KR101584183B1 - Corrosion inhibition and surface hardening of special steels using pulsed electron beam treatment - Google Patents
Corrosion inhibition and surface hardening of special steels using pulsed electron beam treatment Download PDFInfo
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The present invention relates to a corrosion inhibiting and surface hardening method of a special steel by using a pulse beam treatment, and more particularly, to a method of coating a surface of a special steel KP1 and KP4 steel through a pulse beam irradiator in a finishing process of a metal mold, Polishing is performed to form a corrosion potential of 50 ㎷ and 30 각 respectively corresponding to the SCE (Saturated Calomel Electrode), and to increase the corrosion current reduction, surface stability and nano hardness of 50 ((Micro Ampere) The present invention relates to a method of suppressing corrosion and surface hardening of special steel using beam treatment.
In general, injection molding is widely used in the industrial field for forming polymer parts, and injection molding can be performed quickly and is highly cost-effective.
Defects on the mold surface using injection molding can be caused by corrosion or abrasion, and when the mold surface is corroded or abraded, severe defects such as shrinkage may occur in the finished product. The polymer in the liquid state is directly exposed to the surface area of the mold It is very important that the surface shape of the mold can be kept constant in order to produce a good quality product.
KP1 and KP4 (special steels) widely used in injection molding have been actively studied to prevent corrosion or abrasion on the mold surface by using an organic or inorganic inhibitor.
For example, it is well known that the adsorption of organic or inorganic inhibitors improves the corrosion resistance of steels, and prevents the dissolution of bipolar metals to provide corrosion resistance - corrosion resistance for reliability (life cycle, product consistency) It is important to note that the efficiency of adsorption and inhibition of corrosion inhibiting materials is based on the interactions of metals with inhibitors. Studies on corrosion inhibition published by Quantum Chemical show that the phase of the layer This method has been reported to improve the corrosion resistance, which is closely related to the characteristics and has been reported to mainly consider the quantitative structure active correlation which has a great effect on the corrosion resistance. Machine Hammer Peening , Electrochemical Polishing, UV Illumination, and Laser Shock Peening.
On the other hand, PEBP (Pulsed Electron Beam Polishing) has been used for finishing a metal mold having a complex surface. During the PEBP process, the metal surface melts for a very short time, removing traces and pitches of the extensions, and rapidly solidifying. Rapid heating and cooling of the metal surface at 10 ^ 7 K / s can cause phase transformation in the surface layer, which is solidified again, and this phenomenon may cause a change in the structural characteristics of the surface.
Existing prior studies of the PEBP method have found improvements in the surface roughness of metal molds including SUS420J2 and NAK80. After recent PEBP processes, there have been reports on strengthening of hardness of SUS316L and FeAl alloy and water repellency of SUS420J2. In addition, corrosion resistance and abrasion resistance were also improved in SUS316L, D2 steel, and AZ91HP magnesium alloy after PEBP process.
However, despite the above-mentioned research results, corrosion resistance and hardness enhancement of the metal mold after PEBP process remain uncertain, and improvement is needed.
SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, and it is an object of the present invention to solve the above problems by providing a pulsed beam irradiating device for finishing a metal mold, Electrode), corrosion inhibition of special steel by pulse beam treatment to reduce corrosion current of 50 ((Micro Ampere), increase surface stability and nano hardness And to provide a surface hardening method.
In order to accomplish the above object, a corrosion inhibiting and surface hardening method of a special steel using pulse beam treatment according to the present invention comprises the steps of (a) forming a cathode, a solenoid, an anode, and a cathode in a vacuum chamber, Generating a pulse beam between the cathode and the anode; (b) causing the pulse beam generated in step (a) to pass through the argon gas, and generating a plasma between the anode and the cathode; And (c) irradiating the surface of the extrudate with a pulse beam using an electric field and a helical structure by a Lorentz force; Wherein the energy density is in the range of 7-10 J / cm ^ 2, the argon gas pressure in the vacuum chamber is 0.05 Pa, the volume of the substrate is set to 40 mm x 40 mm x 5 mm, and the pulse beam irradiation .
The injection-molded product may be made of any one of special steels KP1 and KP4.
The pulse cycle of the pulse beam with respect to the injection-molded article is a pulse of 8 to 10, which can realize a uniform surface and texture for the injection-molded article.
