CN107576662B - Detection method for judging deformation overburning of structural steel forging - Google Patents
Detection method for judging deformation overburning of structural steel forging Download PDFInfo
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Abstract
A detection method for judging deformation overburning of a structural steel forging belongs to the field of forging defect detection, and is characterized in that appearance characteristics of fractures of structural steel forging parts, such as convex-concave feeling of crystal grains, free crystallization surface, beach-shaped patterns, secondary recrystallization, arc-shaped edge angles of crystal boundaries and round crystal grains, are observed under a scanning electron microscope, the formation reason of cracks or fractures of the structural steel forging parts can be judged to be caused by deformation overburning, and the judgment result not only can facilitate manufacturing enterprises to implement follow-up precaution in time, but also can provide judgment basis for implementing follow-up process improvement or quality improvement. The detection method can judge whether the fracture of the part is caused by deformation overburning or not by 5 steps of collecting and judging the part, intercepting a detection sample, cleaning the detection sample, implementing observation judgment and issuing a detection report.
Description
Technical Field
The invention belongs to the field of forging defect detection, relates to a detection method for judging deformation overburning of a forging, and particularly relates to a detection method for judging deformation overburning of a structural steel forging by observing the morphological characteristics of fracture defects of the structural steel forging under a scanning electron microscope.
Background
It is known that after being forged, the structural steel can eliminate the defects of looseness and the like generated in the smelting process of metal, optimize the microstructure, and simultaneously improve the mechanical properties of parts, such as strength, toughness, fatigue life and the like, because the fiber structure of a forging blank is distributed along the contour shape of the forging and is continuous, and is superior to steel parts processed by cast steel or rolled steel part blanks.
However, two kinds of overburning often occur in structural steels during forging thereof. Firstly, overburning caused by overhigh heating temperature, which is called 'overhigh temperature overburning' for short; and the second is the overburning formed by overlarge deformation amount and too fast deformation speed, which is called deformation overburning for short.
The term "high-temperature overburning" refers to overburning of structural steel caused by oxidation and melting of grain boundaries when the structural steel is heated to a higher temperature than an overheated temperature during forging. The overburning is characterized in that the crystal boundary has lattice defects, namely the crystal boundary can be melted or strongly oxidized, and the appearance characteristic is unique and obvious, so that the appearance characteristic of a fracture can be observed under a scanning electron microscope, and the fracture appearance characteristic is detected and judged to be 'high temperature overburning' by combining the crystal boundary oxygen or melting characteristic. As shown in FIG. 1, the fracture is observed under a scanning electron microscope, the characteristic that the grain boundary is melted in the field of view is observed under the magnification of 500X, and the grain boundary is covered by an oxide, so that the defect of the forge piece is determined to be an overburning defect caused by overhigh forging heating temperature.
Description of the drawings: many relevant descriptions and descriptions are given in the prior art documents such as textbooks and scientific and technical literature regarding the detection and determination method related to "high temperature and excessive burning".
The deformation overburning refers to the overburning condition caused by that the temperature of a slip surface in a local area with overlarge deformation amount and too high deformation speed is quickly increased to be above a liquid phase point because the overlarge and too high deformation mechanical energy is converted into heat energy if the deformation amount and the deformation speed are overlarge and too high in the forging process of the structural steel. The fracture morphology characteristics of the overburning are different from the 'high temperature overburning' morphology characteristics, and the 'deformation overburning' overburning defects are generally distributed in the forge piece, so that the detection and judgment of the 'deformation overburning' are difficult to find by the conventional forge piece quality inspection method, such as dimension inspection, surface defect inspection, hardness inspection and the like, except that the 'high temperature overburning' detection method cannot be applied; in addition, the detection and judgment of the deformation and overburning are not involved in the common methods such as the hot acid etching macroscopic detection, the metallographic microscope observation, the fracture macroscopic observation, the chemical component analysis and the like for years; moreover, some important forgings, especially thick and large forgings, cannot find the defect of deformation and overburning in the forgings by common flaw detection equipment due to the large size of the forgings.
Description of the drawings: regarding the detection judgment method related to the deformation overburning, the method is researched and researched by inquiring and searching: the same, related or similar descriptions and references have not been found in the prior art documents such as textbooks and scientific and technical literature.
