阅读说明：本技术 一种用于制备针贯入仪中贯入针的材料及其制备方法 (Material for preparing penetration needle in needle penetration instrument and preparation method thereof ) 是由 黄裕群 王云安 於开炳 陈学 邓长青 李勇锋 汤罗圣 肜增湘 黎明 李玥 张超 于 2019-11-13 设计创作，主要内容包括：本发明提供了一种用于制备针贯入仪中贯入针的材料及其制备方法,以碳、硅、铬、锰、钴、铝、磷、硫、钛、钽、铌、铁等为原料,掺入和田玉细粉,经浇铸、热轧、冷轧、渗碳处理和热处理,得到所述材料,本发明所制备的材料可用于制备针贯入仪的贯入针,其具有优异的机械强度,且具有一定的摩擦力,耐磨性佳,适用于各种硬度的工程勘察。(The invention provides a material for preparing a penetration needle in a needle penetrometer and a preparation method thereof, wherein carbon, silicon, chromium, manganese, cobalt, aluminum, phosphorus, sulfur, titanium, tantalum, niobium, iron and the like are used as raw materials, are doped with Hetian jade fine powder, and are subjected to casting, hot rolling, cold rolling, carburizing treatment and heat treatment to obtain the material.)

1. A preparation method of a material for preparing a penetration needle in a needle penetrometer is characterized by comprising the following specific steps:

(1) firstly, weighing the following components in percentage by weight: 0.33-0.57% of carbon, 1.25-1.88% of silicon, 1.38-2.11% of chromium, 0.82-1.13% of manganese, 0.79-0.99% of cobalt, 0.08-0.13% of aluminum, 0.009-0.011% of phosphorus, 0.002-0.005% of sulfur, 0.002-0.004% of titanium, 0.22-0.53% of tantalum, 0.03-0.06% of niobium and the balance of iron and inevitable impurities, wherein the sum of the weight percentages of the components is 100%; then mixing and melting the components to be molten into molten liquid, mixing fine nephrite powder with the weight of 0.0005-0.0008 time of the liquid while stirring, uniformly stirring, and casting into a billet;

(2) carrying out hot rolling and cold rolling on the steel billet prepared in the step (1) to obtain a wire rod;

(3) performing carburizing treatment and heat treatment on the wire rod obtained in the step (2) to obtain the material for preparing the needle penetration instrument penetration needle; wherein, the specific method of the heat treatment is as follows: heating to 720-750 ℃ at a heating rate of 15-20 ℃/s, preserving heat for 5-8 minutes, then cooling to 200-250 ℃, preserving heat for 20-30 seconds, and naturally cooling to room temperature.

2. The method according to claim 1, wherein in the step (1), the molten liquid is prepared as follows: firstly, mixing and melting carbon, chromium, manganese, cobalt, aluminum, titanium, tantalum, niobium and iron until the carbon, the chromium, the manganese, the cobalt, the aluminum, the titanium, the tantalum, the niobium and the iron are melted, then adding silicon, phosphorus and sulfur, and continuously heating until the silicon, the phosphorus and the sulfur are completely melted to obtain the molten liquid.

3. The method according to any one of claims 1 to 2, wherein in the step (1), the fine powder of Hetian jade is prepared by: firstly, mechanically crushing leftover materials of Hetian jade to prepare Hetian jade coarse powder with the particle size of less than or equal to 5 mm; then adding sodium silicate into water, stirring and dispersing uniformly, then slowly adding the coarse Hetian jade powder while stirring, uniformly oscillating by ultrasonic waves, grinding for 5-8 minutes by a wet method, centrifuging, freeze-drying in vacuum, and crushing by using a jet mill to prepare the Hetian jade fine powder with the particle size of less than or equal to 1 mu m.

4. The production method according to any one of claims 1 to 3, wherein in the step (2), the process conditions of the hot rolling are: the initial hot rolling temperature is 1100-1200 ℃, the cooling starting temperature is 810-820 ℃, the accumulated deformation is 60-70% after 8-pass rolling, water cooling is carried out after rolling, and air cooling is carried out to the room temperature.

5. The manufacturing method according to claim 4, wherein in the step (2), the process conditions of the cold rolling are as follows: cold rolling to 0.8-0.9 mm, and the total reduction is more than 70%.