The vacuum chamber on which the cathode, the solenoid, and the anode are mounted moves in the X and Y axes through the moving stage in the grid chamber spaced at intervals of 19 to 21 mm to realize a uniform surface and texture for the injection-molded object.
In the finishing step of the metal mold, it is preferable that heating and cooling are performed at a speed of 10 7 K / s during the pulse beam irradiation process on the surface of the injection-molded object.
It is preferable to irradiate the substrate with pulses of 2 s using the pulsed electron beam polishing (PEBP) method during the irradiation time of 9 to 11 seconds after the cooling of the substrate during the pulse beam irradiation process on the injection mold in the finishing process of the metal mold .
As described above, according to the corrosion inhibiting and surface hardening method of the special steel using the pulse beam treatment according to the present invention, the surface of the special steel (KP1, KP2) By irradiating a pulse beam instead of a beam, it forms a corrosion potential of 50 ㎷ and 30 각 respectively corresponding to the SCE (Saturated Calomel Electrode), reducing the corrosion current of 50 ((Micro Ampere), increasing the surface stability and nano hardness Can be realized.
According to the corrosion inhibiting and surface hardening method of the special steel using the pulse beam treatment according to the present invention, the corrosion resistance of both KP1 and KP4 samples can be efficiently improved.
According to the corrosion inhibiting and surface hardening method of the special steel using the pulse beam treatment according to the present invention, corrosion is suppressed by the phase change of the surface shifting from the alpha-phase to the gamma-phase, As the number increases.
According to the corrosion inhibiting and surface hardening method of the special steel using the pulse beam treatment according to the present invention, the PEBP forms a passive recoat layer containing a large proportion of oxides on the surface, and the CTP Charge Transfer Properties) are improved compared to before processing.
According to the corrosion inhibition and surface hardening method of the special steel using the pulse beam treatment according to the present invention, the resolidified layer shows a more stable state as the energy density of the beam is larger.
According to the corrosion inhibiting and surface hardening method of the special steel using the pulse beam treatment according to the present invention, the corrosion of the PEBP-treated surface starts from the crater, and the PEBP-treated sample has the corrosion resistance Excellent surface is formed.
According to the corrosion inhibiting and surface hardening method of the special steel using the pulse beam treatment according to the present invention, the surface nano-hardness and the modulus of elasticity of the surface are significantly increased after PEBP treatment, and the wear resistance is increased accordingly.
According to the corrosion inhibiting and surface hardening method of the special steel using the pulse beam treatment according to the present invention, the surface roughness is reduced after the PEBP process, and the roughness is further reduced as the energy density of the beam and the number of irradiation cycles are increased.
1 is a configuration diagram showing a pulse beam irradiating apparatus according to the present invention.
FIG. 2 is an image of the cross-sectional area SEM of the PEBP of the KP1 and KP4 samples according to the present invention.
FIG. 3 is an image of a state where craters are generated in KP1 and KP4 after PEBP according to the present invention.
4 is a graph of the density of craters based on the number of irradiation cycles according to the present invention.
5 is a graph of Potentiodynamic polarity cuffs of KP1 and KP4 samples before and after PEBP according to the present invention.
6 is a graph showing changes in the angle of the demineralized water before and after the PEBP process according to the present invention.
FIG. 7 is a graph showing an XRD pattern of KP1 using various irradiation cycles as a variable after PEBP according to the present invention. FIG.
Figure 8 is an image of the cross-sectional area of KP1 and KP4 samples after PEBP treatment according to the present invention.
9 is a graph showing Nyquistk plots of KP1 and KP4 special steels according to the present invention.
10 is an image of optical microscopy according to the present invention.
11 is an image showing the corrosion mechanism according to the present invention.
12 is a graph showing the nano hardness and the elastic modulus at an energy density of 10 J / cm < 2 > according to the present invention and a depth of irradiated area after 20 irradiation cycles.
FIG. 13 is an image obtained by analyzing image quality maps (IQMs) of EBSD data according to the present invention.
FIG. 14 is a graph showing changes in weight after a wear test before and after PEBP treatment of KP1 and KP4 samples according to the present invention. FIG.
15 is a stereoscopic profile and a microscope image of a surface wear track according to the present invention.
16 is a graph showing the surface roughness according to the present invention.
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The term is synonymous with the general meaning of the term as understood by those of ordinary skill in the art to which the present invention pertains and if the term used herein is in conflict with the general meaning of the term, And the same reference numerals throughout the specification denote like elements.
