1. A method for testing the solid-liquid phase line temperature of a steel sample is characterized by comprising the following steps: residual oxygen elimination device to eliminate residual oxygen in a differential scanning calorimeter furnace, comprising a tripod (1) and a circular tray (2), the test method comprising the following steps:

shearing a granular sample with the mass of 5-10 mg, cleaning oxide skins and pollutants on the surface of the sample by using a cleaning solution at the temperature of 20-30 ℃, soaking the cleaned sample in gasoline for 2-3 min, taking out and drying;

step (2) opening a furnace chamber of the differential scanning calorimeter, installing a residual oxygen eliminating device to the upper end of a radiating fin of the differential scanning calorimeter, putting sponge zirconium into a circular tray (1-3), and paving the bottom of the circular tray (1-3) with the sponge zirconium; wrapping the surface of the sample cleaned in the step (1) with tantalum sheets with the thickness of 0.1mm, putting the wrapped sample into a graphite crucible, and covering the crucible cover; then the crucible is loaded on a sample rack of a differential scanning calorimeter, a hearth is closed, and protective gas is opened;

step (3) programming a heating process by adopting a sample mode by the differential scanning calorimeter, and raising the room temperature to 1200 ℃ at a temperature rise rate of 40 ℃/min; then raising the temperature of 1200 ℃ to 1600 ℃ at a constant temperature rise rate of 10 ℃/min;

obtaining a DSC curve chart after the temperature rise is finished, and selecting a partial curve with the temperature of 1200-1600 ℃ according to the national standard GB/T1425; the extrapolated onset temperature of the first endothermic peak during melting is judged as the solidus temperature T_iThe unit is that the last peak temperature in the melting process is judged as the liquidus temperature T_fIn units of ℃.

2. The method for testing the solid-liquid phase line temperature of the steel sample according to claim 1, wherein in the residual oxygen eliminating device, the upper end of the tripod (1) is fixedly connected with the circular tray (2), the lower end of the tripod (1) is provided with a hole (1-1), and the circular tray (2) is provided with an open key groove (2-1); the diameter of the circular tray (2) is not more than that of the cooling fins of the differential scanning calorimeter bracket.

3. The method for testing the solid-liquid phase line temperature of the steel sample according to claim 1, wherein the tripod (1) and the circular tray (2) are both made of aluminum oxide.

4. The method for testing the solid-liquid phase line temperature of the steel sample according to claim 1, wherein the depth and the diameter of the hole (1-1) are matched with the convex pin of the cooling fin of the differential scanning calorimeter support, the width d of the open key groove (2-1) is larger than the diameter of the differential scanning calorimeter support, the depth L of the key groove is 1-2 mm through the center of the circular tray (2), so that the three-pin support (1) can be installed on the cooling fin of the differential scanning calorimeter support and cannot touch the differential scanning calorimeter support after being installed.

5. The method for testing the solid-liquid phase line temperature of the steel sample according to claim 1, wherein in the step (1), the cleaning solution comprises 30-35 mL of hydrochloric acid, 20-25 mL of sulfuric acid, 12-14 mL of ethanol, 0.2-0.3 g of hexamethylenetetramine, 24-29 mL of hydrogen peroxide and 10-50 mL of distilled water.

6. The method for testing the solid-liquid phase line temperature of the steel sample according to claim 1, wherein in the step (2), the shielding gas is argon with the purity of more than or equal to 99.999 percent, the flow rate of the gas filled in is 250ml/min, and the purging time is 30-60 min.

7. The method for testing the solid-liquid phase line temperature of the steel sample according to claim 1, wherein in the step (4), when the temperature is between room temperature and 1200 ℃, the gas flow is 150 to 200 ml/min; when the temperature is 1200-1600 ℃, the gas flow is switched to 60-100 ml/min.

Background

In the current metal material research field, when a new product smelting process is prepared, the liquidus temperature is calculated and determined through a calculation model or a field experience formula, and then is compared and confirmed with similar mature products, the liquidus temperature is an important process parameter influencing the whole smelting process temperature control and the steel billet smelting quality, and the accuracy requirement is high. Due to the limitations of the model/empirical formula applicability, it is difficult to adapt to all steel grades. Meanwhile, if the difference between the components of the new product and the mature product is large, an accurate reference value cannot be provided, and the calculation result of the empirical formula cannot meet the actual production requirement. Patent CN 103235001B provides a method for measuring the solid-liquid phase line temperature of steel, but this method has high requirements for the hardware configuration of the equipment, requires the configuration of an evacuation system, and the volatile metal compounds after the sample is melted at high temperature easily contaminate the support of the differential scanning calorimeter (for example, the sample containing aluminum), causing loss. Therefore, a simple, efficient, accurate and safe method for measuring the solid-liquid line temperature of the steel sample is needed.

