将带有V型刻槽的几种钢材试样，先在其奥氏体化温度下保温一段时间进行油淬或水淬，获得淬火马氏体组织，然后经回火空冷，待试样冷却至300～350 ℃（蓝脆温度）迅速将试样折断，最后将试样在空气中自然冷却或采取一定的保温措施冷却，便可获得良好的发蓝断口。经多次试验验证，结果表明：该方法获得的断口面呈均匀明显的深蓝色，夹杂物显示清晰，不存在影响夹杂物评定的不利因素。

Several kinds of steel specimens with V-shaped engraved groove, at first were heated and kept warm at the austenitizing temperature for a period of time and then quenched in oil or water, thus the quenching martensite structure was obtained. Then the specimens were tempered and cooled in the air. When the specimen temperature was 300~350 ℃ (blue brittle temperature), the specimens were fractured promptly and then cooled in the air or with some insulation measurement, finally the well bluing fracture surfaces were obtained. According to the repeating testing verification, the results show that the even and distinct mazarine color appeared in the fracture surface obtained by this method, and the inclusions could be shown clearly without the negative factors to influence the inclusion evaluation.