% of the region, which is characterized by“overall dispersion and local agglomeration”. The high carbon zones are mainly concentrated in the valley, broken plateau area, and urban area. The medium carbon zones are mainly distributed in the broken plateau area and along the traffic line. Low carbon zones are widely distributed in ridge, hill, and gully areas. (3) The county carbon emissions in the Loess Plateau show clear temporal and spatial pattern differences that are affected by differences in topography. The largest patch index of medium and high carbon zones, such as urban areas, industrial zones, and major towns, increases, the integrity improves, the diversity of carbon sources decreases, and the types tend to be single. The carbon source diversity increases and the aggregation degree decreases in the ecotone between medium carbon zones and low carbon zones, such as transportation lines and residential areas.
Subjects: Materials Science >> Materials Science (General) submitted time 2016-11-04 Cooperative journals: 《金属学报》
Abstract：通过冷轧5%变形及1100℃退火30min的晶界工程（GBE）处理工艺可将304奥氏体不锈钢低ΣCSL晶界比例提高到75%（Palumbo-Aust标准）以上，并形成了大尺寸的“互有Σ3n取向关系晶粒的团簇”显微组织 。采用钨极气体保护焊焊接样品，对焊接后样品的焊接热影响区进行显微组织表征和耐腐蚀性能测试。结果表明GBE处理过的304奥氏体不锈钢具有较好的晶界网络稳定性，焊接热影响区仍具有高比例重位点阵晶界，并且晶粒尺寸并未明显变大。在晶间腐蚀实验和EPR测试中，GBE样品HAZ敏化区都表现出了更好的耐腐蚀性能，因此表明晶界工程可以有效改善304奥氏体不锈钢焊接热影响区耐晶间腐蚀性能。
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