As is well known, the forgings cannot be saved after being over-burnt and can only be scrapped. The method comprises the condition of 'deformation overburning' caused by converting deformation mechanical energy into heat energy, and is an irreversible serious forging manufacturing defect.
Further explanation is as follows:
1. the defects of high temperature and over-burning are generally distributed on the surface layer of the forging, and can be broken and exposed in the forging process of the forging when the defects are serious; less severe, it can often be exposed during subsequent heat treatment (normalizing, tempering, quenching, tempering, etc.) or machining, often in the form of cracking or breaking. Therefore, the over-burning under the condition can be found through a detection method, and can be selected through visual observation, so that the forged piece is prevented from entering the next manufacturing procedure, and particularly, the fracture of the manufactured part in the actual use process after assembly can be avoided.
2. The defects of deformation and overburning are generally distributed in the forged piece, and some defects can appear on the outer surface of the manufactured part after subsequent heat treatment or machining and are selected, namely necessary precaution is implemented, but a plurality of defects are difficult to expose and discover after subsequent heat treatment or machining, namely effective precaution is difficult to implement, so that the manufactured part is not subjected to load during working in the process of use after assembly, the manufactured part is broken, an unnecessary quality accident occurs, and personal injuries and deaths can be caused in serious cases, so that great economic loss and unnecessary negative effects can be caused to production enterprises.
3. The defect detection related to deformation and overburning is a pending problem in the field of forging defect detection for many years. With the rise of the society, especially the high-end manufacturing industry, and the increasing demand of high-end forging parts, on one hand, the repeated occurrence of the deformation over-burning defect condition is avoided, and on the other hand, the lack of necessary detection means and effective prevention are avoided, so that the improvement of the product quality of forging enterprises and the sustainable development of enterprises are directly influenced, especially for some enterprises needing to go out of China.
From the above, it is known that how to determine the "deformation and over-sintering" condition of the structural steel after forging, that is, to study the detection and determination method, is a difficult problem to be solved.
Disclosure of Invention
In order to overcome the defects, the invention aims to provide a detection method for judging the deformation overburning of a structural steel forging, the detection method judges the deformation overburning condition of the forging by observing the appearance characteristics of the fracture of the structural steel forging part under a scanning electron microscope, and the judgment result not only can be convenient for a manufacturing enterprise to timely and effectively implement precaution, but also can provide a judgment basis for fracture detection for the subsequent implementation process improvement or quality improvement of the enterprise. The detection method has the advantages of novel conception, simple and convenient operation, rapidness and accuracy and has a practical value which can be popularized.
In order to achieve the above object, the present invention can be achieved by the following technical solutions.
A detection method for judging deformation overburning of a structural steel forging comprises the following steps:
1) collecting and judging parts
Collecting structural steel forged parts which have cracks or fractures and need to be judged, wherein the parts can be forged parts, finished parts or assembled parts;
2) intercepting test sample
Intercepting a sample at the defect position according to the collected required detection position of the structural steel forging part:
2-1) if the part has cracks, adopting a method of cutting, knocking or breaking by a testing machine to open the cracks by force, and intercepting a test sample of the fracture;
2-2) if the part is a broken part, directly intercepting a fracture sample;
3) cleaning test sample
Cleaning oil stains and impurities on the intercepted fracture sample by adopting an ultrasonic cleaning method, wherein the cleaning solution is alcohol or acetone solution;
4) conducting an observation judgment
After cleaning, placing the fracture sample on a sample platform in a vacuum sample chamber of a scanning electron microscope, observing the morphological characteristics of the fracture sample, judging the formation reason of cracks or fractures, and observing and judging as follows:
4-1) Single type 'deformation over-burning'
If the crystal grain characteristics on the fracture are not obvious under a scanning electron microscope, the convex-concave feeling of the fracture surface crystal grains is not strong, wherein, part of the fracture surface grains present free crystallization surface characteristics, the appearance characteristics are beach-shaped patterns formed by deformation sliding friction, and the fracture surface also has the dimple fracture characteristics formed when the fracture is opened, so that the formation reason of the crack or the fracture can be judged, and the fracture belongs to the condition of single type deformation overburning; the single-type deformation overburning refers to the overburning condition of the forge piece caused by only one reason of overlarge deformation amount and too fast deformation speed when the forging heating temperature is the normal process temperature, and is called as single-type deformation overburning;
4-2) mixed type 'deformation burning'
If the crystal grain on the fracture is obvious in characteristic and has obvious convex-concave feeling of the crystal grain under a scanning electron microscope, in addition, the crystal grain is fine and has deformation secondary recrystallization and all presents free crystallization surface characteristics, the appearance characteristic is that the edge angle of the crystal boundary is arc-shaped, and the crystal grain is round particles, so that the forming reason of the crack or fracture can be judged, and the condition belongs to a mixed type deformation overburning condition; the mixed type deformation overburning refers to the overburning condition of the forge piece caused by two common reasons of large deformation amount, high deformation speed and high heating temperature when the forging heating temperature is higher than the normal process temperature, and is collectively called as mixed type deformation overburning;
5) issuing a detection report
And 4) issuing a detection report according to the judgment result of the step 4), and ending the implementation process of the detection method for judging the deformation overburning of the structural steel forging.
