焊接热影响区针状铁素体的形核长大及其对组织的细化作用  

NUCLEATION AND GROWTH OF INTRAGRANULAR ACICULAR FERRITE AND ITS EFFECT ON GRAIN REFINEMENT OF THE HEAT-AFFECTED-ZONE

作　　者：舒玮[1] 王学敏[1] 李书瑞[2] 贺信莱[1] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083 [2]武汉钢铁(集团)公司,武汉430080

出　　处：《金属学报》2011年第4期435-441,共7页Acta Metallurgica Sinica

基　　金：国家高技术研究发展计划资助项目2008AA03Z501~~

摘　　要：通过观察焊接热循环冷却过程中不同温度取样直接淬火后的微观组织,研究了焊接热影响区(HAZ)晶内针状铁素体(IAF)的形核长大过程,论证了针状铁素体分割原奥氏体晶粒及细化晶内组织的机理.Auger电子能谱(AES)证实,在TiO_xMnS型复合夹杂物边界附近存在贫Mn区,IAF易于在这类复合夹杂物上形核,单个复合夹杂物能够诱导多个IAF形核,随着冷却过程中温度的降低,形核后的IAF逐渐长大.淬火马氏体和贝氏体在生长过程中会与IAF发生碰撞,使其发生变形,但不能穿过IAF.正是由于IAF分割了原奥氏体晶粒,阻碍了晶内其它微观组织的生长,焊接热影响区的微观组织得到细化.Nucleation and growth of intragranular acicular ferrites（IAFs） in heat-affected-zone （HAZ） have been investigated by the observation of microstructures quenched at different temperatures during the cooling process of welding thermal cycle.It is proved that IAFs can divide the prior austenite grains and refine the intragranular microstructures.AES show that there is a Mn-depleted-zone near the interface of TiO_x-MnS complex inclusion.IAFs prefer to nucleate on the complex inclusion,and a single inclusion can usually induce several IAFs to nucleate.IAFs grow up with lowering of the temperature during the cooling process.Quenched martensite and bainite could collide with the IAFs and make them deform,but the quenched martensite and bainite can not penetrate through the IAFs. IAFs divide the prior austenite grain and restrain the growth of other intragranular microstructures, and therefore HAZ＇s microstructure is finally refined effectively.

关 键 词：焊接热影响区(HAZ) 晶内针状铁素体(IAF) TiO_x-MnS型复合夹杂 贫Mn区 细化晶粒 

分 类 号：TG142.1[一般工业技术—材料科学与工程]