COLOURING METHOD FOR WROUGHT ALUMINIUM ALLOY WELDED JOINT COLOUR METALLOGRAPHY

Abstract

A colouring method for wrought aluminium alloy welded joint colour metallography, comprising pre-etching and colouring, wherein the pre-etching comprises an acid etching processing step. The acid etching processing is as follows: an acid etching solution is heated to 55° C.-65° C., dripped onto a test piece surface for 50 s-60 s, then flushed with a large amount of deionized water and dried with hot air. The acid etching solution is an aqueous solution comprising 0.3-0.5 mol/L of Cl.sup.−, 1.4-1.8 mol/L of H.sup.+ and 0.3-0.5 mol/L of PO.sub.4.sup.3−. The colouring is as follows: the test piece subjected to the pre-etching processing is completely immersed in a Weck's reagent, shaken slightly for 5-10 s, flushed with a large amount of deionized water after surface colouring and dried with hot air.

Claims

1. A colouring method for wrought aluminum alloy welded joint color metallography comprising pre-etching and colouring, characterized in that: the pre-etching comprises a step of acid etching process; the acid etching process is heating an acid etching solution to 55-65° C., dripping the solution on the sample surface, after 50-60 s washing the sample with a large amount of deionized water, and drying the sample with hot air; the acid etching solution is an aqueous solution containing 0.3-0.5 mol/L of Cl.sup.−; 1.4-1.8 mol/L of H.sup.+; 0.3-0.5 mol/L of PO.sub.4.sup.3−; The colouring is immersing the sample processed by the pre-etching completely into the Weck's reagent, gently shaking it for 5-10 s, rinsing it with a large amount of deionized water after the surface is colored, and drying it with hot air.

2. The colouring method for wrought aluminum alloy welded joint color metallography according to claim 1, characterized in that: the pre-etching further comprises a step of alkaline etching process; the alkaline etching process is immersing the sample processed by the acid etching into an alkaline etching solution for 50-120 s, then rinsing the sample with a large amount of deionized water, and drying it with hot air; the alkaline etching solution is an aqueous solution containing 0.1-0.5 mol/L of OH.sup.−.

3. The colouring method for wrought aluminum alloy welded joint color metallography according to claim 1, characterized in that: the acid etching process is heating the acid etching solution to 65° C. by a water bath, dripping the solution on the sample surface, after 60 s rinsing it with a large amount of deionized water, and drying it with hot air.

4. The colouring method for wrought aluminum alloy welded joint color metallography according to claim 2, characterized in that: the alkaline etching process is heating the alkaline etching solution to 40-60° C., immersing the sample processed by the acid etching into the alkaline etching solution for 50-120 s, then rinsing it with a large amount of deionized water, and drying it with hot air.

5. The colouring method for wrought aluminum alloy welded joint color metallography according to claim 4, characterized in that: the alkaline etching process is heating the alkaline etching solution to 50° C., immersing the sample processed by the acid etching into the alkaline etching solution, carrying out ultrasonic vibration for 60-100 s, then rinsing it with a large amount of deionized water, and drying it with hot air, the ultrasonic frequency being 15-40 kHz.

6. The colouring method for wrought aluminum alloy welded joint color metallography according to claim 1, characterized in that: the acid etching solution is an aqueous solution containing 0.39-0.46 mol/L of Cl.sup.−; 1.43-1.79 mol/L of H.sup.+; 0.35-0.47 mol/L of PO.sub.4.sup.3−; preferably the acid etching solution is an aqueous solution containing 0.40-0.44 mol/L of Cl.sup.−; 1.50-1.73 mol/L of H.sup.+; 0.38-0.45 mol/L of PO.sub.4.sup.3−, and more preferably the acid etching solution is an aqueous solution containing 0.05 mol/L of Na.sup.+ or K.sup.+; 0.43 mol/L of Cl.sup.−; 1.64 mol/L of H.sup.+; 0.42 mol/L of PO.sub.4.sup.3−.

7. The colouring method for wrought aluminum alloy welded joint color metallography according to claim 2, characterized in that: the alkaline etching solution is an aqueous solution containing 0.1-0.3 mol/L of OH.sup.−, preferably the alkaline etching solution is an aqueous solution containing 0.12-0.28 mol/L of OH.sup.−, and more preferably the alkaline etching solution is an aqueous solution containing 0.125 mol/L of OH.sup.− and 0.125 mol/L of Na.sup.+ or K.sup.+.