6. The preparation method according to claim 5, wherein in the step (3), plasma carburizing is adopted, and the carburizing time is 5-8 hours.

7. The preparation method according to any one of claim 6, wherein in the step (3), the cooling comprises two steps of slow cooling and fast cooling, the slow cooling rate is 3-5 ℃/s, the slow cooling is carried out to 600-620 ℃, and the fast cooling rate is 18-22 ℃/s.

8. A material for manufacturing a penetration needle in a needle penetrometer, obtained by the manufacturing method according to any one of claims 1 to 7.

9. Use of the material of claim 8 in the preparation of a needle for penetration in a needle penetrometer.

Technical Field

The invention relates to the technical field of needle penetrometers, in particular to a material for preparing a penetration needle in a needle penetrometer and a preparation method thereof.

Background

For in-situ testing of soil, a static cone penetration test method (CPT) is suitable for sandy soil silty clay, is not suitable for soft rock and has better precision; the dynamic penetration test method (DPT) has wide adaptability, takes mechanical dynamic penetration as an example, has more and heavier instruments, is suitable for soil and is not suitable for rock and stone, and has a plurality of influencing factors of test results and limited precision; the standard penetration test method is suitable for soil and is not suitable for rock; the standard penetration test method (SPT) is suitable for sandy soil and not suitable for peat soil; the side pressure test method is generally suitable for sandy soil, silt soil and cohesive soil, and is not suitable for peat soil.

For in-situ testing of rocks, the point load test method can test the time of irregular rocks and the strength of low-strength and severely weathered rocks, but the test discreteness is large, the test range is 10-100 MPa, and the accuracy of soft rocks is not high; the rock mass resilience hammering test method can quickly obtain the rock mass nondestructive test result, and the test range is 10-350 MPa. In contrast, in the process of highway investigation, a large number of real-time judgment results need to be obtained on site, the integrity of regional stratum rock cores is poor, and a proper rock sample is difficult to obtain for indoor test.

Transition zones from the second step to the third step of the topography of China in the northwest of the jaw are controlled by two Yunne large fractures in the zone, metamorphic rocks in the exposed area are widely appeared, and the main lithologies include Wudangshan group quartz mica schist and mica schist, joram series green mud schist, carbonaceous slate, Hanwu series phyllite, carbonaceous slate, Shikuai series argillaceous slate, silty slate and the like. The lithology and structural characteristics of the rock mass in the region are complex, the weathering degree is deep, the joint cracks develop, the bonding force between the sheet surfaces is weak, the structure is loose, the strength is low, the soft metamorphic rock belongs to soft metamorphic rock, the rock is very easy to break along the sheet surfaces when core sampling and rock sample processing are carried out on the rock, the core is broken, the rock is mostly in a sheet shape, a cake shape and a broken block shape, the compression strength is very difficult to test by using a uniaxial compression test, but the mica sheet rock slope is easy to be unstable, the tunnel is very easy to deform greatly, collapse and secondary liner cracking are caused, and the acquisition of the physical and mechanical property indexes is very important.

The common problem exists in the background of finished engineering projects of the applicant of the invention, such as ten-year-round high speed in 2002, and the core taking rate in deteriorated strata of Wudang mountain rock groups is 20-50%; in 2009, the core is high-speed, and the core taking rate is about 30% -60%; in 2010, the speed of the bamboo is high, and the coring rate is about 20-50%; in 2011, ten rooms are high in speed, and the coring rate is about 30% -60%; ten sago high speed in 2017, and the coring rate is about 30-50%. The regional schist is weak in rock quality, is physically developed, is poor in integrity, is low in rock core taking rate, and is difficult to obtain physical and mechanical property indexes. Therefore, a needle penetrometer, a portable instrument invented by Japan for testing the strength of soft rock, was introduced, and the optimum test range was 0.5-20 MPa.

However, the conventional needle penetrometer often causes the phenomenon of breakage of a penetration needle when performing a needle penetration test on a rock with high hardness, and for softer silt, silty clay, sandy soil and the like, the phenomenon that the penetration depth is too large to cause unstable test results is easy to occur, so that the complicated and variable engineering investigation practice cannot be met.

