Process for surfacing stainless steel sealing face on ductile cast iron valve base

Abstract

The invention discloses a process for surfacing a stainless steel sealing face on a ductile cast iron valve base. The process includes firstly preheating and cleaning up the valve base; adopting pulse gas metal arc welding; performing full-automatic welding, pulsed direct current, anode reversed connection, and protection through argon and carbon dioxide mixed gas, wherein the flow is 18-25L/min and the welding speed is 8-15cm/min; cladding a stainless steel welding cladding with the thickness of 2.5-6mm at a to-be-welded position of the valve base after the welding; and then placing the valve base at the temperature of 350-400 DEG C for 2 hours. The process has the advantages that the welded sealing face is reliable in strength and stable in performance, and has no defects such as air holes and cracks; the utilization rate of welding materials is high, the process is simple, convenient to operate, and capable of achieving automation; and compared with spinning, boxing and stainless steel ring embedding processes, a plurality of processes such as marking, blanking, plate rolling, butt welding and spinning are omitted, and the process is suitable for automatic welding and batch production.

Description

technical field [0001] The invention relates to a processing technology for a valve sealing surface, in particular to a technology for overlaying a stainless steel sealing surface on a nodular cast iron valve base body. Background technique [0002] Compared with cast steel valves, ductile iron valves have higher casting efficiency, lower machining cost, better corrosion resistance and oxidation resistance in use, and higher yield strength, which is better than cast steel in reducing vibration. Valves, so ductile iron valves are more popular in municipal applications. At present, the sealing surfaces of ductile iron valves such as butterfly valves, check valves and ball valves are mostly treated with spinning stainless steel rings, welded stainless steel rings or inlaid stainless steel rings to achieve the effect of ductile iron valves with stainless steel sealing surfaces, but at present These processing methods all have defects such as complex process, high production cos...

AI Technical Summary

Problems solved by technology

At present, the sealing surfaces of ductile iron valves such as butterfly valves, check valves and ball valves are mostly treated with spinning stainless steel rings, welded stainless steel rings or inlaid stainless steel rings to achieve the effect of ductile iron valves with stainless steel sealing surfaces, but at present These processing methods all have defects such as complex process, high production cost, low production efficiency, low material utilization rate and unstable quality.

If manual arc welding or plasma surfacing is used to directly surfacing the stainless steel sealing surface on the substrate, the process flow can be reduced and work efficiency can be improved. However, in actual use, the above two processes have the following disadvantages: when using manual arc welding, The welding surface is prone to defects such as pores, slag inclusions, cracks, etc., and the quality is difficult to guarantee. The dilution rate of the base metal is large during welding. Generally, three layers of surfacing welding are required to ensure the chemical composition and mechanical properties of the surfacing layer, and the utilization rate of welding materials is not high. high

When plasma surfacing is used, the deposition rate is low, and defects such as cracks and pores are prone to occur during welding, and it is difficult to repair

[0003] Pulse MIG welding is also a relatively common welding method. It is easy to operate during the welding process, there is no or little slag, and the production efficiency is high. But so far, no such welding process has been applied to nodular ink Report on the sealing surface of cast iron valves