TRANSFORMATION OF STEEL AND SEGREGATION OF IMPURITY ELEMENTS INDUCED BY RAPID HEATING

快速加热引起的钢的转变和杂质元素的偏析

• 批准号: 05452294
• 负责人: TAMAKI Koreaki
• 金额: $ 3.52万
• 依托单位: MIE UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05452294/
• 关键词: heat affected zone; ferrite; austenite transformation; rapid heating; segregation in grain boundary; Cr-Mo steels; austenite grain; grain boundary of prior-austenite; creep test; クリープ試験; 溶接熱影響部; Cr-Mo鋼; 粒界腐食法; α→γ変態; 超高速変態再現装置; 1 1; 4Cr-1

A rapid transformation from fcrrite to austenite occurs in the heat affected zone (HAZ) of a steel when it is arc-welded. Several problems arising in HAZ would be brought about by this transformation. The process of transformation was examined systematically on HAZ of Cr-Mo steel and the following results were obtained.(1) An experimental method, which used a simulated-HAZ specimen, was newly proposed. A special type of simulator for this experiment was developed in the laboratory, which could produce the heating rate as large as 2000ﾟC/sec.(2) The temperature of ferrite/austenite transformation rose with an increasing heating rate. The A_1 temperature in the equilibrium state (740ﾟC for Cr-Mo steel) rose up to 1120ﾟC by the rapid heating with 2000ﾟC/sec.(3) The following sequence of transforming process was observed in Cr-Mo steel. In the beginning of transformation, fine grains of austenite were produced along the prioraustenite grain boundary. Those grains joined in each other at higher temperature.They grew to a grobular form in the final stage of transformation.(4) During the transformation, impurity elements, such as phosphorus were concentrated in the grain boundary of newly-produced austenite. The greater the heating rate, the larger the concentration of phosphorus in grain boundary.(5) An intergranular fracture was observed in the specimen of creep-rupture test. This type of fracture will be brought about by the segregation of impurity elements in the grain boundary of austenite, which was induced by the rapid transformation.

弧焊时，钢的热影响区（HAZ）发生了由冰晶向奥氏体的快速转变。这种转变会给热影响区带来一些问题。对Cr-Mo钢相变过程的热影响区进行了系统的研究，得到了以下结果：(1)提出了一种模拟热影响区试样的实验方法。本实验在实验室开发了一种特殊的模拟器，可以产生高达2000‰/秒的加热速率。(2)随着升温速率的增加，铁素体/奥氏体相变温度升高。以2000‰/秒的速度加热后，平衡态的A_1温度（Cr-Mo钢为740‰/秒）上升到1120‰/秒。(3) Cr-Mo钢的相变过程如下：在转变初期，沿原奥氏体晶界产生了细小的奥氏体晶粒。这些颗粒在较高的温度下结合在一起。它们在转变的最后阶段变成了球状。(4)在转变过程中，磷等杂质元素集中在新生成的奥氏体晶界处。升温速率越大，晶界磷浓度越大。(5)蠕变破裂试样出现沿晶断裂。这种断口是由奥氏体快速相变引起的晶界杂质元素偏析引起的。

项目成果

玉置,維昭: "Types of Temper Embrittlement in HAZ of Cr-Mo Steel Clossified by Tempering Time" Documents of InTernational Institute of Welding,IX-1745-94. 1-22 (1994)

Tamaki, Yoshiaki：“按回火时间回火处理的 Cr-Mo 钢 HAZ 的回火脆性”，国际焊接学会文件，IX-1745-94 (1994)。

Koreaki TAMAKI: "Formation of Austenite Grains and Grain Boundary Segregation in Heating Process of Steel" Research Reports, Faculty of Engineering, Mie University. Vol.18. 21-32 (1993)

Koreki TAMAKI：“钢加热过程中奥氏体晶粒的形成和晶界偏析”研究报告，三重大学工学部。

玉置維昭: "Low Ductility Creep Fracture in the HAZ of Cr-Mo Steels" Documents of International Institute of Welding,IX-1788-94. 1-27 (1995)

Yoshiaki Tamaki：“Cr-Mo 钢 HAZ 中的低延展性蠕变断裂”国际焊接学会文件，IX-1788-94 (1995)。

Koreaki TAMAKI: "Types of Temper Embrittlement in HAZ of Cr-Mo Steel Classified by Tempering Time" Documents of International Institute of Welding. IX-1745-94. 1-22 (1994)

Kooraki TAMAKI：“按回火时间分类的Cr-Mo钢HAZ中的回火脆性类型”国际焊接学会文献。

玉置,維昭: "Fe-P-C合金の急速加熱時のPの偏析過程" 溶接学会論文集. 5. 403-409 (1987)

Tamaki, Yoshiaki：“Fe-P-C 合金快速加热过程中 P 的偏析过程”，日本焊接学会论文集，5. 403-409 (1987)。