M390高碳马氏体不锈钢与304奥氏体不锈钢TIG焊连接机理

针对M390高碳马氏体不锈钢与304奥氏体不锈钢的连接问题，使用TIG焊接方法，并对M390/304焊接接头进行拉伸、维氏显微硬度测试、SEM及EDS表征焊接接头力学性能及微观组织，X射线衍射分析各区域中相组成，统计焊缝及M390一侧不同区域的晶粒尺寸，揭示焊接接头的断裂机理。研究结果表明，采用TIG焊可以实现M390高碳马氏体不锈钢与304奥氏体不锈钢异种金属连接，得到焊缝形貌美观、无孔洞、无夹杂等缺陷的焊接接头。最佳焊接工艺参数为：焊接电流120 A，电弧电压16 V，焊接速度3.3 mm/s；对应的抗拉强度为266 MPa。焊缝由马氏体、M23C6及M7C3组成，焊缝中晶粒尺寸最大，平均晶粒尺寸为17.96μm。由于焊缝基体组织为马氏体且晶粒尺寸最大，焊接接头断裂在焊缝，断裂类型为解理断裂。M390侧和焊缝中碳化物主要为（Cr、V）碳化物，从M390母材到粗晶区，碳化物形貌逐渐由颗粒状向长条状演变，热的作用导致碳化物长大聚集。     

高碳马氏体不锈钢M390与奥氏体不锈钢304闪光对焊的微观组织及力学性能

通过闪光对焊方法连接M390高碳马氏体不锈钢与304奥氏体不锈钢.通过室温拉伸试验、显微硬度测试表征了焊接接头的力学性能.采用扫描电镜(SEM)、能谱分析(EDS)和X射线衍射(XRD)分析了焊接接头的微观组织形貌、元素扩散及各区域相组成.结果表明,利用合适的焊接工艺参数,M390与304之间可以形成焊缝形貌美观、抗拉...     

焊前热处理对440C不锈钢电子束焊接接头组织与性能的影响

研究了焊前退火和调质2种热处理工艺对440C不锈钢电子束焊接接头的组织和力学性能的影响,分析了2种状态下的组织演变规律、接头拉伸力学性能和硬度分布特点. 结果表明:2种热处理状态的板材经过电子束焊接后,焊缝成形良好,焊缝区域均为马氏体和残留奥氏体组织,呈现出非平衡凝固组织,碳及合金元素以固溶形式存在于马氏体及残余奥氏体中,焊缝区域硬度达到398 HV. 焊前经调质热处理后,母材基体由铁素体转变成回火马氏体和残余奥氏体混合组织,同时部分碳化物固溶在基体组织中,使基体组织硬度提高了60％. 与焊前退火态相比,焊前调质热处理板材经电子束焊接后,可使焊接接头抗拉强度提高20％,焊接热影响区硬度提高35％,但接头的塑性变形能力有所下降,断裂均发生在热影响区.     

超高强度钢35CrMnSi惯性摩擦焊接头组织与性能

对35CrMnSi超高强度钢进行了惯性摩擦焊试验研究,对热处理前后焊接接头组织、显微硬度进行分析测试,并对热处理后焊接接头进行了拉伸性能、冲击性能及拉伸断口分析。结果表明:焊后接头焊缝组织为板条马氏体与残余奥氏体,热力影响区组织为细小的马氏体、索氏体、珠光体和铁素体混合组织;热处理后焊缝组织为回火马氏体与少量铁素体;摩擦焊接头焊缝区的硬度高于热力影响区和母材,热处理后焊接接头硬度趋于一致,焊接接头抗拉强度大于1 890 MPa,断后伸长率大于7. 5%,焊缝区拉伸断口为混合断口;焊接接头冲击吸收能量大于18. 5J。     

Q235钢薄板激光焊接头微观组织与力学性能

为了探索光纤激光在焊接薄板低碳钢中的应用前景，文中采用光纤激光焊接系统分别对0.5 mm和1 mm厚Q235钢板进行了激光焊工艺试验，并对所得到的焊接接头的微观组织和力学性能进行了分析。通过调节激光功率、摆动频率等工艺参数，2种厚度的Q235钢板均可获得单面焊双面成形、无明显缺陷的焊接接头。厚0.5 mm板焊缝区主要由板条马氏体组成，硬度和抗拉强度均高于母材的，断后伸长率为33.1%,约为母材的79%;厚1 mm板焊缝区呈胞状树枝晶组织，主要由铁素体、珠光体和贝氏体组成，硬度和抗拉强度均高于母材的，断后伸长率为34.5%,约为母材的75%。     

