局部脆性区对直接淬火回火钢焊接热影响区断裂韧性的影响

通过焊接热模拟和厚板焊接接头ＣＴＯＤ断裂性能试验,研究了直接淬火回火钢焊接热影响区局部脆性区组织和性能及对厚板焊接接头断裂韧性的影响,结果表明,在γ＋α二相区的内再次加热的粗晶区（ＩＣＣＧＨＡＺ）具有最低冲击韧性值,是焊接接头中最薄弱环节,该区在原奥氏体晶界上分布着“项链”状,ＭＡ组元,引发多层焊热影响区脆断起裂,降低热影响区断裂韧性,局部脆性区韧性的高低和尺寸的大小是控制直接淬火回火钢多层焊热和     

Nb-Cr X80管线钢管焊接接头断裂韧性的研究

对低温环境下Nb—CrX80管线钢管及其焊接接头的断裂韧性进行了深入研究。研究发现．Nb—Cr X80管线钢母材的抗开裂性能要优于热影响区,纵焊缝介于二者之间。对于KOBELB52U φ3．2mm低氢焊条上向根焊＋HOBART X80 φ2．0mm自保护药芯焊丝半自动下向填充盖面焊环焊接头,焊缝NQ方向的抗开裂能力优于NP方向,但热影响区的性能却是NP方向优于NO方向;而对于KOBELB52U φ3．2mm低氢焊条上向根焊＋金桥JC-30φ2．0mm自保护药芯焊丝半自动下向填充盖面焊环焊接头,焊缝及HAZ试样,NQ方向CTOD平均值要高于NP方向．说明NO方向抗开裂能力更好。     

Determination of critical CTOD using crack flank opening angle method in general yield regime

The crack tip opening displacement (CTOD) evaluation from CMOD values using compact tension (CT) specimen geometry and plastic hinge model (PHM) is well standardized in the literature. However, the model is found to be conservative for the general yielding situation. Moreover, the knowledge of the location of apparent axis of rotation which in turn depends on plastic rotational factor, r_pl, is essential for the conversion from CMOD to CTOD. In the present investigation, the ‘crack flank opening angle’ (CFOA) method has been suggested for the evaluation of plastic CTOD. This approach has facilitated the exact determination of apparent axis of rotation. The effect of the specimen thickness and notch root radius on CTOD has been investigated using the PHM and CFOA method. These results have been compared with finite element analysis results. Results achieved point out that the CTOD obtained from the traditional PHM are underestimated for the general yield situation.     

X70钢临界CTOD值ANSYS计算

随着海洋工程的发展,探索海洋油气的项目增多,天然气、石油的输送工程也日渐发展起来。UOE生产工艺下的高强X70钢被广泛运用到油气输运工程中,然后强度越高的钢其断裂韧度越低,需对这种高强钢的断裂韧度值进行确定。材料断裂韧度大小可以用临界裂纹尖端张开位移CTOD(crack tipopening displacement)来度量。临界CTOD是弹塑性断裂力学中重要的参数,其大小直接反映了裂纹尖端材料抵抗开裂的能力,临界CTOD值越大表示材料抗开裂性能越好,反之抗开裂性能越差,确定临界CTOD值意义重大。首先依据BS7448规范对X70钢断裂韧度临界CTOD值进行了测试,然后利用Ansys软件从CTOD定义出发对X70钢临界CTOD进行了计算,实现了试验与模拟的对比分析,可供压力容器和管道生产和结构安全性评估企业借鉴。     

厚钢板焊接接头韧性CTOD试验评定技术及应用

介绍了CTOD的概念、试验方法及试验应用于厚钢板及其焊接接头韧性评定的几个主要领域;焊接工艺评定,海洋平台建造,FPSO的断裂与安全性评估、钢箱梁建造、厚钢板的工厂认证和产品认证等;最后简要谈了CTOD试验的主要特点．     

Fracture toughness analysis of laser-beam-welded superalloys Inconel 718 and 625

In this study, two 3.2‐mm thick Ni‐base superalloys, Inconel 718 and 625, have been laser‐beam‐welded by a 6‐kW CO₂ laser and their room temperature fracture toughness properties have been investigated. Fracture toughness behaviour of the base metal (BM), fusion zone (FZ) and heat affected zone (HAZ) regions was determined in terms of crack tip opening displacement (CTOD) using compact tension‐type (C(T)) specimens. Laser‐beam‐weld regions showed no significant strength overmatching in both alloys. Ductile crack growth analysis (R‐curve) also showed that both materials exhibited similar behaviour. Compared to the BM there is a slight decrease in fracture toughness of the fusion and the HAZ.     

100 mm厚S420高强钢的热处理工艺及焊接性能

采用低C低Si、Ni+Cr+Mo+Cu复合强化的理念设计了100 mm厚的S420高强钢,对钢板焊接前后的微观组织、力学性能和裂纹尖端张开位移CTOD进行了观察和测试.试验结果表明:经过900℃淬火+580℃回火后,钢板的综合性能达到最佳,屈服强度为478 MPa,抗拉强度为581 MPa,伸长率为28.4％;钢板焊后...