富Nb复合碳氮化物对22Cr15Ni3.5CuNbN奥氏体钢焊接模拟热影响区组织和性能的影响

采用Gleeble热模拟的方法, 通过模拟焊接过程中快速加热和冷却的热循环过程, 得到1150~1300 ℃不同峰值温度下22Cr15Ni3.5CuNbN奥氏体钢扩大的热影响区组织, 并对其进行冲击性能分析. 对热影响区组织的研究表明, 实验钢的母材中存在一定量富Nb复合碳氮化物, 有效钉扎晶界, 且与大量位错缠结. 在焊接过程中, 该富Nb复合碳氮化物经历溶解与重新析出的复杂过程: 当峰值温度为1150 ℃时, 仅小颗粒的富Nb碳氮化物发生了溶解, 而峰值温度为1300 ℃时, 富Nb复合碳氮化物经历溶解与重新析出, 呈现网状的组织形貌, 且其整体尺寸增加. 富Nb复合碳氮化物的演化导致了冲击功的变化, 经历焊接热循环条件的实验钢较母材具有更高的冲击韧性, 随着峰值温度的升高, 冲击韧性呈现先升后降的趋势, 其中在峰值温度为1150 ℃时实验钢的冲击韧性最高.      

焊接热循环对微钙钢组织性能的影响

研究了焊接热模拟工艺参数(峰值温度Tp、焊后冷却时间t8/5)和真实焊接对微钙钢热影响区显微组织和性能的影响.用Lepera着色腐蚀剂腐蚀粒状贝氏体中的M-A组元,观察和研究了不同t8/5的热模拟条件下粒状贝氏体中M-A组元的形态、数量及分布特征.结果表明:当冷却速度较快时,M-A组元主要以杆状呈方向性分布;当冷却速度降低时,M-A组元逐渐变成颗粒状,并失去方向性;真实焊接试验结果与热模拟试验结果相符.     

高性能桥梁钢模拟焊接热影响区组织与性能研究

采用热模拟试验机Gleeble 3 800对高性能桥梁钢Q420q D焊接热影响区组织及韧性进行分析,主要研究峰值温度(Tmax)、冷却时间(t8/5)对焊接过程热影响区组织长大及低温韧性的影响。结果表明:Tmax为1 000℃时,模拟焊接热影响区组织为细小的铁素体+少量珠光体,韧性最好;Tmax为1 200~1 300℃时,组织为粗大的上贝氏体及粒状贝氏体,韧性最差;Tmax为1 400℃时,随着冷却时间(t8/5)的延长,粗晶区组织明显长大,先共析铁素体数量增加,M-A组元尺寸变大,韧性降低。     

钇基稀土微合金化E36船板钢热模拟焊接探讨

运用Gleeble—3800热模拟机对添加钇基稀土的E36船板钢(以下称E36RE船板钢)进行热模拟试验,研究不同热输入对E36RE船板钢模拟焊接热影响区组织和性能的影响.结果表明,随冷却时间(t8/5) 的增加,模拟焊接热影响区组织中贝氏体逐渐减少,板条状贝氏体向粒状贝氏体转变,冷却时间(t8/5) 增加到40 s时出现珠光体组织.当模拟热输入线能量为78.37 kJ/cm时,模拟焊接热影响区组织细小均匀,具有较好的强韧性,-40 ℃时冲击韧性为134.6 J.      

04Cr13Ni5Mo超级马氏体不锈钢焊接性能研究

模拟了04Cr13Ni5Mo超级马氏体不锈钢不同焊接热循环条件下热影响区组织,进行了焊条电弧焊接及焊后热处理试验,分析了焊接热模拟试样及焊条电弧焊接头的微观组织、力学性能.焊接热模拟试验结果表明,模拟热影响区的组织主要为低碳板条马氏体,其硬度较母材有较大提高,冲击韧性有所下降;模拟单道焊或多道焊时,不同的冷却速度及层间热处理对模拟热影响区的硬度及冲击韧性影响不大,600℃焊后回火热处理可以明显软化模拟热影响区组织,并让其冲击韧性恢复到较高水平.焊条电弧焊接结果表明,采用04Cr13Ni5MoRe型焊条及配套的焊后热处理工艺,可以获得良好综合力学性能的焊接接头.     

