摘要
用α－粒子径迹显微照相技术，并行电子能量损失谱（ＰＥＥＬＳ）分析电镜技术和金相试验方法，研究了１２Ｃｒ２ＭｏＷＶＴｉＢ（１０２）钢铸态、开坯态（锻造、初轧后）、轧管态（穿孔、连轧、张减后）、热处理态（正火、回火后）及服役态（蠕变、持久试验后）硼元素的存在形式和分布规律。研究表明，铸态（本样为例）硼元素随机分布：晶内固溶，轻度晶界富集。经锻造或初轧开坯后，硼的分布渐趋均匀。穿孔、张减等重复热加工过程使硼出现晶界的偏聚迹象：正火使晶界硼元素明显偏聚，同时伴随Ｃｒ的富集。正火加回火使硼大量向晶界迁移并形成富Ｃｒ的Ｍ_（２３）（Ｂ，Ｃ）_６，其后的服役状态（蠕变或持久试验），含硼的Ｍ_（２３）（ＢＣ）_６碳化物重新溶解而使硼回到晶粒内部并逐步均匀化。研究指出，硼的晶界析出与富Ｃｒ的Ｍ_（２３）（Ｂ，Ｃ）_６相有密切关系，即当（Ｆｅ，Ｃｒ）_（２３）Ｃ_６存在于晶界时，易形成（Ｆｅ，Ｃｒ）_（２３）（Ｃ，Ｂ）_６型碳化物析出（硼相）。１０２钢中硼含量和铬含量及热处理工艺是影响硼元素迁移行为的两大主导因素。
By using of α-particle trace(α-PT) micrography,parallel electron energy-loss spectroscopy(PEELS) electron microscope and metalographic analysis, a study has been made about the existing form and distribution of boron(B) in 12Cr2MoWVTiB(coded as steel 102) during different stages: as melted, cogged(forged and bloomed). pipe hot-rolled(billet piericing ,mandrel mill,stretch reducing),heat treated(as normalized and tempered) and service(after creep and stress rupture testing). The results show that in the melting stage B distributes randomly(as last sample): some are of interstitial solution and others are slightly enriched at grain boundaries.After repeated hot working processes of piercing as well as mandrel mill,stretch reducing,the sign of B segregation at grain boundaries begins to appear.Normalizing makes B segregating at grain boundaries obviously accompanied with Cr enrichment. Heat treatment of normalizing plus tempering makes B migrate to grain boundaries significantly and precipitate carbides containing B in form of M23(C,B)6 which is rich of Cr, At the following service condition (creep or stress rupture testing)carbide containing B M23 (C ,B)6 solutes again thus Bg oes back into grain and homogenizes gradually. This study indicates that there is a close relation between precipitation of B grain and M23 (C,B)6 enriched of Cr.that is(Fe ,Cr)23, (C ,B)6 type carbide boron phase, is easy to form and precipitate if the(Fe ,Cr)23 C6 in the grain boundaries. So control of B and Cr content in steel 102 as well as the design of heat treatment process are two main factors in controlling the migration behavior of boron element in steel 102.
