Q690q耐候桥梁钢免预热焊接热影响区的组织性能

针对Q690q耐候桥梁钢,利用MMS-300热模拟试验机进行焊接热循环过程模拟试验,研究了10.5～114.9 kJ/cm热输入下粗晶热影响区(CGHAZ)、细晶热影响区(FGHAZ)和不完全相变热影响区(ICHAZ)的微观组织以及冲击韧性、硬度的变化情况,并观察了冲击断口形貌,然后采用优选的焊接热输入,进行了免预热的药芯焊丝熔化极气体保护焊(FCAW)和埋弧焊(SAW)的焊接工艺评定试验。结果表明,热输入较低时,CGHAZ和FGHAZ主要生成板条马氏体组织、ICHAZ出现岛状的M/A组元,其冲击韧性低、硬度高;热输入较高时,CGHAZ主要生成大尺寸的粒状贝氏体、准上贝氏体或上贝氏体组织,同时大尺寸的块状M/A组元数量不断增加、尺寸变大,其冲击韧性显著降低。FGHAZ生成较多多边形或准多边形铁素体、珠光体等高温转变组织,其硬度降低明显。ICHAZ除生成准多边形铁素体、无碳化物贝氏体和退化珠光体外,回火索氏体基体组织中的碳化物颗粒尺寸不断变大,其强韧性不断降低;热输入为18.2～25.7 kJ/cm时,CGHAZ以板条束细小且异向的板条贝氏体为主、FGHAZ形成细小均匀的板条贝氏体和粒状...     

Zr微合金化HSLA钢粗晶热影响区的组织和性能

用焊接热模拟法研究了Zr处理对 (%):≤ 0.18C-1.2～1.6Mn低合金高强度(HSLA)钢焊接粗晶热影响区(CGHAZ)组织和性能的影响。试验结果表明,Zr含量在0.01%～0.03%时,经过30～100kJ/cm线能量焊接热模拟后,CGHAZ的强度、塑性和-50℃冲击韧性都高于没有经过Zr处理的试验钢;Zr钢显微硬度(HV10)177～251,具有优良的焊接性。焊接线能量相同时,没有经过Zr处理试验钢CGHAZ的晶粒比Zr处理钢粗大;焊接线能量为 30kJ/cm时 ,各试验钢CGHAZ的组织以贝氏体为主 ,随着焊接线能量提高 ,CGHAZ中出现针状铁素体和少量珠光体。     

海洋平台用EH36厚钢板焊接接头的组织性能分析

按照EN 10225-2009附录E标准要求,采用50 kJ/cm大热输入埋弧焊工艺焊接厚为100 mm海洋平台用EH36钢板,测试分析了焊态及焊后热处理态焊接接头的组织与性能。结果表明,无论焊态还是焊后热处理态,EH36厚钢板焊接接头的硬度HV10≤280,抗拉强度≥510 MPa,-40℃冲击功均值≥50 J,表面组织以粗大的板条状贝氏体＋少量粒状贝氏体为主,心部组织以细小的铁素体＋珠光体为主,表明济钢开发的EH36厚钢板满足海洋平台的焊接生产要求。焊接接头表面与心部熔合线形状及传热状态的差异,是导致表面HAZ晶粒比心部粗大、因而表面韧性低于心部的主要原因。     

细晶组织耐候钢热影响区粗晶区的组织和性能

 采用焊接热模拟技术研究了焊接热循环对细晶组织09CuPCrNi钢热影响区粗晶区 (CGHAZ)显微组织和性能的影响。结果表明,在800~500 ℃冷却时间t8/5≤8 s时,该钢CGHAZ组织为贝氏体和少量马氏体。随着t8/5延长,在原奥氏体晶界上逐渐析出先共析铁素体,当t8/5＞18 s时,显微组织由大量铁素体和珠光体组成,且原奥氏体晶粒明显粗化,先共析铁素体含量增加。在-20 ℃和0 ℃下,t8/5对冲击吸收功影响较小,在-40 ℃时,随着t8/5延长,冲击吸收功下降显著,而且随着t8/5延长,CGHAZ硬度逐渐下降,但硬度值均高于母材,焊接热影响区相对于母材未出现软化倾向。     