HQ130＋QJ63高强钢焊接接头的组织与性能

采用光镜，电镜，冲击和拉伸等试验方法，对气体保护焊“低强匹配”焊材焊制的ＨＱ１３０＋ＱＪ６３高强钢焊接接头的显微组织和力学性能进行了试验研究，并采用模拟焊接热循环的方法研究了不同峰值温度和冷却时间对ＨＱ１３０钢热影响区（ＨＡＺ）组织和冲击韧性的影响，试验结果表明，受焊接热循环影响，ＨＱ１３０钢ＨＡＺ存在回火软化区，该区域软化或失强最大的部位在峰值加热温度为Ａｃ１附近。在ＨＡＺ峰值温度Ａｃ１～Ａｃ３     

V-N微合金钢焊接热影响区组织与力学性能研究

为解决V-N微合金钢焊接热影响区晶粒异常粗化导致局部脆性的问题,采用OM、SEM、TEM、EBSD等手段分析了不同焊接热循环条件下焊接热影响区的显微组织、析出行为和力学性能之间的关系。结果表明,单道次焊接试验中随着线能量的增大,组织中贝氏体数量减少,针状和多边形铁素体数量增多,原奥氏体尺寸和晶界铁素体的尺寸逐渐增大,表现出较差的冲击韧性;双道次焊接试验中随着峰值温度的提高,粗晶热影响区的冲击韧性逐渐提高,铁素体外侧大角度晶界增多。微观组织分析表明,小尺寸的多边形铁素体增加了大角度晶界的比例,提供了较大的解理断裂的阻力,可抑制裂纹的扩展。奥氏体中的V(C,N)可细化M-A岛,改善冲击韧性。     

HQ 100钢焊接性研究

本文研究了HQ 100钢模拟及实际焊接热影响区各部位的韧性及组织变化,并用插销试验、纵向可调拘束裂纹试验和T型坡口再热裂纹试验对HQ 100钢的裂纹敏感性进行了评定。试验结果表明,模拟热循环峰值温度对HQ 100热影响区韧性有明显影响。随峰值温度升高,冲击韧性下降。Δt 8/5对韧性也有一定影响,当Δt 8/5为10 s时,过热区韧性最佳。实际热影响区峰值温度对韧性的影响也具有同样的规律性,但其韧性比模拟热影响区高一倍左右。组织和晶粒度的不同是造成上述变化的重要原因。抗裂性试验结果表明,HQ 100钢具有良好的抗热裂纹,再热裂纹性能。冷裂敏感性也较低,只要严格控制焊条烘干条件,预热和层温不低于130℃,便不会产生冷裂纹。     

高铌X80管线钢焊接粗晶区组织和性能研究

采用焊接热模拟技术对高铌X80管线钢进行了热模拟试验,研究了在不同焊接热模拟工艺下贝氏体组织的转变及冲击韧性的变化.结果表明:在不同的焊接热循环条件下,焊接粗晶区组织主要是板条贝氏体和粒状贝氏体.冷却时间t8/5为10 s时,适量的粒状贝氏体起到了分割板条贝氏体的作用,且MA岛的数量较少,呈粒状均匀分布于奥氏体内,使得...     

应用示波冲击法研究Q960钢焊接热模拟冲击韧性

利用示波冲击方法对Q960钢的焊接热模拟冲击韧性展开研究。对不同热输入下峰值温度分别为1 300℃、1 100℃和850℃的焊接热模拟试样进行了示波冲击和组织检验。结果表明:峰值温度为1 300℃时,热模拟试样的组织以马氏体为主,峰值温度为1 100℃和850℃时,热模拟试样的组织以贝氏体为主;峰值温度为1 300℃时,热模拟试样的裂纹扩展功Wp随焊接热输入的增加先升高后降低,峰值温度为1 100℃和850℃时,热模拟试样的裂纹扩展功Wp随焊接热输入的增加呈现降低的趋势。     

不同冷速下钛微合金化Q345B钢的HAZ组织及性能

焊接热影响区(HAZ)的微观组织很大程度上决定了钢材焊接处的力学性能。为了掌握含钛微合金钢Q345B在不同焊接线能量下热影响区的微观组织及性能演变规律，采用Gleeble 3500热模拟试验机，对含钛微合金钢Q345B焊接过程中热影响区的组织演变进行模拟试验研究，分析了冷却速率对热影响区的微观组织及冲击韧性的影响。结果表明，大线能量焊接低冷速下热影响区组织以粒状贝氏体为主，t8/5为120 s时，析出针状铁素体，针状铁素体的出现有利于焊接热影响区冲击韧性的提升。     