Disclosure of Invention

The invention aims to provide a material for preparing a penetration needle in a needle penetrometer and a preparation method thereof, wherein the material has excellent mechanical strength and good wear resistance and is suitable for engineering investigation of various hardness.

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

a method for preparing a material for preparing a penetration needle in a needle penetrometer comprises the following specific steps:

(1) firstly, weighing the following components in percentage by weight: 0.33-0.57% of carbon, 1.25-1.88% of silicon, 1.38-2.11% of chromium, 0.82-1.13% of manganese, 0.79-0.99% of cobalt, 0.08-0.13% of aluminum, 0.009-0.011% of phosphorus, 0.002-0.005% of sulfur, 0.002-0.004% of titanium, 0.22-0.53% of tantalum, 0.03-0.06% of niobium and the balance of iron and inevitable impurities, wherein the sum of the weight percentages of the components is 100%; then mixing and melting the components to be molten into molten liquid, mixing fine nephrite powder with the weight of 0.0005-0.0008 time of the liquid while stirring, uniformly stirring, and casting into a billet;

(2) then carrying out hot rolling and cold rolling on the steel billet to obtain a wire rod;

(3) finally, carrying out carburizing treatment and heat treatment on the wire to obtain the material for preparing the penetration needle of the needle penetration instrument; wherein, the specific method of the heat treatment is as follows: heating to 720-750 ℃ at a heating rate of 15-20 ℃/s, preserving heat for 5-8 minutes, then cooling to 200-250 ℃, preserving heat for 20-30 seconds, and naturally cooling to room temperature (25 ℃).

As one of preferable technical means, in the step (1), the molten liquid is prepared by the following method: firstly, mixing and melting carbon, chromium, manganese, cobalt, aluminum, titanium, tantalum, niobium and iron until the carbon, the chromium, the manganese, the cobalt, the aluminum, the titanium, the tantalum, the niobium and the iron are melted, then adding silicon, phosphorus and sulfur, and continuously heating until the silicon, the phosphorus and the sulfur are completely melted to obtain the molten liquid.

As one of the preferable technical solutions, in the step (1), the preparation method of the fine powder of the nephrite jade is as follows: firstly, mechanically crushing leftover materials of Hetian jade to prepare Hetian jade coarse powder with the particle size of less than or equal to 5 mm; then adding sodium silicate into water, stirring and dispersing uniformly, then slowly adding the coarse Hetian jade powder while stirring, uniformly oscillating by ultrasonic waves, grinding for 5-8 minutes by a wet method, centrifuging, freeze-drying in vacuum, and crushing by using a jet mill to prepare the Hetian jade fine powder with the particle size of less than or equal to 1 mu m.

In a further preferred embodiment, the mechanical pulverization is selected from one or more of jaw pulverization, cone pulverization, roll pulverization, hammer pulverization, and impact pulverization.

As a further preferable technical scheme, the mass ratio of the sodium silicate to the water to the nephrite rough powder is 1: 25-35: 5 to 6.

As a further preferable technical scheme, the wet grinding adopts a vibration mill, zirconia balls with the diameter of 10-12 mm are used as grinding media, the volume percentage of the zirconia balls is 70-80%, the volume percentage of slurry in gaps among the grinding media is 80-90%, the angle range of an eccentric block in the vibration mill is 40-50 degrees, the vibration frequency is 20-30 Hz, and the amplitude is 2-5 mm.

As a further preferred technical solution, the process conditions of centrifugation are: centrifuging at 10000-12000 r/min for 5-6 minutes, and discarding the supernatant.

As a further preferred technical solution, the process conditions of vacuum freeze drying are as follows: cooling to-40 to-50 ℃, vacuumizing to 15-20 Pa, raising the temperature to 20-30 ℃, and maintaining the vacuum degree for 5-6 hours.

As a further preferred technical solution, the operating conditions of the jet mill are: the airflow pressure is 1100kPa, the feeding speed is 180r/min, the grading frequency is 35Hz, and the crushing time is 5-6 minutes.

As one of the preferable technical solutions, in the step (2), the hot rolling process conditions are as follows: the initial hot rolling temperature is 1100-1200 ℃, the cooling starting temperature is 810-820 ℃, the accumulated deformation is 60-70% after 8-pass rolling, water cooling is carried out after rolling, and air cooling is carried out to the room temperature.