油罐钢焊接接头的组织与力学性能分析

通过拉伸、冲击、组织观察等方法对油罐钢气电立焊焊接接头的力学性能和显微组织进行了研究。结果表明,在100 kJ/cm线能量的条件下,接头具有良好的抗剪切强度和低温韧性。粗晶区组织主要由粒状贝氏体和板条贝氏体组成,并存在一定数量的M-A岛,细晶区主要为块状和多边形铁素体组织。     

大线能量焊接用船体结构钢的研究进展

介绍了大线能量焊接在船舶建造中的应用,对比了船体结构钢与其它钢种对大线能量焊接适应性的不同要求。针对大线能量焊接热影响区韧性下降问题,提出了目前提高热影响区韧性的主要措施。指出降低碳当量、细化热影响区奥氏体晶粒尺寸、利用有益氧化物诱导晶内铁素体析出是提高船体结构钢大线能量焊接适应性的有效途径。介绍了鞍钢在热影响区组织调控技术和氧化物诱导机理研究等方面取得的成果。     

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。     

�����ǿ���߸ֺ�����Ӱ��������֯������

The distribution of microstructure and mechanical properties in welding heat affected zone (HAZ) of a high-Nb high strength pipeline steel was studied by simulating two type welding heat inputs on Gleeble-3500 thermal simulator. The results show that the micro-hardness of HAZ is higher then base metal without obvious softening. However, the toughness for intercritical heat affected zone and coarse grain zone of heat affected zone deteriorates. M/A islands with large size distributed in chain structure along prior austenite grain boundary cause the decrease of toughness in intercritical heat affected zone. Coarsening and mixed crystal of prior austenite grain, coarse bainite lath cluster and M/A island with large size distributed at boundary of bainite lath cluster result in deterioration of toughness in coarse grain. High alloy content and carbon equivalent are main reason to result in the decrease of the toughness.     

低成本高焊接性能船板钢EH36的开发

工业化试制了3种厚度规格(20,26和36mm)的新型低成本高焊接性能船板钢EH36。试制钢板的显微组织由多边形铁素体和针状铁素体构成,其力学性能满足EH36级别船板要求并具有优异的低温韧性。采用焊接热模拟评价了钢板的焊接性能,当热输入由30kJ/cm升高至160kJ/cm时,粗晶区原奥氏体晶粒尺寸逐渐增大,其组织也逐渐由粒状贝氏体向晶界铁素体+晶内针状铁素体+晶内多边形铁素体转变,维氏硬度逐渐下降,低温韧性优异。得益于TiN粒子对奥氏体晶粒长大的抑制作用,微量B元素对先共析铁素体转变的抑制作用以及BN粒子对晶内铁素体形核的促进作用,焊接粗晶区获得了有利于韧性的细化组织,保证了粗晶区具有优异的低温韧性。双丝埋弧焊试验也验证了钢板具有优异的焊接性能。     

Development of oxide metallurgy technology at Baosteel

Oxide metallurgy technology has been developed at Baosteel for improving the heat affected zone toughness of steel plates for high heat input welding. After deoxidation with strong deoxidizers of Mg alloy,the complex inclusions containing parts of compounds of MgO,Ti2O3,MnO,Al2O3,MnS,CaS and TiN are formed.These kinds of inclusions are beneficial for promoting the formation of intragranular ferrite.After two-electrode vibratory electrogas arc welding with the V-type groove and a high heat input of 395 kJ/cm in a single pass,the former austenite grain is very fine in size,with an average grain size of only 85 μm.Excellent heat affected zone toughness is obtained for the developed steel plates with a thickness up to 68 mm.     

