技术领域technical field
本发明涉及一种钛合金塑性成形工艺，属于金属板、型材加工领域，具体是一种用于测定钛合金高温拉伸缺口试样塑性应变的方法The invention relates to a titanium alloy plastic forming process, which belongs to the field of metal plate and profile processing, in particular to a method for measuring the plastic strain of a titanium alloy high-temperature tensile notched sample
背景技术Background technique
为深入研究钛合金板料高温冲压成形中复杂的应力状态，常采用缺口试样在高温单向拉伸来模拟应力状态，但缺口试样的应变测量则是一个难题。In order to deeply study the complex stress state in high-temperature stamping of titanium alloy sheets, notched specimens are often used to simulate the stress state by uniaxial stretching at high temperature, but the strain measurement of notched specimens is a difficult problem.
由于高温引伸计价格昂贵且使用寿命短，故亟需选择一种更为经济便捷的应变测量方法。Because high temperature extensometers are expensive and have a short service life, it is urgent to choose a more economical and convenient strain measurement method.
在钛合金高温成形温度700～800℃下，打标液(腐蚀液)可实现2～3小时不被氧化，能在高温拉伸试验结束后完整清晰的保存下来。At the high-temperature forming temperature of titanium alloy at 700-800°C, the marking solution (corrosion solution) can not be oxidized for 2-3 hours, and can be preserved completely and clearly after the high-temperature tensile test.
发明内容Contents of the invention
为解决高温复杂应力状态下应变的测量，本发明采用网格法计算断口处等效塑性应变的方法解决现有技术中的问题，提出一种用于钛合金缺口试样在高温复杂应力状态下应变测量的方法，采用网格法对缺口试样进行测量。先进行网格预制，之后采用激光切割加工缺口试样，完成高温拉伸试样后进行应变计算，实现高精度、快速测量断裂应变的方法。该工艺满足工程应用的批量化生产需求，提高生产效率，节约能源，并降低了钛合金损伤建模的制造成本。In order to solve the measurement of strain under high-temperature complex stress state, the present invention adopts the grid method to calculate the equivalent plastic strain at the fracture to solve the problems in the prior art, and proposes a method for titanium alloy notched specimen under high-temperature complex stress state The strain measurement method adopts the grid method to measure the notched sample. The mesh is prefabricated first, then the notched sample is processed by laser cutting, and the strain calculation is performed after the high-temperature tensile sample is completed, so as to realize the method of high-precision and rapid measurement of fracture strain. The process meets the mass production needs of engineering applications, improves production efficiency, saves energy, and reduces the manufacturing cost of titanium alloy damage modeling.
本发明是这样实现的：The present invention is achieved like this:
一种用于测定钛合金高温拉伸缺口试样塑性应变的方法，其特征在于，所述的方法为采用网格法计算断口处等效塑性应变的方法，步骤如下：A method for measuring the plastic strain of a titanium alloy high-temperature tensile notched sample, characterized in that the method is a method for calculating the equivalent plastic strain at a fracture using a grid method, and the steps are as follows:
步骤一、进行钛合金板材进行网格预制，采用激光切割制备缺口试样；Step 1. Carry out mesh prefabrication of the titanium alloy plate, and prepare notched samples by laser cutting;
步骤二、完成常规拉伸试样，初步确定钛合金高温拉伸工艺参数的范围，制定成形温度和应变速率；Step 2. Complete the conventional tensile sample, preliminarily determine the range of the titanium alloy high-temperature tensile process parameters, and formulate the forming temperature and strain rate;
步骤三、选择合适的打标液(腐蚀液)在钛合金板材上印刷网格，之后用激光切割机切割缺口试样，对缺口试样的表面喷涂防氧化剂；需要选择合适的打标液(腐蚀液)，确保印制的网格足够深。Step 3. Select a suitable marking solution (corrosion solution) to print the grid on the titanium alloy plate, then cut the notched sample with a laser cutting machine, and spray antioxidant on the surface of the notched sample; it is necessary to select a suitable marking solution ( etchant), make sure the printed grid is deep enough.
步骤四、装配高温拉伸缺口试样，之后完成缺口试样高温单轴拉伸实验并对断口处网格进行应变测量；Step 4: Assemble the high-temperature tensile notched sample, and then complete the high-temperature uniaxial tensile test of the notched sample and measure the strain of the grid at the fracture;
步骤五、在orgin软件中绘制断口处等效塑性应变(εe)的云图分布；Step five, draw the contour distribution of the equivalent plastic strain (εe ) at the fracture in the orgin software;
步骤六、进行有限元拉伸模拟仿真，将两者断裂应变结果相互对比验证。Step 6: Carry out finite element tensile simulation and compare and verify the fracture strain results of the two.
