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weldability and liquation cracking behavior of ZhS6U superalloy during electron-beam welding

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International Journal of Minerals,Metallurgy and Materials 2019年第2期26卷 251-259页

作者： Arash Khakzadshahandashti Mohammad Reza Rahimipour Kourosh Shirvani Mansour Razavi Department of Ceramic Materials and Energy Research Center Department of Material and Renewal Energy Iranian Research Organization for Science and Technology (IROST)

The weldability of the ZhS6U nickel-based superalloy, which is prone to solidification cracking during electron-beam welding(EBW) repair processes, was investigated. The effects of two different pre-weld heat-treatment cycles on the final microstructure before and after welding were examined. Welds were made on flat coupons using an EBW machine, and the two heat-treatment cycles were designed to reduce γ′ liquation before welding. Microstructural features were also examined by optical and scanning electron microscopy. The results showed that the change in the morphology and size of the γ′ precipitates in the pre-weld heat-treatment cycles changed the ability of the superalloy to release the tensile stresses caused by the matrix phase cooling after EBW. The high hardness in the welded coupons subjected to the first heat-treatment cycle resulted in greater resistance to stress release by the base alloy, and the concentration of stress in the base metal caused liquation cracks in the heat-affected zone and solidification cracks in the weld area.

关键词： weldability ZhS6U superalloy electron beam welding heat-affected zone liquation cracking pre-weld heat treatment

weldability of 780 MPa Super-High Strength Heavy-Duty Truck Crossbeam Steel

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Journal of Iron and Steel Research International 2012年第6期19卷 64-69页

作者： WANG Xiao-nan DI Hong-shuang ZHANG Chit DU Lin-xiu DONG Xue-xir Shagang School of Iron and Steel Soochow University Suzhou 215021 Jiangsu China State KeyLaboratory of Rolling and Automation of Northeastern University Shenyang 110004 Liaoning China）

CO2-shielded welding experiments of newly developed, 780 MPa super-high strength heavy-duty truck crossbeam steel were conducted, and the microstructure, microhardness, mechanical properties, and impact tough- hess of the welded joint were studied. The evolution of the microstructure of the welded joint occurred as follows.. welding seam （acicular ferrite＋proeutectoid ferrite）→fusion zone （granular bainite-long strip M/A island）→coarse grain zone （granular bainite-long strip or short bar M/A island）→fine grain zone （ferrite＋ pearlite＋ blocky M/A is- land）→mixed grained zone （ferrite＋granular bainite＋blocky M/A island）→base metal （proeutectoid ferrite＋gran- ular bainite-hlocky or granular M/A island）. Increasing the density of the grain boundaries can effectively improve the impact toughness, and the blocky M/A island hindered crack propagation more effectively than the long strip M/A island. The new hot-rolled 780 MPa super-high strength steel had excellent weldability. The welding technology was applied under the following conditions： welding voltage was 20 to 21 V, welding current was 200 to 210 A, and the gas flow rate was 25 L/rain.

关键词： super-high strength steel crossbeam steel weldability M/A island impact toughness

weldability of Low Carbon Transformation Induced Plasticity Steel

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Journal of Iron and Steel Research International 2008年第5期15卷 61-65,87页

作者： ZHANG Mei LI Lin FU Ren-yu ZHANG Ji-cheng WAN Zi Department of Material Science and Engineering Shanghai University Shanghai 200072 China RDC Shanghai Huizhong Automotive Manufacturing Co Ltd Shanghai 200122 China

Transformation induced plasticity （TRIP） steel exhibited high or rather high carbon equivalent （CE） because of its chemical composition, which was a particularly detrimental factor affecting weldability of steels. Thus the weldability of a TRIP steel （grade 600） containing （in mass percent, %） 0.11C-1. 19Si-1.67Mn was extensively studied. The mechanical properties and impact toughness of butt joint, the welding crack susceptibility of weld and heat affected zone （HAZ） for tee joint, control thermal severity （CTS） of the welded joint, and Y shape 60° butt joint were measured after the gas metal arc welding （GMAW） test. The tensile strength of the weld was higher than 700 MPa. Both in the fusion zone （FZ） and HAZ for butt joint, the impact toughness was much higher than 27 J, either at room temperature or at -20 ℃, indicating good low temperature impact ductility of the weld of TRIP 600 steel. In addition, welding crack susceptibility tests revealed that weldments were free of surface crack and other imperfection. All experimental results of this steel showed fairly good weldability. For application, the crossmember in automobile made of this steel exhibited excellent weldability, and fatigue and durability tests were also accomplished for crossmember assembly.

