CN101294265A - Titanium alloy smithing technological parameter testing method - Google Patents

Abstract

The invention relates to a test mode of a titanium alloy smithing technological parameter. The test mode has the steps that: (1) multi-forging various-direction smithing is performed on a titanium alloy steel bar to obtain an original structure which is as uniform as possible; (2) the steel bar after substituting forging is made into stocks under the temperature ranging from 30 to 50 DEG C below a Beta transformation point (TBeta); (3) the stocks are preheated for 1 to 2 hours under the temperature which is about 200 DEG C, and then are coated with special lubricant Ti-6 of a titanium alloy die forming; (4) the surface of a die is preheated until the temperature is more than 350 DEG C, the die forming is finished with 1 to 2 fire levels, and three different deformation amounts of 10 percent, 35 percent and 60 percent are obtained on a forgeable piece; (5) after the forgeable piece is processed through heat treatment, various types of mechanical property samples are get from the parts with different deformation amounts, and the quantitative relation between the parameters such as the smithing temperature, the heat preservation time, the deformation amounts, etc. and the mechanical property as well as microscopic constitutions is determined. A technician can adjust the sizes of the stocks according to the quantitative relation, and ensure reasonable deformation amounts on a stamp work, thereby obtaining the optimum matching between the plasticity and the fracture toughness.

Description

A kind of test method of titanium alloy smithing technological parameter

Technical field

The present invention relates to a kind of test method of titanium alloy smithing technological parameter, belong to the metallic substance science and technology field.

Background technology

Along with advanced aircraft to improving constantly that high loss of weight, long lifetime require, the titanium alloy of specific tenacity height, corrosion resistance and good consumption aboard is also in continuous increase.Titanium alloy die forging spare is mainly used in the important load component of making on the aircraft such as bulkhead, beam and engine compressor dish, and forging performance is had high requirements.Different with aluminium alloy, structure iron, titanium alloy smithing technological parameter has a significant impact alloy microscopic structure and mechanical property.With TC6, TC11 titanium alloy is example, and under chemical ingredients fixed situation, forging process changes can make unit elongation δ maximum fluctuation reach 15%, and relative reduction in area ψ reaches 45%, impelling strength a _KUReach 50J/cm ², fracture toughness property K _ICReach The safe range of stress of smooth sample reaches 150MPa, and creep rupture strength and creep strength reach 80～120MPa.In certain sense, forging process is more remarkable than the influence of alloying constituent to Effect on Performance.

The test method of research titanium alloy smithing technological parameter mainly contains 3 kinds:

(1) thermal modeling test

Thermal analogy is the basic test method of each metalloid of research stress-strain behavior under the different distortion condition.By setting processing parameters such as different Heating temperatures, strain rate, deflection, can obtain the stress-strain curve of metal in stretching or compression process, be used to instruct the formulation of forging process.Because the thermal analogy specimen size is little, can only carry out microstructure and hardness analysis usually after the thermal analogy, can't cut mechanical property samples such as stretching, impact, fracture, therefore can not effectively set up " technology-tissue-performance " three's corresponding relation.

(2) rammer cake test

The test of rammer cake is the test method that parameter and forging mechanical property relation are forged in the most frequently used research.When new alloy being carried out forging process research or existing alloy carried out process optimization, adopt this method usually.The main points of rammer cake test method are: cut onesize test blank earlier, by different technology blank is carried out the jumping-up distortion then, set up " technology-tissue-performance " corresponding relation by cut the mechanical property sample from biscuit.The shortcoming of this test method mainly contains: (a) there is tangible zone nonuniformity in the jumping-up distortion.Have distortion dead band, gross distortion district and free deformation zone on the biscuit cross section simultaneously, structure property all has very big-difference on the different zones.The sample position is improper to be easy to cause the mechanical property test result dispersed big, when serious even can mislead contour forging technique and formulate.When (b) the research deflection was to the influencing of mechanical property, every kind of deflection all needed to be swaged into independently blank, and test efficiency is low.In addition, the blank deformation amount guarantees by control press or tup draught, influenced by operator's subjective factor, be difficult to accomplish and the deflection that designs in full accord.

(3) die forging test

This method is directly to adopt ready-made mould to study the influence of smithing technological parameter to forging performance.The test-results that this method obtains can be represented the actual performance level of alloy under different forging procesies, but also there is shortcoming, mainly comprise: (a) can't the quantitative examination deflection to the influence of forging mechanical property, because the forging on the aircraft mostly is high muscle thin-wall construction form, muscle portion is by backward extrusion, and deflection is difficult to accurate calculation; (b) it is few to cut the position of mechanical property sample on the forging, and material use efficiency is low; (c) forging is complex-shaped, and base needs many fire to finish, and workload is big.