Due to the adoption of the technical scheme, the invention can achieve the following beneficial effects:
1. according to the invention, by observing the appearance characteristics of the fracture of the structural steel forged part under a scanning electron microscope, such as convex-concave feeling of crystal grains, free crystallization surface, beach-shaped patterns, secondary recrystallization, arc-shaped crystal grain boundary edges and circular crystal grains, the formation reason of the crack or fracture of the structural steel forged part can be judged to be caused by deformation overburning, and the judgment result not only can facilitate the manufacturing enterprise to timely and effectively implement subsequent precaution, but also can provide the judgment basis of fracture detection for the subsequent implementation process improvement or quality improvement of the enterprise.
2. The invention can complete the observation and judgment of whether the fracture of the structural steel forged part is caused by deformation overburning or not by implementing 5 detection method steps of collecting and judging the part, intercepting the detection sample, cleaning the detection sample, implementing observation and judgment and issuing a detection report.
Drawings
FIG. 1 shows the "high temperature over-burning" morphology of structural steel forging fracture;
FIG. 2 is a "normal grain" morphology feature of a fracture of a structural steel part;
FIG. 3 is a single-type deformation overburning morphology feature of a fracture of a structural steel part;
FIG. 4 is a mixed type deformation overburning morphology feature of a fracture of a structural steel part;
FIG. 5 is a single-type deformation overburning morphology characteristic of a crack fracture of a crankshaft part;
FIG. 6 is a mixed type deformation overburning morphology feature of a fracture of a power output shaft head part.
Detailed Description
The present invention will be explained in more detail by the following examples, which are not intended to limit the present invention, and all changes and modifications within the scope of the present invention are intended to be protected by the disclosure of the present invention.
The detection method for judging deformation and overburning of the structural steel forging is described by combining the figures 1 to 4 and collecting 8 forging examples which need to be judged, and comprises the following steps:
1) collecting and judging parts
Collecting structural steel forged parts which have cracks or fractures and need to be judged, wherein the parts can be forged parts, finished parts or assembled parts; wherein, the manufactured part can be a forged part or a forged part in the subsequent heat treatment or machining process; in this embodiment, the total number of the collected forgings to be determined is 8, as follows:
① carbon structural steel parts, 45 steel-fork shaft, braided into No. 1 sample;
② alloy structural steel parts, namely a 50CrVA power output shaft, which are compiled into a No. 2 sample;
③ alloy structural steel part, 42CrMo crankshaft, 3# sample;
④ alloy structural steel parts, namely 20CrMnTi plunger sleeves, which are woven into a No. 4 sample;
⑤ alloy structural steel parts, namely 40Cr crankshafts, which are compiled into No. 5 samples;
⑥ alloy structural steel part, 40Cr front drive shaft, braided into 6# sample;
⑦ alloy structural steel parts, namely a 42CrMo cylinder cover plate screw rod which is compiled into a 7# sample;
⑧ alloy structural steel parts, namely a 20CrMnMo bevel pinion shaft, which is weaved into a No. 8 sample;
2) intercepting test sample
According to the collected required detection positions of the samples from 1# to 8# of the structural steel forged parts, cutting out samples at the defect positions, and correspondingly compiling fracture samples from 1# to 8# according to the numbers:
2-1) if the part has cracks, adopting a method of cutting, knocking or breaking by a testing machine to open the cracks by force, and intercepting a test sample of the fracture;
2-2) if the part has a fracture, directly intercepting a fracture sample;
3) cleaning test sample
Cleaning oil stains and impurities on the intercepted fracture samples from 1# to 8# by adopting an ultrasonic cleaning method, wherein the cleaning solution is alcohol or acetone solution;
4) conducting an observation judgment
The structural steel forging is a polycrystalline material, and for the convenience of understanding the content of the present invention, first, the normal crystal grain characteristics are explained, as shown in fig. 2, the crystal grains are crystal sugar-like characteristics with distinct edges (i.e., grain boundaries). The description is continued below.