8. The colouring method for wrought aluminum alloy welded joint color metallography according to claim 1, characterized in that: the acid etching process is carried out within 2-5 hours after the preparation of the acid etching solution is completed, and preferably the acid etching process is carried out within 4 hours after the preparation of the acid etching solution is completed.

9. The colouring method for wrought aluminum alloy welded joint color metallography according to claim 1, characterized in that: the method for preparing the acid etching solution is: adding 0.5-1.8 g of potassium chloride, 25-32 ml of 35% phosphoric acid solution and 10 ml of 37% hydrochloric acid solution to 280 ml of deionized water and mixing them to obtain the acid etching solution; preferably adding 1.2 g of potassium chloride, 30 ml of 35% phosphoric acid solution and 10 ml of 37% hydrochloric acid solution to 280 ml of deionized water and mixing them to obtain the acid etching solution.

10. The colouring method for wrought aluminum alloy welded joint color metallography according to claim 2, characterized in that: the method for preparing the alkaline etching solution is: adding 1-3 g of solid NaOH to 250 ml of deionized water and mixing them to obtain the alkaline etching solution; preferably adding 1.25 g of solid NaOH to 250 ml of deionized water and mixing them to obtain the alkaline etching solution.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a metallographic photo of the welds (welding seam) colored filled with welding wire ER4043 according to the present method;

[0026] FIG. 2 is a metallographic photo of the welds filled with welding wire ER5356 by multi-pass and multi-layer welding colored according to the present method;

[0027] FIG. 3 is a metallographic photo of the heat-affected zone of welded 7N01 aluminum alloy colored according to the present method;

[0028] FIG. 4 is a metallographic photo of 7N01 wrought aluminum after colouring according to the present method;

[0029] FIG. 5 is a metallographic photo of the fusion zone of 7N01 wrought aluminum and filler wire ER5356 colored according to the present method;

[0030] FIG. 6 is a metallographic photo of 6N01 wrought aluminum colored according to the present method;

[0031] FIG. 7 is a metallographic photo of the fusion zone of 6N01 wrought aluminum and filler wire ER4043 colored according to the present method;

[0032] FIG. 8 is a metallographic photo of the fusion zone of 6N01 wrought aluminum and filler wire ER5356 colored according to the present method;

[0033] FIG. 9 is a metallographic photo of the fusion zone of 6N01 wrought is aluminum and filler wire ER4043 colored according to the method of Example 5 of the invention CN103471897A.

DETAILED DESCRIPTION

EXAMPLE 1

[0034] 1) 0.5 g of potassium chloride, 32 ml of 35% phosphoric acid solution and 10 ml of 37% hydrochloric acid solution were added into and mixed with 280 ml of deionized water to obtain the acid etching solution;

[0035] 2) The acid etching solution was heated to 55° C., and dripping the solution on the ground and polished surface of the weld sample filled with welding wire ER4043, after 60 s, the sample was washed with a large amount of deionized water and dried with hot air;

[0036] 3) The sample processed by acid etching was completely immersed into the Weck's reagent, gently shaken for 5 s, washed with a large amount of deionized water after the surface was colored, and dried with hot air.

[0037] The obtained metallographic photo is shown in FIG. 1. From FIG. 1 clear grain boundaries and grain morphology of the weld seam filled with welding wire ER4043 can be seen.

EXAMPLE 2

[0038] 1) 1.8 g of potassium chloride, 32 ml of 35% phosphoric acid solution and 10 ml of 37% hydrochloric acid solution were added into and mixed with 280 ml of deionized water to obtain the acid etching solution;

[0039] 2) 1 g of solid NaOH was added into and mixed with 250 ml of deionized water to obtain the alkaline etching solution;

[0040] 3) The alkaline etching solution was heated to 65° C., and dripping the solution on the grounded and polished surface of the weld sample filled with welding wire ER5356 by multi-pass and multi-layer welding, after 60 s, the sample was washed with a large amount of deionized water and dried with hot air;

[0041] 4) The alkaline etching solution was heated to 50° C., and the sample processed by acid etching was immersed into the alkaline etching solution for 100 s, then washed with a large amount of deionized water, and dried with hot air;

[0042] 5) The sample processed by alkaline etching was completely immersed into the Weck's reagent, gently shaken for 10 s, washed with a large amount of deionized water after the surface was colored, and dried with hot air.

[0043] The obtained metallographic photo is shown in FIG. 2, and it can be seen clearly from FIG. 2 that the weld fusion zone of the weld filled with welding wire ER5356 by multi-pass and multi-layer welding has small grains, and the grains are columnar-shaped and arranged radially from the center of the fusion zone to the periphery. The base metal has larger grains, and the grain boundaries and grain structures of the base metal and weld are clearly displayed.

