热输入对高强度气体保护焊丝焊缝金属强韧性的影响

采用拉伸、冲击试验和显微组织观察,研究了热输入在10~27 kJ/cm时对超低碳气体保护焊丝焊缝金属强度、韧性及显微组织的影响。结果表明,随着焊接热输入的增加,焊缝金属的强度和韧性呈下降趋势,其原因在于,随热输入的提高,合金元素烧损增多,焊缝冷却时间延长,焊缝金属高温再热区中强度较低、韧性较差的铁素体含量增加。     

用于制造堆内构件压紧弹簧的Z12CN13不锈钢大锻环国产化材料

通过材料成分控制和热处理制度优化掌握了主要合金元素、淬火和回火温度以及淬火冷却速度对压紧弹簧用国产Z12CN13不锈钢大锻环力学性能的影响规律。完成国产Z12CN13不锈钢大锻环的评定,达到了设计标准要求的各项性能。结果表明要同时达到技术条件规定的强度和韧性指标,主要合金元素应取中上限。随淬火温度的升高,国产Z12CN13不锈钢强度、塑性、韧性下降;随回火温度的升高,其强度下降,塑性、韧性升高;淬火冷却速度明显影响材料的抗拉强度和冲击韧性,提高淬火冷却速度可同时满足强度和冲击韧性指标要求。985℃淬火并快冷,640℃回火后国产Z12CN13不锈钢综合力学性能和强韧性配比最佳。     

E36钢板成分对埋弧焊接头韧性的影响

针对TMCP工艺生产的3个炉批次E36钢12 mm板,开展了钢板及埋弧焊接头力学性能、系列温度冲击试验,研究了钢中C、Ni、Nb、Ti元素对钢板埋弧焊接头韧性的影响。研究结果表明,降低钢中C含量、添加少量Ni元素有利于提高埋弧焊接头低温韧性,采用Nb、Ti微合金化,有利于细化母材晶粒及抑制焊接热影响区晶粒粗化,而钢中Nb元素对焊缝微观组织及韧性有不利影响,应进行适量控制。      

奥氏体化合金元素Mn和Ni对FV520B焊缝组织与力学性能的影响EI北大核心CSCD

采用金相观察及扫描电镜(SEM)等研究了奥氏体化合金元素Mn和Ni对FV520B马氏体不锈钢的焊缝组织及力学性能的影响。结果表明,FV520B不锈钢的焊缝组织以回火马氏体为主,随着合金元素增加,焊缝组织变得更加细小。Mn,Ni元素能够有效提高焊缝中奥氏体的含量。合金元素对焊缝强度的影响较小,但当同时添加Mn,Ni元素时,焊缝抗拉强度和屈服强度得到提高。Mn,Ni元素能够通过提高焊缝奥氏体量改善焊缝的冲击韧度。相对于Mn元素,Ni元素提高焊缝韧性的效果更好。     

合金元素和控轧控冷工艺在管线钢研制中的应用

通过在管线钢中添加Mn、Nb、V、Ti和Mo等合金元素与采用控轧控冷工艺可获得良好的微观组织和综合力学性能.具体论述了控轧控冷过程中合金元素和控轧控冷工艺参数对管线铜微观组织和力学性能的影响;同时分析了微合金元素(Nb、V、Ti)碳氮化物的析出行为.结果表明,在适当范围内降低终轧温度和终冷温度,提高轧后冷却速度和增大精轧总变形量都可有效改善钢的综合性能.     

大热输入对焊条电弧焊低合金钢力学性能的影响

本工作研究了用E9015-B3焊材焊接ZG15Cr1Mo1V低合金钢的接头在大热输入条件下的组织与综合性能。结果表明:热输入的变化对焊接接头有一定的影响,随着热输入的增加,高温停留时间更长而冷却速度也降低,焊缝主要强化元素Cr、Mo等呈下降特征,焊缝出现明显的块状铁素体和粗大的贝氏体组织,降低了接头的常温和高温抗拉强度,其中当立向上焊接摆幅在30～50 mm时,焊接点热源对固定位置的高温停留时间影响最大,此时焊缝的综合力学性能最差。为了保证产品焊接接头的质量,需要在一定程度上控制焊接热输入,尤其需要在焊接摆幅为30～50mm时选择较小的焊接电流。     

