1、NF L06-832fvrier 2008Ce document est usage exclusif et non collectif des clients Saga Web.Toute mise en rseau, reproduction et rediffusion, sous quelque forme que ce soit,mme partielle, sont strictement interdites.This document is intended for the exclusive and non collective use of Saga Web custome
2、rs.All network exploitation, reproduction and re-dissemination,even partial, whatever the form (hardcopy or other media), is strictly prohibited.Saga Web Pour SHANGHAI INTERNAT SCIENCE painting. 2 NFL 06-832C Sommaire Page0 Avant-propos.21 Objet et domaine dapplication32 Rfrences normatives.33 Terme
3、s et dfinitions44 Procds de grenaillage de prcontrainte conventionnel65 Technique de grenaillage.76 Contrle des pices grenailles87 Recommandations et rgles gnrales10Annexe A (normative) prouvettes type Almen13Annexe B (normative) Schma de lappareil de mesure.15Annexe C (normative) Courbe de saturati
4、on.16Annexe D (informative) Analyse de saturation Almen17Annexe E (informative) Exemple de dtermination pratique du point de contrle priodique partir de la courbe de saturation.19Annexe F (informative) Illustrations de lvolution des diffrents taux de recouvrement20Annexe G (informative) Mthode pour
5、dtermination du temps de base.240 Avant-propos Il existe deux types de grenaillage : le grenaillage de prcontrainte conventionnel et le grenaillage par ultrasons (trait dans la norme NF L 06-833). Le grenaillage destin crer des contraintes superficielles de compression consiste en un traitement de s
6、urface ralis par action mcanique, dont les effets doivent tre contrls et reproductibles. Il est important de noter que cette opration ne doit pas tre confondue avec certaines oprations de formage par grenaillage (peen forming) ou redressage de pices (peen straightening), ni de projetage effectues po
7、ur prparer, conditionner ou nettoyer des surfaces de pices pour dautres applications notamment de : rechargement : mtallisation, plastification ; peinture. NF L 06-832C 3 1 Scope and field of application The purpose of this standard is to indicate the conditions in which shot peening for inducing su
8、perficial compressive stresses shall be performed, the methods and the technique to be used, on the one hand, and to specify the measures to be taken and the operations to be carried out for monitoring shot peening, on the other hand. The surface treatment using shot peening, which is the subject of
9、 this standard, applies to parts which are highly stressed, for which improving or restoring the serviceability characteristics is desired. By delaying or avoiding crack initiations, shot peening increases the fatigue behaviour, stress corrosion behaviour, corrosion fatigue behaviour, fretting fatig
10、ue behaviour and fretting corrosion behaviour. Considering the noticeable improvements it brings about, shot peening as defined is recommended as a treatment prior to surface treatments which normally induce tensile stresses and also as a treatment after manufacturing operations which may cause tens
11、ile stress or a condition detrimental to fatigue behaviour. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document ap
12、plies (including any amendments). EN ISO 1207, Slotted cheese head screws Product grade A (classification index: E 25-127). EN ISO 4288, Geometrical Product Specifications (GPS) Surface texture: Profile method Rules and procedures for the assessment of surface texture (classification index: E 05-054
13、). EN ISO 4762, Hexagon socket head cap screws (classification index: E 25-125). EN ISO 7380, Hexagon socket button head screws (classification index: E 25-126). NF L 06-831, Aerospace series Metallic parts Inducement compressive surface stresses Steel shot, glass beads and ceramic beads.NF L 06-833
14、, Aerospace series Ultrasonic shot peening for inducement of compressive surface stresses for metallic parts. 1)NF L 06-835, Aerospace series Metallic parts Inducement compressive surface stresses Steel shot cut wire (spherical).SAE AMS-S-13165, Shot peening of metal parts.SAE J442, Test Strip, Hold
15、er, and Gage for Shot Peening.XP A 09-285, Non destructive testing Test methods for residual stress analysis by x-ray diffraction. 1) In preparation. 3 NFL 06-832C 1 Objet et domaine dapplication La prsente norme a pour objet dune part, dindiquer les conditions suivant lesquelles doit tre effectu le
16、 grenaillage de prcontrainte conventionnel destin crer des contraintes superficielles de compression, les moyens et la technique utiliser et dautre part, de prciser les dispositions prendre et les oprations effectuer pour contrler lopration de grenaillage de prcontrainte. Le traitement de surface pa