EXAMPLE 3

[0044] 1) 1.2 g of potassium chloride, 25 ml of 35% phosphoric acid solution and 10 ml of 37% hydrochloric acid solution were added into and mixed with 280 ml of deionized water to obtain the acid etching solution;

[0045] 2) 3 g of the solid NaOH was added into and mixed with 250 ml of deionized water to obtain the alkaline etching solution;

[0046] 3) The acid etching solution was heated to 60° C., and dripping the solution on the ground and polished sample surface of the heat affected zone of welded 7N01 aluminum alloy, after for 50 s, the sample was washed with a large amount of deionized water and dried with hot air;

[0047] 4) The alkaline etching solution was heated to 40° C., and the sample processed by acid etching was immersed into the alkaline etching solution, subjected to ultrasonic vibration for 60 s, then washed with a large amount of deionized water, and dried with hot air. The ultrasonic frequency is 15 kHz.

[0048] 5) The sample processed by alkaline etching was completely immersed into the Weck's reagent, gently shaken for 5 s, washed with a large amount of deionized water after the surface was colored, and dried with hot air.

[0049] The obtained metallographic photo is shown in FIG. 3, and clear grain boundaries and grain morphology of the heat affected zone of welded 7N01 aluminum alloy after welding can be seen from FIG. 3.

EXAMPLE 4

[0050] 1) 1.2 g of potassium chloride, 30 ml of 35% phosphoric acid solution and 10 ml of 37% hydrochloric acid solution were added into and mixed with 280 ml of deionized water to obtain the acid etching solution;

[0051] 2) 1.25 g of the solid NaOH was added into and mixed with 250 ml of deionized water to obtain the alkaline etching solution;

[0052] 3) The acid etching solution was heated to 65° C., and dripping the solution on the ground and polished surface of the 7N01 wrought aluminum sample, after 60 s, the sample was washed with a large amount of deionized water and dried with hot air;

[0053] 4) The alkaline etching solution was heated to 50° C., and the sample processed by acid etching was immersed into the alkaline etching solution, subjected to ultrasonic vibration for 100 s, then washed with a large amount of deionized water, and dried with hot air, the ultrasonic frequency being 40 kHz;

[0054] 5) The sample processed by alkaline etching was completely immersed into the Weck's reagent, gently shaken for 5 s, washed with a large amount of deionized water after the surface was colored, and dried with hot air.

[0055] The obtained metallographic photo is shown in FIG. 4, and clear grain boundaries and grain morphology of 7N01 wrought aluminum can be seen from FIG. 4.

EXAMPLE 5

[0056] 1) 1.2 g of potassium chloride, 30 ml of 35% phosphoric acid solution and 10 ml of 37% hydrochloric acid solution were added into and mixed with 280 ml of deionized water to obtain the acid etching solution;

[0057] 2) 1.25 g of the solid NaOH was added into and mixed with 250 ml of deionized water to obtain the alkaline etching solution;

[0058] 3) The acid etching solution was heated to 65° C., and dripping the solution on the ground and polished sample surface of the fusion zone between 7N01 wrought aluminum and filler wire ER5356, after 60 s, it was washed with a large amount of deionized water and dried with hot air;

[0059] 4) The alkaline etching solution was heated to 50° C., and the sample processed by acid etching was immersed into the alkaline etching solution, subjected to ultrasonic vibration for 100 s, then washed with a large amount of deionized water, and dried with hot air. The ultrasonic frequency being 40 kHz;

[0060] 5) The sample processed by alkaline etching was completely immersed into the Weck's reagent, gently shaken for 5 s, washed with a large amount of deionized water after the surface was colored, and dried with hot air.

[0061] The obtained metallographic photo is shown in FIG. 5, and clear grain boundaries and grain morphology of the fusion zone of 7N01 wrought aluminum and filler wire ER5356 can be seen from FIG. 5. By comparing FIGS. 4 and 5 it can be seen that the base metal, the 7N01 wrought aluminum has larger grains which are regularly arranged as long strips, while the fusion zone of weld filler wire ER5356 has smaller grains which are arranged as dots. The base metal and weld are etched evenly and uniformly with clear grain boundaries.