Summary of the invention

The present invention on the basis of present technology, has proposed a kind of test method of titanium alloy smithing technological parameter just, its objective is and finds a kind of novel method of studying titanium alloy smithing technological parameter.The special-purpose forging macrostructure of the test of adopting this method to obtain is even, performance data dispersed little, material use efficiency is high, tissue and the performance ununiformity that can effectively avoid traditional rammer cake test to cause.Adopt this test method can accurately study quantitative relationship between smithing technological parameter and the forging mechanical property, disclose alloy " technology-tissue-performance " internal relation.

The objective of the invention is to realize by following measure:

The test method of this kind titanium alloy smithing technological parameter is characterized in that: the step of this method is:

1) titanium alloy rod bar is carried out many fire time all directions and forge, obtain to try one's best uniform original structure, macrostructure should meet 1～3 grade in " 10 grades of grading figure of titanium alloy macrostructure ";

2) will change bar after the forging at beta transformation point (T _β) following 30～50 ℃ make thickness 100 ± 2mm, width 130 ± 2mm, the blank of length 260mm;

3) blank applies titanium alloy die forging lubricant agent special Ti-6 at 200 ℃ of left and right sides preheating 1～2h;

4) die surface is preheated to more than 350 ℃, puts into the mould type groove after blank is come out of the stove rapidly and carry out die forging, die forging is finished in 1～2 fire, and on blank, obtain 10%, 35% with 60% 3 different deflection;

5) after the forging thermal treatment, cut various types of mechanical property samples, be used for determining that forging temperature, soaking time, deflection etc. forge the quantitative relationship between parameter and forging mechanical property and the microstructure at different distortion amount position.

In order to realize this requirement, this test method is to realize on the forging of definite shape, on this forging, obtain simultaneously 10%, 35% with 60% 3 different deflection.Adopt the blank of different thickness, can also obtain the more different distortion amount of wide region.This test method can replace conventional forging process research method-rammer cake method, and all round properties of be used for existing titanium alloy smithing technological optimization, newly developing between titanium alloy smithing technological formulation and the close alloy compares.Can also obtain the quantitative relationship that deflection, forging temperature, soaking time etc. are forged mechanical properties such as parameter and tensile strength, unit elongation, relative reduction in area, impelling strength, fracture toughness, fatigue strength by this test method, this quantitative relationship can be directly used in the production of instructing titanium alloy die forging spare on aircraft, the engine.

Description of drawings

Fig. 1 is the deflection of the embodiment of the invention 2 and the corresponding relation figure of unit elongation, relative reduction in area, impelling strength and fracture toughness.

Embodiment

Below with reference to embodiment technical solution of the present invention is further described:

The simultaneous test of embodiment 1 rammer cake method and the inventive method

Starting material adopt TC18 (Ti-5Al-5Mo-5V-1Cr-1Fe) titanium alloy φ 155mm bar.At first to bar at T _β-30 ℃ are carried out all directions forging, divide two fire to finish, every fiery upsetting pull each once, the upsetting pull deflection is all about 50%.To change bar after the forging and forge the size that provides to the table 1, and adopt rammer cake method and test method of the present invention that blank is forged then respectively, the concrete processing parameter of the inventive method sees Table 1 and following steps:

1) titanium alloy rod bar is carried out many fire time all directions and forge, obtain to try one's best uniform original structure, macrostructure should meet 1～3 grade in " 10 grades of grading figure of titanium alloy macrostructure ";

2) will change bar after the forging below transformation temperature 30～50 ℃ make thickness 100 ± 2mm, width 130 ± 2mm, the blank of length 260mm;

3) blank applies titanium alloy die forging lubricant agent special Ti-6 at 200 ℃ of left and right sides preheating 1～2h;

4) die surface is preheated to more than 350 ℃, puts into the mould type groove after blank is come out of the stove rapidly and carry out die forging, die forging is finished in 1～2 fire, and on forging, obtain 10%, 35% with 60% 3 different deflection;

5) after the forging thermal treatment, cut various types of mechanical property samples, be used for determining that forging temperature, soaking time, deflection etc. forge the quantitative relationship between parameter and forging mechanical property and the microstructure at different distortion amount position.

The smithing technological parameter that table 1 rammer cake method and test method of the present invention adopt

Test-results sees Table 2.By table 2 as seen, all very big to performance difference and data dispersiveness in length and breadth when adopting rammer cake method to test, σ on the adjacent samples position _bThe fluctuation maximum value reaches 50MPa, and ψ reaches 15%, K _ICReach

In addition, the test-results of fracture toughness does not meet the basic law of structure property relation yet.As everyone knows, titanium alloy obtains to wait axle or bifurcation tissue when two-phase region forges, and fracture toughness is lower; When more than beta transformation point, forging, the primary phase morphology by etc. axle change sheet into, fracture toughness can obviously improve.From rammer cake test-results, two-phase region forges and at β district forging K _ICBe suitable.