进一步，所述的步骤二中，应变速率采用大于超塑性拉伸，即大于0.01s-1，以此避免高温拉伸存在颈缩现象。Further, in the second step, the strain rate is higher than that of superplastic stretching, ie greater than 0.01s-1 , so as to avoid necking phenomenon in high temperature stretching.
进一步，所述的步骤三中的氧化剂为氮化硼。在缺口试样上喷涂防氮化硼，并用暖风机烘干。Further, the oxidizing agent in the step three is boron nitride. Spray anti-boron nitride on the notched sample and dry it with a warm air blower.
进一步，所述的步骤四中，在高温单轴拉伸实验完成后采用水淬冷却，并清洗防氧化剂；并且网格测量在光学放大镜下进行。Further, in step 4, after the high-temperature uniaxial tensile test is completed, water quenching is used to cool down, and the antioxidant is cleaned; and the grid measurement is performed under an optical magnifying glass.
进一步，所述的步骤四中，在光学放大镜下对断口处网格进行测量计算等效塑性应变εe，具体计算公式如(1)～(4)所示：Further, in step four, the equivalent plastic strain εe is measured and calculated on the grid at the fracture under an optical magnifying glass, and the specific calculation formulas are shown in (1) to (4):
ε1＝l1/l0 (1)ε1 = l1 /l0 (1)
ε2＝m1/m0 (2)ε2 =m1 /m0 (2)
ε3＝t1/t0 (3)ε3 =t1 /t0 (3)
式中，ε1、ε2和ε3分别代表长、宽和厚度方向的应变，l1和l0则分别为单个网格变形后的长和未变形的长，单位：mm；m1和m0则代表单个网格在变形后的宽度和变形前的宽度，单位：mm；t1和t0则代表单个网格在变形后的厚度和变形前的厚度，单位：mm；εe则是等效塑性应变值。In the formula, ε1 , ε2 and ε3 represent the strains in the length, width and thickness directions respectively, and l1 and l0 are the deformed and undeformed lengths of a single grid, respectively, unit: mm; m1 and m0 represents the width of a single grid after deformation and the width before deformation, unit: mm; t1 and t0 represent the thickness of a single grid after deformation and the thickness before deformation, unit: mm; εe is is the equivalent plastic strain value.
进一步，所述的步骤四中装配高温拉伸缺口试样具体为：Further, the assembly of the high-temperature tensile notched sample in the step four is specifically:
首先将缺口试样(6)通过上下设置的拉伸试样上固定螺栓(4)和拉伸试样下固定螺栓(9)连接安装在上固定板(5)、下固定板(7)之间；之后将上述装配好的试样放置在拉伸夹头中，即分别通过上固定杆(3)连接到拉伸装置上夹头(2)上、下固定杆(8)连接到拉伸装置下夹头(10)上；最后将上述装配好的整体置于加热炉(1)中。First, the notched sample (6) is connected and installed between the upper fixing plate (5) and the lower fixing plate (7) through the upper and lower fixing bolts (4) of the tensile sample and the lower fixing bolts (9) of the tensile sample. Afterwards, the above-mentioned assembled sample is placed in the tensile clamp, that is, the upper clamp (2) of the upper clamp (2) and the lower fixed rod (8) are connected to the tensile device through the upper fixed rod (3) respectively. On the lower chuck (10) of the device; finally, place the above-mentioned assembled whole in the heating furnace (1).
进一步，所述的加热炉上、中、下三部位分别设置仿真热电偶，即上部热电偶(11)、中部热电偶(12)，下部热电偶(13)，加热炉采用三段式测温以实现温度的精整控制。Further, the upper, middle and lower parts of the heating furnace are respectively provided with simulated thermocouples, namely the upper thermocouple (11), the middle thermocouple (12), and the lower thermocouple (13), and the heating furnace adopts a three-stage temperature measurement method. In order to realize the precise control of temperature.
本发明与现有技术相比的有益效果在于：The beneficial effect of the present invention compared with prior art is:
本发明在钛合金高温拉伸条件下采用网格法测量应变，并结合有限元仿真进行对比验证，解决了钛合金高温成形损伤应变测量的难题，促进了损伤模型的建立，提高钛合金零件复杂成形精度和损伤预测，具有较高的工程价值。The invention adopts the grid method to measure the strain under the high-temperature tensile condition of the titanium alloy, and combines the finite element simulation for comparative verification, solves the difficult problem of measuring the damage strain of the high-temperature forming of the titanium alloy, promotes the establishment of the damage model, and improves the complexity of the titanium alloy parts. Forming accuracy and damage prediction have high engineering value.
充分运用网格法的优点，可快速测量钛合金的高温复杂应力状态下损伤应变，具有精度高等优点，对损伤模型建立具有重要的意义，提高钛合金零件复杂成形精度和损伤预测，具有较高的实用和经济价值。Making full use of the advantages of the grid method, it can quickly measure the damage strain of titanium alloy under high temperature and complex stress state. practical and economic value.
