CN86104601A - Technology for copper alloy powder plasma-arc welding on surface of cast iron - Google Patents

Abstract

The present invention relates to metal thermal spraying and welding technique, particularly on cast iron matrix, adopt the processing method of positive polarity plasma arc spray-welding copper alloy.The invention reside in provides a kind of new copper-alloy-powder-based material, solving wettability problem and the weldability problem between cast iron matrix and the copper alloy, with between find out the processing method of an adaptation in arc surfacing process.A certain amount of alloying element such as Cr, Mn, Ni etc. are provided in the new cu-based alloy powder material that provides, and non-metallic element P, Si.Facts have proved that the present invention compares with built-up welding or mechanize built-up welding with oxyacetylene torch with traditional edge circle technology, is that significant effect is arranged.

Description

The present invention relates to metal thermal spraying and welding technique.Particularly adopt the positive polarity plasma arc pressure spray process, in the processing method of cast iron (especially grey cast iron) matrix surface spray-welding copper alloy.

As everyone knows, be the low pressure valve of matrix with the grey cast iron, the material of its trim nearly all is to adopt copper alloy.Usually people mainly take methods such as edge circle, oxyacetylene torch manual build up welding or mechanize built-up welding to the process for machining and manufacturing of low pressure valve trim.Facts have proved: these two kinds of processing methodes, all there is different drawbacks separately, one is because edge circle technology is taked " single face dovetail shrink-fit " structure, lead when changing processing turning, the Cu alloy material consumption is big, and tightness can be also undesirable, shows according to pertinent data, the copper material utilization ratio of edge circle technology has only 20～30%, and the seepage scrap rate that is caused by pressure testing accounts for 30～38% of waste product sum; It two adopts oxyacetylene torch manual build up welding or mechanize surfacing of Cu alloy prior on cast iron, obviously can enhance productivity, reduce cost, but deadly defect is to carry out before the built-up welding that high temperature gives heat more than 700 ℃ to ironcasting, and surfacing layer quality is also unstable.Therefore, all trying to explore research on cast iron both at home and abroad at present, adopting the weldability problem of plasma arc spray copper alloy, but all do not tackle the problem at its root.In-problem major cause is: (one) electric arc instability; (2) the mutual wettability of cast iron matrix and copper alloy is very poor; (3) be easy to generate hole and hardened structure in the overlay cladding.In the 1984 disclosed patent No. 2130242 of Britain, be entitled as the data of " as the alloy coat of cast-iron parts: for example mould ", this patent declares that on cast iron matrix the nickel-base alloy that adopts the plasma transferred arc spray to have minimum pore belongs to.This shows that before the present invention, also nobody really solves a difficult problem of utilizing copper alloy powder plasma-arc welding on cast iron.

Starting point of the present invention is very clear and definite; be to provide a kind of new copper-base alloy powder; to solve the problem of wettability difference between cast iron matrix and the copper alloy; the form of adjustment electric arc and reinforcement are to the protection of copper alloy under the high temperature; seek an adaptation simultaneously and on cast iron, take the processing method of copper alloy powder plasma-arc welding; to replace the technology of oxyacetylene torch manual build up welding or mechanize surfacing of Cu alloy, reach traditional edge circle technology.

In order to realize that effectively above-mentioned purpose, the present invention give one's full attention to and considered protection to LMP such as Zn, Sn alloying element in the copper alloy, and the problem of wettability difference between cast iron matrix and the copper alloy.According to physicochemical reaction under the plasma-arc welding effect, the invention provides the copper-based alloy powder material of several groups of different components, see Table one, table two, table three:

In several groups of new copper-based alloy powder materials that more than provide, add alloying elements such as a certain amount of Si, Cr, Mn, Ni, can form sosoloid and intermetallic compound with copper, can form sosoloid or intermetallic compound with cast iron again, thereby reduced the interfacial tension of copper liquid and cast iron, improved the wettability between copper alloy and the cast iron and the intensity of layer.Simultaneously under the effect of electric arc, P, Mn, Si in copper liquid with copper powder in copper powder in remaining Cu ₂Behind the oxide compound generation oxidation-reduction reactions such as O, form one deck composite oxide film, braze layer is played provide protection, and can suppress the scaling loss evaporation of alloying elements such as Zn, Sn effectively, and improved the stability of electric arc on the braze layer surface.The specific embodiment of copper alloy powder plasma-arc welding is: (one) dries copper powder: want the strict drying copper powder before the surfacing, the temperature and time of oven dry should be controlled at 150～200 ℃ * 1h～2h, bake out temperature can not be too big, otherwise the oxidation of copper powder helps forming pore; (2) regulate processing parameter: obtain through refining in the meeting at plasma-arc welding and carry out, regulate and adopt the positive polarity plasma arc surfacing.Its concrete processing parameter sees Table four:

The new copper-base alloy powder and the technology of the present invention's development, in test, obtained the ideal effect, compare with the technology of tradition processing low pressure valve, every performance index of the trim of its surfacing all are better than casting the copper ring trim, and can save copper material more than 60%, the finished product that improves four times of surfacing trims of work efficiency can reach more than 95%.Because processing method of the present invention adopts consing, therefore, the level of automation height, favorable reproducibility, this is that traditional edge circle technology and oxyacetylene torch manual build up welding and mechanize built-up welding are incomparable.

Implementing best method of the present invention is: the residual iron rust of at first eliminating Cast Iron Surface, impurity such as paint, secondly packed in the bronze gold powders end of oven dry in the powder feeder,, enable to obtain best technological effect according to the different weldment adjusting process parameters and the position of spray welding gun.

Claims (5)

1, a kind of based on copper powder, be used for the copper-gold alloy powder of copper alloy powder plasma-arc welding, it is characterized in that adding certain alloy element Zn, Sn, Mn, Ni, Cr or a certain amount of non-metallic element P, Si.

2, a kind of on cast iron matrix, adopt the processing method of copper alloy powder plasma-arc welding, it is characterized in that adopting the positive polarity plasma arc surfacing, processing parameters such as electric current, argon gas, powder sending quantity, surfacing speed, pendulum are wide, wobble frequency, spray distance, regulate by supervisory control desk, copper-base alloy powder is dried processing.

3, alloying element according to claim 1 and non-metallic element, it is characterized in that the amount that alloying element adds is: Zn is 2～10%; Sn is 2～15%; Mn is 2～5%; Ni is 1～10%; Si is 0.1～0.8%; Cr is 0.2～1%.

4, processing method according to claim 2 is characterized in that it is 100～300 that electric current (A) changes arc, and non-arc is 40～120, argon gas (m ³/ n) ion gas is 0.25～0.3, and powder feeding gas is 0.4～0.60, and powder sending quantity (g/min) is 60～130, surfacing speed (rev/min) be 0.09～0.59, putting wide (mm) is 10～30; Wobble frequency (inferior/minute) be 65～80; Spray is 10～15 apart from (mm).

It is characterized in that according to claim 1,3 described copper-base alloy powders that 5, the temperature and time of copper-base alloy powder oven dry should be controlled at 150～200 ℃ * 1h～2h.