EXAMPLE 6

[0062] 1) 1.5 g of potassium chloride, 32 ml of 35% phosphoric acid solution and 10 ml of 37% hydrochloric acid solution were added into and mixed with 280 ml of deionized water to obtain the acid etching solution;

[0063] 2) The acid etching solution was heated to 65° C., and dripping the solution on the ground and polished surface of the 6N01 wrought aluminum sample, after 50 s, the sample was washed with a large amount of deionized water and dried with hot air;

[0064] 3) The sample processed by acid etching was completely immersed into the Weck's reagent, gently shaken for 5 s, washed with a large amount of deionized water after the surface was colored, and dried with hot air.

[0065] The obtained metallographic photo is shown in FIG. 6, and clear grain boundaries and grain morphology of 6N01 wrought aluminum can be seen from FIG. 6.

EXAMPLE 7

[0066] 1) 0.5 g of potassium chloride, 30 ml of 35% phosphoric acid solution and 10 ml of 37% hydrochloric acid solution were added into and mixed with 280 ml of deionized water to obtain the acid etching solution;

[0067] 2) 1.25 g of the solid NaOH was added into and mixed with 250 ml of deionized water to obtain the alkaline etching solution;

[0068] 3) The acid etching solution was heated to 60° C., and dripping the solution on the ground and polished sample surface of the fusion zone of 6N01 wrought aluminum and filler wire ER4043, after 60 s, the sample was washed with a large amount of deionized water and dried with hot air;

[0069] 4) The alkaline etching solution was heated to 50° C., and the sample processed by acid etching was immersed into the alkaline etching solution, subjected to ultrasonic vibration for 100 s, then washed with a large amount of deionized water, and dried with hot air, the ultrasonic frequency being 40 kHz;

[0070] 5) The sample processed by alkaline etching was completely immersed into the Weck's reagent, gently shaken for 10 s, washed with a large amount of deionized water after the surface was colored, and dried with hot air.

[0071] The obtained metallographic photo is shown in FIG. 7. As shown in is FIG. 6, 6N01 wrought aluminum has large grains and clear grain boundaries. As shown in FIG. 1, the fusion zone of filler wire ER4043 has small grains which are irregularly arranged as worm-shaped. The upper part of FIG. 7 is the welds (weld seams) and the fusion zone of filler wire ER4043; the lower part of FIG. 7 is the base metal, 6N01 wrought aluminum. In FIG. 7, clear grain boundaries and grain morphology can be seen in both the base metal and welds. The simultaneous etching of the base metal and weld has a good effect.

EXAMPLE 8

[0072] 1) 1.2 g of potassium chloride, 30 ml of 35% phosphoric acid solution and 10 ml of 37% hydrochloric acid solution were added into and mixed with 280 ml of deionized water to obtain the acid etching solution;

[0073] 2) 1.25 g of the solid NaOH was added into and mixed with 250 ml of deionized water to obtain the alkaline etching solution;

[0074] 3) The acid etching solution was heated to 60° C., and dripping the solution on the ground and polished sample surface of the fusion zone of 6N01 wrought aluminum and filler wire ER5356 and holding for 60 s, the sample was washed with a large amount of deionized water and dried with hot air;

[0075] 4) The alkaline etching solution was heated to 50° C., and the sample processed by acid etching was immersed into the alkaline etching solution, subjected to ultrasonic vibration for 100 s, then washed with a large amount of deionized water, and dried with hot air, the ultrasonic frequency being 30 kHz;

[0076] 5) The sample processed by alkaline etching was completely immersed into the Weck's reagent, gently shaken for 10 s, washed with a large amount of deionized water after the surface was colored, and dried with hot air.

[0077] The obtained metallographic photo is shown in FIG. 8, and it can be seen from FIG. 8 that the right side is the base metal of 6N01 wrought aluminum with large grains, and the left side is the weld fusion zone of filler wire ER5356 with small grains. The grain boundaries and grain morphology of the base metal is and weld can be clearly seen from FIG. 8.

COMPARATIVE EXPERIMENT EXAMPLE 1

[0078] The fusion zone of 6N01 wrought aluminum and filler wire ER4043 was colored using the method used in Example 5 of the patent CN 103471897A, and the obtained color metallographic photo is shown in FIG. 9. As can be seen from FIG. 9, part of the base metal of 6N01 wrought aluminum was not etched, the grain contours are not clear, and clear grain boundaries and grain morphology can not be displayed, while as the weld part of the fusion zone of filler wire ER4043 was etched excessively and there were many etching pits, the grain structure can not be distinguished either.

[0079] The examples of the present invention have been described in detail above, but the content stated is only preferred examples of the present invention, and can not be considered as limitation to the scope of the present invention. All the equivalent modifications and improvements that are made according to the claims of the present invention fall within the scope encompassed by the present invention.