As can be seen from Table 2, the forging performance homogeneity that adopts test method of the present invention to obtain is tested significantly better than the rammer cake.Forging is all very little to performance difference and data dispersiveness in length and breadth, σ on the adjacent samples position _bThe fluctuation maximum value only is 9MPa, and ψ is 4%, K _ICFor

K when forging more than the beta transformation point _ICMean value is

When two-phase region forges

Be not difficult to find out from The above results, adopt the inventive method research titanium alloy smithing technological parameter that obvious superiority is arranged.

The main Mechanics Performance Testing result of TC18 titanium alloy forging (ε=35%) under the table 2 different tests method

Annotate: forge 825 ℃ of postheat treatment systems, 2h, stove are chilled to 750 ℃, 2h, AC+585 ℃, 4h, AC.

Embodiment 2:

Starting material are TC18 titanium alloy φ 170mm bar.At first bar is carried out all directions at T β-40 ℃ and forges, divide three fire to finish, every fiery upsetting pull each once, the upsetting pull deflection changes that to forge the back billet size be 100 * 130 * 260mm all about 50%.The die forging Heating temperature is T β+25 ℃, and soaking time is divided two sections calculating: T _β-30 ℃, insulation 60min is warming up to T β+25 ℃ with stove, insulation 40min.Mechanical property test the results are shown in Table 3, and the corresponding relation of deflection and mechanical property is seen Fig. 1.

The main Mechanics Performance Testing result of TC18 titanium alloy forging under the table 3 different distortion amount

Annotate: forge 825 ℃ of postheat treatment systems, 2h, stove are chilled to 750 ℃, 2h, AC+620 ℃, 4h, AC.

As seen from Figure 1, under the optional test temperature, deflection and unit elongation, relative reduction in area and fracture toughness all are good linear relationship, and formula is as follows:

δ ₅(％)＝0.07ε+11.9?R ²＝0.9992 (1)

ψ(％)＝0.43ε+20.1 R ²＝0.9986 (2)

$K_{\mathrm{IC}}\left(\mathrm{MPa}\sqrt{m}\right)=-0.32\mathrm{\ϵ}+102.1R^2=0.9892---\left(3\right)$

a _KU(J/cm ²)＝-0.013ε ²+1.2ε+29.7R ²＝1 (4)

Relation conefficient is respectively 0.9992,0.9986,0.9892.The every increase by 10% of deflection ε, unit elongation improves 0.7%; Relative reduction in area improves 4.3%; K _ICDescend Be quadratic relation between impelling strength and the deflection, a _KUIncrease with deflection earlier and improve, after deflection surpasses 35%, a _KUBegin again to reduce.

Although by in the past forging process test method, the technician has gained some understanding to deflection and the universal law between titanium alloy plasticity, the fracture toughness, and promptly deflection increases plasticity and improves fracture toughness decline.But yet there are no the research report of relevant deflection and titanium alloy mechanical property quantitative relationship.The test-results that adopts the present invention to obtain shows that deflection is very remarkable to the influence of unit elongation, relative reduction in area and fracture toughness.The technician can adjust billet size according to above-mentioned quantitative relationship, guarantees rational deflection on the stamp work, thereby obtains the optimum matching of plasticity and fracture toughness.

Claims (1)

1. the test method of a titanium alloy smithing technological parameter, it is characterized in that: the step of this method is:

1) titanium alloy rod bar is carried out many fire time all directions and forge, obtain to try one's best uniform original structure, macrostructure should meet 1～3 grade in " 10 grades of grading figure of titanium alloy macrostructure ";

2) will change bar after the forging at beta transformation point (T _β) following 30～50 ℃ make thickness 100 ± 2mm, width 130 ± 2mm, the blank of length 260 ± 2mm;

3) blank applies titanium alloy die forging lubricant agent special Ti-6 at 200 ℃ of left and right sides preheating 1～2h;

4) die surface is preheated to more than 350 ℃, puts into the mould type groove after blank is come out of the stove rapidly and carry out die forging, die forging is finished in 1～2 fire, and on forging, obtain 10%, 35% with 60% 3 different deflection;

5) after the forging thermal treatment, cut various types of mechanical property samples, be used for determining that forging temperature, soaking time, deflection etc. forge the quantitative relationship between parameter and forging mechanical property and the microstructure at different distortion amount position.

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