It should be noted that the corrosion inhibiting and surface hardening methods of the special steel using the pulse beam treatment described in this specification may be implemented in various embodiments and are not limited to the embodiments described herein.
In the corrosion inhibition and surface hardening method of the special steel using the pulse beam treatment according to the present invention, the PEBP process is used as a finishing method for the KP1 and KP4 steels, which are widely used in injection molding, and the corrosion resistance, abrasion resistance, hardness, Surface characteristics including roughness were analyzed before and after the PEBP process and SEM (Scanning Electron Microscopy), EBSD (Electron Back-Scattered Diffraction) and EPMA (Electron Probe Micro Analysis) .
The following is an explanation of an experiment according to a corrosion inhibiting and surface hardening method of a special steel using the pulse beam treatment according to the present invention.
The materials used in the experiments of the present invention are KP1, which is used for manufacturing large molds because of low carbon content which is often used in injection molding and excellent cutting ability, and relatively low chromium (Cr) and molybdenum (Mo) content KP4, which is used to form core cavities due to its high hardness, was used.
Of these, KP4 has relatively better corrosion and abrasion resistance, but it is less machinable than KP1.
The pulse
The electron beam generated between the
In the pulse
The volume of the substrate used in the experiment was set to 40 mm x 40 mm x 5 mm. The energy flux of the electron followed the Gaussian distribution. For uniform surface and texture of the extrudate, the transmission cycle of each pulse beam was 8-10 And the pulse
Electrochemical analysis uses three kinds of electrode test in the 1% NaCl solution on the surface of KP1 and KP4 specimens, which are special steels, and the electrochemical impedance test Respectively.
These tests were conducted to investigate the effect of corrosion on the surface of extruded products due to rapid solidification after heating. SCE (Standard Calomel Electrode) was used as a reference electrode and PE (Platinum Electrode) was used as a counter electrode. The working electrode exposure range on the surface of the extrudate was 1 cm ^ 2.
The surface of each of the special KP1 and KP4 samples was exposed to the solution for 30 minutes for a stable OCP (open circuit potential) prior to the electrochemical test and was performed at +400 mV / SCE for a scan rate of 1 mV / s and OCP All.
EIS Spectra measured the impedance of the electrochemical in the oscillation band of 100kHz-100MHz in the OCP, the amplitude of the signal was 10mV, and the result for comparing the CTR (Charge Transfer Resistance) of the PEBP-processed samples is shown in the Nyquist Plot .
In the present invention, the nano-indentation test was performed on the surface of samples using VT (Verkovich Tip) in the process of nano-hardness and wear measurements. Unlike the micro or macro scale test, Was measured using a depth sensing indentation technique.
In addition, the plastic deformation point after the indentation test was 10 times larger than the point at which the indentation test was performed, and the indentation depth was set to 250 탆 to prevent the interposition between the points of contact.
In addition, DWT (Dry Wear Test) was carried out before and after the PEBP process using the pin-on-disk method SKD11 pin, and a commercial load of 5 kgf was measured at 300 rpm with 60 rpm cone advancement.
Meanwhile, in the surface roughness measurement of the present invention, the surface roughness was measured using a profilometer (SV-C3100, Mitutoyo, Japan) having a resolution of 10 nm and an error range of 3% 0.8 nm, and observed five times at intervals of 4.8 nm.
In this process, the first and last 0.4 nm sections are ignored in accordance with ISO 4287: 1997.
In the process of irradiating the surface of KP1 and KP4, which are injection-molded specimens of the present invention, with a pulse beam, the metal on the thin surface is solidified again while the heating and cooling are performed at a speed of 10 7 K / s It goes fast. After the substrate has cooled, the substrate is irradiated with a 2 μs pulse in the PEBP process for a relatively long 10 second irradiation time. This is because the layer depth of the solidified surface is not much different for each irradiation time so that the irradiation by the PEBP process becomes independent for each wave.
FIG. 2 is an image of cross-sectional area SEM (Scanning Electron Microscopy) of the KP1 and KP4 samples before and after the PEBP process. As can be seen in FIG. 2, the crystal phase of the resolidified layer is significantly different from that before PEBP.
That is, the recoat layer of KP1 showed a depth of 4.2 ㎛ at the energy density of 7 J / cm ^ 2 and 5.3 ㎛ at the depth of 10 J / cm ^ 2. The recoat layer of KP4 showed 7 J / cm ^ cm < 2 > at an energy density of 2.4 [mu] m and 4.4 [mu] m, respectively.
