FR2917428A1 - PROCESS FOR PRODUCING AN ALUMINUM ALLOY SEMI-PRODUCT, IN PARTICULAR FOR A MOTOR VEHICLE STRUCTURE - Google Patents

Abstract

A process for manufacturing an aluminum alloy half-product, in particular for forming a motor vehicle structure component that allows irreversible energy absorption during a collision against an obstacle or impact, comprising the steps of in an extrusion (E6) of aluminum alloy on a press through a die to obtain a semi-finished product, a step of heat treatment of the semi-finished product (E13). Before the revenue step (E13), a sample (e) is taken (E10) from a batch (L) comprising a set of semi-finished products having common manufacturing parameters, in order to undergo a test (E11) of at least one of its functional characteristics (F), the conditions (T, Deltat) of the income step (E13) being determined (E12) as a function of the measured value (Fm) during the test (E11) and a target value (Fc) of the at least one functional characteristic (F), the heat treatment stage of income (E13) being applied under the conditions (T, Deltat) determined to the whole batch (L) of which is the sample (e).

Description

Process for producing a semi-finished product made of aluminum alloy

  for motor vehicle structure

Field of the invention

  The invention relates to a method for producing a semi-finished product made of aluminum alloy sheet or section, intended in particular to form a motor vehicle structure component that allows the absorption of energy in such a way that irreversible during a collision against an obstacle or shock. For example, the case of the shock absorber made from a profile and used, in association with a beam, to form the entire bumper of said vehicle. The beam is disposed transversely relative to the direction of movement of the vehicle, and the absorber or absorbers are generally arranged either transversely or longitudinally with respect to this direction. A shock absorber is sometimes referred to as the deformation element or crashbox. Other types of profiles or sheets of aluminum alloy can also be manufactured from the method according to the invention.

State of the art

  Until the mid-1990s, the components intended to absorb energy irreversibly during a collision against an obstacle, or shock, in particular the bumper beams, consisted of a shaped sheet metal, usually made of steel. The more stringent requirements of car manufacturers, especially with the appearance of repairability tests, led to change this function and brought two types of evolution. On the one hand, the geometry and materials constituting the structural components or beams have evolved, leading to the use of tubular beams, multicellular or not, of aluminum alloy or steel. On the other hand, particularly in the case of bumper beams, an absorbent interface between the beams and the longitudinal supports of the vehicles has been introduced: the shock absorbers, also called deformation elements or "crash boxes". This double evolution has responded to the need, in Europe in particular, to have a beam / absorber or beam / support system or even a structural / support component, no longer only resistant, that is to say which deforms without laminating. but absorbing, that is to say, which deforms by absorbing energy in a controlled manner. The structural component of the automobile body therefore has a dual role: on the one hand to deform elastically during small shocks or collisions against an obstacle, on the other hand to absorb energy and transmit the effort in a controlled manner, in particularly without collapsing abruptly during deformation, the absorbers or supports. In known manner, the method of manufacturing a semi-finished product made of aluminum alloy sheet or section, intended in particular to form such a component, comprises the steps consisting in: a step of manufacturing the semi-finished product, consisting of rolling and quenching or extrusion of aluminum alloy, and a step of semi-finished product heat treatment. The industrial variability of the parameters of the steps of the manufacturing process results in variability of the characteristics of the half-products obtained such as the energy absorption capacity and consequently a variability of their behavior in the event of a collision. The variability of the characteristics of the semi-finished product is dependent on several factors, the two main ones being the mechanical properties and the geometry of the semi-finished product. The variations of the mechanical properties are related to the variability of the material from which they come, for example the variability on the chemical composition of the metal. The variations in geometry are related to the extrusion or rolling process, for example to the geometric quality of the dies used in the case of an extrusion process. In known manner, the verification of the half-products obtained after the heat treatment requires the performance of frequent and extensive quality tests. In these tests, the intrinsic characteristics of the semi-finished product, ie, the mechanical properties such as breaking load, yield strength or elongation, geometrical characteristics and / or characteristics of the product. chemical composition are measured, for example in manual geometric measurements, tensile tests or bundling tests. These destructive experiments are most commonly performed on finished products. In case of non-compliance, the products found to be defective can be separated from other products. However, this separation operation being difficult to achieve, it is often decided to discard the entire production of the product deemed to be defective 5 is derived, or to accept significant variability and difficult to control the functional characteristics of the finished product.

