Creep-Embrittlement and Creep-Cracking in Heat Affected Zone of Cr-Mo Steel

铬钼钢热影响区的蠕变脆化与蠕变裂纹

• 批准号: 63420048
• 负责人: TAMAKI Koreaki
• 金额: $ 12.1万
• 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 (A)
• 财政年份: 1988
• 资助国家: 日本
• 起止时间: 1988 至 1990
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63420048/
• 关键词: Cr-Mo steel; Heat-affected-zone(HAZ); HAZ-creep-embrittlement; HAZ-creep-cracking; Simulation system; Transition temperature; Grain-boundary-cracking; Prior-austenite grain boundary; シャルピ-衝撃試験; クリ-プ割れ; クリ-プ脆化; 専用クリ-プ試験機; りんの粒界偏析; 粒界の脆弱化; Cr-

Creep-embrittlement and creep-cracking have recently been inspected in certain welded constructions, such as boilers and reactors. They occur in the grain-coarsened-zone (GCZ) of heat-affected-zone (HAZ) when it is reheated in the temperature range of 500 to 600^OC. 11/Cr-1/Mo heat-resisting steel is very susceptible to them. These investigators have constructed an experimental system for simulating those phenomena ; it was composed of (1) a simulator of weld-thermal-cycle, (2) creep-loading test machines and (3) a Charpy-impact-test machine. The main results obtainedby using this experimental system are summarized as follows.1. Nature of HAZ-creep-cracking : HAZ-creep-cracking can be defined as "the cracking which occurs along the prior-austenite grain boundary in GCZ, with a very small quantity of deformation at the time when the HAZ is reheated". This cracking occurs in an earlier time-period with an increasing stress and a raising temperature.2. Nature of HAZ-creep-embrittlement : HAZ-creep-embrittlement can be defined as "the phenomenon of raising the transition temperature of GCZ after a prolonged reheating, such as 2000hr at 550^OC". This embrittlement occurs in an earlier time-period with an raising temperature.3. Mechanism of causing these phenomena : HAZ-creep-cracking is produced by the following process. (1) Impurity elements segregate in the grain boundary of austenite during welding process, (2) their concentrations are enhanced by reheating process, (3) voids are produced in the grain boundary whereimpurity elements segregate. (4) stress connects the voids to form cracking.The origin of brittle fracture in HAZ-creep-ement will be voids or micro-cracks which are formed by the processes of (1) to (4).

在某些焊接结构中，如锅炉和反应堆，最近已经检测到蠕变脆化和蠕变开裂。它们发生在热影响区(HAZ)的颗粒粗化区(GCZ)，当HAZ在500~600℃温度范围内重新加热时。11/Cr-1/Mo耐热钢对它们非常敏感。这些研究人员已经建立了一个模拟这些现象的实验系统，它由(1)焊接热循环模拟器，(2)蠕变加载试验机和(3)夏比冲击试验机组成。利用该实验系统所取得的主要结果如下：1.实验结果。热影响区蠕变开裂的性质：热影响区蠕变开裂可定义为“在热影响区重新加热时，沿原奥氏体晶界发生的、具有极少量变形量的开裂”。这种开裂发生在应力增加和温度升高的较早的时间段。HAZ-蠕变-脆化的性质：HAZ-蠕变-脆化可以定义为“GCZ在长时间再加热后，如在550℃下加热2000小时，转变温度升高的现象”。这种脆化发生在温度升高的较早时间段。产生这些现象的机理：HAZ蠕变开裂是由以下过程产生的。(1)焊接过程中杂质元素偏聚在奥氏体晶界，(2)二次加热提高了杂质元素的浓度，(3)在杂质元素偏聚的晶界产生空洞。(4)应力将孔洞连接在一起形成裂纹，HAZ蠕变脆性断裂的起因是(1)到(4)过程中形成的孔洞或微裂纹。

项目成果

玉置 維昭,鈴木 実平,他: "StressーInduced PhosphorusーSegregation and Intergranular Cracking in Welded Zone of 1Crー1/2Mo Steel" Research Reports,Faculty of Engineering,Mie University. 14. 9-22 (1989)

Yoshiaki Tamaki、Jipei Suzuki 等人：“1Cr-1/2Mo 钢焊接区的应力诱导磷偏析和晶间裂纹”研究报告，三重大学工学部，14. 9-22 (1989)。

玉置維昭: 溶接学会溶接冶金研究委員会資料. (1989)

Yoshiaki Tamaki：焊接学会焊接冶金研究委员会材料（1989）。

K. TAMAKI, J. SUZUKI et al.: "System for Simulating the Embrittlement Induced by Creep in steel Weld." Research Reports, Faculty of Engineering, Mie University. 15. 1-8 (1990)

K. TAMAKI、J. SUZUKI 等人：“模拟钢焊缝蠕变引起的脆化的系统”。

玉置維昭: Research Reports of the Faculty of Engineering,Mie University. 13. 21-30 (1988)

玉木义明：三重大学工学部研究报告。13. 21-30 (1988)

玉置 維昭,鈴木 実平他: "System for Simulating the EmbriHlement Induced by Creep in Steel Weld" Reseach Reports,Faculty of Endineering,Mie University. 15. 1-8 (1990)

Yoshiaki Tamaki、Jipei Suzuki 等人：“模拟钢焊缝蠕变引起的胚胎的系统”研究报告，三重大学Endineering 学院，15. 1-8 (1990)。