ZG 1Mn19Ni3Al 铸焊结构低温性能研究

通过化学成分设计和金相组织设计，开发了一种适用于与１６Ｍｎ钢组成铸焊结构的新铸钢ＺＧ１Ｍｎ１９Ｎｉ３Ａｌ。研究了这两种材料组成的焊板在常温、低温（－１９６℃）下的力学性能和冲击断口形貌。试验结果表明，夹杂物和焊接线能量对其低温冲击韧性有着显著的影响。具有γ＋ε双相组织的ＺＧ１Ｍｎ１９Ｎｉ３Ａｌ钢用于低温（－１９６℃）铸焊结构中时要注意钢水精炼和采用适当的焊接线能量     

局部脆化区对结构冷脆行为的影响

以１６Ｍｎ钢落锤试样进行了系列温度下的静载弯曲试验，发现在母材的冷脆特征温度Ｔｃ处，局部脆化区的启裂对结构断裂强度的影响作用发生明显转折。     

16Mn钢轧后控制冷却的贝氏体组织与性能

研究了１６Ｍｎ钢轧后会冷却工艺对贝氏体组织与性能影响，结果表明，采取适当的控冷工艺所得到细化铁素体和粒状贝氏体组织，可使１６Ｍｎ钢获得良好手强韧性配合，文中还对１６Ｍｎ钢轧后控冷所产生的贝氏体组织进行了分析。     

3种船用钢在南海海洋环境中8年的腐蚀行为

研究了３Ｃ（Ｗ ）、１６Ｍｎ、９２１ 三种钢在南海榆林海域全浸、潮差、飞溅环境中暴露８ 年的腐蚀行为。其中,９２１ 钢在飞溅区具有优良的耐蚀性,而在全浸和潮差区耐蚀性不如３Ｃ（Ｗ）钢和１６Ｍｎ 钢的。发现９２１ 钢在全浸区暴露２ 年后发生腐蚀率随时间增加而增大的“逆转”现象。     

低合金高强度钢的微观组织和疲劳裂纹扩展行为

用透射电镜观察了３０ＣｒＭｎＳｉＮｉ２Ａ钢等温的微观组织，疲劳裂纹扩展行为、裂纹尖端塑性区和位错结构，结果表明，等温状态组织由马氏体和贝氏体组成。在一个奥氏体晶粒内一般存在四个板条领域、裂纹尖端的塑性区内存在主位错带，疲劳断裂的基本组织单元为板条晶或板条束。裂纹遇到板条束界时方向发生较大偏斜。     

16Mn钢在H2S溶液中的脆断敏感性

采用慢性变速率拉伸实验（ＳＳＲＴ）、扫描电镜及电化学渗氢技术研究了Ｈ２Ｓ浓度、电位对１６Ｍｎ钢在Ｈ２Ｓ溶液中脆断敏感性的影响，结果表明：１６Ｍｎ钢在Ｈ２Ｓ溶液中的断裂是一种氢脆控制的断裂，随Ｈ２Ｓ浓度（Ｎ）增大，应力腐蚀断裂的机理从韧性转变的脆性；１６Ｍｎ钢片在Ｈ２Ｓ溶液中的稳态渗氢电流值ＩＨ和Ｈ２Ｓ浓度（Ｎ）满足ＩＨ＝８．５２５×Ｎ＾０．７２４９；ＩＨ受温度的影响主要表现在氢在１６Ｎｎ钢中的扩散     

塑料模具标准件顶杆用65MnV钢的组织分析

对新型塑料模具标准件顶杆用钢６５ＭｎＶ在淬火和氏温回火过程组织的变化进行了系统的研究。结果表明,６５ＭｎＶ钢的低温淬火组织为位错马氏体组织,随淬火温度的升高,淬火组织逐渐由针状与板条状马氏体的混合组织变成针状马氏体组织,马氏体组织的亚结构由位错型马氏体向孪晶马多体转变。钢在低温回火时析出与基体共格的弥散分布的须状ε碳化物,ε碳化物随回火温度的升高而发生转变,形成非共格的棒状渗碳体组织。     

C—Mn钢焊接接头的解理断裂应力的研究

测定了Ｃ－Ｍｎ钢焊接接头不同焊缝百分含量ｗ％的光滑试样,缺口试样和裂纹试样的解理断裂应力,发现不同试样有两个解理断裂应力表征了解理断裂起裂于母材、焊颖两区。而且发现裂纹试验解理断裂应力比缺口试样高,缺口试样解理断裂应力比光滑试样高,其原因是因为裂纹试样解理断裂临界事件最小,光滑试样最大。     

16Mnq钢用于焊接桥梁的防断适用性研究（续完）

１６Ｍｎｑ钢用于焊接桥梁的防断适用性研究（续完）洛阳船舶材料研究所刘家驹，蒋和岁，严明君，毕传堂６１６Ｍｎｑ钢用于焊接桥梁的分级使用在本文第４节，已提出了以大量试验为基础，考虑了加载速率和裂纹尖锐度的影响后的１６Ｍｎｑ钢板及焊缝金属的断裂抗力表达式（...     