  Problem The invention aims to overcome these drawbacks by proposing a manufacturing process that makes it possible to control and reduce the variability of at least one functional characteristic of the half-product and consequently of the finished product, in particular the structural component, resulting from this process. semi-finished product. Object of the invention

  The invention relates to a manufacturing method of the aforementioned type characterized in that, before the income step, a sample is taken from a batch comprising a set of half-products having common manufacturing parameters, in order to undergo a test. at least one of its functional characteristics, the conditions of the income step being determined as a function of the value measured during the test and a target value of the at least one functional characteristic, the heat treatment step income being applied under the conditions determined to the entire batch from which the sample originated. Thanks to the provisions according to the invention, the conditions of the heat treatment of the income stage are determined as a function of the value of the characteristics measured on the sampled sample and of the target value which one wishes to obtain for these characteristics, the The conditions of the heat treatment of income are thus specific to each batch. It is thus possible to control and reduce the variability of the final functional characteristic. This reduction in the variability makes it possible, for example, to optimize the behavior of the elements intended to absorb energy. It should be noted that the use of functional characteristics measurements during the test is intended to produce semi-finished products which are custom-designed with respect to the desired functional result, this type of process which can still be called "Tailored extrusion", in the case of a profile. Advantageously, all the semi-products of the same batch is derived from the same alloy and the same casting of this alloy.

  Advantageously, all the semi-products, consisting of sheets or profiles, of the same batch is produced on the same rolling mill or the same extrusion press respectively. Advantageously, all the semi-products of the same batch is made through respectively the same rolling mill rolls or the same die. Advantageously, all the semi-finished products of the same batch are respectively derived from the rolling and quenching or from the extrusion of the same quantity of metal whose mass is limited and for which the interruption respectively is the same. rolling and / or quenching or extrusion between two portions of the amount of metal does not exceed a specified time. Advantageously, a maturation period at room temperature is observed before testing the functional characteristics of a sample extracted from a batch. The ripening period makes it possible to reduce the dispersion of the measurement of the functional characteristics of the semi-finished product. According to one embodiment, the test of the functional characteristics of the sample taken is a crushing test of a sample of length given by a press, during which the displacement of the crushing head of the press and the The forces applied by the crushing head of the press are recorded. According to another embodiment, the test of the functional characteristics of the sample taken is a tensile test of a sample. According to yet another embodiment, the functional characteristics test of the sample taken is a sample folding test. According to one possibility, the measured functional characteristic of the sample taken during the crushing test is the value of the maximum force to be exerted on the half-product to obtain a deformation of the half-product corresponding to a predetermined displacement. According to another possibility, the measured functional characteristic of the sample taken during this same test is the value of the energy absorbed to obtain a deformation of the half-product corresponding to a predetermined displacement. Thanks to the provisions of the two possibilities described above, the manufacturing process makes it possible to prevent the overrun of a target effort and to reduce the associated energy dispersion. According to yet another possibility, the measured functional characteristic of the sample taken during the test is a mechanical characteristic representative of the tensile behavior of the yield strength type, breaking load and / or elongation.

  According to yet another possibility, the measured functional characteristic of the sample taken during the test is a mechanical characteristic representative of the bending behavior of the bending limit angle type.

  Advantageously, the conditions of the heat treatment of income determined according to the results of the test are at least a pair of treatment time and treatment temperature.

  According to one embodiment, the temperature and the duration of the treatment are determined in:

  - choosing the value of one of the two conditions,

  taking into account the measured value of the functional characteristic of the sample taken and the target value of the characteristic,

  mapping these values to reference curves to determine the second condition.