Disclosure of Invention

Aiming at the problems, the invention aims to provide a method for testing the solid-liquid phase line temperature of a steel sample, which has the characteristics of simple and convenient operation, safe use, accurate data, high detection efficiency and the like.

In order to achieve the purpose, the invention is realized by the following specific scheme:

the invention provides a method for testing the solid-liquid phase line temperature of a steel sample, which comprises the following steps: a residual oxygen elimination device for eliminating residual oxygen in a differential scanning calorimeter furnace, the residual oxygen elimination device comprising a tripod stand and a circular tray, the testing method comprising the steps of:

shearing a granular sample with the mass of 5-10 mg, cleaning oxide skins and pollutants on the surface of the sample by using a cleaning solution at the temperature of 20-30 ℃, soaking the cleaned sample in gasoline for 2-3 min, taking out and drying to prevent the sample from rusting;

opening a furnace chamber of the differential scanning calorimeter, mounting a residual oxygen eliminating device to the upper end of a radiating fin of the differential scanning calorimeter, and putting zirconium sponge into a circular tray to enable the zirconium sponge to be paved at the bottom of the circular tray; wrapping the surface of a cleaned sample with a tantalum sheet with the thickness of 0.1mm, putting the wrapped sample into a graphite crucible, and covering the crucible cover; then the crucible is loaded on a sample rack of a differential scanning calorimeter, a hearth is closed, and protective gas is opened;

step (3) programming a heating process by adopting a sample mode by the differential scanning calorimeter, and raising the room temperature to 1200 ℃ at a temperature rise rate of 40 ℃/min; then raising the temperature of 1200 ℃ to 1600 ℃ at the heating rate of 10 ℃/min;

step (4) literObtaining a DSC curve chart after the temperature is over, and selecting a partial curve with the temperature of 1200-1600 ℃ according to the national standard GB/T1425; the extrapolated onset temperature of the first endothermic peak during melting is judged as the solidus temperature T_iIn units of; the last peak temperature in the melting process is determined as the liquidus temperature T_fIn units of ℃.

The surface of the sample is wrapped with the flat sheet, so that the effect of preventing the sample from being oxidized can be achieved; and put into the zirconium sponge in the circular tray of remaining oxygen remove device in order to be used for absorbing the residual oxygen in the argon gas, improve the interior argon gas purity of furnace to can further prevent that the sample from being oxidized.

Furthermore, in the step (1), the cleaning solution comprises 30-35 mL of hydrochloric acid, 20-25 mL of sulfuric acid, 12-14 mL of ethanol, 0.2-0.3 g of hexamethylenetetramine, 24-29 mL of hydrogen peroxide and 10-50 mL of distilled water.

Further, in the step (2), the protective gas is argon with the purity of more than or equal to 99.999%, the gas flow is set to be 250ml/min, and the purging time is 30-60 min. And high-purity argon is adopted for purging, so that oxygen in the hearth can be removed, and the concentration of the protective atmosphere is improved.

Furthermore, in the step (4), when the temperature is between room temperature and 1200 ℃, the gas flow is 150-200 ml/min; when the temperature is 1200-1600 ℃, the gas flow is switched to 60-100 ml/min.

The invention also provides a residual oxygen eliminating device for testing the solid-liquid phase line temperature of the steel sample, which comprises a tripod bracket and a circular tray, wherein the upper end of the tripod bracket is fixedly connected with the circular tray, the lower end of the tripod bracket is provided with a hole, the depth and the diameter of the hole are consistent with those of a convex pin of a bracket radiating fin of the differential scanning calorimeter, the residual oxygen eliminating device is conveniently installed on the bracket radiating fin of the differential scanning calorimeter so as to prevent the residual oxygen eliminating device from falling off in the testing process, and the diameter of the circular tray is not more than that of the bracket radiating fin of the differential scanning calorimeter. The circular tray is provided with an opening key groove, the width d of the key groove is larger than the diameter of the differential scanning calorimeter support, the depth L of the key groove is 1-2 mm over the circle center of the circular tray, so that the tripod support can be arranged on a heat dissipation sheet of the differential scanning calorimeter support, and the tripod support cannot touch the differential scanning calorimeter support after being arranged.

Furthermore, the tripod support and the round tray are both made of aluminum oxide.

