氧化时间对低合金弹簧钢奥氏体晶粒度测定的影响

氧化法可用于钢中晶粒度的测定.研究控制氧化时间对弹簧钢50CrV奥氏体晶粒度的影响.结果发现,氧化过程大致分为3个阶段:第一阶段,过剩铁素体相不断转变为奥氏体;第二阶段,基体与氧化膜之间的阴阳离子再次加快扩散,下层金属基体继续氧化脱碳,部分之前试样表面的奥氏体晶界被替代;第三阶段,一、二阶段的奥氏体晶粒逐渐长大,新旧氧...

Effect of oxidation time on evaluation of austenite grain size of low alloy spring steel

Oxidation method can be used to determine the grain size of steel. The effect of oxidation time on the evaluation of the austenite grain size of spring steel 50CrV was studied. It was found that the oxidation process can be divided into three stages. In the first stage, the excess ferrite phase is continuously transformed into austenite. In the second stage, the diffusion of anions and cations between the substrate and the oxide film is accelerated again, and the underlying metal substrate continues to oxidize and decarburize, and part of the austenite grain boundary on the surface of specimen is replaced. In the third stage, the austenite grains in the first and second stages gradually grow, and the old and new oxide films are superimposed to grow, which are verified in 55SiCr, 60Si2Mn and 65Si2CrV steels. Without affecting the accuracy of the test results, the oxidation time can be shortened from the standard 60 min to about half, and then the grain size can be obtained by modification, which is close to 11.00 grade of direct corrosion method and 11.09 grade of hydrogen induced intergranular fracture.