After the fracture samples from 1# to 8# are cleaned, the fracture samples are sequentially placed on a sample platform in a vacuum sample chamber of a scanning electron microscope one by one, the appearance characteristics of each fracture sample are observed, the crack or fracture formation reason is sequentially judged, and the observation and judgment are as follows:
4-1) Single type 'deformation over-burning'
If the crystal grain characteristics on the fracture are not obvious under a scanning electron microscope, the convex-concave feeling of the fracture surface crystal grains is not strong, wherein, part of the fracture surface grains present free crystallization surface characteristics, the appearance characteristics are beach-shaped patterns formed by deformation sliding friction, and the fracture surface also has the dimple fracture characteristics formed when the fracture is opened, so that the formation reason of the crack or the fracture can be judged, and the fracture belongs to the condition of single type deformation overburning; the single-type deformation overburning refers to the overburning condition of the forge piece caused by only one reason of overlarge deformation amount and too fast deformation speed when the forging heating temperature is the normal process temperature, and is called as single-type deformation overburning;
as shown in fig. 3, the fracture sample morphology observed under the scanning electron microscope at a magnification of 500X can be determined from the following: the cracks or fractures of the forge piece belong to the condition of single type deformation and overburning caused by single reason of overlarge deformation amount and overhigh deformation speed under the condition that the forging heating temperature is the normal process temperature;
4-2) mixed type 'deformation burning'
If the crystal grain on the fracture is obvious in characteristic and has obvious convex-concave feeling of the crystal grain under a scanning electron microscope, in addition, the crystal grain is fine and has deformation secondary recrystallization and all presents free crystallization surface characteristics, the appearance characteristic is that the edge angle of the crystal boundary is arc-shaped, and the crystal grain is round particles, so that the forming reason of the crack or fracture can be judged, and the condition belongs to a mixed type deformation overburning condition; the mixed type deformation overburning refers to the overburning condition of the forge piece caused by two common reasons of large deformation amount, high deformation speed and high heating temperature under the condition that the forging heating temperature is higher than the normal process temperature, and is collectively called as mixed type deformation overburning;
as shown in fig. 4, the fracture sample morphology characteristics observed under the scanning electron microscope at 320X times, wherein the circular crystal grains are the expression of grain boundary melting caused by overburning, and are also the surface characteristics of free crystallization of liquid metal, which are important criteria for judging metal deformation and overburning melting, so that the formation cause of the crack or fracture can be judged, and the fracture is a mixed type "deformation and overburning" condition caused by two common causes of "deformation amount is larger, deformation speed is faster" and "heating temperature is higher" when the forging heating temperature is "higher than" normal process temperature;
description of the drawings: in this embodiment, the detection and determination results of the fracture samples "1 # to 8 #" are all cracks or fractures of the forged piece caused by "deformation and overburning", and include two cases of single type "deformation and overburning" and mixed type "deformation and overburning".
Further explanation is as follows: in the detection and determination process of some fracture sample morphology features other than this embodiment, regarding the crack or fracture problem of the forged piece, besides the formation cause of the above-mentioned "deformation and overburning", there are some other formation causes, such as the formation cause of "high temperature and overburning" observed under the scanning electron microscope of 500X shown in fig. 1. The cracking or breaking problem of the forged piece caused by other forming reasons is not described because the cracking or breaking problem does not belong to the content of the detection method of the invention.