热处理工艺对压裂泵阀体用钢4330MOD组织及性能的影响

为提高压裂泵阀体的强度和韧性,研究了不同热处理工艺对改进型4330钢组织及力学性能的影响。结果表明:4330MOD钢通过添加微合金元素及调质工艺优化能够提高强度和韧性。微合金元素Nb、V,正火+调质工艺能够降低晶粒尺寸,提高强韧性。4330MOD钢在550℃～700℃回火时,组织为回火索氏体组织,随回火温度的升高强度降低,韧性先升高后降低,在600℃～650℃回火强韧性匹配较好。4330MOD钢通过微合金元素添加及热处理工艺优化使晶粒尺寸及板条块宽度细小,大角度晶界比例高,从而提高了钢的强韧性。      

基于正交试验的TC4钛合金激光焊工艺优化研究

目的 探究激光功率、焊接速度、离焦量对TC4钛合金激光焊接接头宏观形貌、微观组织及力学性能的影响。方法 通过正交试验方法,研究激光功率、焊接速度、离焦量对接头拉伸性能的影响,并将这3个工艺参数转换为热输入,进一步研究热输入对接头形貌、组织及力学性能的影响。结果 当热输入低于95 J/mm时,焊接接头上下熔宽比较大,焊缝截面呈“V”形;当热输入高于250 J/mm时,接头组织晶粒粗大,甚至出现气孔、错边等冶金缺陷;当热输入为125 J/mm时,焊缝成形美观,焊接接头上下熔宽比接近1,焊缝截面呈“H”形。焊缝区组织主要由原始α相、β相及冷却阶段生成的αʹ相组成,随着热输入的增大,β相柱状晶尺寸逐渐粗化,αʹ针状马氏体相尺寸也相应增大。此外,焊接速度和离焦量对拉伸性能有显著影响,拉伸性能随着热输入的增大呈现先升高后降低的趋势,断口呈韧性断裂特征。当热输入为125 J/mm时,拉伸性能达到最佳,断裂位置发生在母材区,抗拉强度为1 010 MPa,断后延伸率为9.82%;焊缝区中心区域显微硬度高于热影响区及母材区显微硬度。结论 当热输入为125 J/mm时,在TC4钛合金激光焊下,可获得成形美观、性能优良的焊接接头。     

药皮合金元素对FV520(B)钢焊缝组织和韧性的影响

在焊条药皮中添加中碳锰铁和镍粉将Mn、Ni元素过渡到FV520(B)钢焊缝,用金相分析、冲击试验、XRD分析和SEM观测等手段研究了药皮合金元素对FV520(B)钢焊缝的组织和韧性的影响。结果表明:FV520(B)钢焊缝组织以回火索氏体和板条马氏体为主,出现残余奥氏体和二次析出相;随着合金元素的增加,焊缝的组织更加细小致密,马氏体片层更加均匀细小,分布更加弥散。与酸性药皮相比,碱性药皮过渡合金元素的效果更显著,因此焊缝的冲击韧性更优良。用药皮过渡Mn、Ni能提高焊缝中奥氏体的含量,进而改善FV520(B)钢焊缝的冲击韧性。与Mn相比,添加Ni提高焊缝韧性的效果更为显著。     

热输入对1200MPa级HSLA钢焊缝组织性能的影响

为了研究焊接工艺条件对焊缝金属组织性能的影响,采用不同热输入对1200 MPa级低合金高强钢进行熔化极气体保护焊,利用OM、SEM、TEM观察并分析不同焊接热输入对焊缝组织及力学性能的影响规律。结果显示,当热输入为16、20、25 k J/cm时,焊缝组织主要以针状铁素体为主,并含有少量M-A组元以及粒状贝氏体。随焊接热输入增大,针状铁素体组织有所增多且板条宽度逐渐增大,而粒状贝氏体组织减少。焊缝内非金属夹杂物类型多为促进针状铁素体形核的Ti-Mn-Al-O-S系复合氧化物夹杂。焊缝金属硬度、冲击韧性及焊接接头强度随热输入增大基本呈下降趋势,并且各焊接热输入条件下焊缝金属具有良好的强韧性匹配。随热输入增大,焊缝金属断裂特征由韧性、脆性混合型断裂向脆性断裂转变。热输入为20 k J/cm时,焊接接头综合性能最佳。     

Effect of heat-input and cooling-time on bead characteristics in SAW

Load-carrying capacity of weld joints could be identified by its shape and size where weld bead geometry and shape relationship parameters are of utmost importance. Heat input and preheating temperature together can control the cooling time of weld, which in turn determines the weld microstructure and its mechanical properties. To control the shape and geometry of weld bead, it is necessary to understand its relationship with cooling time. In present work, preheating temperature is used as process variable along with heat input varying parameters for understanding their effects on weld bead geometry and shape relationship parameters using submerged arc welding process on high-strength low alloy pipeline steel. The experimental investigation was then analyzed by using the mathematical modeling in context with response surface methodology. The mathematical model predicts the influential dependency of cooling time on the preheating temperature than the other weld process parameters. The associated effects in relation to the process parameters have been discussed and analyzed in the present study.     