Improving the Toughness of Heat Affected Zone of Steel Plate by Use of Fine Inclusion Particles

There are two kinds of mechanisms of the improvement of Heat Affected Zone(HAZ) toughness with fine inclusion particles. One is to prevent the austenite grain growth during welding process with the aid of the pinning effect of fine particles. The other is to promote the Intragranular Ferrite growth during phase transformation process with fine particles. The oxide metallurgy technology with strong deoxidizers is developed in Baosteel. With the pinning effect of fine particles, after welding with high‐heat input of 400 kJ/cm, the average austenite grain size decreased to 61 µm in HAZ, the average energy absorbed value increased to 142 J for V notch Charpy test at 1653 K.     

Effects of Widmanstätten ferrite on the mechanical properties of a 0.2 pct C-0.7 pct Mn steel

Laboratory melted and rolled C-Mn steel plates were austenitized at either 925 °C or 1150 °C to produce nominal austenite grain sizes of 60 and 200 μm, resspectively. The plates were then cooled at rates in the range of about 2 °C/min to 400 °C/min to produce mixed polygonal ferrite/Widmanst?tten ferrite/pearlite microstructures. The percentage of Widmanst?tten structure (a Widmanst?tten ferrite/pearlite aggregate) increases with increasing prior austenite grain size and cooling rate. Both yield strength and impact toughness increase with decreasing austenite grain size and increasing cooling rate. This simultaneous improvement in strength and toughness is attributed to overall refinement of both the polygonal ferrite and Widmanst?tten structure. Both yield and tensile strength increase with an increase in the volume fraction of Widmanst?tten ferrite and a reduction in ferrite grain size. In contrast, the toughness level achieved in these polygonal ferrite/Widmanst?tten ferrite/pearlite microstructures depends largely on the ferrite grain size; the finer the grain size, the better the toughness.     

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.      

EH40级船体钢中焊接热影响区组织特征

近年来,中国船舶与海洋工程制造业迅猛发展,高强度、高韧性、易焊接性、耐蚀性已成为造船及海洋工程用钢的发展方向.焊接是船体制造的关键环节,采用大线能量焊接来提高造船效率已成为造船企业的首选.但是,焊接线能量的提高导致钢板焊接热影响区晶粒严重粗化、局部软化和脆化,其低温冲击韧性变差,严重威胁船 体钢的安全使用.氧化物冶金是...     

焊接热循环参数对大线能量焊接用钢EH40热影响区组织和性能的影响

利用热模拟技术及光学显微镜、透射电镜研究了焊接热循环参数对大线能量焊接用船板钢热影响区组织和性能的影响.发现模拟焊接热影响区组织主要由粒状贝氏体、铁素体和珠光体组成,且随着峰值温度和冷却时间的变化,热影响区的组织发生较大的变化;热影响区的冲击韧性总体水平较高,均在200 J以上,冲击韧性并不随着峰值温度和冷却时间的增加而单调变化;热影响区M-A岛的数量、尺寸、分布和形态影响热影响区的韧性.      

氧化物冶金在大线能量焊接用钢中的应用

 为了分析氧化物冶金钢中不同类型夹杂物的形核能力及其对大线能量焊接性能的提升效果，对Ti Ca、Ti Mg试验钢进行了模拟焊接热循环并利用氧化物冶金技术实现了不同钢种的工业化生产。结果表明，在1 400 ℃峰值温度等温30 s后，Ti Mg复合夹杂物可有效钉扎奥氏体晶界移动，并在后续冷却过程中作为形核质点诱导针状铁素体形核。为了保持氧化物冶金技术所需的氧含量，建立了转炉Si Mn预脱氧加Ti Mg脱氧的优化工艺路线。采用新技术冶炼的钢种具有200 kJ/cm气电立焊性能。-40 ℃下HAZ冲击韧性达到200 J，焊接接头内观察到大量针状铁素体板条组织。     

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。      

Microstructure,Composition, and Impact Toughness Across the Fusion Line of High-Strength Bainitic Steel Weldments

