CN104630693A - Combined treatment method of surface of austenitic stainless steel - Google Patents

Abstract

The invention discloses a combined treatment method of the surface of an austenitic stainless steel, and belongs to the technical field of surface modification of a metal material. The combined treatment method comprises the following steps of firstly carrying out electrochemical treatment on the austenitic stainless steel; then preparing a nitriding modified layer by adopting an ion nitriding technology to finally obtain a modified austenitic stainless steel. The combined treatment method disclosed by the invention performs combined treatment on the austenitic stainless steel by combining the electrochemical treatment with the ion nitriding technology, thereby sufficiently exerting the advantages of surface texturing and ion nitriding, enhancing the tribological property of the austenitic stainless steel, reducing the friction coefficient and reducing the abrasion weight loss.

Description

A composite treatment method for the surface of austenitic stainless steel

technical field

The invention relates to a composite treatment method for the surface of austenitic stainless steel, which belongs to the technical field of surface modification of metal materials.

Background technique

Austenitic stainless steel has been widely used in industry, civil, national defense and other fields due to its good comprehensive mechanical properties and process properties, and good corrosion resistance in both oxidizing and reducing media. At present, austenitic stainless steel is also a kind of steel with the largest variety and the largest amount of use among stainless steels, and its production and use account for more than half of the total output and use of stainless steel. However, due to the disadvantages of low surface hardness, high friction coefficient, and poor wear resistance, austenitic stainless steel cannot generally be used to make sliding friction parts, and its wider use is limited. Based on the fact that friction and wear begin on the surface of the material, studies have shown that the wear resistance of austenitic stainless steel can be effectively improved by means of surface technology. The selection of appropriate surface treatment technology is of great significance for expanding the application of austenitic stainless steel as friction material.

Contents of the invention

The invention aims to provide a composite treatment method for the surface of austenitic stainless steel, and the obtained austenitic stainless steel has excellent grease lubrication tribological properties.

The present invention provides a composite treatment method for the surface of austenitic stainless steel. Firstly, the austenitic stainless steel is electrochemically treated, and then the nitriding modified layer is prepared by ion nitriding technology.

The above processing method includes the following steps:

(1) Pretreatment of austenitic stainless steel workpieces: after degreasing the surface of austenitic stainless steel workpieces, use SiC water sandpaper to perform step-by-step grinding, cleaning, and drying for later use;

(2) Leave the pretreated austenitic stainless steel workpiece on the working surface, seal the rest with epoxy resin, dry it, use it as the working electrode, use the saturated calomel electrode as the reference electrode, and the platinum sheet as the auxiliary electrode Placed in a NaCl solution with a concentration of 10-25 wt. %, the open-circuit potential and potentiodynamic polarization curve tests were carried out at 20-30 °C, the open-circuit potential test time was 10-20 min, and the polarization curve test was taken relative to Open circuit potential -0.25 V is the initial voltage, +2.0 V is the final voltage, and the scan rate is 1mV/s;

(3) Put the austenitic stainless steel processed in step (2) on the workpiece table in the glow ion metallization furnace, and connect the cathode of the pulse power supply through the workpiece table to become the workpiece pole, the furnace shell and the pulse power supply. Anode connection, and ground;

(4) Evacuate the interior of the glow ion metal infiltration furnace cavity to a vacuum of 0.1 Pa, and feed ammonia gas with a flow rate of 30 sccm to 35 sccm into the furnace cavity to maintain the pressure in the furnace cavity at 35 Pa to 45 Pa. Start the pulse power supply, apply a DC bias voltage between the anode and the cathode, and when the temperature of the workpiece rises to 350 ℃ ~ 450 ℃, perform ion bombardment cleaning on the austenitic stainless steel for 20 minutes to 40 minutes;

(5) Adjust the workpiece pole voltage to -600 V ~ -500 V, the workpiece pole current to 30 A ~ 40 A, maintain the workpiece pole temperature at 500 ℃ ~ 550 ℃, keep warm for 8 h ~ 10 h, turn off the pulse power supply, Allow the austenitic stainless steel to cool slowly to room temperature.

In the above scheme, the mass concentration of the NaCl solution in the step (2) is preferably 15-20%.

In the above scheme, in the step (5), the workpiece pole voltage is preferably -550 V, the workpiece pole current is preferably 35A, and the workpiece pole temperature is preferably 525°C to 535°C.

The invention belongs to the technical field of surface modification of metal materials. Utilizing the characteristics of austenitic stainless steel with high sensitivity to Cl ^- pitting corrosion, first electrochemically treat 316 stainless steel to obtain surface texture, and then use ion nitriding technology to prepare nitriding modified sex layer.