低碳贝氏体钢双面埋弧焊接头的组织和低温韧性

对低碳贝氏体钢进行双面埋弧焊焊接,并用光学显微镜和PSW750型示波冲击试验机对焊接接头进行表征,研究了钢的显微组织和低温韧性。结果表明:低碳贝氏体钢双面埋弧焊后,焊缝区的组织为针状铁素体和粒状贝氏体;HAZ的组织为贝氏体铁素体和粒状贝氏体;HAZ熔合线附近的硬度最高,远离熔合线硬度降低并逐渐接近母材金属的硬度;随着温度的降低焊接过程中的凝固偏析、高度集中的位错源来不及松弛应力集中以及分布在晶界上的Ti、Mo等微合金元素形成的碳氮化物,导致焊接接头焊缝区和HAZ韧性降低并在-20℃和-60℃发生韧脆转变。     

EFFECT OF AN ELASTIC-PLASTIC SHOCK WAVE PART A: ON THE FATIGUE STRENGTH OF WELDED JOINTS

Fatigue data for welded joints subjected to an explosion treatment (ET) were obtained using rotary bending fatigue specimens. The fatigue fracture surfaces were observed by SEM and the dislocation morphologies by TEM. Mechanical properties have been quantitively studied by considering elastic and plastic shock wave characteristics. The test results indicate that the fatigue strength of welded joints subjected to ET is apparently improved due to the action of elastic or plastic stress waves while the ductility of the welded joints, i.e., reduction in area, is greatly increased.     

浅水爆炸下高桩钢管柱表面作用荷载实验研究

通过不同炸药量、不同爆炸距离、不同起爆深度的水中爆炸模型实验,研究了浅水爆炸条件下高桩钢管柱表面压力特征和空间分布规律,分析了比例爆距对冲击波峰值及空间分布影响,给出了钢管柱表面冲击波反射系数、绕射系数和抗爆设计中实际作用冲击波的工程算法。研究结果表明:水中爆炸作用下,反射和绕射冲击波近似同时作用在钢管柱表面,峰值沿柱身高度方向非均匀分;冲击波受水面影响程度相对较小,二次气泡脉动受水面影响程度较大;反射和绕射冲击波峰值均随炸药量增加、作用距离减小而增加。比例爆距相同,反射冲击波峰值相同,但炸药量小、爆炸距离近的实验工况绕射冲击波峰值相对较小;钢管柱表面冲击波反射系数和绕射系数随比例爆距增加而减小。比例爆距≥1.71时,钢管柱实际作用冲击波峰值可近似按自由场冲击波峰值的1.37倍计算。     

Evaluation of fatigue fracture mechanism in a flash butt welding joint of a U75V type steel for railroad applications

Nowadays, U75V steel is widely used in high speed railway construction, and commonly jointed by means of flash butt welding procedure. Considering the fact that fatigue failure is the main failure mode of railways, to ensure an adequate service life of railways, especially railways in coastal areas, this work mainly investigated the fatigue fracture mechanism of flash butt welding joints of U75V rail steel. First, the flash butt welding joints were prepared under two sets of process parameters and certain welding joints were corroded beforehand. Then, the microstructure, hardness, S–N curve and fatigue fracture of welding joints were analyzed in detail. Finally, the fracture mechanism was comprehensively discussed by considering the effect of welding parameters. It was concluded that the fatigue performance of flash welding joint is mainly determined by the upset pressure. Higher upset pressure is conducive to improve the fatigue strength. The fatigue crack source of fractured specimens under the condition of corrosion environment is at interface area and at the subsurface of sample. Meanwhile, the corrosion fatigue life obviously reduces.     

Endurance of cruciform welded joints in 13KhGMRB high-strength steel produced by mechanized submerged-arc and gas shielded welding

Investigations were carried out into the fatigue failure resistance of welded joints in 13KhGMRB high-strength steel in relation to the methods and technological processes of welding. Bend tests were carried out on cruciform specimens welded in CO₂, in a Ar + CO₂ mixture, as well as under a flux with and without preheating, with a symmetric load cycle. The results show that the maximum values of the endurance limit are recorded for welded joints produced by mechanized submerged-arc welding with preheating. The endurance limits of the welded joints produced by submerged-arc welding without preheating and in CO₂ are very similar. The lowest endurance limit is typical of the welded joints produced in Ar+CO₂ mixture.Translated from Problemy Prochnosti, No. 7, pp. 61–64, July, 1991.     

Effect of welding processes on fatigue crack growth behaviour of AISI 409M ferritic stainless steel joints fabricated using duplex stainless steel fillers

The present investigation aims to study the effect of welding processes such as shielded metal arc welding (SMAW), gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) on fatigue crack growth behaviour of the ferritic stainless steel (FSS) conforming to AISI 409M grade. Rolled plates of 4 mm thickness were used as the base material and AISI 2209 grade duplex stainless steel (DSS) was used as filler metal, for preparing single pass butt welded joints. Centre cracked tensile (CCT) specimens were used to evaluate the fatigue crack growth behaviour. From this investigation, it is found that the GTAW joints showed superior fatigue crack growth resistance compared with SMAW and GMAW joints. The reasons for the superior performance were discussed in detail.     

