岳鹏宇
,
苗张木
机械工程材料
在分析现有CTOD直接观测方法的基础上,提出了针对高强钢厚板贯穿裂纹CTOD的直接观测法,该方法将光学显微镜和扫描电镜结合使用,运用多剖面法和图像后期处理技术;用该法对调质EQ56和EQ70高强钢32 mm厚板贯穿裂纹CTOD沿厚度的分布曲线进行了测定.结果表明:此方法可在缩减成本的前提下,获得了厚度方向较为稳定平滑的CTOD曲线.
关键词:
CTOD
,
高强钢
,
厚板
,
直接观测
,
多剖面法
杨秀芝
,
霍光瑞
,
余圣甫
,
付秀娟
材料开发与应用
doi:10.3969/j.issn.1003-1545.2009.06.001
根据GB/T2358-1994标准,对16mm厚的高强船体钢焊接接头的焊缝中心- 40℃的裂纹尖端张开位移(CTOD)进行测试, 绝大部分试样的断裂韧性值是有效合格的,其CTOD值大于0.15mm,符合DNV验收标准.试验结果表明,在给定的双丝埋弧焊接工艺下,该钢种焊缝低温韧性好.该钢种中等厚度双丝埋弧焊焊接接头可以在不进行焊后热处理的情况下使用.
关键词:
埋弧焊
,
焊丝间距
,
CTOD
,
有效性
徐斌
,
颜银标
材料导报
介绍了裂纹尖端张开位移(CTOD)评定技术的概念、发展历程、技术特点、试验方法等,提出了CTOD评定技术现有的问题并概述了这些问题的研究进展.最后简述了CTOD评定技术在工程中的广泛应用.随着相关研究的进展,CTOD理论体系必将更加完善并拥有广阔的发展前景.
关键词:
CTOD
,
试验方法
,
技术特点
,
应用
,
断裂韧性
江超
,
陈辉
,
车小莉
,
苟国庆
,
马纪军
材料科学与工艺
为了研究高速列车常用A6005A铝合金材料抵抗裂纹扩展能力,对其焊接接头断裂韧性和冲击韧性进行了求解.采用三点弯曲法、扫描电子显微镜等求出焊接接头各部位冲击韧性、断裂韧性以及断口形貌,得到断裂韧性CTOD值δm(8)和J积分值Jm(8)·试验结果表明,热影响区的冲击功为16.3 J；母材冲击功为11.5 J；焊缝区域最差,冲击功为5.5 J.CTOD数据表明,HAZ处δm(8)=0.373 9 mm,母材δm(8)=0.089 2 mm,焊缝δm(8) =0.069 7 mm.J积分数据表明,HAZ处Jm(8)=109.454 kJ/m2,母材Jm(8)=38.249 kJ/m2,焊缝Jm(8)=16.231 kJ/m2.热影响区断口上韧窝比母材上韧窝大,其韧性更好.焊缝上气孔、夹杂较多,其塑性较差,冲击吸收功很低.冲击韧性和断裂韧性表征规律一样,热影响区值抵抗裂纹扩展能力最好,母材次之,焊缝区最差.
关键词:
A6005A铝合金
,
焊接接头
,
三点弯曲
,
断裂韧性
,
CTOD
,
Jm(8)
张红宇
,
岑风
物理测试
doi:10.13228/j.boyuan.issn1001-0777.20160014
通过对实验室现有1 200 kN液压万能试验机的改造,结合使用100 kN疲劳试验机,完成了EH40高强度船板钢母材及焊接接头低温CTOD试验.应用试验结果对焊接接头韧性进行评价,结果显示,EH40船板钢埋弧焊焊接接头的低温CTOD断裂韧性良好,母材和焊缝均符合Rules for Classification and Construction Ship Technology船舶技术规范要求.不同位置、不同热输入量的试验比较表明,焊接部分的韧性主要与位置有关,而与热输入量关联不大.此外,英标BS 7448对最小裂纹长度的有效性判据更为严格,为各家船级社认证所采用.
关键词:
CTOD
,
低温韧性
,
装置改造
,
船板钢
,
焊接接头
W.Tong
,
N.Zhang
材料科学技术（英文）
Serrated plastic flows in an Al sheet (AA5182-H19) were first characterized temporally and spatially under quasistatic uniaxial tension. Discrete types B and C serrations or Portevin Le-Chatelier (PLC) bands started to appear at a plastic strain of 2.54% with an average stress drop of 2.5 MPa and an average time interval of 7.75 s between serrations. The width of the individual PLC bands was about twice of the thickness of the sheet (0.235 mm) and the plastic strain inside the bands was as high as 2%. V-notched tear test coupons made of the same Al alloy were then stretched under both continuous monotonic and periodic interrupted loading conditions and their crack initiation and growth processes were monitored by direct digital imaging. The crack tip opening angle (CTOA) and the crack tip opening displacement (CTOD) were measured to be about 2.5～3℃ and 0.07～0.1 mm, respectively. While no major load serrations were observed before crack initiation at the notch tip, discontinuous or intermittent crack advances or crack jumps were unambiguously detected in the crack growth stage. The unstable crack propagation in the AA5182-H19 sheet seems to be related closely with its strong dynamic strain aging behavior exhibited under quasistatic loading conditions at the ambient temperature.
关键词:
Crack growth
,
null
,
null
,
null