  Advantageously, the relationship between the duration of the heat treatment of income At, the temperature T during this treatment, the measured value of the functional characteristic Cm and the desired value of the functional characteristic Cc, is calculated by the following formula: Cc ù Cm 20 At =, the parameters a, b and c being constants determined aT + bT + c

empirical.

  According to one embodiment, the semi-finished products are intended for the manufacture of shock absorbers of an energy absorption system of the "automobile bumper" type, providing the interface between a bumper beam. -chocs and others

  25 components of the body structure.

  According to another embodiment, the semi-finished products are intended for the manufacture of bumper beams.

  In any case, the invention will be better understood from the description which follows, with reference to the appended diagrammatic drawings showing, by way of nonlimiting example, two embodiments of this method. DESCRIPTION OF THE FIGURES FIG. 1 is a flowchart showing the steps of a first method according to the invention.

  FIG. 2 represents an exemplary section of a profile manufactured by the method of FIG. 1. FIG. 3 represents the evolution of a force applied to a sample as a function of displacement during a bundling test.

  FIG. 4 represents the evolution of the maximum force of a profile as a function of the duration of a heat treatment of income and the temperature of this treatment. FIG. 5 represents the evolution of the force applied on a batch of bumper assemblies according to the state of the art as a function of a displacement during a bunching test. FIG. 6 represents the evolution of the force applied to a batch of bumper assemblies comprising profiles obtained by the method of FIG. 1 as a function of displacement during a bunching test. FIG. 7 represents the evolution of the breaking load of a profile as a function of the duration of a heat treatment of tempering and the temperature of this treatment, the curves thus formed being used in a second method according to FIG. invention. FIG. 8 represents the evolution of the elastic limit of a profile as a function of the duration of a heat treatment of tempering and the temperature of this treatment, the curves thus formed being used in a third method according to FIG. 'invention.

Description of the invention

  According to a first embodiment of the invention described in FIG. 1, a method of manufacturing an aluminum alloy profile comprises, in known manner, the following steps: an electrolysis step E1 to produce aluminum - a step E2 of the foundry metal, consisting in particular of the addition of alloying elements to aluminum, for example Mg magnesium, Mn manganese or Si silicon, - a step casting of the metal E3 to form billets, - a preheating step E4 of the billets, - a cutting step E5 of the billets, - a spinning / extruding step E6 of the metal through a die with the aid of a press to obtain the desired section of the profiles, - an optional step of quenching E7 with air or with water, - a step of cutting profiles E8. According to this first embodiment, the aluminum alloy used complies with the EN AW-6060 standard. The section of the profile is shown in FIG.

  The outer shape of the section is a hexagon, the midpoints of three sides of the hex being joined by three partitions meeting at the center of the hexagon. After the extrusion step E6, the cutting step E8 or the quenching step E7, the obtained sections are put on hold at ambient temperature for a predetermined period constituting a so-called ripening step E9.

  This ripening step preferably lasts at least two days. According to the first embodiment of FIG. 1, this maturation stage lasts from three to five days. In known manner, the profiles subsequently undergo a heat treatment step in an oven, said step of income.

  However, in the method according to the invention, the complementary steps below are provided before the income step. In a subsequent step E10 sampling, the profiles are constituted in batches L, each batch comprising a set of profiles having common manufacturing parameters.

  In particular, according to the first embodiment of FIG. 1, all the sections of the same batch L are: (a) derived from the same alloy and the same casting, (b) produced on a same extrusion press, (c) made through the same die, and (d) from the extrusion of the same quantity of metal whose mass is limited and for which the interruption of the extrusion between two portions of the billet do not exceed a fixed period. If one of the conditions (a) to (d) is no longer respected, a change of batch is made.

  It should be noted that the limited mass of metal is of the order of a ton or ten tons, and that the duration not to be exceeded for the interruption between two portions of billet is of the order of magnitude of the minute. During the sampling step, a sample e is taken from each batch of profiles comprising for example a profile.