关键词： TRIP steel weldability welding crack susceptibility mechanical property impact toughness

weldability of Ferritic Ductile Cast Iron Using Full Factorial Design of Experiment

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Journal of Iron and Steel Research International 2014年第2期21卷 252-263页

作者： Mohsen Askari-Paykani Mehrdad Shayan Morteza Shamanian Department of Materials Engineering Isfahan University of Technology

The weldability of a ferritic ductile cast iron was investigated as a function of different consumables and welding conditions. A 23 full factorial experimental design was used to analyze the effect of factors and their interac- tions on ultimate tensile strength of weldments. The shielded metal arc welding （SMAW） process was used with two types of consumables （E7018 and ENi-CI） under eight different conditions using as-cast samples. The microstructur- al evolution and fracture mechanisms were investigated by optical microscopy and scanning electron microscopy （SEM）, respectively. The hardness, tensile and impact tests were also performed to determine the weld quality. Based on experiment design, preheat, consumable, cooling condition, preheat cooling and preheat-consumable inter- actions were significant factors. Preheat is the most effective factor and in the case of E7018, preheat and cooling conditions were the most sensible factors. It was found that buttering was the most appropriate welding method for ferritic ductile cast iron.

关键词： ferritic ductile cast iron shielded metal arc welding weldability full factorial experimental design

weldability and Microstructure of Nickel-Silicon Based Alloys

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Journal of Iron and Steel Research International 2006年第3期13卷 61-67页

作者： LIU Qing-cai LIU Yi YANG Jian J. W. Newkirk ZHANG Shan-hong State Key Laboratory of Mechanical Transmissions Chongqing University Chongqing 400044 China Department of Metallurgical Engineering University of Missouri-Rolla Rolla MO 65401 USA Yuanda Environmental Protection Co Ltd Chorgqing 400060 China

The NiSix based alloy typically has poor weldability due to its lower ductility. A limited amount of work has been performed on the weldability of NiSix based alloys. Therefore, the effect of heat treatment and welding parameters on weldability of the alloys, and the relationship between the weldability and microstructure were studied. The results show that the as-cast Ni-Si-Nb-B alloy （Ni 76. 5%, Si 20%, Nb 3%, and B 0. 5%） could be successfully welded after preheating at 600 ℃. The welding procedure should be performed on the alloys before any heat treatment and a preheating at 600 ℃ should be used. The fusion zone is harder than the matrix due to a large amount of 7 phase and a finer microstructure. The cracks are predominantly intergranular in heat affected zone and associated with the needle-like ）, phase. The heat treatment before welding increases the tendency of cracking in the fusion zone.

关键词： weldability Ni3Si based alloy heat treatment heat affected zone

weldability and SAW welding wire of X80 pipeline steel

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China Welding 2006年第1期15卷 74-80页

作者：黄治军胡伦骥缪凯张小枫陈浮 Huazhong University of Science and Technology Wuhan430074 Wuhan Iron and Steel (Group) Corporation Wuhan430080

weldability test was carried out on the newly developed fine grain, low sulphur, high strength and high toughness pipeline steel of X80 and its matching SAW wire. Test of maximum hardness in welding heat-affected zone and test of Y groove cracking show that X80 steel features low hardenability and good cracking resistance. The submerged arc welding joint made with the newly developed low carbon and multi-alloyed SAW wire of WGX2 exhibits a little higher strength than the base metal, qualified bending performance, under maximum limitation hardness and good impact toughness, which can completely meet the technical requirement of X80 steel. Despite somewhat coarsening the grain size in welding heat-affected zone is still much finer than that of traditional steels, and the microstructure in weld metal is almost full acicular ferrite. The results show that X80 steel and WGX2 wire are of great weldability.