17、r grenaillage de prcontrainte conventionnel, objet de cette norme, sapplique des pices fortement sollicites dont on veut amliorer ou restaurer les caractristiques de tenue en service. En retardant ou en vitant lamorage de fissures, le grenaillage de prcontrainte conventionnel augmente la tenue en fa
18、tigue, en corrosion sous tension, en fatigue corrosion, en fretting fatigue, et en fretting corrosion. Compte tenu des amliorations sensibles quil apporte, le grenaillage de prcontrainte conventionnel ainsi dfini est recommand comme traitement pralable aux traitements de surface qui induisent normal
19、ement des contraintes de traction et galement comme traitement postrieur aux oprations de fabrication qui peuvent provoquer un tat de contrainte de traction ou un tat prjudiciable la tenue en fatigue. 2 Rfrences normatives Les documents de rfrence suivants sont indispensables pour lapplication du pr
20、sent document. Pour les rfrences dates, seule ldition cite sapplique. Pour les rfrences non dates, la dernire dition du document de rfrence sapplique (y compris les ventuels amendements). EN ISO 1207, Vis mtaux tte cylindrique fendue Grade A (indice de classement : E 25-127). EN ISO 4288, Spcificati
21、on gomtrique des produits (GPS) tat de surface : Mthode du profil Rgles et procdures pour lvaluation de ltat de surface (indice de classement : E 05-054). EN ISO 4762, Vis tte cylindrique six pans creux (indice de classement : E 25-125). EN ISO 7380, Vis tte cylindrique bombe plate six pans creux (i
22、ndice de classement : E 25-126). NF L 06-831, Srie arospatiale Pices mtalliques Mise en contrainte de compression superficielle Billes dacier, billes de verre et billes de cramique (grenailles sphriques).NF L 06-833, Srie arospatiale Grenaillage par ultrasons destin la mise en contrainte de compress
23、ion superficielle de pices mtalliques. 1)NF L 06-835, Srie arospatiale Pices mtalliques Mise en contrainte de compression superficielle Billes dacier, sphriques en fil coup rod (Grenailles sphriques).SAE AMS-S-13165, Shot peening of metal parts.SAE J442, Test Strip, Holder, and Gage for Shot Peening
24、.XP A 09-285, Essais non destructifs Mthodes dessais pour lanalyse des contraintes rsiduelles par diffraction des rayons X. 1) En prparation. NF L 06-832C 4 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1shot peening shot peening consists in
25、inducing residual compressive stresses into superficial layers of materials by means of impacts distributed over the surface to be treated as evenly as possible These impacts are obtained from the kinetic energy effect of calibrated balls projected on to the surface to be treated in a controlled man
26、ner using machines acting:either by throw-off with turbine machines; or by pressurized fluid flow: jet peening with nozzle machines. 3.2Almen deflection (Almen arc height) this is the deflection (arc height) of a calibrated steel plate secured to a standardized device (see Annex A) and a side of whi
27、ch is exposed to the shot peening The Almen deflection (arc height) is measured in hundredths of a millimetre on the non peened side by slightly translating the specimen from the left to the right in order to find the maximum deflection (arc height). Each specimen is only used once. This plate, the
28、size and material of which are standardized is called the Almen specimen (N, A or C types). The deflection (arc height) is measured with a suitable and standardized device (see Annex B). Other similar devices are described in SAE AMS-S-13165 and SAE J442 standards. In the case of a specimen with an
29、initial deflection (arc height) remaining within the tolerance (see Annex A), the convex side of the specimen is exposed to the shot peening. The repeatability of the deflection (arc height) measurements can be improved by reducing the tolerance of the hardnesses and/or the initial Almen specimen de
30、flections (arc height) through selection when receiving. The repeatability of the deflection (arc height) measurements can also be improved by subtracting the initial deflection (arc height) from the measured result. 3.3definition of Almen specimens for peening monitoring type of specimens used: 3 t
31、ypes N - A - C, determined by their thickness characteristics: see Annex A indicative utilization limits: Type N: up to an intensity of F 30 N Type A: from an intensity of F 10 A up to one of F 60 A Type C: above an intensity of F 10 C For information, a correspondence between these three Almen inte
32、nsity ranges is given in Clause A.1. 3.4measuring device description of the measuring instrument: see diagram in Annex B. 3.5saturation curve the saturation curve is obtained by measuring the variation of the Almen deflection (arc height) according to the exposure time 2) with constant shot peening