5) Issuing a detection report
According to the detection of the fracture samples from 1# to 8# in the step 4), the judgment results shown in the table 1 are obtained, and the following results are obtained:
TABLE 1 "1 # to 8 #" fracture specimen judgement results
The description is repeated:
a. the single type is 'deformation over-burning'. The method is characterized in that under the condition that the forging heating temperature is the normal process temperature, the condition of overburning is generated only due to the single reason of overlarge deformation amount and overhigh deformation speed.
b. The mixed type is 'deformation over-burning'. The method is characterized in that under the condition that the forging heating temperature is higher than the normal process temperature, the condition of overburning is generated due to two common reasons of large deformation amount, high deformation speed and high heating temperature.
Subsequently, according to the determination results in table 1, a detection report of cracks or fractures of the '1 # to 8# fracture samples' is issued, and thus, the implementation process of the detection method for determining deformation overburning of the structural steel forgings (1 # to 8# fracture samples) is completed.
Next, two embodiments are given to illustrate the implementation process of the detection method for determining deformation and overburning of structural steel forgings according to the present invention.
Example 1
A batch of crankshaft parts forged and formed by 6-cylinder engines produced by a certain enterprise are made of 42CrMo, and after forging, heat treatment and machining are carried out, and in the process of flaw detection after products are formed, 20 crankshaft parts are found to have 'crack' defects on the surfaces of connecting rod journals. The blank of the batch of parts is alloy structural steel, is subjected to forging forming and thermal treatment of 'quenching and tempering, induction quenching', and is also in accordance with the national standard requirement through chemical composition detection, and is further subjected to metallographic detection: the surface of the part presents the normal metallographic structure characteristic after the induction quenching heat treatment, the core part of the part presents the normal metallographic structure characteristic after the quenching heat treatment, in addition, the cracks are observed to be distributed on the forging parting surface in the low-power thermal acid corrosion test, and the cracks penetrate through the whole crankshaft journal, and the forming reason of the cracks generated on the batch of parts is difficult to judge, so the detection method is required to be adopted for detection and judgment.
Description of the drawings: in this embodiment, "detection and determination" relates to the following main devices, detection apparatuses, instruments, and solutions:
electric spark numerical control wire cut electrical discharge machining bed: model DK7745, manufacturer-Jiangsu Tongfang NC machine tool Co., Ltd; hydraulic universal material testing machine: model WE-30, manufacturer-Guangzhou laboratory Instrument manufacturer; an ultrasonic cleaner: model KQ-500, manufacturer-Kunshan city lake testing instrument factory; analytically pure absolute ethanol solution: manufacturer-Deen chemical reagents, Inc. of Tianjin; scanning electron microscope: model QUANTA 650 FEG, manufacturer-FEI USA.
The following describes a detection method for judging deformation and overburning of a structural steel forging, with reference to fig. 5, and comprises the following steps:
1) collecting and judging parts
Collecting a cracked crankshaft part which is a finished product after being subjected to heat treatment and machining after forging and forming a product, namely performing final finished product flaw detection;
2) intercepting test sample
Intercepting a fracture sample at the defect part according to the position to be detected of the collected crankshaft part sample, and numbering the fracture sample with a number of 1 #;
description of the drawings: because the part is a cracked part, the crack part is forcefully opened according to the crack defect position of the crankshaft part, and a fracture detection sample is intercepted, namely, a cracked sample block is intercepted by using a model DK7745 electric spark numerical control linear cutting machine, then the sample block is pressed and broken along the crack on a model WE-30 hydraulic universal material testing machine to form a crack fracture, and the sample at the fracture is intercepted and compiled into a '1 #' fracture sample;
3) cleaning test sample
Cleaning oil stains and impurities on the intercepted fracture sample of the '1 #' by adopting an ultrasonic cleaning method, wherein the model of the ultrasonic cleaner is KQ-500, and the cleaning liquid is analytically pure absolute ethanol solution;
4) conducting an observation judgment
After the 1# fracture sample is cleaned, the 1# fracture sample is placed on a sample platform in a vacuum sample chamber of a scanning electron microscope, the morphological characteristics of the 1# fracture sample are observed, the crack formation reason is judged, and the observation and judgment are as follows:
through detection and observation, under a scanning electron microscope, the crystal grain characteristics on the fracture are not obvious, the convex-concave feeling of the fracture surface crystal grains is not strong, wherein, part of the fracture surface crystal grains presents free crystallization surface characteristics, the appearance characteristics are beach-shaped patterns formed by deformation sliding friction, and the fracture surface also has the dimple fracture characteristics formed when the fracture is opened, so that the formation reason of the crack or the fracture can be judged, and the fracture belongs to the condition of single type deformation overburning;
description of the drawings: the morphological characteristics of the No. 1 fracture sample of the part, as shown in FIG. 5, observed under a scanning electron microscope at a magnification of 1000X, can be determined from: the cracks of the part belong to single type deformation overburning generated only by single reasons of overlarge deformation amount and overhigh deformation speed under the condition that the forging heating temperature is normal process temperature; in addition, the adopted scanning electron microscope model is QUANTA 650 FEG;
5) issuing a detection report
And (4) issuing a crack detection report of the crankshaft part according to the judgment result in the step 4), and ending the implementation process of the detection method for judging the deformation overburning of the structural steel forging (the crack 1# fracture sample of the crankshaft part).