As one of the preferable technical solutions, in the step (2), the process conditions of the cold rolling are as follows: cold rolling to 0.8-0.9 mm, and the total reduction is more than 70%.

As one preferable technical scheme, in the step (3), plasma carburization is adopted, and the carburization time is 5-8 hours.

As a further preferable embodiment, a specific method of carburizing is: placing the wire on a cathode disc of a nitriding furnace, vacuumizing the nitriding furnace, inputting pulse voltage with the voltage of 600V and the duty ratio of 0.1 when the pressure in the furnace is less than or equal to 50Pa, starting brightness on the surface of the wire, filling argon into the furnace until the pressure is increased to 150-180 Pa, keeping for 20-30 minutes, performing argon plasma bombardment on the surface of the wire, and starting to increase the temperature of the wire; slowly increasing the duty ratio and the voltage value, simultaneously filling hydrogen into the furnace to adjust the pressure in the furnace until the temperature of the wire rod rises to 400-450 ℃, the voltage value rises to 650-680V, the pressure in the furnace rises to 480-500 Pa, then filling methane into the furnace, and simultaneously keeping the temperature, the voltage value and the pressure in the furnace constant; adjusting the flow rates of hydrogen and methane to make the volume flow rate ratio H of hydrogen and methane ₂：CH ₄Is 100: 1, starting timing carburization when methane is filled; and stopping introducing hydrogen and methane after carburization is finished, closing voltage input, extracting carburizing gas in the furnace, filling air, and cooling the wire in the furnace to room temperature along with the air.

As one of the preferable technical scheme, in the step (3), the cooling comprises two steps of slow cooling and fast cooling, wherein the cooling rate of the slow cooling is 3-5 ℃/s, the cooling rate of the slow cooling is 600-620 ℃, and the cooling rate of the fast cooling is 18-22 ℃/s.

In addition, the invention also claims a material for preparing a penetration needle in a needle penetrometer, which is obtained by the preparation method, and application of the material in preparing the penetration needle in the needle penetrometer.

As one of the preferable technical proposal, the material is cut to 39-40 mm short, and then the material can be used as a penetration needle of a needle penetrometer.

Compared with the prior art, the invention has the following beneficial effects:

(1) the material is prepared by taking carbon, silicon, chromium, manganese, cobalt, aluminum, phosphorus, sulfur, titanium, tantalum, niobium, iron and the like as raw materials, doping Hetian jade fine powder, and carrying out casting, hot rolling, cold rolling, carburizing treatment and heat treatment, can be used for preparing a penetration needle of a needle penetrometer, has excellent mechanical strength, certain friction force and good wear resistance, and is suitable for engineering investigation of various hardness;

(2) in order to ensure the mechanical strength and the wear resistance of the material, a large amount of silicon and chromium are added in the preparation process of the material, but researches show that although the silicon is beneficial to improving the mechanical strength and the chromium is beneficial to improving the wear resistance, the high silicon and the high chromium can cause the hardness of the material to be lower, on the premise of keeping the content of the silicon and the chromium unchanged, the precipitation of cementite can be promoted by improving the content of cobalt and manganese, and the strength of the material is further improved; in addition, the addition of the fine Hetian jade powder improves the material strength and effectively prevents the penetration needle from breaking; on the other hand, the surface is partially separated out in the casting process, so that the surface of the material is rough, the friction force between the material and rock soil is increased when the material is used, and the excessive penetration depth is avoided;

(3) according to the invention, acid washing or mechanical polishing for removing oxides is omitted between hot rolling and cold rolling, the original rough state of the surface of the material is kept as much as possible, the subsequent carburization treatment is combined, the roughness of the surface of the material is improved, the friction force between the material and rock soil is increased during use, and the excessive penetration depth is avoided.

(4) When the molten liquid is prepared, carbon and metal components are mixed and melted, then silicon, phosphorus and sulfur are added, so that the metal components are fully mixed, on the basis, the nonmetal components, namely silicon, phosphorus and sulfur are added, on one hand, the nonmetal components and the metal components are fully mixed, on the other hand, the interaction of carbon and silicon promotes the precipitation of cementite, and the strength of the material is improved.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, 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 derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.