National Standard of the People's Republic of China. l:f:l~a~~~~ ~*t~ft. Steel Forgings-Method for Ultrasonic Testing

Transcription

1 ICS H26 National Standard of the People's Republic of China l:f:l~a~~~~ ~*t~ft GBff Replacing GBff Steel Forgings-Method for Ultrasonic Testing Issue on: May 13, 2008 Implemented on: November 1, 2008 Issued by General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Standardization Administration of the People's Republic of China

2 Foreword This standard is modified in relation to EN :1998 "Non-destructive Testing of Steel Forgings-Part 3: Ultrasonic Testing offerritic or Martensitic Steel Forgings" and EN "Nondestructive Testing of Steel Forgings-Ultrasonic Testing of Austenitic and Austenitic-Ferritic Stainless Steel Forgings" (English edition). This standard was redrafted according to EN :1998 and EN :1999. In order to convenient for comparison, it lists out reference schedule of this standard and EN standard clauses in Appendix A (Informative). When this standard adopting EN standard, it makes some revisions, these technical differences is marked in page margin of clauses it concerned to with vertical mongline. It presents schedule for technical difference and reasons in Appendix B. In order to be convenient for usage, this standard also makes the following editing and technical revisions: --It deletes two forewords of EN standard; --It merges scopes ofltem 1 in EN and Item 4 in EN and adds: forgings in other organizations may also be used referring to this; --Staff qualification and verification are changed to be: it shall make qualification training according to GB/T 9445 or corresponding standards and obtain certificate of competency; --It adds concrete content required by EN probe shoe cited in EN in of this standard; --It merges recording level and acceptance standard in Part 3 and Part 4 of EN and simplifies to form quality level table of recording level and acceptance standard in this standard; --This standard deletes DGS method and all the content related to DGS in of the two Parts of EN It is replaced with bottom echo reflection method and adds corresponding AppendixE; --It deletes Appendix Z in EN ; --EU standards in normative documents of EN are all replaced by corresponding national standards in this standard. This standard replaces GB/T "Steel Forgings-Method for Ultrasonic Examination". Comparing with former GB/T , this standard has the following characteristics: --Test method is same with former standard, but it adopts EU standard mode in structural arrangement. -Classification and quality levels of the forgings are more detailed. Appendix A, Appendix B, Appendix C, Appendix D and Appendix E of this standard are Informative. This standard was proposed by China Iron and Steel Association.

3 Steel Forgings-Method for Ultrasonic Testing 1 Scope. This standard specifies term of an agreement for steel forgings-ultrasonic testing, editing of operation specifications, staff qualification, equipment, and Appendix, calibration and checking, testing time, surface condition, sensitivity, scanning, classification, recording level and acceptance standard. This standard is applicable to ultrasonic pulse-echo handiwork test method for Ferritic-Martensitic steel forgings, Austenitic and Austenitic-Ferritic stainless steel forgings. By the negotiation between the parties, it may also use mechanization scanning method with immersion method testing. Other organizational forgings may also be used by referring to. This standard divides forgings into 4 types according to shapes and manufacturing methods. Types 1, 2 and 3 are forgings with simple shape and type 4 is forgings with complicated shape. This standard is not applicable to compact stamp work, turbine rotor and engine forgings. 2 Normative References The following normative documents contain provision which, through reference in this text, constitute provisions of this national standard. For dated reference, subsequent amendments to, or revision (excluding error content) of, any of these publications do not apply. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated references, the latest edition of the normative document referred to applies. GB/T 9445 "Non-destructive Testing-Qualification and Certification of Personnel" (GB/T , ISO 9712:1999, IDT) GB "Ultrasonic Angle Beam Examinations by the Contact Method" GB/T "Non-destructive Testing-Terminology-Terms Used in Ultrasonic Testing" GB/T "Non-destructive Testing-Ultrasonic Inspection-Characterization of Search Unit and Sound Field" [GB/T , eqv ISO 10375:1997(E)] GB/T "Non-destructive Testing-Ultrasonic Testing-Calibration Block No.1" (GB/T , eqv ISO 2400:1972) JB/T 4009 "Recommended Practice for Ultrasonic Pulse-echo Straight-beam testing by the Contact Method" -JB/T 9214 "Practice for Evaluating Performance Characteristics of A Scope Ultrasonic Pulse Echo Testing Systems" JB/T "Commonly Used Specification for A-mode Ultrasonic Flaw Detector Using Pulse Echo Technique" 3 Terminologies and Definitions Terminologies and definitions determined in GB/T are applicable to this standard.