Further explanation is as follows: according to the crack detection report of the crankshaft part, an enterprise improves the forging process, such as reducing the deformation amount once and increasing the deformation times, so that the quality accident that the crankshaft part cracks in the machining process and the flaw detection process does not occur, and a good quality improvement effect is achieved.
Example 2
A batch of 'power output shaft head' parts produced by a certain enterprise are made of 50CrVA steel and break in the machining process. The blank of the batch of parts is alloy structural steel, is formed by forging and is subjected to 'quenching and tempering' heat treatment, and also meets the national standard requirement through chemical composition detection, and is further subjected to metallographic detection: the parts present normal metallographic structure characteristics after quenching and tempering heat treatment, oxidation characteristics distributed along grain boundaries are not found at the fracture, and the formation reason of the batch of parts with fracture is difficult to judge, so the detection method needs to be adopted, and the detection and the judgment are carried out.
Description of the drawings: in this embodiment, "detection and determination" relates to the following main devices, detection apparatuses, instruments, and solutions:
metallographic specimen cutting machine: model QG-5A, manufacturer-Shanghai metallographical mechanical equipment Limited company; an ultrasonic cleaner: model KQ-500, manufacturer-Kunshan city lake testing instrument factory; analytically pure absolute ethanol solution: manufacturer-Deen chemical reagents, Inc. of Tianjin; scanning electron microscope: model QUANTA 650 FEG, manufacturer-FEI USA.
The detection method for judging the deformation and overburning of the structural steel forging, which is disclosed by the invention, is described with reference to fig. 6, and comprises the following steps:
1) collecting and judging parts
Collecting a broken part of the power output shaft head, wherein the part is a forged part, namely a forged part in the machining process;
2) intercepting test sample
Intercepting a fracture sample at the defect position according to the position required to be detected of the collected part sample of the power output shaft head, and compiling the fracture sample into a fracture sample of 2 #;
description of the drawings: because the part is a broken part, a No. 2 fracture sample can be directly cut at the fracture by a model QG-5A metallographic sample cutting machine;
3) cleaning test sample
Cleaning oil stains and impurities on the intercepted fracture sample of the 2#, wherein the model of the ultrasonic cleaner is KQ-500, and the cleaning liquid is analytically pure absolute ethanol solution;
4) conducting an observation judgment
After the '2 # fracture sample is cleaned, placing the' 2# fracture sample on a sample platform in a vacuum sample chamber 'of a scanning electron microscope, observing the morphological characteristics of the' 2# fracture sample, judging the fracture formation reason, and observing and judging as follows:
through detection and observation, under a scanning electron microscope, the crystal grain on the fracture has obvious characteristics and obvious convex-concave feeling of the crystal grain, in addition, the crystal grain is fine, has deformation secondary recrystallization and completely presents free crystallization surface characteristics, and the appearance characteristics are that the edge angle of the crystal boundary is arc-shaped, and the crystal grain is round particles, so that the forming reason of the fracture can be judged and belongs to the mixed type deformation overburning condition;
description of the drawings: the morphological characteristics of the part 2# fracture sample are observed under a scanning electron microscope at a multiple of 1000X as shown in fig. 6, wherein the circular crystal grains are the expression of grain boundary melting caused by overburning and are also the surface characteristics of free crystallization of liquid phase metal, which are important bases for judging metal deformation and overburning melting, so that the following can be judged: the fracture of the part belongs to a mixed type 'deformation overburning' generated by two common reasons of 'large deformation amount, high deformation speed' and 'high heating temperature' under the condition that the forging heating temperature is higher than the normal process temperature; in addition, the adopted scanning electron microscope model is QUANTA 650 FEG;
5) issuing a detection report
And (4) issuing a part fracture detection report of the power output shaft head according to the judgment result of the step 4), and ending the implementation process of the detection method for judging the deformation overburning of the structural steel forging (the fracture sample of the power output shaft head part with the fracture No. 2).