Simulation study on heat-affected zone of high-strain X80 pipeline steel

The microstructure evolution and impact-toughness variation of heat-affected zone(HAZ)in X80 highstrain pipeline steel were investigated via a welding thermal-simulation technique,Charpy impact tests,and scanning electron microscopy observations under different welding heat inputs and peak temperatures.The results indicate that when heat input was between 17 and 25kJ·cm~(-1),the coarse-grained heat-affected zone showed improved impact toughness.When the heat input was increased further,the martensite-austenite(M-A)islands transformed from fine lath into a massive block.Therefore,impact toughness was substantially reduced.When the heat input was 20kJ·cm~(-1) and the peak temperature of the first thermal cycle was between 900 and 1300°C,a higher impact toughness was obtained.When heat input was 20kJ·cm~(-1) and the peak temperature of the first thermal cycle was 1300°C,the impact toughness value at the second peak temperature of 900°C was higher than that at the second peak temperature of 800°C because of grain refining and uniformly dispersed M-A constituents in the matrix of bainite.     

大线能量焊接船板钢的研究现状与发展

大线能量焊接过程中,焊接HAZ高温停留时间延长,相变冷却速度减慢,HAZ奥氏体晶粒急剧长大。采用TiN、Ti-B等技术抑制HAZ奥氏体晶粒长大以提高大线能量焊接性能难以满足更高线能量的要求。氧化物冶金技术的提出对大线能量焊接用钢HAZ韧性的改善具有重要的意义。文章主要叙述了大线能量焊接HAZ韧性改善的方法以及发展方向,并重点对稀土Y应用于大线能量焊接HAZ韧性改善的可能性进行分析预测。     

大线能量焊接高强船板钢氧化物冶金技术的新进展

分析了中国船舶工业的现状、成就、挑战及发展趋势.为了提高船舶制造效率,采取了增加焊接线能量的措施.大线能量焊接时,由于高温停留时间长,相变冷却速度慢,焊接热影响区奥氏体晶粒急剧长大,得到侧板条铁素体为主的凝固组织,韧性恶化.氧化物冶金技术利用钢中的细小氧化物,通过促进晶内铁素体形核可明显改善焊接热影响区的组织.叙述了氧化物冶金的主要内容和该技术对船板钢的组织和性能的影响.介绍了日本一些钢铁公司开发的大线能量焊接高强船板钢氧化物冶金新技术.     

Microstructural changes in HSLA-100 steel thermally cycled to simulate the heat-affected zone during welding

The microstructural changes that occur in a commercial HSLA-100 steel thermally cycled to simulate weld heat affected zone (HAZ) behavior were systematically investigated primarily by transmission electron microscopy (TEM). Eight different weld thermal cycles, with peak temperatures representative of four HAZ regions (the tempered region, the intercritical region, the fine-grained austenitized region, and the coarse-grained austenitized region) and cooling rates characteristic of high heat input (cooling rate (CR) = 5 °C/s) and low heat input (CR = 60 °C/s) welding were simulated in a heating/quenching dilatometer. The as-received base plate consisted of heavily tempered lath martensite, acicular ferrite, and retained austenite matrix phases with precipitates of copper, niobiumcarbonitride, and cementite. The microstructural changes in both the matrix and precipitate phases due to thermal cycling were examined by TEM and correlated with the results of (1) conventional optical microscopy, (2) prior austenite grain size measurements, (3) microhardness testing, and (4) dilatometric analysis. Many of the thermal cycles resulted in dramatic changes in both the microstructures and the properties due to the synergistic interaction between the simulated position in the HAZ and the heat input. Some of these microstructures deviate substantially from those predicted from published continuous cooling transformation (CCT) curves. The final microstructure was predominantly dependent upon peak temperature(i.e., position within the HAZ), although the cooling rate(i.e., heat input) strongly affected the microstructures of the simulated intercritical and finegrained austenitized regions. A. MATUSZESKI, formerly Summer Student, Physical Metallurgy Branch, Naval Research Laboratory.     

钙处理对稀土在大线能量焊接HAZ中作用的影响

 为了探明钙处理对稀土改善C-Mn钢焊接HAZ韧性作用的影响,利用Gleeble模拟了热输入为339 kJ/cm的焊接热循环过程,对比研究了稀土处理钢和Ca-稀土处理钢焊接HAZ中夹杂物、显微组织和低温冲击韧性差异,分析了钙对稀土在HAZ中作用的影响规律,发现钙处理能促进稀土改善HAZ低温冲击韧性。钙能使稀土处理钢HAZ中的夹杂物从稀土氧化物复合夹杂转变为稀土-Ca的复合夹杂,平均尺寸从1.5增大到2.2 μm,长宽比从1.5减小到1.4,夹杂物总量降低。虽然钙对稀土处理钢HAZ中晶内针状铁素体的含量影响不大,但钙能增强稀土对HAZ原奥氏体晶粒粗化的抑制作用,Ca-稀土处理钢HAZ原奥氏体晶粒尺寸比稀土处理钢小。热输入为339 kJ/cm时,钙处理能使稀土处理钢HAZ低温冲击韧性明显提高。     