本发明深入研究钛合金板料高温冲压成形中复杂的应力状态，解决了钛合金缺口试样的在高温复杂应力状态下应变测量的难题；The invention deeply studies the complex stress state in the high-temperature stamping and forming of titanium alloy sheet metal, and solves the problem of strain measurement of the titanium alloy notched sample under the high-temperature complex stress state;
相比于传统的高温引伸计，其存在价格昂贵、寿命短、误差大等缺点，网格法不仅可以在高温下实现精确测量，更具有成本低廉的优势，同时解决了缺口试样应变测量的难题。并且相比于传统的高温引伸计，网格法可实现快速测量断裂应变。该工艺满足工程应用的批量化生产需求，提高生产效率，节约能源，具有精度高等优点，并降低了钛合金损伤建模的制造成本，同时也为其它合金材料高温复杂应力状态下加工提供指导性意见。Compared with the traditional high-temperature extensometer, which has disadvantages such as high price, short life, and large error, the grid method can not only achieve accurate measurement at high temperature, but also has the advantage of low cost, and solves the problem of strain measurement of notched specimens. problem. And compared with the traditional high-temperature extensometer, the grid method can realize rapid measurement of fracture strain. This process meets the mass production needs of engineering applications, improves production efficiency, saves energy, has the advantages of high precision, and reduces the manufacturing cost of titanium alloy damage modeling, and also provides guidance for processing other alloy materials under high temperature and complex stress states Opinion.
附图说明Description of drawings
图1是本发明用于测定钛合金高温拉伸缺口试样塑性应变的方法的工艺流程图；Fig. 1 is the process flow diagram of the method for measuring the plastic strain of titanium alloy high-temperature tensile notched sample of the present invention;
图2是本发明实施例中高温拉伸试样具体尺寸图，单位：mm；Fig. 2 is a specific size diagram of the high temperature tensile sample in the embodiment of the present invention, unit: mm;
图3是本发明用于测定钛合金高温拉伸缺口试样塑性应变的方法中网格法测应变工艺的具体示意图；Fig. 3 is that the present invention is used for measuring the concrete schematic diagram of grid method measuring strain technique in the method for measuring the plastic strain of titanium alloy high-temperature tensile notch sample;
图4是本发明用于钛合金高温拉伸装置及加热装置简图；Fig. 4 is a schematic diagram of the high-temperature stretching device and heating device for titanium alloys of the present invention;
图5是本发明实施例中缺口试样ANS2在高温拉伸下位移—力曲线；Fig. 5 is the displacement-force curve of the notched sample ANS2 under high temperature stretching in the embodiment of the present invention;
图6是本发明实施例中缺口试样ANS2的断口处塑性应变云图分布；Fig. 6 is the contour distribution of the plastic strain at the fracture of the notched sample ANS2 in the embodiment of the present invention;
图7是本发明实施例中缺口试样ANS2在有限元软件中断裂云图分布。Fig. 7 is the fracture nephogram distribution of the notched sample ANS2 in the finite element software in the embodiment of the present invention.
其中，1-加热炉，2-拉伸装置上夹头，3-上固定杆，4-拉伸试样上固定螺栓，5-上固定板，6-拉伸试样，7-下固定板，8-下固定杆，9-拉伸试样下固定螺栓，10-拉伸装置下夹头，11-上部热电偶，12-中部热电偶，13-下部热电偶。Among them, 1- heating furnace, 2- upper chuck of tensile device, 3- upper fixing rod, 4- upper fixing bolt of tensile sample, 5- upper fixing plate, 6- tensile sample, 7- lower fixing plate , 8- the lower fixed rod, 9- the lower fixed bolt of the tensile sample, 10- the lower chuck of the tensile device, 11- the upper thermocouple, 12- the middle thermocouple, and 13- the lower thermocouple.
具体实施方式Detailed ways
为使本发明的目的、技术方案及效果更加清楚，明确，以下列举实例对本发明进一步详细说明。应当指出此处所描述的具体实施仅用以解释本发明，并不用于限定本发明。In order to make the object, technical solution and effect of the present invention clearer and clearer, the following examples are given to further describe the present invention in detail. It should be pointed out that the specific implementations described here are only used to explain the present invention, not to limit the present invention.
