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采用Gleeble 1500D热模拟试验机对Ti和Al处理船体钢进行不同热输入焊接热模拟实验,并利用OM和SEM研究了母材和热模拟粗晶区氧化物夹杂及显微组织。结果表明:Ti处理钢中弥散分布的Ti氧化物具有良好的高温稳定性,75 kJ/cm的焊接热输入对其形貌、成分及尺寸无影响,能有效促进晶内针状铁素体(AF)形核长大。Al处理钢中以Al_2O_3为核心的复合夹杂高温易分解,不能促进晶内AF形核。线能量大于50 kJ/cm的大热输入条件下,Ti处理钢模拟粗晶区的低温韧性明显高于Al处理钢。t_(8/5)>40 s时,Ti处理钢中较多的晶内AF组织抑制了M-A岛形成,细化了基体铁素体组织,Al处理钢中的TiN和Nb(C,N)第二相粒子粗化,粗晶区晶粒异常长大,大于Ti处理钢中的奥氏体晶粒尺寸。
The thermal simulation of Ti and Al treated hull steels was carried out by using Gleeble 1500D thermal simulator. The OM and SEM were used to study the inclusions and microstructures of the oxides in the parent material and the thermally simulated coarse grains. The results show that the Ti oxides dispersed in the Ti treated steel have good high temperature stability. The welded heat input of 75 kJ / cm has no effect on the morphology, composition and size of the Ti oxides. It can effectively promote the intragranular acicular ferrite AF) nucleation grow up. Al-treated steel with Al_2O_3 as the core of the composite inclusions high temperature decomposition, can not promote the intragranular AF nucleation. Under the conditions of large heat input with line energy greater than 50 kJ / cm, the low temperature toughness of the simulated coarse grain zone of Ti-treated steel is obviously higher than that of Al-treated steel. In the case of t_ (8/5)> 40 s, more intragranular AF in the Ti-treated steel inhibited the formation of MA islands and refined the matrix ferrite and TiN and Nb (C, N) in the Al- The second phase particles roughening, coarse grain abnormal grain growth, larger than Ti austenite grain size.