590 MPa级高强钢双面双弧立焊焊缝组织性能

为研究590 MPa级高强钢双面双弧工艺得到的焊接接头组织与性能的关系,采用钨极氩弧焊(TIG)与熔化极气体保护焊(MAG)方法获得成型良好的焊接接头,经过拉伸、冲击、弯曲试验及光学显微镜、扫描电镜、EBSD分析,对590 MPa级高强钢双面双弧立焊打底焊与盖面焊焊接接头的组织及性能进行了研究.结果表明:打底焊缝组织主要为贝氏体,盖面焊缝组织以贝氏体与针状铁素体为主;打底焊缝经历过一次热循环后组织得到一定程度的细化;打底焊缝硬度值与盖面焊缝相近,盖面焊缝热影响区最高硬度值高于打底焊缝热影响区最高硬度;2 mm坡口间隙性能较5 mm坡口间隙有较大提高,2 mm坡口间隙断口以韧窝断裂为主,5 mm坡口间隙断口以解理断裂为主.     

Effect of welding wire and groove angle on mechanical properties of high strength steel welded joints

Mechanical properties of high strength steel welded joints strictly depend on the welding process, the filler material composition and the welding geometry. This study investigates the effects of using cored and solid welding wires and implementing various groove angles on the mechanical performance of weld joints which were fabricated employing the gas metal arc welding process. It was found that weld joints of low alloy, high strength steels using low alloy steel cored welding wires exhibited higher tensile strength than that of low alloy steel solid wire and chromium‐nickel steel bare welding wire when the method of gas metal arc welding is employed. The effect of groove angle on the strength and toughness of V‐groove and double V‐groove butt‐joints was investigated. V‐groove joints, with higher tensile strength than double V‐groove joints in the whole range of groove angles, were superior in toughness for small groove angles, but impact toughness values of both joints were comparable for large angles. The effect of heat input and cooling rate on the weld microstructure and weld strength was also investigated by performing thermal analysis employing the commercial software ANSYS. It was concluded that cooling rate and solidification growth rate determined the microstructure of the weld zone which had great consequences in regard to mechanical properties.     

Experimental investigation on the effects of process parameters of GMAW and transient thermal analysis of AISI321 steel

Gas metal arc welding (GMAW) develops an arc by controlling the metal from the wire rod and the input process parameters. The deposited metal forms a weld bead and themechanical properties depend upon the quality of the weld bead. Proper control of the process parameters which affect the bead geometry, the microstructures of the weldments and the mechanical properties like hardness, is necessary. This experimental study aims at developing mathematical models for bead height (HB), bead width (WB) and bead penetration (PB) and investigating the effects of four process parameters
viz: welding voltage, welding speed, wire feed rate and gas flow rate on bead geometry, hardness and microstructure of AISI321 steel with 10 mm thickness. The transient thermal analysis shows temperature and residual stress distributions at different conduction and convection conditions.     

高强钢焊接接头显微组织的研究进展

综述了热输入、合金元素、冷却速率和应变速率对高强钢焊接接头显微组织的影响和高温共聚焦显微镜原位观察高强钢显微组织的最新研究进展,总结了高强钢焊接接头粗晶热影响区显微组织的转变机理。结果表明:通过延长冷却时间、减少热输入量、控制合金元素的含量和采用预处理提高应变速率等方法,可以调控高强钢焊接接头显微组织中马氏体、粒状贝氏体和针状铁素体的含量达到最佳比例,从而优化高强钢焊接接头的力学性能。通过高温共聚焦显微镜可以观察到高强钢相变的动态过程,从而得出高强钢的相变原理,为高强钢焊接工艺的制定提供指导。     

Effect of welding parameters on microstructure and mechanical properties of friction stir welded joints of AA7039 aluminum alloy