  In a next functional characteristic test step El 1, at least one functional characteristic of the sample e is measured.

  For example, the measured functional characteristic Fm of the profile taken during the test is the value of the maximum force Fm or maximum force to be exerted on the profile to obtain a deformation of the profile corresponding to a predetermined displacement do.

  Still according to this example of implementation, the test used to measure the functional characteristics of the profile taken is a bundling test. FIG. 3 gives an example of the type of curves obtained during a bunching test which consists in the overwriting of a sample e of a given length of the profile. The sample e is deposited on a press so that the latter can apply a compressive force in one direction. The base on which it rests on the press is flat and orthogonal to the crash direction. During the crushing, the displacement d of the crushing head of the press and the applied forces F by the crushing head of the press are recorded. The maximum effort Fm of the crash test corresponds to the first peak or local maximum of the curve representing the crushing force F of the press as a function of the displacement d of the press head. It is usually picked up in the first moments of the crash test. In the curve of FIG. 3, the value of the maximum force Fm is of the order of 95 kN, ie 95000 N.

  It should be noted that the energy absorbed by the profile during the measurement corresponds to the area under the curve, that is to say to the integral of the curve. In order to be able to compare the crush tests with each other, it is useful to set a maximum displacement value of the head of the press. In a next step of determining E12 conditions of the revenue step, a desired target value is taken into account for each functional characteristic whose value is measured in the test step. In the first embodiment of FIG. 1, the target value Fc of the maximum force for the profile is taken into account. The conditions of the income step are then determined as a function of the measured value Fm and a target value Fc of the functional characteristics. The conditions of the heat treatment determined are at least a pair of duration At / temperature T. The determination can in particular be made by considering the measured value Fm of the functional characteristic of the section taken and the target value Fc of the characteristic, and then by correlating these values or calculated deviation E of its values and empirically derived reference curves in order to propose a suitable heat treatment in terms of time and temperature.

  A set of possible configurations of durations and temperatures is thus obtained. By choosing a given temperature or time value, the value of the other condition is derived from the curves.

  FIG. 4 shows reference curves making it possible to describe the evolution of the force Fm as a function of the temperature T and the duration of the heat treatment t. In particular, three line segments represent the evolution of the maximum force Fm for three temperatures T1, T2, T3 respectively corresponding in

the example at 100, 110 and 120 C.

  By choosing a temperature value T3, if the value of the measured effort Fm is 95000 N and the desired value Fc is 100000 N, it appears by plotting these values on the curve that the necessary duration of income At is the order of 8 hours.

  The relationship expressed by the curves shown in FIG. 4 between the duration of the heat treatment of income At, the temperature T during this treatment, the measured maximum force Fm and the desired maximum force Fc can be calculated also by the formula following: Fc ù Fm 4t =, the parameters a, b and c being constants determined aT + bT + c

Empirically.

  The duration of the heat treatment of income At is expressed in hours (h), the temperature T during this treatment in degrees Celsius (C), the measured force Fm and the desired force Fc in Newton (N). In particular, according to the first embodiment of FIG.

  For a duration of the income stage of between 0 and 7 h, and a temperature of between 100 ° C. and 135 ° C., and for the geometry according to FIG. 2, the values of these constants are as follows:

a = 1.74

b = -328

30 c = 16012

  Once the conditions of the heat treatment of the income stage are determined, in a subsequent step E13, the heat treatment thus defined is applied to all the batch L from which the sample e is derived.

