Microstructure and Toughness in Weld Metal and Its Reheated Zone of High Strength Steel

高强钢焊缝金属及其再加热区的显微组织和韧性

• 批准号: 60550524
• 负责人: ARAKI Takao
• 金额: $ 1.22万
• 依托单位: Osaka University, Faculty of Engineering
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60550524/
• 关键词: 80 kgf; <mm^2> class high strength low alloy steel; Weld metal; Multipass welding Heat input; Microstructure; 靭性; 組織; 島状マルテンサイト

The multipass welding are carried out for high strength low alloy steels such as 80 kgf/ <mm^2> class steel in order to mitigate the heat affected zone (HAZ) embrittlement. In that case weld pass is reheated to various temperature by welding heats of the subsequent ones. This effect will naturally lead to the microstructural change of weld metal, and as a result, to the change of fracture toughness.The objectives of this study were to provide a detailed analysis of microstructure that can be found in 80 kgf/ <mm^2> class tensile strength weld metal as a function of heat input, chemical compositions and reheating temperature which was decided by imagining multipass welding, and then to discuss the relationship between microstructure and toughness. The major findings of this work are as follows.(1) In the weld metal of high strength steel the degradation of toughness was found at high heat input welding conditions as well as in the HAZ of base metal. (2) Such an embrittlement seemed to be caused by both the increasing in the area fraction of M-A constituent and the coarsening of microstructure. (3) In the reheated zone of weld metal the degradation of toughness was found in the peak temperature range between 750 and 950゜C at the multi-thermal cycles in spaite of welding conditions. The degradation of toughness was remarkable at high heat input welding conditions. (4) This embrittlement also seemed to be mainly caused by the increasing in the area fraction of M-A constituent. (5) Therefore, it implied that the decreasing in the area fraction of M-A constituent was effective as a method of improvement of toughness in both the weld metal and its reheated zone.

对高强度低合金钢（例如 80 kgf/ <mm^2> 级钢）进行多道焊接，以减轻热影响区 (HAZ) 脆化，在这种情况下，通过焊接热量将焊道重新加热到不同温度。这种影响自然会导致焊缝金属的微观结构发生变化，从而导致断裂韧性的变化。本研究的目的是提供对微观结构的详细分析，可以发现80 kgf/<mm^2>级焊缝金属的抗拉强度与热输入、化学成分和再加热温度的函数关系，这是通过想象多道焊决定的，然后讨论显微组织与韧性之间的关系。这项工作的结果如下。 (1) 在高线能量焊接条件下，高强度钢的焊缝金属以及母材的热影响区都发现韧性下降。脆化似乎是由M-A成分面积分数的增加和显微组织的粗化共同引起的。 (3)在焊缝金属的再加热区，在750和950℃之间的峰值温度范围内发现韧性下降。在各种焊接条件下的多次热循环中，韧性的降低在高热输入焊接条件下是显着的。 (5)因此，表明降低M-A成分的面积率作为提高焊缝金属及其再加热区的韧性的方法是有效的。

项目成果

Yoneo KIKUTA: "Relationship between Microsturucture and Toughness in Weld Metal and Its Reheated Zone of High Strength Steel" TECHNOLOGY REPORTS OF THE OSAKA UNIVERSITY. 37. 75-83 (1987)

Yoneo KIKUTA：“高强度钢焊缝金属及其再加热区的显微组织和韧性的关系”大阪大学技术报告。

Yoneo KIKUTA: TECHNOLOGY REPORTS OF THE OSAKA UNIVERSITY. 37. 75-83 (1987)

Yoneo KIKUTA：大阪大学的技术报告。