Also, as shown in Table 1, the thermal diffusivity of KP1 is greater than KP4. When the pulse beam is irradiated in the PEBP process, the energy flux penetrates deeper into the KP1 steel. As a result, The reappearance layer is deeper.
And, in the PEBP process for KP1 and KP4 samples, a partial crater (pit) can occur due to partial evaporation and ejection of nonmetal parts such as MnS and Calbide.
Both KP1 and KP4 samples contain MnS base metal, and as shown in Fig. 3, pits were observed in the KP1 and KP4 samples after the PEBP process.
Figure 4 shows the density of craters with the number of irradiation cycles as a variable. Referring to FIG. 4, the crater density was larger in the KP4 samples containing more manganese.
During repeated irradiation, the non-metallic material near the surface of the KP4 sample could be completely vaporized or decomposed, thus reducing the crater density as the number of irradiation cycles increased.
Figure 5 shows the potentiodynamic polarity curves before and after the PEBP process for KP1 and KP4 samples.
Referring to FIG. 5, the Tafel extrapolation method for calculating the corrosion potential E_corr and the i_corr, which is the corrosion current density, is used, and the corrosion potential and the corrosion current density are shown in Table 2.
Density (I / cm2)
KP1
KP4
Referring to Table 2 above, the corrosion resistance of the irradiated surface was improved with an increased corrosion potential (E_corr) and a reduced corrosion current density (i_corr).
Corrosion potentials are closely related to the running energy for corrosion, and the higher the potential, the faster the activation. Therefore, the free corrosion potential by the PEBP process has increased corrosion resistance compared to before the PEBP process.
Increased corrosion potential after PEBP was more increased at 10 J / cm ^ 2 than at 7 J / cm ^ 2. The energy density of the KP1 sample was 10 J / cm ^ 2 and the highest corrosion resistance after 20 irradiation cycles (-725 mV / SCE to -661 mV / SCE).
These improvements were twice as effective in KP1 than in KP4.
Prior to the PEBP process, the KP4 sample showed higher nobler corrosion potential than the KP1 sample. However, as a result of PEBP, the corrosion potential of both samples was almost the same after treatment.
The corrosion current density decreased after the PEBP run and the larger energy density was smaller. The corrosion rate can be expressed by Equation (1).
In
Calculation of erosion rate from other PPD (Potentiodynamic Polarization Data) is energy density as summarized in Table 2.
Referring to Table 2, it can be seen that the corrosion rate is decreased due to PEBP because the corrosion rate is proportional to the corrosion current density.
The improvement in this corrosion resistance is related to the surface energy, the larger activation energy of the corrosion corresponds to better corrosion resistance, and the surface energy can be characterized through CAM (Contact Angle Measurement).
Typically, larger contact angles indicate lower surface energy and lower reactivity.
6 shows the change in angle of the demineralized water before and after the PEBP process. In the case of an energy density of 7 / cm < 2 >, the contact angle of the KP1 sample was greatly increased by irradiation, Was less than that of KP1. This phenomenon is sufficient to accommodate the displacement of the corrosion potential before and after PEBP.
The corrosion potential of KP1 was initially lower than that of KP4, but both samples had similar corrosion potentials after PEBP (see Table 2).
In addition, the close angle of the KP1 sample was initially lower than the KP4 sample, but with a more similar angle after PEBP. Taken together, the surface of KP1 and KP4 samples (especially KP1) can be said to be more stable after PEBP.
X-ray diffraction (XRD) patterns were run after PEBP to investigate phase transformation that may affect corrosion resistance.
FIG. 7 shows the pattern of XRD of KP1 with various irradiation cycle number as a variable after PEBP. The peaks of the alpha-phase and gamma-phase steels were identical, and the XRD patterns of the initial KP1 samples were all peaking at the alpha-phase. After 5 runs, the peak was still alpha-phase, but after more than 10 investigations, the peak of KP1 was gamma-phase.
As the cycle of investigation increased, the proportion of alpha-phase to peak reached less. Deformation of the phase leading to the gamma-phase due to rapid melting and resolidification during PEBP can occur due to undecomposed carbon atoms in the matrix. It is known that the corrosion resistance can be improved more efficiently by using austenitizing with increased content of austenite.
