| 摘要 |
PURPOSE:To enable the detection of any phosphor segregation part quickly and handily as discoloring point by employing phosphor with a large coagulative regregation as subject component in place of sulfur. CONSTITUTION:A paper piece surface to be detected of a steel material is brought into contact with a reagent for metal corrosion and a test paper containing a salt solution of heavy metal is applied on the surface being detected to detect a phosphor segregation part as black point. Because of a large coagulative segregation rate, phosphor is densified remarkably at the final coagulated part. On the other hand, increase in the phosphor content auguments the corrosion rate of steel so that the coagulative segregation part of a test piece is dissolved in a corrosion liquid preferentially. Then, when a test paper impregnated with a silver nitrate solution is applied over the entire surface to be detected after the corrosion is done in this way, silver ion is precipitated as metal silver by reducing action of phosphine and a black point appears on the test paper. In this manner, any phosphor segregation part can be detected. |