超塑成形TC4薄板激光焊接头组织及性能研究

对1mm厚Ti6A14V钛合金薄板进行了激光焊接工艺试验,研究结果表明:激光焊配合修饰焊工艺获得成形均匀和质量良好的接头,且焊缝内部无气孔、裂纹等缺陷。接头焊缝区组织以针状α′马氏体相为主,热影响区组织分为粗晶区和细晶区,粗晶区包含较多的针状马氏体,细晶区则为板条状α相+少量针状马氏体;接头硬度由母材区到焊缝区呈逐渐增高趋势,焊缝区显微硬度最高,为371 HV。薄板TC4钛合金激光焊接头拉伸强度与基材相当,断后伸长率略低于母材,接头横弯弯曲角度略低于母材,弯曲断裂于母材侧。     

焊后低温热处理对马氏体不锈钢组织和性能的影响

对ZG06Cr13Ni4Mo马氏体不锈钢进行了焊后低温热处理工艺试验(240、300 ℃),通过显微组织分析、拉伸及弯曲试验、硬度试验及残余应力测试对不同低温热处理下焊接接头的显微组织、力学性能、硬度和残余应力等进行了研究。结果表明,经低温热处理后,接头焊缝热影响区组织为回火马氏体及碳化物,接头焊缝区的组织为低碳马氏体+块状马氏体+碳化物,接头的抗拉强度变化不大,硬度略有下降,经240 ℃低温热处理后,焊接接头焊缝处的残余应力消除了69.1%。     

超声振动对304不锈钢窄间隙TIG焊接接头组织和力学性能的影响

针对304不锈钢窄间隙TIG(非熔化极惰性气体保护电弧焊)焊接焊缝晶粒粗大、接头拉伸性能较差等问题，采用将超声振动头施加在试板，在TIG焊接过程引入超声振动的方法对其进行焊接，研究了焊接接头的组织和力学性能。结果表明：引入超声振动后，在热力学和动力学综合作用下，焊缝熔深增加，焊缝区柱状晶向等轴晶转变速率提高，等轴晶占比增多，晶粒细化；与常规TIG相比，引入超声振动后改善了304不锈钢窄间隙焊接接头的焊缝组织，提高了其力学性能，焊缝区的硬度明显提高，接近于母材，焊接接头的抗拉强度和屈服强度也均高于常规TIG焊接接头，伸长率也得到提高；当超声振幅为40μm时，焊接接头的抗拉强度最高，为674 MPa,屈服强度也较高，为376 MPa,断后伸长率为25%。     

2205双相不锈钢与304奥氏体不锈钢的焊接

采用焊条电弧焊(SMAW),以E2209作填充材料对2205双相不锈钢与304奥氏体不锈钢异种金属焊接工艺进行研究,通过优化焊接工艺参数,获得了具有良好力学性能和合适双相比例的焊接接头.接头力学性能测试表明,拉伸试样断裂发生在强度相对较低的304母材侧;2205母材侧热影响区的显微硬度值高于焊缝和2205母材,而304...     

TWIP钢激光焊接接头的显微组织和力学性能

研究了孪晶诱导塑性(TWIP)钢经3种不同工艺参数激光焊接后的焊接接头的显微组织和力学性能。结果表明:焊接接头焊缝区为全奥氏体组织,与母材相比,焊缝区的Mn含量略有降低;较大的焊接热输入可以保证焊缝的连续性,但也会导致焊缝组织粗大、粗晶区宽度增大;焊缝熔融区为树枝晶组织,热影响区含0. 3～0. 4 mm宽的软化区和0. 5～0. 6 mm宽的硬化区;焊接接头的最高抗拉强度和断后伸长率分别为900 MPa和33%,约为母材的90%和50%。     

Microstructure and mechanical properties of dissimilar welds between 16Mn and 304L in underwater wet welding

Dissimilar joint between 304L austenitic stainless steel and low-alloy steel 16Mn was underwater wet welded using self-shielded nickel-based tubular wire. Microstructure, mechanical properties and corrosion behaviour of dissimilar welded joints were discussed. Ni-based weld metal was fully austenitic with well-developed columnar sub-grains. Type II boundary existed between Ni-based weld metal and ferritic base metal in underwater welds similar to that in air welds. Major alloying elements distributed non-uniformly across the austenitic weld metal/16Mn interface. Maximum hardness values in wet welding appeared in a coarse-grained heat-affected zone at the 16Mn side, which possessed very low impact toughness. Underwater Ni-based welded joints fractured at Ni-based weld metal under tensile test. Ni-based weld metal had favourable corrosion resistance similar to 304L base metal.     

中低温热处理对SUS304不锈钢TIG焊接接头组织及力学性能的影响

轨道交通车辆在冲击振动试验后,部分设备SUS304不锈钢焊接件出现断裂失效现象.为了提升SUS304不锈钢焊后机械性能,采用金相显微镜、扫描电镜、硬度测试及拉伸试验等方法,研究了中低温热处理工艺对2 mm厚SUS304不锈钢板TIG焊接接头的组织及力学性能的影响.研究发现,经400℃热处理30 min及焊接后未处理态焊...     

