低合金钢活塞杆线性缺陷原因分析

Analysis of Linear Defects in Piston Rod Made from Low alloy steel

通过对韧性不足的活塞杆进行无损检测,发现内部存在较多线状密集分布的缺陷。金相观察表明,尺寸较大的缺陷实为多个小缺陷的集合体,小缺陷的尺寸从十几微米到数百微米不等。能谱分析确认缺陷为氧化铝和氧化钙的夹杂物,表明氧化物夹杂是活塞杆缺陷的主要组成部分。后续经过双真空冶炼(VD+VC)并增加钢锭的切头去尾率后,该缺陷消除,材料的韧性也达到了标准要求。

The piston rod with inadequate toughnesswas analyzedby nondestructivetesting(NDT).Lots of concentrated linear defects distributed were found.inside of the products.The metallographicobservation showedthat.the larger size of defects are actually the aggregationof multiple small defects.The small defects are about a dozen to hundreds of micrometers.Spectrumanalysis confirmedthat the defects are aluminumoxide and calcium oxide,so that the oxide inclusion is the dominating defect.The defecis can he eliminatedwhilethe product;undergoa doublevacuum smelting(VD+VC)and after increasingthe proportionof the headand tail of ingot cut off.Meanwhile the toughness of the material meets the standard requirements.