33、parameters and conditions 2) Shot peening time in units of time, number of passes, number of cycles, etc. 4 NFL 06-832C 3 Termes et dfinitions Pour les besoins du prsent document, les termes et dfinitions suivants sappliquent. 3.1grenaillage de prcontrainte conventionnelle grenaillage de prcontraint
34、e conventionnel consiste introduire des contraintes rsiduelles de compression dans les couches superficielles des matriaux au moyen dimpacts rpartis le plus uniformment possible sur la surface traiter Ces impacts sont obtenus par leffet de lnergie cintique de billes calibres qui sont projetes de fao
35、n contrle sur la surface traiter laide de machines agissant : soit par projection centrifuge avec machines turbines ;soit par coulement de fluide sous pression : grenaillage par jets avec machines buses. 3.2flche Almen (hauteur darc Almen) cest la flche (hauteur darc) que prend une plaquette dacier
36、calibre fixe sur un dispositif normalis (voir Annexe A) et dont une face est expose au jet de grenailles La flche Almen (hauteur darc) se mesure en centimes de millimtre sur la face non grenaille en translatant lgrement de gauche droite lprouvette pour trouver la flche maximale (hauteur darc). Chaqu
37、e prouvette nest utilise quune fois. Cette plaquette de dimensions et matire normalises sappelle prouvette Almen (types N, A ou C). La flche (hauteur darc) est mesure avec un dispositif adapt et galement normalis (voir Annexe B). Dautres dispositifs proches sont dcrits dans les normes SAE AMS-S-1316
38、5 et SAE J442. Dans le cas dune prouvette prsentant une flche initiale (hauteur darc) et restant dans la tolrance (voir Annexe A), on expose au jet de grenailles la face convexe de lprouvette. La rptabilit des mesures de flche (hauteur darc) peut tre amliore en rduisant la tolrance des durets et/ou
39、des flches initiales (hauteur darc) des prouvettes Almen par slection lors de la rception. La rptabilit des mesures de flche (hauteur darc) peut galement tre amliore en retranchant dans le rsultat mesur la valeur de la flche initiale (hauteur darc). 3.3dfinition des prouvettes Almen de contrle du gr
40、enaillage types dprouvettes utilises : 3 types N - A - C, dtermins par leur paisseur caractristiques : voir Annexe A limites dutilisation indicatives : Type N : jusqu une intensit F 30 N Type A : de lintensit F 10 A lintensit F 60 A Type C : au-dessus dune intensit F 10 C titre indicatif, une corres
41、pondance entre ces trois gammes dintensit Almen est donne lArticle A.1. 3.4dispositif de mesure description de lappareil de mesure : voir schma en Annexe B 3.5courbe de saturation la courbe de saturation est obtenue en mesurant la variation de la flche Almen (hauteur darc) en fonction du temps dexpo
42、sition 2) paramtres et conditions de grenaillage constants 2) Temps de grenaillage, nombre de passes, nombre de cycles, etc. NF L 06-832C 5 This curve is used to define the saturation point S. It is essential to plot it to determine the Almen intensity with a minimum of 4 points of which at least on
43、e is located before the S point (origin not included).The saturation curve shall have a shape close to that indicated in Annex C. In particular, it shall have a clear slope change immediately before the S point. 3.6saturation time the saturation time ts is the first time t such that at time 2t the d
44、eflection (arc height) variation is equal to or less than 10% of the deflection (arc height) at time t, by making sure that the coverage is complete and homogeneous over the complete surface of the Almen specimen. NOTE A method for analysing the Almen saturation is attached in Annex D (for informati
45、on). 3.7Almen intensity this is the value of the deflection (arc height) obtained at time ts on the saturation curve It is expressed in hundredths of a millimetre, is preceded by the letter F, and followed by the Almen specimen designation. EXAMPLE 1 F 25 ALetter F ValueType of Almen specimen NOTE T
46、he absence of F refers to the American system where the unit for measuring Almen intensity is in thousandths of inches, for example: intensity 12 N: 12 deflection (arc height) of 0.012 inches N type N specimen. The Almen intensity shall be located between the specified boundary values. EXAMPLE 2 F 2
47、0/30 ALetter F Min./max. value Type of Almen specimen The Almen intensity does not characterize the value of the stresses induced in the material of the part to be shot peened, it is only used for shot peening machine adjustments. 3.8 Coverage rate 3.8.1coverage the coverage is related to the distribution and to the quantity of marks result
