低合金钢焊缝金属中的夹杂物及针状铁素体形核

INCLUSIONS AND NUCLEATION OF ACICULAR FERRITE IN WELD METALS IN HSLA

关键词:  焊缝金属  杂质  铁素体

Key words:  Weld metal  Impurity  Ferrite

摘要:

近年来,焊缝金属中的夹杂物及它在铁素体形核中的作用受到了许多焊接冶金作业工作者的注意。本文用透射电子显微镜(TEM)观察了堆弧焊焊缝金属中针状铁素体的形核现象,用X射线微区能潜仪及电子衍射确定了形核夹杂物的相成分和相结构。研究结果表明,焊缝金属中的夹杂物为多元复相夹杂,而非单相。已确定的夹杂物相有a-MnS、TiO、Al₂O₃-MnO(锰尖晶石)和3MnO·Al₂O₃·3Sio₂(锰铝榴石)等。夹杂物作为惰性介质表面成为针状铁素体的核心,从而降低了形核的能垒。这种形核机制可以很好地解释多个铁素体在同一夹杂物上的"多维形核"现象。

Abstract:

In the past few years,weld-metallurgists have paid a good of attention to inclusions and their role in the nucleation of acicular ferrite.In this research the nucleation of acicular ferrite in submerged arc weld metals has been observed by transmission electron microscopy (TEM).Inclusion phase composition and construction have been analyzed by X-ray microanalysis and electron diffraction.These analysis have shown that the inclusions in weld metals are not single phase but contain many different elements and compounds.Following phaseshave been indentified:α-MnS,TiO,Al₂O₃·MnO(Galaxite) and 3MnO·Al₂O₃·3Sio₂(Spessartite) and etc.It is concluded that inclusions nucleate acicularferrite by acting as inert substrates,so that energy barrier to nucleation isreduced.This mechanism successfuly explains multi-nucleation of ferrite grainswhich takes place at most inclusions.