This paper analyzed the evolution of microstructure, composition, and impact toughness across the fusion line of high-strength bainitic steel weldments with different heat inputs. The main purpose was to develop a convenient method to evaluate the HAZ toughness quickly. The compositions of HAZ were insensitive to higher contents of alloy elements (e.g., Ni, Mo) in the weld metal because their diffusion distance is very short into the HAZ. The weld metal contained predominantly acicular ferrite at any a heat input, whereas the main microstructures in the HAZ changed from lath martensite/bainite to upper bainite with the increasing heat input. The evolution of HAZ toughness in relation to microstructural changes can be revealed clearly combined with the impact load curve and fracture morphology, although the results of impact tests do not show an obvious change with heat input because the position of Charpy V notch contains the weld metal, HAZ as well as a part of base metal. As a result, based on the bead-on-plate welding tests, the welding parameter affecting the HAZ toughness can be evaluated rapidly.     

DP590钢薄板单道次焊接区的组织和性能

在不同焊接参数下分别通过Φ3 mm E4303碳钢焊条（/%:≤0.12C、≤0.25Si、0.30～0.60Mn）和Φ1mm H10MnSi焊丝（/%:0.14C、0.65～0.95Si、0.80～1.10Mn）对3.8 mm DP590钢薄板（/%:0.07C、0.45Si、1.61 Mn）进行手工电弧焊接和CO₂气体保护焊接,并利用ZEISS光学显微镜、LEICA显微硬度计分别对焊接接头的组织和显微硬度进行了观察和分析。结果表明,在焊缝区手工电弧焊焊缝组织为沿柱状晶分布的先共析铁素体和珠光体,CO₂气体保护焊为针状铁素体和少量贝氏体,在粗晶区手工电弧焊为贝氏体和先共析铁素体,CO₂气体保护焊为板条马氏体和贝氏体,且其粗晶区晶粒尺寸大于手工电弧焊;采用CO₂气体保护焊,选择较大的热输入,焊缝和粗晶区的魏氏组织消失;显微硬度最大值均出现在粗晶区,手工电弧焊的热影响区宽度小于CO₂气体保护焊。     

Microstructure and Precipitation Behavior in HAZ of V and Ti Microalioyed Steel

Three steels containing 0.05%C-0.1%V-0.01%N (steel V-LN),0.05%C-0.1%V-0.02%N (steel V-HN),and 0.05%C-0.1%V-0.02%N-0.01%Ti (steel V-HN-Ti),which were all essentially vanadium microalloyed steels,were subjected to simulating the microstructure of a coarse grained heat affected zone (CGHAZ).The process involved reheating to 1 350 ℃,rapid cooling to room temperature,and varying the welding heat input from 15 kJ/cm to 54 kJ/cm,including four cooling rates of t8/5 equal to 7.5 s,20 s,40 s,100 s,and the relationship of heat input to t8/5 was calculated by Quiksim software.The microstructure and precipitation of vanadium and titanium carbon nitrides are studied.The results indicate that the microstructure consists of granular bainite and some side plate ferrite in the grain boundary when the steels are produced with the highest heat input.As the heat input decreased,numerous polygonal ferrites and grain boundary ferrites appeared,and the size apparently increased.When the steel contained high nitrogen,it was considerably easier to form martensite-austenite island,which was even worse for the toughness and other properties of the steel.For the limitation of cooling time,vanadium carbon nitrides could not precipitate sufficiently,but as titanium was added,the unmelted or precipitated TiN on cooling absorbed some fraction of nitrogen in the matrix and made more precipitate positions for the round V(C,N),and thus several useful round particles could be seen in titanium-contained steel,and most of them were around TiN.By this experiment,we can conclude that with the help of titanium,nitrogen-enhanced steel had a better prior austenite grain size,was considerably easier to precipitate,reduced free nitrogen in the matrix effectively,and provided a very effective mechanism for restriction grain growth in the HAZ.