WC-20Co硬质合金与1045钢的焊条电弧焊研究

Shielded metal arc welding of cemented carbide WC-20Co to steel 1045

用Z408焊条对WC-20Co硬质合金与1045钢进行了焊条电弧焊,并与J422焊条对比分析了所焊接头的组织与力学性能。试验结果表明:采用J422碳钢焊条焊接WC-20Co与1045钢时,在焊缝与硬质合金界面处生成η碳化物层,焊缝组织以马氏体和共晶为主,接头结合强度仅为硬质合金母材的1/5,不适于硬质合金焊接;用Z408铸铁焊条焊接时则不产生界面η碳化物,接头结合强度达到1180 MPa,可用于WC-20Co与1045钢的焊接;但Z408焊条易在焊缝中残留夹渣,影响接头强度,焊接时应适当提高热输入;焊前450℃预热和焊后450℃保温可以防止裂纹的产生。

Cemented carbide WC-20 Co and steel 1045 were joined by shielded metal arc welding with electrode Z408 as filler metal,the microstructure and mechanical properties of joint were analyzed and compared with those with electrode J422.The results showed that η-carbides layer formed along the interface between WC-20 Co and weld metal and the microstructure of weld metal mainly contains martensite and eutectics,and the bonding strength of the joint only achieve 1/5 of the cemented carbide substrate,so the electrode J422 is not fit for welding of cemented carbide WC-20 Co to steel 1045.But with the electrode Z408,no η-carbides formed in the joint,the bonding strength reaches up to 1180 MPa,so it is suitable for the welding of cemented carbide WC-20 Co to steel 1045.However,the heat input should be increased properly because the weld metal of electrode Z408 is easy to form slag inclusion which has influence on the bonding strength.The cemented carbide WC-20 Co and steel 1045 is difficult to be welded without preheating.Preheating at 450℃ before welding together with post weld heat preservation at 450℃ are helpful for prevention of the welding cracking.