The residual oxygen eliminating device can eliminate the residual oxygen in the furnace chamber of the differential scanning calorimeter in the testing process, prevent the test sample from being oxidized, influence the test result and improve the accuracy of the test result.

Compared with the prior art, the invention has the beneficial effects that: (1) by the cleaning solution provided by the invention, a test sample without oxide scale and pollutants on the surface can be obtained; (2) the tantalum sheet is used for wrapping the sample, so that the sample can be protected, and the sample can be prevented from being oxidized. (3) And the purity of the protective atmosphere in the hearth is improved by purging with large-flow argon. (4) Sponge zirconium is put into the circular tray to absorb residual oxygen in the hearth, so that the sample is further prevented from being oxidized. The invention has the advantages of low requirement on equipment hardware, simple and accurate testing method, high efficiency and low cost through a simple device and a simple operation method, and can meet the testing requirement on the solid-liquid phase line temperature of the steel sample in the technical field of metal materials.

Description of the drawings:

in order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a DSC plot of a SWRH82A coil provided by the present invention;

FIG. 2 is a DSC curve chart of the W800 silicon steel sheet provided by the present invention;

fig. 3 is a residual oxygen eliminating device provided by the present invention.

Description of reference numerals: 1. a tripod stand; 2. a circular tray; 1-1, holes; 2-1, an open keyway; d. the width of the key slot; l, keyway depth.

Detailed Description

The technical solutions in the embodiments of the present invention will be described in detail below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

As shown in fig. 3, the residual oxygen eliminating device for testing the solid-liquid phase line temperature of a steel sample provided by the invention is used for eliminating residual oxygen in a furnace chamber of a differential scanning calorimeter, and comprises a tripod bracket 1 and a circular tray 2, wherein the upper end of the tripod bracket 1 is fixedly connected with the circular tray 2, the lower end of the tripod bracket 1 is provided with a hole 1-1, the depth and the diameter of the hole 1-1 are consistent with those of a convex pin of a bracket radiating fin of the differential scanning calorimeter, the diameter of the circular tray 2 is not more than that of the bracket radiating fin of the differential scanning calorimeter, the circular tray 2 is provided with an open key groove 2-1, the width d of the key groove is more than that of the bracket of the differential scanning calorimeter, the depth L of the key groove is 1-2 mm through the center of the circle of the circular tray 2, so that the tripod bracket can be installed on the radiating fin of the bracket of the differential scanning calorimeter, and the differential scanning calorimeter support cannot be touched after the device is installed. The tripod bracket 1 and the round tray 2 are both made of aluminum oxide.

The invention provides a method for testing the solid-liquid phase line temperature of a steel sample, which comprises the following steps:

shearing a granular sample with the mass of 5-10 mg, cleaning oxide skins and pollutants on the surface of the sample by using a cleaning solution at the temperature of 20-30 ℃, soaking the cleaned sample in gasoline for 2-3 min, taking out and drying to prevent the sample from rusting; the cleaning solution comprises 30-35 mL of hydrochloric acid, 20-25 mL of sulfuric acid, 12-14 mL of ethanol, 0.2-0.3 g of hexamethylenetetramine, 24-29 mL of hydrogen peroxide and 10-50 mL of distilled water.

Step (2) opening a furnace chamber of the differential scanning calorimeter, mounting a residual oxygen eliminating device to the upper end of a radiating fin of the differential scanning calorimeter, and putting sponge zirconium into a circular tray to enable the sponge zirconium to be paved at the bottom of the circular tray 1-3; wrapping the surface of a cleaned sample with a tantalum sheet with the thickness of 0.1mm, putting the wrapped sample into a graphite crucible, and covering the crucible cover; and then, loading the crucible into a sample rack of a differential scanning calorimeter, closing a hearth, opening argon with the purity of more than or equal to 99.999 percent for protection, setting the gas flow rate to be 250ml/min, and purging for 30-60 min.

Step (3) adopting a sample mode for the differential scanning calorimeter, programming a heating process, raising the temperature of a room to 1200 ℃ at a temperature rise rate of 40 ℃/min, and controlling the gas flow to be 150-200 ml/min; and then raising the temperature of 1200 ℃ to 1600 ℃ at the heating rate of 10 ℃/min, and switching the gas flow to 60-100 ml/min.

Obtaining a DSC curve chart after the temperature rise is finished, and selecting a partial curve with the temperature of 1200-1600 ℃ according to the national standard GB/T1425; the extrapolated onset temperature of the first endothermic peak during melting is taken as the solidus temperature T_iIn units of deg.C, the last peak temperature in the melting process is the liquidus temperature T_fIn units of ℃.