In addition, studies of alpha / gamma-phase ratios for corrosion resistance are underway, and the results show that increasing gamma-phase ratios can improve corrosion resistance. Thus, an increase in the austenite ratio can lead to an improvement in corrosion resistance after PEBP treatment on the surfaces of KP1 and KP4.
Another hypothesis for corrosion protection is that metal oxide is formed on the resolidified surface. Passivating fims such as metal oxides on the surface of bulk metals are known to inhibit corrosion, which can not proceed smoothly to the oxidized layer.
Thus, unstable passive fim results in increased current density. Improved temperature in the formation of the recoat layer creates a stable oxide layer.
Figure 8 shows the cross-sectional area of KP1 and KP4 samples after PEBP treatment. Significant increases in the oxygen content of the reapproval can be seen in EPMA measurements.
This is also shown in the potentiodynamic polarization test, close-up angular measurement and EIS results. An increase in the oxygen content of the recapture layer after PEBP treatment can lead to a more passive layer of metal oxides. The resurfaced layer of the PEBP treated surface has corrosion potentials that are more resistant to corrosion than those that do not. The Nyquist plot results from the EIS measurements strongly indicate the increase in corrosion resistance of the surface after PEBP treatment. By semicircle Nyquist plot we can estimate the ohmic behavior. The difference between real and imaginary impedance at high and low frequencies indicates charge transfer resistance. Therefore, the corrosion resistance of the passive reac- tion layer can be compared in the Nyquist plot.
Figure 9 shows the Nyquist plot of KP1 and KP4 steels. Comparing the diameters of semicircular platelets, we can see that the PEBP treatment rapidly increases the capacitance resistance of KP1 and KP4. The increase of resistance was more than 10 J / cm ^ 2 at 7 J / cm ^ 2 energy density. This leads to the PEBP surface of the passive recoat layer in the NACL nucleus. Therefore, it can be said that the corrosion resistance has increased.
Improvements to this corrosion resistance can also be seen in the optical microscopy images shown in FIG. As the numerical density of the surface craters was greater than KP1 (see FIG. 4), more holes were found in the KP4 samples on the surface after PEBP treatment. The formation of rust by corrosion was significantly reduced after PEBP treatment. In addition, corrosion on the PEBP treated surface was found to be largely confined around the crater.
As shown in Fig. 11 (c), corrosion was generated and developed around the craters. The recoat layers on the craters appeared to be thinner than the other parts. This is because PEBP is formed by molten pools around non-metallic precipitates due to partial melting and evaporation. This thin film can be chemically degraded smoothly, especially against solutions containing chloride ions.
Once the re-solidified layer after PEBP treatment is destroyed by corrosion, this part creates a node and the other part creates a cathode. The Mns postings left around the crater can be more easily corroded than the river, and corrosion can occur predominantly at cracks around the crater. Therefore, the corrosion mechanism involves hole erosion around the crater.
11 shows the corrosion mechanism according to the present invention. Referring to FIG. 11, it can be seen that the difference in the hole density on the KP1 and KP4 samples is included. This is because the density of the surface craters is higher in the KP4 samples.
As shown in Figure 10, more holes were observed in the KP4 sample after PEBP treatment. Increasing energy density and number of irradiation cycles proved to lead to better corrosion resistance. This phenomenon may be caused by surface oxidation contributing to the formation of the passivation layer. In addition, the number of irradiation cycles can be removed by repeated melting and evaporation of precipitates which are susceptible to corrosion, such as craters, MnS and Carbides, and which are harmful.
Figure 12 shows the nano-hardness and elastic modulus at an energy density of 10 J / cm ^ 2 and a depth of irradiated area after 20 irradiation cycles.
On the PEBP-treated surface, we can see that the hardness and elastic modulus are greatly increased. The nano-hardness of the KP1 sample increased from 3.75 GPa before treatment to 15.4 GPa after PEBP treatment, and the elastic modulus increased from 205.64 GPa to 298.66 GPa in the same irradiation condition. In the KP4 sample, the nano-hardness increased from 4.9 GPa to 12 GPa and the elastic modulus increased from 222.84 GPa to 271.02 GPa. Improvements after PEBP treatment showed higher efficiency in KP1 than in KP4. The surface hardness and elastic modulus of KP1 before treatment were much lower than those of KP4, but KP1 was higher than KP4 in both surface hardness and elastic modulus after PEBP treatment.
There are several other factors that can affect hardness after PEBP. One of them is residual tensile stress.
