偏析

　　钢中化学成分与杂质漫衍的不匀称征象，称为偏析。普通将高于平衡成分者，称为正偏析，低于平衡成分者，称为负偏析。尚有宏观偏析，如区域偏析与微观偏析，如枝晶偏析，晶间偏析之分。

　　大锻件中的偏析与钢锭偏析亲切相关，而钢锭偏析程度又与钢种、锭型、冶炼质量及浇注条件等有关。合金元素、杂质含量、钢中气体均加剧偏析的开展。钢锭愈大，浇注温度愈高，浇注速率愈快，偏析程度愈紧张。

　　（1）区域偏析  属于宏观偏析，是由钢液在凝集历程中选定结晶，溶解度变更和比重迥异惹起的。

　　对策是：

　　1）低落钢中硫、磷等偏析元素和善体的含量，如接纳炉外精炼，真空碳脱氧（VCD）处理及锭底吹氩工艺。

　　 2）接纳多炉合浇、冒口补浇、振动浇注及发烧绝热冒口，加强冒口补缩才气等措施。

　　3）严酷控制注温与注速，接纳短粗锭型，改善结晶条件。

　　 （2）枝晶偏析  属于微观偏析。树枝状结晶与晶间微区成分的不匀称性，大概惹起构造性能的不匀称漫衍。接纳扫描电镜（SEM）、波谱仪（WDS）、能谱仪（EDS）进行微区调查和成分说明能够检出并阐明缘故，普通经历高温分散加热，锻压合理变形与匀称化热处理能够消除或减轻其不良影响。

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Segregation

The uneven sign of chemical composition and impurity diffusion in steel is called segregation. Ordinary will be higher than the balance component, called positive segregation, lower than the balance component, called negative segregation. There are still macro segregation, such as regional segregation and microsegregation, such as dendrite segregation, intergranular segregation.

Segregation in large forgings is closely related to segregation of steel ingots, and the degree of segregation of steel ingots is related to steel grade, ingot type, smelting quality and casting conditions. Alloying elements, impurity content, and gas in steel all exacerbate the development of segregation. The larger the ingot, the higher the pouring temperature, the faster the casting rate, and the more segregation.

(1) Regional segregation It is a macrosegregation, which is caused by the selection of crystals in the agglomeration process of molten steel, the change in solubility and the difference in specific gravity.

The countermeasures are:

1) The content of segregation elements and good bodies such as sulfur and phosphorus in low steel, such as refining outside the furnace, vacuum carbon deoxidation (VCD) treatment and ingot bottom blowing argon.

2) Accept multi-furnace pouring, riser refilling, vibrating pouring and heat-insulating riser, and strengthen measures such as feeding and refining.

3) Strictly control the temperature injection and injection speed, accept short and thick ingot type, and improve crystallization conditions.

(2) Dendritic segregation belongs to microsegregation. The unevenness of dendritic crystals and the intergranular micro-area components probably cause the uneven distribution of structural properties. Acceptance of scanning electron microscopy (SEM), spectrometer (WDS), energy spectrometer (EDS) for micro-area investigation and composition description can detect and clarify the reason, ordinary experience high temperature dispersion heating, forging reasonable deformation and uniform heat treatment can eliminate or reduce Its adverse effects.