Friction stir welding of multilayered steel

Abstract

This study investigates the mechanical properties and microstructure of friction stir butt welded high strength/ductility multilayered steel consisting of 15 alternating layers of SUS 301 austenitic stainless steel (eight layers) and SUS 420J2 martensitic stainless steel (seven layers) with a total thickness of 1·2 mm. With optimised welding parameters, defect free welds with an ultimate tensile strength (UTS) of 1240 MPa and a fracture elongation of 13% were accomplished. This corresponds to a joint efficiency of 90%. In this case, fracture occurred in the heat affected zone as a result of a very pronounced hardness drop in the martensitic layers resulting from the formation of a large amount of grain boundary precipitates, which were formed at temperatures ～750°C slightly below A_c1. By applying post-weld heat treatment, the hardness drop in the martensitic layers was removed and the tensile properties were enhanced to UTS of 1310 MPa (95% joint efficiency) and a fracture elongation of 22%.     

Evaluation of Microstructure and Mechanical Properties in Dissimilar Austenitic/Super Duplex Stainless Steel Joint

To study the effect of chemical composition on microstructural features and mechanical properties of dissimilar joints between super duplex and austenitic stainless steels, welding was attempted by gas tungsten arc welding process with a super duplex (ER2594) and an austenitic (ER309LMo) stainless steel filler metal. While the austenitic weld metal had vermicular delta ferrite within austenitic matrix, super duplex stainless steel was mainly comprised of allotriomorphic grain boundary and Widmanstätten side plate austenite morphologies in the ferrite matrix. Also the heat-affected zone of austenitic base metal comprised of large austenite grains with little amounts of ferrite, whereas a coarse-grained ferritic region was observed in the heat-affected zone of super duplex base metal. Although both welded joints showed acceptable mechanical properties, the hardness and impact strength of the weld metal produced using super duplex filler metal were found to be better than that obtained by austenitic filler metal.     

热处理工艺对0Cr13Ni5Mo钢焊接接头组织和性能的影响

对马氏体不锈钢0Cr13Ni5Mo焊接接头经过1000℃油淬后,分别进行了600℃,620℃+600℃,400℃回火。通过显微组织分析、拉伸试验、冲击试验和硬度检测对3种焊接接头的组织和力学性能进行了研究。结果表明,3种焊接接头中焊缝组织粗大,硬度最高;焊接接头的韧性低于相应热处理状态下母材的韧性;随着回火温度的降低,韧性下降,强度提高。二次回火比一次回火组织更加细小,强度和韧性更好;620℃+600℃二次回火后焊接接头具有比较理想的综合力学性能。     

22MnB5超高强钢焊接组织与性能

采用钨极氩弧焊方法,实现了22MnB5超高强钢淬火前后同种材料之间的连接,进行了焊接接头拉伸试验和热影响区内显微组织及硬度分布试验,并对焊接前后材料的抗腐蚀性能进行了试验分析.结果表明,淬火处理后22MnB5组织结构从铁素体+珠光体组织转变为马氏体组织,显微硬度与抗拉强度大幅度提高,原始及淬火后材料的焊接接头具有良好的力学性能和组织形貌,焊后焊接接头抗拉强度和硬度略低于原始母材,经淬火处理后的材料焊后抗拉强度达到1179.59 MPa,略低于淬火材料但比原始母材高很多,淬火热处理材料的腐蚀速率略有上升,而焊接后将大幅度增加腐蚀速率,通过比较淬火焊缝钢腐蚀速率最大.     

配分工艺对301奥氏体不锈钢组织和力学性能的影响

拟以淬火-配分的新型热处理工艺替代冷变形加工硬化工艺,进而提高亚稳态奥氏体不锈钢的力学性能。以301不锈钢为研究对象,采用光学显微镜、扫描电镜、X射线衍射仪、铁素体测量仪、万能试验机及显微硬度计等表征手段,分析了不同配分热处理制度对301不锈钢微观组织及力学性能的影响。结果表明:301亚稳态奥氏体不锈钢经不同淬火-配分工艺热处理后,其显微组织主要由板条状马氏体、奥氏体以及微量碳化物组成;其力学性能对配分温度不够敏感,但随配分时间的延长会不断优化。在450 ℃配分30 min后,301奥氏体不锈钢的综合力学性能达到最优,其屈服强度、抗拉强度、伸长率及硬度分别为432.37 MPa、1212 MPa、44.28%及193.16 HV0.2。     

Welding austenitic steel to copper with the defocused radiation of a fibre laser

Special features of producing butt welded joints between 12Cr18Ni10Ti austenitic steel and M1 copper by laser welding are investigated. Welding was carried out without filler or intermediate material. The defocused beam of the fibre laser, displaced to the austenitic steel, was used. The welded joints in dissimilar materials produced in the selected conditions were without defects and their strength was comparable with the M1 copper parent metal. The tensile tests and hardness measurements were carried out on the resultant welded joints. The microstructure of the welded joints was investigated and the transition zone was examined by chemical analysis.