When a martensitic transformation occurs under the surface, it induces tensile residual stress on the surface and weakens the hardness of the material. On the other hand, a large dislocation density on the surface after PEBP treatment can cause surface hardening. Phase change and amorphization can occur on the surface of alloy steel because the heating and cooling rates are very fast during PEBP treatment. In order to observe such phenomena, image quality maps (IQMs) of EBSD data were analyzed (see FIG. 13).
During fast cooling, the carbon atoms can not diffuse in the crystal structure, and the resulting shear deformation results in a condensed dislocation. This is one of the first strengthening mechanisms of special steel.
The quality of the electron diffraction pattern was analyzed using image quality factor (IQF). (The quality of the electron diffraction pattern appeared to be lower after PEBP treatment). It is possible to specify dislocation density using IQF.
The left column of Figure 13 shows all IQMs. And the right row shows the sample of the other part than the average of the sample.
The condensed dislocations produced both PEBP treated KP1 and KP4 samples, but no phase change was observed. Therefore, tensile residual attraction can not be expected on the PEBP surface.
The low IQF also shows a large dislocation density, and it was predicted that the hardness of the djEJs portion is proportional to the dislocation density.
13 (b) and (d) show that the thicker region of KP1 has a dislocation density greater than that of KP4. The increased carbon content of KP1 may be due to the high dislocation density. During rapid cooling, unfurled carbon atoms twist the matrix and overlap with the metal particles, resulting in a large dislocation density on the surface. Thus, more carbon content in the KP1 sample may have produced more potential on the surface.
The thermal diffusivity of KP1 is larger than that of KP4. Therefore, the time for the carbon element to diffuse was shorter because the KP1 sample cooled faster during PEBP treatment. The results of the nano-indentation test include an IQM analysis of the EBSD data. The hardness of the surface of KP1 was larger than that of KP4 after PEBP treatment, although there was an opposite relationship compared with that before PEBP treatment.
Thus, both KP1 and KP4 concluded that one of the major factors of elevated hardness was the dislocation density rise due to the phase change in the phase recrystallization step. An increase in hardness and elastic modulus causes a change in wear resistance.
Fig. 14 shows the weight change after the wear test before and after the PEBP treatment of KP1 and KP4 samples.
The weight loss after PEBP treatment was significantly reduced in both samples. The weight loss before treatment of KP1 sample decreased from 0.01 g to 0.009 g at 7 J / cm ^ 2 energy density after treatment and decreased to 0.002 g at 10 J / cm ^ 2. In the case of KP4, the weight loss before treatment was reduced to 0.03 g, and the energy density was reduced to 0.003 g at 7 J / cm ^ 2 and 10 J / ^ 2 energy density after treatment.
Stereoscopic profiles and microscope images of the surface wear track are shown in FIG. The rotating pin on the surface of the KP1 sample before treatment produced a 43 micrometer depth of wear track, but after PEBP treatment the wear track had a depth of 2 micrometers. Also, the rotating pin on the surface of the KP4 sample before treatment made a 125 micrometer depth of wear track, but after PEBP treatment the wear track had a depth of 3.35 micrometers.
Also, the wear mechanism seems to have changed after PEBP treatment. In a sliding wear test, materials can undergo both plastic and elastic deformation for shear stress. In the untreated samples (low hardness and elasticity) wear debris was visible on the wear track.
15 (b) and 15 (f) show the tackiness of the wear mechanism. However, after the PEBP treatment, it can be seen that any part of the surface is not peeled or deformed at all as shown in Figs. 15 (d) and (h).
This shows that the wear pin did not exceed the yield point of the hardened and resilient surface after PEBP treatment, indicating that the wear mechanism of the surface after PEBP treatment is predominantly rough.
Also, since the surface hardness is greater after PEBP treatment, the SKD11 wear pin itself may have been worn during testing. After the PEBP-treated KP1 sample was tested, it was confirmed that a large wound was formed as shown in FIG. 15 (d).
The change in surface roughness is a very important factor in PEBP. As shown in Fig. 16, the surface roughness decreased with increasing the number of irradiation cycles in both energy densities (7 J / cm ^ 2, 10 J / cm ^ 2).
The surface roughness showed the greatest decrease (R_a = 4 micrometer to R_a = .271 micrometer) for 30 repeated counts with an energy cycle of 10 J / cm ^ 2 for the KP1 sample. The KP4 sample also showed the greatest reduction under the same conditions (R_a = 3.2 micrometers to R_a = .0.267 micrometers).