  FIGS. 5 and 6 show the evolution of the force applied to a set of bumper assemblies as a function of a displacement during a bunching test, respectively: for a set of bumper assemblies formed from a batch of profiles obtained by a method according to the state of the art, and - for a batch of sets of bumpers comprising profiles obtained by the method according to the invention. In known manner, a set of bumpers comprises a beam, at least two shock absorbers or crashboxes connected by the beam, and plates 10 for fixing the absorbers on the vehicle body. It appears by comparison of the curves in FIGS. 5 and 6 that the method of manufacturing the profiles forming the shock absorbers makes it possible to prevent the exceeding of a target effort and to reduce the associated energy dispersion. The energy dispersion is halved and passes in the example illustrated by FIGS. 5 and 6 from 1600 to 800 J. It should be noted that the curves described with reference to FIG. 4, as well as the corresponding formula, are dependent on a given profile geometry and a type of alloy used. It is possible to easily determine new curves for a different geometry and / or a different alloy by subjecting a set of profiles to thermal tempering treatments with different conditions of time and temperature, then performing tests to determine corresponding maximum effort on each profile. This gives a set of points for drawing the desired curves. According to a variant of the first embodiment, the measured functional characteristic of the section taken during the test may be the value of the energy absorbed for a predetermined displacement or another critical functional characteristic in the functional response of the profile. According to a second embodiment, a method according to the invention is applied to the manufacture of a profile of the same type as that described for the first embodiment, and whose section is shown in FIG. However, in this second mode of implementation, the predominant functional characteristic chosen is the breaking load Rm, the characteristic test used being a static tensile test, which is well known to those skilled in the art. FIG. 7 shows reference curves for describing the evolution of the breaking load Rm of a profile as a function of the temperature T and II of the duration of the heat treatment t. In particular, three line segments represent the evolution of the load at break for three temperatures T1, T2, T3 respectively corresponding in the example to 100, 110 and 120 C.

  It is thus possible to determine the amount of time required to reach a target value of the breaking load as described for the first embodiment.

  The relation expressed by the curves shown in FIG. 7 between the duration of the heat treatment of income At, the temperature T during this treatment, the measured breaking load Rmn, and the desired breaking load Rm, can be

  Also calculated by the following formula: Rm, where Rm, n At = z, the parameters a, b and c being constants determined aT + bT + c

empirical.

  The duration of the heat treatment of income At is expressed in hours (h), the temperature T during this treatment in degrees Celsius (C), the load at break

  Measured Rm ,,, and the desired breaking load Rm, in Mega Pascal (MPa).

  In particular, according to the second embodiment, for a duration of the income stage of between 0 and 7h, and a temperature of between 100 C and 135 C, the values of these constants are as follows:

a = 0.0018

20 b = -0.3143

c = 14.545

  As previously for the first embodiment, once the conditions of the heat treatment of the tempering stage are determined, in a next step, the heat treatment thus defined is applied to all the batch L of which

25 is the sample e.

  According to a third embodiment, a method according to the invention is applied to the manufacture of a profile of the same type as that described for the first embodiment, and whose section is shown in Figure 2. However, in this third mode of implementation, the predominant functional characteristic

  30 is the elastic limit Rpo, 2 denoted Rp subsequently, the characteristic test used being also a static tensile test.

  FIG. 8 shows reference curves making it possible to describe the evolution of the elastic limit Rp of a profile as a function of the temperature T and the duration of the heat treatment t. In particular, three line segments represent the evolution of the elastic limit Rp for three temperatures Ti, T2, T3 respectively corresponding in the example to 100, 110 and 120 C.

  It is thus possible to determine the income time necessary to reach a target value of the yield strength as described for the first embodiment.

  The relationship expressed by the curves shown in FIG. 8 between the duration of the heat treatment of income At, the temperature T during this treatment, the measured yield strength RN, and the desired yield strength Rp, can also be calculated. by the following formula: Rpc ù Rpm At =, the parameters a, b and c being constants determined in a '+ bT + c' manner

empirical.

  The duration of the heat treatment of income At is expressed in hours (h), the temperature T during this treatment in degrees Celsius (C), the measured elastic limit Rp ,,, and the desired elasticity limit Rpc in Mega Pascal (MPa).

  In particular, according to the third embodiment, for a duration of the revenue stage of between 0 and 7h, and a temperature between 100 C and 135 C, the values of these constants are as follows:

a = 0.0035

b = -0.697

c = 35.135

  According to a fourth mode of implementation, a manufacturing method according to the invention is applied to the manufacture of aluminum alloy sheets by rolling. This method comprises a step of rolling between two rolls of a rolling mill of an aluminum alloy mass and a quenching heat treatment, hereinafter referred to as quenching, to obtain a sheet.