A high strength Al–Zn–Mg alloy AA7039 was friction stir welded by varying welding and rotary speed of the tool in order to investigate the effect of varying welding parameters on microstructure and mechanical properties. The friction stir welding (FSW) process parameters have great influence on heat input per unit length of weld, hence on temperature profile which in turn governs the microstructure and mechanical properties of welded joints. There exits an optimum combination of welding and rotary speed to produce a sound and defect free joint with microstructure that yields maximum mechanical properties. The mechanical properties increase with decreasing welding speed/ increasing rotary speed i.e. with increasing heat input per unit length of welded joint. The high heat input joints fractured from heat affected zone (HAZ) adjacent to thermo-mechanically affected zone (TMAZ) on advancing side while low heat input joints fractured from weld nugget along zigzag line on advancing side.     

Effect of cooling rate on microstructure,inclusions and mechanical properties of weld metal in simulated local dry underwater welding

Quenched and tempered E550 steel was joined using flux-cored arc welding. The effect of cooling rate on microstructure, inclusions and mechanical properties of the weld metal was investigated by optical microscope, scanning electron microscope, transmission electron microscope and mechanical testing. Results show that weld metal microstructures consist of proeutectoid ferrite, ferrite side plate and acicular ferrite. As the cooling rate increased, the volume fraction of proeutectoid ferrite and ferrite side plate decreased, acicular ferrite increased accompanied with refined grain. Furthermore, inclusions of Ti, Mn oxide with diameter below 2.0 μm were found in the weld metal and rapid cooling rate causes distinct Mn-depleted zone between inclusions and matrix. Excellent balance of high strength and toughness is obtained as more acicular ferrite in weld metal with rapid cooling rate. This can attribute to the increased of acicular ferrite with its refined grain and high density dislocation. These findings suggest that the rapid cooling rate can improve the impact toughness and tensile strength of weld metal in local dry underwater welding.     

超级双相不锈钢焊条焊缝相比例的影响因素

研究了25％ Cr型超级双相不锈钢焊条焊缝组织,分析了合金成分及焊接工艺对焊缝组织的影响,结果表明,焊缝需要较高的铬镍当量比值方可达到较理想的组织,手工电弧焊时,焊接热输入对焊缝组织的影响不显著,后续焊道的退火作用可提高先焊道中奥氏体相的含量.     

超细晶Q460高强钢焊接接头组织与韧性研究

采用手工焊条电弧焊和熔化极活性气体保护焊对超细晶Q460钢进行了焊接,分析表征了焊接接头的组织结构、显微硬度和冲击韧性的变化规律。研究结果表明,采用E5515焊条焊接,焊缝金属主要为先共析铁素体、多边形铁素体与少量珠光体。采用ER55-G焊丝,熔化极活性气体保护焊,焊缝金属主要由针状铁素体和少量多边形铁素体组成,焊丝中Ti元素的添加有利于获得针状铁素体组织。采用较小的焊接线能量,超细晶Q460钢热影响区粗晶区组织为粒状贝氏体组织。焊缝金属的显微硬度高于热影响区和母材的显微硬度,热影响区未出现软化现象。冲击试验表明,焊缝金属和热影响区均具有较高的冲击韧性,而且热影响区的韧性高于焊缝金属的韧性。     

热输入对Q1100钢焊接接头低温韧性及耐蚀性能的影响

采用10 kJ/cm和15 kJ/cm两种焊接热输入对Q1100超高强钢进行熔化极气体保护焊,研究焊接接头的组织性能及局部腐蚀行为。结果表明：两种热输入焊接接头的焊缝组织主要为针状铁素体和少量的粒状贝氏体,粗晶区组织均为板条贝氏体,细晶区组织均为板条贝氏体和粒状贝氏体,临界相变区组织为多边形铁素体、马奥岛和碳化物的混合组织。两种热输入焊接接头中电荷转移电阻均为母材>热影响区>焊缝区,母材耐蚀性最好,热影响区次之,焊缝区耐蚀性最差。在腐蚀过程中,焊缝区作为阳极最先被腐蚀,当腐蚀一定时间后,腐蚀位置发生改变,阳极腐蚀区域转移到母材区,而焊缝区作为阴极得到保护。热输入为10 kJ/cm时,焊接接头具有更好的低温韧性和耐蚀性,其焊缝和热影响区-40℃冲击功分别为46.5 J和30.2 J。