Further explanation is as follows: according to the part fracture detection report of the power output shaft head, an enterprise improves and promotes the forging process and equipment, such as reducing the forging heating temperature, reducing the primary deformation and increasing the deformation times, so that the quality accident that the part of the power output shaft head is fractured in the machining process does not occur, and a good quality promotion effect is achieved.
Finally, the embodiments selected from the detailed description herein for the purpose of disclosing the invention are presently deemed suitable, but it will be understood that the invention is intended to cover all variations and modifications of the embodiments, which fall within the spirit and scope of the present inventive concept.
The present invention is not described in detail in the prior art.
Claims (1)
1. A detection method for judging deformation overburning of a structural steel forging is characterized by comprising the following steps of: the detection method comprises the following steps:
1) collecting and judging parts
Collecting structural steel forged parts which have cracks or fractures and need to be judged, wherein the parts can be forged parts, finished parts or assembled parts;
2) intercepting test sample
Intercepting a sample at the defect position according to the collected required detection position of the structural steel forging part:
2-1) if the part has cracks, adopting a method of cutting, knocking or breaking by a testing machine to open the cracks by force, and intercepting a test sample of the fracture;
2-2) if the part is a broken part, directly intercepting a fracture sample;
3) cleaning test sample
Cleaning oil stains and impurities on the intercepted fracture sample by adopting an ultrasonic cleaning method, wherein the cleaning solution is alcohol or acetone solution;
4) conducting an observation judgment
After cleaning, placing the fracture sample on a sample platform in a vacuum sample chamber of a scanning electron microscope, observing the morphological characteristics of the fracture sample, judging the formation reason of cracks or fractures, and observing and judging as follows:
4-1) Single type 'deformation over-burning'
If the crystal grain characteristics on the fracture are not obvious under a scanning electron microscope, the convex-concave feeling of the fracture surface crystal grains is not strong, wherein, part of the fracture surface grains present free crystallization surface characteristics, the appearance characteristics are beach-shaped patterns formed by deformation sliding friction, and the fracture surface also has the dimple fracture characteristics formed when the fracture is opened, so that the formation reason of the crack or the fracture can be judged, and the fracture belongs to the condition of single type deformation overburning; the single-type deformation overburning refers to the overburning condition of the forge piece caused by only one reason of overlarge deformation amount and too fast deformation speed when the forging heating temperature is the normal process temperature, and is called as single-type deformation overburning;
4-2) mixed type 'deformation burning'
If the crystal grain on the fracture is obvious in characteristic and has obvious convex-concave feeling of the crystal grain under a scanning electron microscope, in addition, the crystal grain is fine and has deformation secondary recrystallization and all presents free crystallization surface characteristics, the appearance characteristic is that the edge angle of the crystal boundary is arc-shaped, and the crystal grain is round particles, so that the forming reason of the crack or fracture can be judged, and the condition belongs to a mixed type deformation overburning condition; the mixed type deformation overburning refers to the overburning condition of the forge piece caused by two common reasons of large deformation amount, high deformation speed and high heating temperature when the forging heating temperature is higher than the normal process temperature, and is collectively called as mixed type deformation overburning;
5) issuing a detection report
And 4) issuing a detection report according to the judgment result of the step 4), and ending the implementation process of the detection method for judging the deformation overburning of the structural steel forging.
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