The removal of tool marks showed that surface roughness decreased after PEBP treatment, but the creation of surface craters resulted in large surface roughness results.
Both the KP1 and KP4 samples showed that removing the tool mark had the greatest effect on reducing roughness. (Craters have had a much smaller impact on roughness than tool marks, so the tool mark removal / roughness has been reduced during the creation of the craters).
According to the corrosion inhibiting and surface hardening method of a special steel using the pulse beam treatment according to the present invention, it is possible to prevent corrosion and surface hardening of a special steel by the following processes: (a) (50 ㎂ and 30 ㎷) corresponding to the SCE (Saturated Calomel Electrode) by irradiating the pulsed beam instead of the pulsed beam, thereby reducing the corrosion current of 50 ((Micro Ampere), increasing the surface safety and increasing the hardness of the nano , B) can effectively improve the corrosion resistance of both the KP1 and KP4 samples, and c) inhibits corrosion through the phase change of the surface that goes to the gamma-phase on the alpha-phase, D) PEBP forms a passive recoat layer containing a large proportion of oxides on the surface, and CTP (Charge Transfer) of the PEBP-treated surface Properties) are improved compared to before treatment, e) the resolidification layer is more stable as the energy density of the beam is greater, f) the corrosion of the PEBP-treated surface starts from the crater, and the PEBP- G) The nano-hardness and elastic modulus of the surface increase considerably both in KP1 and KP4 after PEBP treatment, resulting in increased abrasion resistance, and h) the surface after PEBP process The roughness is decreased, and the roughness is further decreased as the energy density of the beam and the number of irradiation cycles are increased.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, As shown in FIG.
100: a pulse beam irradiating device,
110: Vacuum Operating Chamber,
120: Cathode,
130: Solenoid.
Claims (6)
(b) causing the pulse beam generated in step (a) to pass through the argon gas, and generating a plasma between the anode and the cathode; And
(c) irradiating the surface of the extrudate with a pulse beam using an electric field and a helical structure by a Lorentz force;
, ≪ / RTI &
The energy density range is 7-10 J / cm < 2 >, the argon gas pressure in the vacuum chamber is set to 0.05 Pa, the pulse beam irradiation is performed on the extrudate,
The injection-molded product is a special steel KP1 or KP4,
Wherein the pulse cycle of the pulse beam for the injection-molded product is a pulse of 8 to 10, thereby realizing a uniform surface and texture of the injection-molded product. Hardening method.
In the step (c) of irradiating the pulse beam,
The volume of the substrate is set to 40 mm x 40 mm x 5 mm, and the vacuum chamber on which the cathode, the solenoid, and the anode are mounted is moved in the X and Y axes through the movable stage in the grid chamber spaced at intervals of 19 to 21 mm, A method for inhibiting corrosion and surface hardening of special steels using pulse beam treatment, characterized by providing uniform surface and texture to the molding.
Wherein the heating and cooling are performed at a speed of 10 < 7 > K / s during the pulse beam irradiation process on the surface of the injection-molded object.
Wherein the substrate is irradiated with a pulsed beam having a pulse width of 2 microseconds (Pulse Electron Beam Polishing) during the irradiation time of 9 to 11 seconds after cooling the substrate during the pulse beam irradiation process on the injection-molded product. Corrosion inhibition and surface hardening of special steels.
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| CN110592592A (en) * | 2019-09-23 | 2019-12-20 | 江苏大学 | Laser cladding high-temperature protective coating surface polishing and purifying method based on pulsed electron beam technology |
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| KR100901545B1 (en) | 2001-05-11 | 2009-06-08 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Pulsed Electron Beam Polymerization |
| KR20140038994A (en) | 2011-05-27 | 2014-03-31 | 쓰리엠 이노베이티브 프로퍼티즈 캄파니 | Scanned, pulsed electron-beam polymerization |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR100901545B1 (en) | 2001-05-11 | 2009-06-08 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Pulsed Electron Beam Polymerization |
| KR20140038994A (en) | 2011-05-27 | 2014-03-31 | 쓰리엠 이노베이티브 프로퍼티즈 캄파니 | Scanned, pulsed electron-beam polymerization |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110592592A (en) * | 2019-09-23 | 2019-12-20 | 江苏大学 | Laser cladding high-temperature protective coating surface polishing and purifying method based on pulsed electron beam technology |
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