Beneficial effects of the present invention:

The present invention combines electrochemical treatment with ion nitriding technology, and performs composite treatment on austenitic stainless steel, fully exerts the advantages of surface texture and ion nitriding, improves the tribological performance of austenitic stainless steel, reduces the Coefficient of friction, reducing wear and weight loss.

Description of drawings

Fig. 1 is the friction coefficient figure of untreated austenitic stainless steel and the austenitic stainless steel and GCr15 after the treatment of embodiment 1;

Fig. 2 is the coefficient of friction figure of untreated austenitic stainless steel and austenitic stainless steel treated in embodiment 1 and Si ₃ N ₄ against grinding;

Fig. 3 is untreated austenitic stainless steel and the austenitic stainless steel and GCr15 after the treatment of embodiment 1 wear loss weight diagram;

Fig. 4 is untreated austenitic stainless steel and embodiment 1 treated austenitic stainless steel and Si ₃ N ₄ wear loss weight diagram for grinding;

Fig. 5 is the coefficient of friction figure of untreated austenitic stainless steel and the austenitic stainless steel and GCr15 after the treatment of embodiment 2;

Fig. 6 is the coefficient of friction figure of untreated austenitic stainless steel and austenitic stainless steel treated in embodiment 2 and Si ₃ N ₄ against grinding;

Fig. 7 is untreated austenitic stainless steel and embodiment 2 processed austenitic stainless steel and GCr15 to the wear loss figure of grinding;

Fig. 8 is untreated austenitic stainless steel and the austenitic stainless steel after the treatment of embodiment 2 and Si ₃ N ₄ wear loss weight diagram of grinding;

Among Fig. 1 1—the friction coefficient figure of untreated austenitic stainless steel and GCr15 grinding; 2—the friction coefficient figure of the austenitic stainless steel and GCr15 grinding of the processed austenitic stainless steel after embodiment 1;

Among Fig. 2, 3—the friction coefficient diagram of untreated austenitic stainless steel and Si ₃ N ₄ grinding; 4—the friction coefficient diagram of austenitic stainless steel and Si ₃ N ₄ grinding after the treatment of embodiment 1;

Among Fig. 3, 5—untreated austenitic stainless steel and GCr15 wear loss weight map; 6—austenitic stainless steel and GCr15 wear loss weight map after the treatment of embodiment 1;

Among Fig. 4, 7—untreated austenitic stainless steel and Si ₃ N ₄ pair grinding wear loss diagram; 8—austenitic stainless steel after embodiment 1 treatment and Si ₃ N ₄ Wear loss weight diagram of pair grinding;

Among Fig. 5, 9—the friction coefficient figure of untreated austenitic stainless steel and GCr15 grinding; 10—the friction coefficient figure of the austenitic stainless steel and GCr15 grinding of the processed austenitic stainless steel after embodiment 2;

Among Fig. 6, 11—the friction coefficient diagram of untreated austenitic stainless steel and Si ₃ N ₄ grinding; 12—the friction coefficient diagram of austenitic stainless steel and Si ₃ N ₄ grinding after the treatment of Example 2;

Among Fig. 7, 13—untreated austenitic stainless steel and GCr15 wear loss weight map; 14—embodiment 2 treated austenitic stainless steel and GCr15 wear loss weight map;

Among Fig. 8, 15—untreated austenitic stainless steel and Si ₃ N ₄ pair grinding wear loss weight map; 16—austenitic stainless steel and Si ₃ N ₄ pair grinding wear loss weight map after processing in Example 2;

In Fig. 1, Fig. 2, Fig. 5, and Fig. 6, μ—friction coefficient; T—friction time; in Fig. 3, Fig. 4, Fig. 7, and Fig. 8, G—wear weight loss.

Detailed ways

The present invention is further illustrated below by means of the accompanying drawings and examples, but is not limited to the following examples.

Now taking 316 austenitic stainless steel as an example, the present invention is implemented:

Example 1:

Composite surface treatment method in the present embodiment specifically comprises the following steps:

(1) Pretreatment of austenitic stainless steel workpieces: after degreasing the surface of austenitic stainless steel workpieces, use SiC water sandpaper to perform step-by-step grinding, cleaning, and drying for later use;

(2) Leave the pretreated austenitic stainless steel workpiece on the working surface, seal the rest with epoxy resin, dry it, use it as the working electrode, use the saturated calomel electrode as the reference electrode, and the platinum sheet as the auxiliary electrode Placed in a NaCl solution with a concentration of 15 wt.%, the open circuit potential and potentiodynamic polarization curve tests were carried out at 25 °C. The open circuit potential test time was 15 min, and the polarization curve test was taken relative to the open circuit potential -0.25 V as The initial voltage, +2.0 V is the end voltage, and the scan rate is 1mV/s;

(3) Put the austenitic stainless steel processed in step (2) on the workpiece table in the glow ion metallization furnace, and connect the cathode of the pulse power supply through the workpiece table to become the workpiece pole, the furnace shell and the pulse power supply. Anode connection, and ground;