  In known manner, the sheets subsequently undergo, as previously described in the first embodiment, a step of heat treatment in an oven, said step of income.

  As we have seen above for the first to third embodiments, complementary steps are provided before the revenue step. Thus, the method comprises a sampling step, in which the

  sheets are constituted in batches L, each batch comprising a set of sheets having common manufacturing parameters.

  In particular, all the sheets of the same batch L are: (a) derived from the same alloy and the same casting, (b) produced on the same rolling mill, (c) made through the same rolling mill rolls, and (d) resulting from the rolling and quenching of the same quantity of metal whose mass is limited and for which the interruption of rolling and / or quenching does not exceed a predetermined period. If one of the conditions (a) to (d) is no longer respected, a change of batch is made. During the sampling step, a sample e is taken from each batch of sheets comprising, for example, a sheet. In a next functional characteristic test step, at least one functional characteristic of the sample e is measured. In particular, in this fourth embodiment, the measured functional characteristic is a bending limit angle A, representative of the bending behavior of the sheet. The test used to measure this characteristic is a bend or bend test. This test consists in making a cut of test pieces in one or more sheets, preferably of square shape, to identify the direction of rolling, to choose a folding test in the long direction or in the cross direction with respect to the direction of 20 rolling, and position it on a test bench, comprising: - two horizontal cylinders on which the test piece is placed, the air gap between the rolls being a function of the thickness of the sheet, and - a punch intended to form localized support on the specimen, between the two cylinders, to cause a folding of the specimen between the cylinders. The criteria for stopping the test are: penetration of the punch to a predefined depth, for example of the order of 15 mm, or force drop of a predetermined value, for example 15 N after observing maximum effort. When the test is stopped, the bend limit angle A formed by the sample is measured using a protractor. As a result of the test step, it is thus possible to determine the necessary income time to reach a target value of the bending limit angle Ac from a measured value Am for the batch of sheets using curves obtained in a manner similar to those described for the first embodiment.

  Of course, whatever the mode of implementation, a sample e may comprise several test pieces. Similarly, several samples e from separate L batches can give the same results in the test El 1. In this case, it is possible to collect these batches in a set to which will be applied the same heat treatment income. As goes without saying, the invention is not limited to the preferred embodiments described above, by way of non-limiting examples; on the contrary, it embraces all variants. Other applications of the process, apart from the manufacture of shock absorbers or bumper beams, are also possible. In particular, it is possible to manufacture profiles or sheets of aluminum alloy intended to form door reinforcements or side reinforcements, anti-intrusion rails, longitudinal members, and in general, all the profiles or sheets of aluminum alloy. aluminum whose predominant functional characteristic is a static mechanical characteristic of the yield strength type, breaking load and / or elongation or whose predominant functional characteristic is the bending behavior, for example the bending limit angle. Depending on the applications, the functional characteristic tests may be adapted to the type of semi-finished product used or the functional characteristic to be measured.

Claims (15)

