Ni元素扩散行为对硬质合金/钢钎焊接头力学性能及微观组织的影响

Effect of element Ni diffusion on the mechanical properties and microstructure of joints brazed of cemented carbide and steel

摘要:

本文采用不同含量的Ni元素的钎料对YG15硬质合金与35CrMo钢进行了钎焊,分别研究了Ni元素含量,钎焊温度以及有无超声作用等因素对接头力学性能与微观组织的影响,研究表明钎焊温度为800°C时随钎料中含Ni元素的增加,界面处可获得连续的α-Cu固溶体层,当钎料中Ni元素含量为4.7%时,其接头剪切强度最高,为295MPa。发现钎焊温度将影响Ni元素的扩散行为,从而影响界面处贫Co区的宽度,在温度为730℃时贫Co区宽度最小,其接头剪切强度值也最高,为350MPa。施加超声可以使增加贫Co区宽度,降低共晶组织含量,并使得WC颗粒迁移进入钎缝金属。当超声时间为30s时,贫Co区宽度为17.5μm,接头剪切强度为378MPa,比无超声时接头强度提高6%。

Abstract:

YG15 cemented carbides and 35CrMo steel were brazed with different content of element Ni in the article. The effect of the content of element Ni, brazing temperature and ultrasonic vibration on the mechanical properties and microstructure of the joints was investigated. It shows that continued α-Cu solution layers can be obtained by increasing the content of element Ni, and the shear strength peaked at 295 Mpa with the 4.7 wt.% Ni content filler metal at the brazing temperature of 800°C. It found that the brazing temperature influence the depleted zone width of element Co of joints through the impact on the diffusion of element Ni. The minimum of the depleted zone width of element Co is observed in the joints at the brazing temperature of 730°C, and the shear strength of the joints reached maximum 350 MPa. The brazing process with ultrasonic vibration can enlarge the width of the depleted zone of element Co of the joints, decrease the content of eutectic structure, and drive the WC particles migration into the bonds. The maximum shear strength of the joints with 17.5 μm depleted zone of element Co was obtained at 378 Mpa with ultrasonic brazing for 30s, increasing the shear strength of the joints by 6% than the joints without ultrasound.