Fatigue performance of butt welds between cast steel joint and steel tubular members

Cast steel joints have gained increasing popularity for use in engineering. The fatigue performance of butt welds between cast steel joint and steel tubular members, however, is not yet well characterized. A series of fatigue tests were conducted on a new type of welding detail, cast steel joint with sloped end and integrated backing ring (Type C), for butt welds between cast steel joint and steel tubular members. Fatigue failure mechanism and S–N curves obtained from the tests were compared with those of Type A connection with backing ring and Type B cast steel joint with integrated nose obtained in literature. Fatigue behaviours of all three welding details were successfully predicted by local strain approach, the results of which are consistent with test results, especially for Types A and B welding details. According to the results of tests and analysis, fatigue cracking of butt welds between cast steel joint and steel tubular members always initiates from the bottom of the weld root, and the fatigue performance of Type C welding detail is better than those of Types A and B because of its lower stress concentration level. A simplified fatigue design equation was then proposed based on the results of local strain approach, in which the fatigue notch factor was adopted in fatigue behaviour evaluation. The accuracy of this simplified fatigue design equation was verified for Type C welding details with various geometry configurations.     

SUS304不锈钢点焊与胶焊接头的疲劳强度分析

通过拉剪实验测定1.5mm厚SUS304不锈钢点焊接头、胶焊接头的抗拉强度,并开展疲劳实验,获得不同应力水平下两种接头的疲劳寿命,得到两种接头的载荷-寿命曲线;借助扫描电镜分析接头疲劳失效过程。结果表明:当焊接电流为10.0kA、焊接时间为80ms、电极压力为0.5 MPa时,能获得较好的胶焊接头。在此焊接参数下,点焊接头、未固化胶焊接头和固化胶焊接头的平均失效载荷分别为12 825.5N、10 345.6N、10 022.9N;在疲劳实验载荷-寿命曲线的有限寿命区内,SUS304不锈钢胶焊接头的疲劳强度均大于点焊接头;点焊接头和胶焊接头的疲劳失效形式主要由母材眉状裂纹失效和界面撕裂失效两种形式组成;胶焊接头的疲劳失效过程中,首先是胶层粘接失效,随后疲劳裂纹从板间内表面热影响区边缘萌生,沿板厚与板宽方向扩展直至发生疲劳失效。     

焊接方法对10Ni5CrMoV钢接头疲劳性能的影响

针对屈服强度为785MPa级别的10Ni5CrMoV钢,分别采用焊条手工焊、气体保护焊和埋弧焊三种方法在其表面堆焊单层焊并设计成板状疲劳试样,研究三种焊接方法对10Ni5CrMoV钢接头疲劳性能的影响。结果表明:对于堆焊单层焊道试样,焊址处应力集中程度对疲劳启裂寿命起主要作用,随应力集中程度的增大,疲劳启裂寿命减小。焊条手工焊、埋弧焊和气体保护焊三种焊接方法中,气体保护焊焊趾处应力集中程度最大,疲劳启裂寿命最低;焊条手工焊焊趾处应力集中程度最小,疲劳启裂寿命最高。     

Fatigue behaviour of AISI 304 steel to AISI 4340 steel welded by friction welding

In the presented study, The weldability of AISI 304 austenitic stainless steel to AISI 4340 steel joined by friction welding in different rotational speeds and fatigue behaviour of friction-welded samples were investigated. Tension tests were applied to welded parts to obtain the strength of the joints. The welding zones were examined by scanning electron microscopy (SEM) and analyzed by energy dispersive spectroscopy (EDS). The Vıckers microhardness distributions in welding zone were determined. Fatigue tests were performed using a rotational bending fatigue test machine and the fatigue strength has been analysed drawing S-N curves and critically observing fatigue fracture surfaces of the tested samples. The experimental results indicate that mechanical properties and microstructural features are affected significantly by rotation speed and the fatigue strength of friction-welded samples decrease due to chromium carbide precipitation in welding zone with increasing rotation speed in choosen conditions.     

Effect of welding processes on toe cracking behaviour of pressure vessel grade steel

The effect of welding processes on fatigue crack growth behaviour of load carrying cruciform joints has been analysed. Cruciform joints were fabricated from pressure vessel grade (ASTM 517 ‘F’ grade) steel using shielded metal arc welding (SMAW) and flux cored arc welding (FCAW) processes. Fatigue crack growth experiments were carried out in a mechanical resonance vertical pulsator (SCHENCK 200 kN capacity) with a frequency of 30 Hz under constant amplitude loading (R=0). It was found that the toe crack growth rates were relatively lower in the joints fabricated by SMAW process than the joints fabricated by FCAW process. The heat affected zone (HAZ) region of SMAW joints contains a low carbon martensitic structure and exhibited better fatigue resistance compared to the bainitic HAZ microstructure of FCAW joints. Relatively higher heat input involved in FCAW process resulted in the above variation in HAZ microstructure and led to inferior fatigue performance of FCAW joints compared to SMAW joints.