(4) Evacuate the chamber 1 of the glow ion metal infiltration furnace to a vacuum degree of 1× ^10-1 Pa, and feed ammonia gas with a flow rate of 30 sccm to 35 sccm into the furnace chamber to maintain the pressure in the furnace chamber at 40 Pa, start the pulse power supply, apply a DC bias voltage between the anode and the cathode, and when the temperature of the workpiece rises to 350 ℃ ~ 450 ℃, perform ion bombardment cleaning on the austenitic stainless steel for 30 minutes;

(5) Adjust the workpiece pole voltage to –550 V, the workpiece pole current to 35 A, maintain the workpiece pole temperature at 525 °C, keep warm for 9 h, turn off the pulse power supply, and slowly cool the austenitic stainless steel to room temperature.

Example 2:

The difference between this embodiment and Example 1 is that the concentration of the NaCl solution in step (2) is 20 wt.%, the temperature of the workpiece pole in step (5) is maintained at 535 ° C, and other steps and parameters are the same as in Example 1.

The treated austenitic stainless steel obtained in Example 1 and Example 2 was subjected to a tribological performance test.

During the friction and wear test, the surfaces of all samples were coated with a layer of grease. In order to give full play to the advantages of surface texturing and ion nitriding, the present invention: the surface texture can store grease, and the nitriding treatment can improve the surface wear resistance, and the two have the effect of "complementing each other"; so when performing friction and wear tests, All specimen surfaces were coated with a layer of grease.

Under the above process conditions, the austenitic stainless steel has excellent tribological properties. The test data are shown in Table 1.

Table 1

From the test results provided in Table 1, it can be seen that compared with untreated stainless steel, after 316 stainless steel has undergone composite surface treatment, the wear test results show that the friction coefficient and wear loss weight of austenitic stainless steel after composite treatment are significantly lower than those of untreated stainless steel. Handle stainless steel. From the above results, it can be seen that the austenitic stainless steel obtained excellent tribological properties after composite surface treatment.

Claims (5)

1. the compounding method on austenitic stainless steel surface, is characterized in that: first carry out electrochemical treatment to austenitic stainless steel, then adopts ion nitriding technology to prepare nitrogenize modified layer.

2. the compounding method on austenitic stainless steel surface according to claim 1, is characterized in that: comprise the following steps:

(1) to the pre-treatment of austenite stainless steel workpiece: by using SiC waterproof abrasive paper to polish step by step after the oil removing of austenite stainless steel workpiece surface, clean, drying for standby;

(2) austenite stainless steel workpiece good for pre-treatment is reserved working face, rest part uses epoxy sealing, dry after, it can be used as working electrode, be placed in as supporting electrode the NaCl solution that concentration is 10 ~ 25 wt. % as reference electrode, platinized platinum by saturated calomel electrode;

(3) put in the work stage of metallic glow ion cementation stove by the austenitic stainless steel that step (2) is handled well, and be connected with the negative electrode of the pulse power by work stage, become workpiece pole, furnace shell is connected with the anode of the pulse power, and ground connection;

(4) be 0.1 Pa metallic glow ion cementation stove furnace chamber inside degree of being evacuated, passing into flow is that the ammonia of 30 sccm ~ 35 sccm is to furnace chamber, furnace chamber internal gas pressure is made to maintain 35 Pa ~ 45 Pa, starting impulse power supply, direct current (DC) bias is applied between anode and negative electrode, when workpiece pole temperature rises to 350 DEG C ~ 450 DEG C, icon bombardment cleaning 20 min ~ 40 min is carried out to austenitic stainless steel;

(5) by workpiece pole tension Tiao Zhi – 600 V～– 500 V, workpiece electrode current is adjusted to 30 A ~ 40 A, and workpiece pole temperature maintains 500 DEG C ~ 550 DEG C, is incubated 8 h ~ 10 h, closes the pulse power, makes austenitic stainless steel slow cooling to room temperature.

3. the compounding method on austenitic stainless steel surface according to claim 2, is characterized in that: in described step (2), the mass concentration of NaCl solution is 15 ~ 20 %.

4. the compounding method on austenitic stainless steel surface according to claim 2, it is characterized in that: in described step (2), open circuit potential and dynamic potential polarization curve test is carried out respectively at 20 ~ 30 DEG C, the open circuit potential test duration is 10 ~ 20 min, polarization curve test get relative to open circuit potential-0.25 V be starting voltage ,+2.0 V are final voltage, scanning speed is 1mV/s.

5. the compounding method on austenitic stainless steel surface according to claim 2, is characterized in that: in described step (5), and workpiece pole tension Wei – 550 V, workpiece electrode current is 35 A, and workpiece pole temperature maintains 525 DEG C ~ 535 DEG C.