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钢坯中的气体和非金属夹杂物在轧制过程中都可能形成条状缺陷,磁粉检验时,两种缺陷的磁痕特征基本一样,通常称这类冶金缺陷为发纹,也称作非金属夹杂物。对这类缺陷检查验收时,宏观检验法多采用酸浸或磁粉检验。目前,在国内有关技术标准中,所规定的塔形试样磁粉检验验收办法,存在着一定的弊病:其一,利用塔形试样三个阶梯表面上的磁痕条数所反映的质量来代表整根钢材的质量,不尽合理。这主要是钢材中心部位和各阶梯下面较大范围内的冶金缺陷,用磁粉检验发现不了;其二,验收标准中试样每个阶梯上所允许存在的发纹条数和发纹总长度,不随钢材塔形试样的直径变化而变化。作者参考国外有关资料,并根据多年的生产实践经验,认为对目前国内的塔形试样磁粉检验方法,有必要按国外的先进方法进行改进,使之对钢材的发纹验收更趋合理。
Billet gas and non-metallic inclusions in the rolling process may form strip defects, magnetic particle testing, the two defects of the magnetic marks are basically the same characteristics, usually referred to as such metallurgy defects hair pattern, also known as non-metallic Inclusion. Inspection and acceptance of such defects, the macro test method using acid leaching or magnetic particle testing. Currently, the relevant technical standards in the country, the provisions of the tower-shaped sample magnetic inspection and acceptance methods, there are some drawbacks: First, the use of tower-shaped sample three steps on the surface of the magnetic stripe number reflects the quality The quality of the whole steel represents unreasonable. This is mainly the central part of the steel and metallurgical defects within the larger scope of the ladders, which can not be found by the magnetic particle test. Second, the number of hair lines and the total length of the hair lines allowed on each step of the sample in the acceptance standard, Does not vary with the diameter of the steel tower-shaped specimen. With reference to relevant foreign information and based on many years of production experience, the author believes that it is necessary to improve the current domestic tower-shaped sample magnetic particle inspection method according to the advanced foreign methods so that it is more reasonable to inspect the hairline of steel products.