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The solidification crack tendency of weld metals of fifteen types of fully austenitic stainless steels and heat-resistant cast alloys were overall quantitatively evaluated by using the tester having been carried out an improvement on Trans-Varestraint test and made in our institute. These indices-BTR of seven types of fully austenitic heat-resistant cast alloys and their corresponding solidification ductility curves have been first proposed in this paper. According to morphology regularity of solidification,... The solidification crack tendency of weld metals of fifteen types of fully austenitic stainless steels and heat-resistant cast alloys were overall quantitatively evaluated by using the tester having been carried out an improvement on Trans-Varestraint test and made in our institute. These indices-BTR of seven types of fully austenitic heat-resistant cast alloys and their corresponding solidification ductility curves have been first proposed in this paper. According to morphology regularity of solidification, cracking occurring in weld metals during the testing, new points on solidification cracking have been advanced, such as the use of the two-dimensional temperature field to analyse the characteristic of fracture mophology corresponding to the solidification cracking, the "horn-fracture model of solidification cracks" and the approximately formula for calculating horn-fracture area of solidification cracks-S being served as a new index to quantitatively evaluate the solidification crack tendency of weld metals. Therefore a new approach is provided for the investigation of propagation mechanism of solidification cracks in weld metals . 文中通过改进的TransVarestraint试验法(采用我院研制设备)对15种全奥氏体不锈钢及铸造耐热合金的焊缝凝固裂纹倾向进行全面的定量评定。首次提出了七种全奥氏体铸造耐热合金的BTR指标和对应的凝固塑性曲线。并对试验条件下产生的凝固裂纹形态规律提出了新的观点:采用二维温度场分析凝固裂纹断口的对应形貌特征;提出了“角形凝固裂纹断口模型”;推导了角形断口面积的近似计算公式。进而可得出评定焊缝凝固裂纹倾向的新的定量指标——角形断口面积S。为研究焊缝凝固裂纹扩展机制提供一新的途径。 Theoretical studying has indicated that the behaviour of surrounding medium of water has a large effect on the stress corrosion process of fracture in rock. So far, experiments made for stress corrosion in rock have been done under the situation of static water. In this experiment, the subcritical develop characteristics of fracture caused by stress corrosion n Yuennan marble samples under the situation of static and flowing distilled water have been studied respectively. The results show that flowing... Theoretical studying has indicated that the behaviour of surrounding medium of water has a large effect on the stress corrosion process of fracture in rock. So far, experiments made for stress corrosion in rock have been done under the situation of static water. In this experiment, the subcritical develop characteristics of fracture caused by stress corrosion n Yuennan marble samples under the situation of static and flowing distilled water have been studied respectively. The results show that flowing of the medium of water around fracture may accelerate the stress corrosion process of the end of fracture. It is perharps of great signifieanse to the study of earthquake source process and the precursor just before earthquake. 理论研究[1]表明,环境水介质的动态对岩石中裂缝的应力腐蚀过程有很大的影响。但迄今为止,岩石的应力腐蚀实验都是在水介质静止情况下作的。本实验对比研究了蒸馏水静止和流动情况下云南大理岩试件应力腐蚀引起的亚临界裂缝扩展特征。结果表明,裂缝周围水介质的流动会加速裂缝端部的应力腐蚀过程,这对于震源过程及临震前兆的研究可能有重要意义。样品采用紧凑拉伸试件,同时测量了断裂韧性K_(Ic)=(1.41±0.013)kg·mm~((-3)/2),并对人工狭窄锯口与天然初始裂缝的试件进行了对比测量,认为对于云南大理岩的紧凑拉伸试件可以用人工狭窄锯口代替天然初始裂缝。 The fracture appearance of Horn-Shaped propagation of solidification cracks occured in weld metals of two austenitic heat-resistant steels was presented in this paper. SEM observation was performed following the Trans-Varestraint test. The fracture morphology near the higher temperature side of Horn-Shaped (Brittleness Temperature Range-BTR) shows that the cracked surface has the characteristic of fracture morphology of higher temperature crack-openning, that is, there are intergranular liquid films and/or... The fracture appearance of Horn-Shaped propagation of solidification cracks occured in weld metals of two austenitic heat-resistant steels was presented in this paper. SEM observation was performed following the Trans-Varestraint test. The fracture morphology near the higher temperature side of Horn-Shaped (Brittleness Temperature Range-BTR) shows that the cracked surface has the characteristic of fracture morphology of higher temperature crack-openning, that is, there are intergranular liquid films and/or liquidus bridges observed on the fracture surface. The fracture morphology near the lower temperature side of Horn-Shaped (BTR) shows that the cracked surface has the characteristic of fracture morphology of lower temperatme crack-openning, that is, intercolumnar ridge line and/or ring ridge or some bud segregation for fully austenitic cast steels. It is proposed that there are three stages in the process of complete columnar crystal growth in weld metals. The Ta maximum and Tb minimum isotherm of BTR (Horn-Shaped) were discussed. 文中介绍了二种奥氏体耐热钢(4Cr25Ni13、4Cr22Ni14)横向可调拘束裂纹试验的角形裂纹断口扫描电镜观察研究的形貌特征。首次提出了焊缝脆性温度区间(BTR)高温侧开裂区常具有晶间液相膜和/或液相断桥的特征以及ETR低温侧开裂区常具有条形脊和/或环形脊的特征形貌。还验证了焊缝区内所具有的三种结晶形貌的柱状晶组织。在讨论中提出了BTR(角形裂纹)上、下极限等温线的温度值。
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