Example 1

A SWRH82A wire rod is selected as a test sample to test the solid-liquid line temperature, and the steps are as follows:

(1) shearing a plurality of 5mg granular samples;

(2) and cleaning oxide skin and pollutants on the surface of the sample, and cleaning by using a cleaning solution at 20-30 ℃ for 3min to ensure that the oxide skin and pollutants on the surface of the sample are cleaned. The formula of the cleaning solution comprises the following components: 30-35 mL of hydrochloric acid, 20-25 mL of sulfuric acid, 12-14 mL of ethanol, 0.2-0.3 g of hexamethylenetetramine, 24-29 mL of hydrogen peroxide and 10-50 mL of distilled water. Soaking the cleaned sample in gasoline for 2min, taking out and drying to prevent the sample from rusting;

(3) opening a furnace chamber of the differential scanning calorimeter, exposing the bracket and the radiating fins, installing the residual oxygen eliminating device at the upper end of the radiating fins of the equipment, and fully paving the sponge zirconium in the circular tray; so that the zirconium sponge absorbs the residual oxygen in the hearth.

(4) Tightly wrapping the cleaned sample with tantalum sheets with the thickness of 0.1mm, putting the wrapped sample into a graphite crucible, covering a crucible cover, putting the crucible into a sample rack of a differential scanning calorimeter, and closing a hearth; argon with the purity of the protective gas being more than or equal to 99.999 percent is opened, the gas flow is set to be 250ml/min, and the purging time is 30 min;

(5) the differential scanning calorimeter adopts a sample mode, a heating process is programmed, the temperature rise rate is 40 ℃/min at room temperature to 1200 ℃, and the gas flow is set to be 150 ml/min; the temperature rising rate is 10 ℃/min at 1200-1600 ℃, and the gas flow is switched to 60 ml/min;

(6) and (4) analyzing results: and obtaining a DSC curve graph after the test, and selecting the curve with the temperature of 1200-1600 ℃ with the extrapolated initial point temperature of the first endothermic peak in the melting process as the solidus temperature of 1448 ℃ and the temperature of the last peak in the melting process as the liquidus temperature of 1466 ℃ according to the national standard GB/T1425.

Example 2

The solid-liquid phase line temperature test of the W800 silicon steel sheet comprises the following steps:

(1) shearing a plurality of 10mg granular samples;

(2) and cleaning oxide skin and pollutants on the surface of the sample, and cleaning by using a cleaning solution for 5min at the temperature of 20-30 ℃ to ensure that the oxide skin and pollutants on the surface of the sample are cleaned. The formula of the cleaning solution comprises the following components: 30-35 mL of hydrochloric acid, 20-25 mL of sulfuric acid, 12-14 mL of ethanol, 0.2-0.3 g of hexamethylenetetramine, 24-29 mL of hydrogen peroxide and 10-50 mL of distilled water. Soaking the cleaned sample in gasoline for 3min, taking out and drying to prevent the sample from rusting;

(3) opening a furnace chamber of the differential scanning calorimeter, exposing the bracket and the radiating fins, taking out the old sponge zirconium in the circular tray 2, and replacing with a proper amount of new sponge zirconium;

(4) tightly wrapping the cleaned sample with tantalum sheets with the thickness of 0.1mm, putting the wrapped sample into a new graphite crucible, covering a crucible cover, taking down an old crucible, putting the new crucible into a sample rack of a differential scanning calorimeter, and closing a hearth; opening protective gas argon (the purity is more than or equal to 99.999%), setting the gas flow rate at 250ml/min, and purging for 60 min;

(5) the differential scanning calorimeter adopts a sample mode, a heating process is programmed, the temperature rise rate is 40 ℃/min at room temperature to 1200 ℃, and the gas flow is set to be 200 ml/min; the temperature rise rate is 10 ℃/min at 1200-1600 ℃, and the gas flow is switched to 100 ml/min;

(6) and (4) analyzing results: and obtaining a DSC curve graph after the test, and selecting the curve with the temperature of 1200-1600 ℃ from the extrapolated initial point temperature of the first endothermic peak in the melting process to the solidus temperature of 1512 ℃ and from the last peak temperature in the melting process to the liquidus temperature of 1529 ℃ according to the national standard GB/T1425.

The solid-liquid phase line temperature testing method for the steel sample overcomes the defects in a theoretical calculation method through a simple device and a simple operation process, has low requirement on equipment hardware, can obtain the solid phase line temperature and the liquid phase line temperature of steel through a one-time temperature rise curve, greatly improves the testing accuracy, and has the characteristics of quickness, safety and accuracy.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.