  1. A method of manufacturing a half-product: consisting of a sheet or a profile of aluminum alloy, intended in particular to form a motor vehicle structure component for the absorption of energy irreversibly when collision against an obstacle or shock, comprising the steps of: - a step of manufacturing the semi-finished product, consisting of rolling and quenching or extrusion (E6) of aluminum alloy in order to obtain a half-product, a step of semi-product (E13) heat treatment, characterized in that, before the revenue step (E13), a sample (e) is taken (ElO) from a batch (L ) comprising a set of half-products having common manufacturing parameters, in order to undergo a test (El 1) of at least one of its functional characteristics (F), the conditions (T, At) of the income stage (E13) being determined (E12) as a function of the measured value (Cm Fm, Rm ,,,, Rp ,,,, Am) during the test (El 1) and a target value (Cc, Fc, Rmc, Rp ,. Ac) of the at least one functional characteristic (F), the heat treatment stage of income (E13) being applied under the conditions (T, At) determined to the whole batch (L) from which is derived the sample (e).   2. The manufacturing method according to claim 1, wherein all the semi-products of the same batch (L) is derived from the same alloy and the same casting (E3) of this alloy.   3. The manufacturing method according to one of claims 1 or 2, wherein all the semi-products of the same batch (L) is produced on the same rolling mill or the same extrusion press.   4. The manufacturing method according to one of claims 1 to 3, wherein all the semi-products of the same batch (L) is made through respectively the same rolling mill rolls or the same die. 35   5. Manufacturing process according to one of claims 1 to 4, wherein all of the semi-products of the same batch (L) is respectively from either lamination and quenching or extrusion of a the same amount of metal whose mass is limited and for which the interruption respectively is rolling and / or quenching or extrusion between two portions of the amount of metal does not exceed a predetermined period.   6. The manufacturing method according to one of claims 1 to 5, wherein a maturation period at room temperature (E9) is observed before the test (El 1) of the functional characteristics of a sample (e) extracted from a lot (L). 10   7. The manufacturing method according to one of claims 1 to 6, wherein the test (El 1) of the functional characteristics of the sample (e) taken is a crushing test of a sample (e) of given length. by a press, during which the displacement (d) of the crushing head of the press and the applied forces (F) by the crushing head of the press are recorded. 15   8. The manufacturing method according to one of claims 1 to 6, wherein the test (El 1) of the functional characteristics of the sample (e) taken is a tensile test of a sample (e). 20   9. The manufacturing method according to one of claims 1 to 6, wherein the test (E 11) of the functional characteristics of the sample (e) taken is a bend test of a sample (e).   10. The manufacturing method according to one of claims 1 to 7, wherein the measured functional characteristic of the sample (e) taken during the test (El 1) is the value of the maximum effort (Fm) to be exerted on the half-product to obtain a deformation of the half-product corresponding to a predetermined displacement (do). 30   11. The manufacturing method according to one of claims 1 to 7, wherein the measured functional characteristic of the sample (e) taken during the test is the value of the energy absorbed to obtain a deformation of the half-product corresponding to a predetermined displacement (do). 35   12. The method of manufacture according to one of claims 1 to 6 and claim 8, wherein the measured functional characteristic of the sample (e) taken during the test is a mechanical characteristic representative of the tensile behavior of the limit type of elasticity (Rp). breaking load (Rm) and / or elongation.   13. The manufacturing method according to one of claims 1 to 6 and claim 9, wherein the measured functional characteristic of the sample (e) taken during the test is a mechanical characteristic representative of the bending behavior of the angle limit type. folding (A).   14. The manufacturing method according to one of claims 1 to 13, wherein the conditions of the heat treatment of income (E13) determined according to the test results (E11) are at least a pair of treatment duration (At) and temperature treatment (T).   15. A method of manufacturing a semi-finished product according to claim 14, wherein the temperature (T) and the duration of the treatment (At) are determined by: - choosing the value of one of the two conditions (T, At ), taking into account the measured value (Fm, Rmm, Rp ,,,, Am) of the functional characteristic of the sampled sample and the target value (Fc, Rm ,, Rp ,, Ac) of the characteristic, - matching these values and reference curves to determine the second condition (T, At). 19. A method of manufacturing a half-product according to claim 14, wherein the relation between the duration of the heat treatment of income At, the temperature T during this treatment, the measured value of the functional characteristic Cm and the desired value of the functional characteristic Cc is calculated by the following formula: Cc ùCmAt = =, the parameters a, b and c being constants determined empirically as aT` + bT +. 20. Method according to one of claims 1 to 16, wherein the semi-finished products are intended for the manufacture of shock absorbers of an energy absorption system type "automotive bumper", ensuring the interface between a bumper beam and the other components of the body structure. 1518. Method according to one of claims 1 to 16, wherein the semi-finished products are intended for the manufacture of bumper beams.