TA1-X65鈦-鋼復(fù)合板焊接工藝及焊縫組織和性能

TA1/X65鈦-鋼復(fù)合板焊接工藝及焊縫組織和性能INVESTIGATION ON THE WELDING PROCESS AND MICROSTRUCTURE AND MECHANICAL PROPERTY OF BUTT JOINTS OF TA1/X65 CLAD PLATES

采用 TIG+MIG+MAG 焊接工藝對 TA1/ X65 爆炸冶金復(fù)合板(復(fù)層 Ti 厚 2 mm, 基層 X65 管線鋼厚 14 mm)試件進(jìn)行了以 V/Cu 作為過渡填充金屬的板-板對接焊實(shí)驗. 利用 OM, XRD, EDS 面掃描, 顯微硬度測試和拉伸實(shí)驗, 研究了焊縫區(qū)組織特征、界面元素分布、主要物相、顯微硬度分布及焊縫力學(xué)性能. 結(jié)果表明, 圓弧狀“U”型坡口設(shè)計有利于過渡層 Cu 的 MIG 焊接, 在 Cu-鋼界面不會引起應(yīng)力集中而萌生裂紋. 熔敷金屬 Ti, V, Cu 和 Fe 有明顯分區(qū), 擴(kuò)散互融現(xiàn)象不明顯, 各區(qū)域間由固溶體相過渡連接, Ti/V 過渡界面組織結(jié)構(gòu)為鈦基固溶體, V/Cu 過渡界面組織結(jié)構(gòu)為釩基固溶體, Cu/Fe 過渡界面組織結(jié)構(gòu)為銅基固溶體. 焊縫硬度較高區(qū)域出現(xiàn)在 Ti/V 過渡界面和 V/Cu 過渡界面處, 硬度值達(dá) 326 和 336 HV10, 對過渡界面層塑韌性有一定影響. 焊縫抗拉強(qiáng)度可達(dá) 558 MPa, 主要由碳鋼層貢獻(xiàn).

Titanium/steel clad material with excellent mechanical properties and corrosion resistance has important application in storage and transportation equipment of oil and gas. Due to the metallurgical incompatibility of titanium and steel, the mechanical properties of weld joint would completely lose when the brittle intermetallic phase TixFey and TiC appeared in the fusion welding process. Therefore, the gas tungsten arced welding (TIG), metal inert-gas welding (MIG) and metal active-gas welding (MAG) with V/Cu composite filler metals for butt joint in this study was carried out on TA1/X65 pipeline steel clad plates with thickness 16 mm ( titanium cladding with thickness 2 mm, X65 pipeline steel with thickness 14 mm). The microstructure, interface element distribution, main phase, microhardness distribution on cross section and mechanical properties of butt welds were investigated by using OM, XRD, EDS element mapping, microhardness and tensile test. The results indicate that the design of “U-type” circular groove advantageous to the MIG of Cu transition-metals, because of the “U-type” circular groove does not cause stress concentration and crack initiation. The deposited metal of Ti, V, Cu and Fe have obvious zoning, interdiffusion melting phenomenon is not severe, and by using solid solution phases to transit zonings of deposited metal. The microstructure of Ti and V transition interface was composed of Ti-based solid solution, the microstructure of V and Cu transition interface was composed of V-based solid solution, and the microstructure of Cu and Fe transition interface was composed of Cu-based solid solution. The high hardness region of butt weld cross section appeared in the Ti/V transition-interface and V/Cu transition-interface, the hardness value was respectively 326 HV10 and 336 HV10, and weakened the ductility of transition interfacial layer. A joint with a tensile strength of 558 MPa, mainly of that of the carbon steel was obtained.

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