关键词： X80 weldability welding wire mechanical properties acicular ferrite bainite

weldability of 610MPa Grade High Strength Plate Steel 12MnNiVR for Oil Storage Tanks

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Journal of Iron and Steel Research International 2011年第S1期18卷 769-772页

作者： YANG Han ZHAO Wen-gui HUA Yan-ping CHEN Shao-hui ZHANG Xiao-bing QU Jin-bo Institute of Research of Iron and Steel(IRIS) Sha-steel Chief Engineer Office Sha-steelJiangsu215625China

The weldability of 12MnNiVR was examined in terms of the simulated HAZ continuous cooling transformation (SH-CCT) diagram,microstructure and mechanical properties of the simulated coarse grain heat-affected zone (CGHAZ).When t 8/5 is shorter,the microstructure mainly consists of lath *** t 8/5 is 60 s,the microstructure becomes coarser *** acicular ferrite appears beside lath bainite when t 8/5 =***,a microstructure composed of polygonal ferrite,acicular ferrite,and small amount pearlite is obtained with a small amount of bainite at t 8/5 >*** the increase of t 8/5,the hardness of CGHAZ decreases *** minimum impact toughness of CGHAZ appears at t 8/5 =*** hardness and the toughness of CGHAZ remain above the specified values for steel 12MnNiVR.

关键词： 12MnNiVR weldability SH-CCT coarse grain heat-affected zone

New approach for assessing the weldability of precipitation-strengthened nickel-base superalloys

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International Journal of Minerals,Metallurgy and Materials 2013年第12期20卷 1183-1191页

作者： Homam Naffakh Moosavy Mohammad-Reza Aboutalebi Seyed Hossein Seyedein Meisam Khodabakhshi Carlo Mapelli School of Metallurgy and Materials Engineering Iran University of Science and Technology (IUST) MAPNA Turbine Engineering and Manufacturing Company (TUGA) Dipartimento di Meccanica Politecnico di Milano

A new procedure was proposed for evaluating the weldability of nickel-base superalloys. The theory is on the basis of two microstructural patterns. In pattern I, the weld microstructure exhibits severe alloying segregation, many low-melting eutectic structures, and low weldability. The weld requires a weaker etchant and a shorter time for etching. In pattern Ⅱ, the weld microstructure displays less alloying segregation, low quantity of eutectic structures, and high weldability. The weld needs a stronger etchant and a longer time for etching. Five superalloys containing different amounts of Nb and Ti were designed to verify the patterns. After welding operations, the welds were etched by four etchants with different corrosivities. The weldability was determined by TG-DSC measurements. The metallography and weldability results confirmed the theoretic patterns. Finally, the etchant corrosivity and etching time were proposed as new criteria to evaluate the weldability of nickel-base superalloys.

关键词： superalloys nickel alloys weldability metallography etching segregution eutectics

Investigation on the weldability of a Zr-Ti microalloyed X120 linepipe

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China Welding 2015年第4期24卷 46-50页

作者：雷玄威王红鸿吴开明尹雨群李丽赵晋斌 International Research Institute for Steel Technology Wuhan University of Science and Technology Wuhan 430081. Nanjing Iron & Steel Group Co. Ltd. Nanjing 210035.

Three-wire submerged arc welding was utilized to weld a newly developed Zr-Ti microalloyed X120 linepipe with heat input of 21 kJ/cm. The microstructure in the heat-affected zone （HAZ）, predominantly consisted of bainite, was examined by means of optical and scanning electron microscope. The average Vickers hardness of grain coarsening heat-affected zone （GCHAZ） is about 290 HV0. 2. The lowest Vickers hardness in HAZ is about 265 HV0. 2. No obvious softening occurred in HAZ. The average impact toughness at -30 ℃ in HAZ was 186 -191 J. The tested results indicated that HAZ of newly developed Zr-Ti microalloyed X120 linepipe steel had high strength and excellent low temperature toughness which met the requirements of API 5L standard.

关键词： X120 submerged arc welding heat-affected zone bainite weldability