本实施例选用TC4钛合金锻态板材，结合图1～7具体说明实施网格法测量缺口试样的塑性应变如下：In this embodiment, the TC4 titanium alloy forged plate is selected, and the plastic strain of the notched sample is measured by the grid method as follows in combination with Figures 1 to 7:
(1)首先进行TC4钛合金材料的常规高温拉伸性能测试，获取钛合金材料的流动应力应变曲线和性能数据，并初步确定成形工艺参数的范围(温度：720～800℃，应变速率：0.1s-1)；(1) Firstly, carry out the conventional high-temperature tensile performance test of TC4 titanium alloy material, obtain the flow stress-strain curve and performance data of titanium alloy material, and preliminarily determine the range of forming process parameters (temperature: 720-800°C, strain rate: 0.1 s-1 );
(2)选择合适的打标液(腐蚀液)在钛合金板材上印刷网格，之后用激光切割机切割缺口试样，并喷涂防氧化剂；(2) Select a suitable marking solution (corrosion solution) to print the grid on the titanium alloy plate, then cut the notched sample with a laser cutting machine, and spray anti-oxidant;
(3)在加热炉中上、中和下部分别放置热电偶，并实现温度的实时监控；(3) Place thermocouples in the upper, middle and lower parts of the heating furnace respectively, and realize real-time monitoring of temperature;
(4)设置缺口试样合适的工装夹具；(4) Set up suitable fixtures for notched samples;
(5)高温拉伸完成后采用水淬冷却，并清洗防氧化剂，在光学放大镜下进行网格测量；(5) After the high-temperature stretching is completed, it is cooled by water quenching, and the anti-oxidant is cleaned, and the grid measurement is performed under an optical magnifying glass;
(6)具体实验操作过程：(6) Specific experimental operation process:
①先用酒精清洗钛合金TC4板材，并用打标机预先印刷1mm×1mm规格的正方形网格，然后用激光切割机切割缺口试样6，并喷涂防氧化剂，之后烘干即可；①Clean the titanium alloy TC4 plate with alcohol first, and pre-print a square grid of 1mm×1mm size with a marking machine, then cut the notched sample 6 with a laser cutting machine, spray anti-oxidant, and then dry it;
②装配高温拉伸缺口试样：首先将拉伸试样6通过拉伸试样上固定螺栓4和拉伸试样下固定螺栓9连接安装在上固定板5和下固定板，7上，之后放置在拉伸夹头中，即分别通过上固定杆3连接到拉伸装置上夹头2上，通过下固定杆8连接到拉伸装置下夹头10上；② Assembling the high-temperature tensile notched sample: first, the tensile sample 6 is connected and installed on the upper fixing plate 5 and the lower fixing plate 7 through the upper fixing bolt 4 of the tensile sample and the lower fixing bolt 9 of the tensile sample, and then Placed in the stretching chuck, that is, respectively connected to the upper chuck 2 of the stretching device through the upper fixing rod 3, and connected to the lower chuck 10 of the stretching device through the lower fixing rod 8;
③调整温度控制系统：连接加热炉中的上部热电偶11、中部热电偶12和下部热电偶13三个热电偶，实现实时控温，③Adjust the temperature control system: connect the upper thermocouple 11, the middle thermocouple 12 and the lower thermocouple 13 in the heating furnace to realize real-time temperature control.
④高温拉伸完成后采用水淬冷却，并清洗防氧化剂，在光学放大镜下进行网格测量；④ After the high temperature stretching is completed, it is cooled by water quenching, and the anti-oxidant is cleaned, and the grid measurement is carried out under an optical magnifying glass;
⑤此处选择缺口试样ANS2(温度：720～800℃，应变速率：0.1s-1)为例，其位移—力曲线如图6所示；⑤ Here, the notched sample ANS2 (temperature: 720-800°C, strain rate: 0.1s-1 ) is selected as an example, and its displacement-force curve is shown in Figure 6;
⑥以缺口试样ANS2在高温720℃和应变速率0.1s-1条件下为例进行计算，通过式(1)～(4)计算等效塑性应变，将计算结果通过origin软件绘制应变分布云图。图6显示其实验断口处最大等效塑性应变约0.344，图7显示有限元仿真的最大等效塑性应变约0.343，两者误差较小且最大损伤位置分布基本一致，证明了网格法测量高温缺口试样塑性应变的准确性和可靠性。⑥ Taking the notched sample ANS2 at a high temperature of 720 °C and a strain rate of 0.1 s-1 as an example to calculate, the equivalent plastic strain is calculated through formulas (1) to (4), and the calculation results are used to draw strain distribution cloud diagrams through origin software. Figure 6 shows that the maximum equivalent plastic strain at the experimental fracture is about 0.344, and Figure 7 shows that the maximum equivalent plastic strain of the finite element simulation is about 0.343, the error of the two is small and the distribution of the maximum damage position is basically the same, which proves that the grid method is used to measure high temperature Accuracy and reliability of plastic strain in notched specimens.
以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进，这些改进也应视为本发明的保护范围。The above description is only a preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements can also be made, and these improvements should also be regarded as the present invention. protection scope of the invention.
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| CN202310543053.7ACN116593289A (en) | 2023-05-15 | 2023-05-15 | A method for determining plastic strain of titanium alloy high temperature tensile notched specimen |
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