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Welding thermal simulation tests were performed on E550 shipbuilding steel and the effect of welding parameters on the microstructure and mechanical properties of the simulated heat affected zone (HAZ) was investigated. The result indicates that the microstructure of coarse-grained heat affected zone (CGHAZ) is strongly affected by t8/5. When t8/5 is shorter, the microstructure mainly consists of lath bainite and granular bainite. With the increase of t8/5, the impact toughness decreases, the volume fraction of granular bainite increases and becomes dominant when t8/5=300s. With the increase of welding peak temperature, the impact toughness of the single-pass weld specimens increases first and then decreases, while that of the double-pass weld specimens increases, with intercritically reheated coarse-grained heat affected zone (IRCGHAZ) has the lowest value. Microstructural examination reveals that the embrittlement of CGHAZ and IRCGHAZ is mainly caused by the formation of coarse granular bainite for the former, and coarse M-A constituents along grain boundaries for the latter.     

大线能量焊接用EH420海工钢生产工艺及焊接性能

河钢集团有限公司开发了利用钢液中形成TiO_x?MgO?CaO细小粒子改善焊接粗晶热影响区韧性的ITFFP技术（Improve the toughness of HAZ by forming TiO_x?MgO?CaO fine particles in steel）,成功试制生产出大线能量焊接用30 mm厚度规格（H30）和60 mm厚度规格（H60）EH420海洋工程用钢。母材力学性能试验结果表明,H30和H60试制钢屈服强度分别达到461 MPa和534 MPa,抗拉强度分别达到570 MPa和628 MPa,延伸率分别为26%和24.5%,满足EH420海洋工程用钢国家标准要求。采用Gleeble-3800型热模拟试验机对试制钢进行了200 kJ·cm?1条件下热模拟试验,并对焊接热影响区中的显微组织和?40 ℃冲击韧性进行了分析和测试。结果表明,试制钢中形成的CaO(?MgO)?Al₂O₃?TiO_x?MnS夹杂物可以有效地诱导针状铁素体析出,显著提高钢材的冲击韧性。另外,利用气电立焊设备对H30和H60试制钢分别进行了焊接线能量为247 kJ·cm?1和224 kJ·cm?1的实焊试验,结果显示,H30试制钢焊接接头表面和根部焊缝处?40 ℃冲击吸收功值≥74 J,焊接热影响区≥115 J,H60试制钢焊接接头表面和根部焊缝处?40 ℃冲击吸收功值≥91 J,焊接热影响区≥75 J,焊接接头的冲击性能远高于国家标准值42 J。      

Characterization of HAZ of API X70 Microalloyed Steel Welded by Cold-Wire Tandem Submerged Arc Welding

High-strength low-carbon microalloyed steels may be adversely affected by the high-heat input and thermal cycle that they experience during tandem submerged arc welding. The heat-affected zone (HAZ), particularly the coarse-grained heat-affected zone (CGHAZ), i.e., the region adjacent to the fusion line, has been known to show lower fracture toughness compared with the rest of the steel. The deterioration in toughness of the CGHAZ is attributed to the formation of martensite-austenite (M-A) constituents, local brittle zones, and large prior austenite grains (PAG). In the present work, the influence of the addition of a cold wire at various wire feed rates in cold-wire tandem submerged arc welding, a recently developed welding process for pipeline manufacturing, on the microstructure and mechanical properties of the HAZ of a microalloyed steel has been studied. The cold wire moderates the heat input of welding by consuming the heat of the trail electrode. Macrostructural analysis showed a decrease in the CGHAZ size by addition of a cold wire. Microstructural evaluation, using both tint etching optical microscopy and scanning electron microscopy, indicated the formation of finer PAGs and less fraction of M-A constituents with refined morphology within the CGHAZ when the cold wire was fed at 25.4 cm/min. This resulted in an improvement in the HAZ impact fracture toughness. These improvements are attributed to lower actual heat introduced to the weldment and lower peak temperature in the CGHAZ by cold-wire addition. However, a faster feed rate of the cold wire at 76.2 cm/min adversely affected the toughness due to the formation of slender M-A constituents caused by the relatively faster cooling rate in the CGHAZ.