Preparation of ultra-fine iron powders by water-gas atomization and its application on laser welding saw blades

Abstract

Ultra-fine iron powder was prepared by water-gas atomization process. The physical properties and the micro morphologies of the ultra-fine iron powder, the reduced iron powder and the carbonyl iron powder were compared. The sintered blocks of three kinds of iron powders were prepared under a certain hot pressing process, and their fracture morphologies and mechanical properties were investigated. At the same time, the three kinds of iron powders were applied to the transition layer of laser welding saw blades under certain welding conditions to investigate their welding performances. The results show that the ultra-fine iron powder prepared by water-gas atomization process has fine particles, lower oxygen content, higher purity and sphericity, and better sintering activity. There are obvious dimple structures on the fracture surface of the sintered block, which has higher toughness and can achieve greater density, hardness and bending strength at lower sintering temperature. When the ultra-fine iron powder is applied to the transition layer of the laser welding saw blade, the welding strength of the saw blade is much higher than 600 MPa specified in the EU EN13236 standard. When the sintering pressure is 35 MPa, the sintering temperature is 810 ℃ and the holding time is 3 min, the cutter head is made, and then the saw blade is made with this cutter head. The maximum welding strength of the saw blade is 1 900 MPa.

Keywords

• water-gas atomization
• ultra-fine iron powder
• laser welding saw blade
• transition layer
• weld strength