Mg对X80管线钢夹杂物和奥氏体晶粒尺寸的影响

Effect of Mg on inclusion and austenite grain size of X80 pipeline steel

在实验室条件下,对X80钢进行了镁处理和热处理试验,分析了镁对钢中夹杂物和奥氏体晶粒尺寸的影响。结果表明,镁处理后,钢中钙铝酸盐类夹杂物含量减少,MgO·Al_(2)O_(3)夹杂物含量增加。Mg含量进一步增加,钢中会形成MgO夹杂物,导致MgO·Al_(2)O_(3)和Al_(2)O_(3)夹杂物含量减少。镁处理对钢中硫化物、碳化物和氮化物的类型和含量影响不大。镁处理可使钢中小尺寸夹杂物数量增加,夹杂物尺寸平均值减小。镁处理X80钢热处理后,钢中夹杂物主要为尺寸小于1μm的MgO·Al_(2)O_(3),具有钉扎晶界的作用,从而使镁处理后试样的奥氏体晶粒尺寸明显减小。

Magnesium treatment and heat treatment were carried out on X80 steel in a laboratory, and the effect of Mg on inclusion and austenite grain size of the steel was analyzed. The results show that the content of calcium aluminate inclusion decreases and the content of MgO·Al_(2)O_(3)inclusion increases in the steel after magnesium treatment. With the further increase of Mg content in the steel, MgO inclusions are formed, resulting in the decrease of MgO·Al_(2)O_(3)content and Al_(2)O_(3)content. Magnesium treatment has a little effect on the type and content of sulfide, carbide and nitrides in the steel. After magnesium treatment, the quantity percentage of small-sized inclusion is increased and the average size of inclusion is decreased in the steel. The main inclusion is MgO·Al_(2)O_(3)with a size of less than 1 μm in the magnesium treated X80 steel after heat treatment, which has an effect of pinning grain boundaries, and significantly reduces the austenite grain size of the steel.