4 --Description for the testing equipment; ---Calibration and setting; --Scanning plan; --Description and sequence for testing operation; --Record/evaluation rating; - -Discontinuousness characteristic; --Acceptance standard; --Testing report. 6 Staff Qualification Staff qualification and verification shall be trained according to GB/T 9445 or corresponding standards and obtain certificate of competency. 7 Equipment and Accessory 7.1 Defectoscope It shall be defectoscope giving priority to A-scope presentation and it shall meet the requirement of JB/T Probe General Requirements Straight beam probe and transverse wave probe shall meet the requirement of GB/T If further information is required, other probes may also be used. But other probes cannot be used for initial discontinuousness testing and the probe shall also meet the requirement of GB/T Replica of Probe Shoe In order to avoid probe shaking, and ensure favorable and even acoustic coupling and keep constant sound beam angle with workpiece, it may install replica of probe shoe (see Figure 1). Probe shall be set with detection coverage and sensitivity on reference block with shape similar to the tested material. When longitudinal scanning is on convex surface, width Wps of probe shoe shall be larger than 1/10 of diameter D obj of the tested material. When lateral scanning, length lps of probe shoe shall be larger than 1/10 of diameter Dobj of the testecj material. When scanning on concave surface, it also requires installing replica of probe shoe, unless diameter of concave surface is too large and it can obtain appropriate coupling Nominal Frequency Probe nominal frequency is within scope of l.omhz~6.0mhz Straight Beam Probe 3

5 --Material with similar acoustic characteristic with the tested material. Note: Size stipulation for reference block reflector is as follows: Ferrite-Martensitic forging steel is in accordance with those specified in Table 4; sizes of Austenitic and Austenitic-Ferritic stainless steel forgings is in accordance with those specified in Table 5 and Table 6. Reflectors with different sizes are for verification of testing sensitivity. 7.5 Couplant Couplant shall be used exactly. When checking, setting sensitivity and making scanning and discontinuousness evaluation, it shall use couplant with same type. After the testing, if couplant may influence the following production, integrity of testing process or finished product, it shall be purged and cleaned. Note: It may use appropriate couplant: such as (with or without anticorrosive composition or emollient), grease, oil, glycerol and water quality paste. 8 General Calibrations and Checking Clustered aggregates ( defectoscope and probe) shall be calibrated and checked according to stipulation in JB/T Testing Time Ultrasonic testing shall be made after final heat-treatment, unless otherwise specified when ordering; forgings cannot be tested after final heat-treatment shall be made in some appropriate phase before this. Note: For cylindrical and rectangular forgings are about to be drilling, it shall be suggested to be made with ultrasonic testing before drilling. 10 Surface Conditions 10.1 General Requirements Scanning surface shall be without oil paint, surface of nonscale and dry-clean couplant shall be without roughness, or any other substance invoking coupling invalidation, impeding probe moving freely and causing misjudgments Surface Roughness Related to Quality Level Roughness Ra corresponding with surface of quality level 1 and level 2 is RaSI2.5µm; roughness Ra corresponding with surface phase of quality level 3 or higher level is RaS6.3µm Surface Condition of Forgings If surface condition of forgings can satisfy specified quality level, it may be tested. Note: When it is difficult to test forgings surface completely, it may use abrasive grit, sandblast or surface grinding to ensure acoustic coupling, usually, it is only applicable to quality level I. 11 Sensitivities 11.1 General Requirements Sensitivity shall ensure testing of minimal discontinuousness size required for recording level in the appointed quality level. 5

6 It shall use method in 11.2 and/or Determine scanning sensitivity with specific probe (see Chapter 4). Procedures used in all the conditions shall meet the requirement of JB/T Straight Beam Probe It may determine scanning sensitivity with one of the following methods Distance-amplitude curve (DAC) method with fundament is flat bottomed hole When the testing surface is parallel to the bottom surface or cylindrical surface and thickness or diameter is larger than 3 times of near-field region of the probe, it may be bottom-echo reflection method (see Appendix E) Transverse Wave Probe Use cross bore with diameter is 3mm through DAC method Repeat Testing state. If making repeat testing, method for determining sensitivity shall be the same with its initial 12 Scanning 12.1 General Requirements It shall make scanning of handiwork contact method with pulse-echo type, minimal scanning scope required shall be depended on forging types; whether to scan with grid scanning or 100% scanning, it shall be indicated in the contract. Table 1 Divides forgings into 4 types according to shapes and production methods of the forgings. Table 2 Present scanning regions of straight beam probe for forgings of types 1, 2 and 3. Table 3 Presents detail requirements for transverse wave probe scanning scope of forgings of types 3a and 3b, effective depth of transverse wave and circumferential direction scanning is restricted by probe angle and forgings diameter, ratio between outside diameter and inside diameter of forgings is less than 1.6 (see Appendix C) Complicated Forgings For complicated shape forgings or complicated part of the forgings (type 4) and forgings with minor diameter, when the parties are ordering, it shall negotiate scanning requirement and the content at least includes: probe angle, scanning direction and scanning scope (grid or 100% scanning) (see Chapter 4) Grid Scanning Table 3. Grid scanning shall use one or more probes reciprocating along grid line specified in Table 2 and When grid scanning is showing recordable indication, it shall make additional scanning around the indication to ensure its extension conditions % Scanning Coverage 6

7 AppendixE (Informative) Method Adopting Workpiece Bottom Echo Adjusting Sensitivity E.1 Find out the position in forgeable piece representing forging material state is in good condition, then adjust height of the first bottom surface echo to 40%-80% of the full amplitude to be act as benchmark for evaluating echoed signal. E.2 According to the requirement of the tested forgings makes adjustment from E.3 or E.4 act as detection sensitivity. E.3 When testing solid forgings, gaining numerical value requires improving is calculated according to formula (E.1 ): 2 }.,T A= 201 g mj.2 (E.l) Where A--Gaining value requires improving, unit is decibel (db); T--Thickness or diameter of the tested part, unit is millimeter (mm); d--diameter of flat bottomed hole, unit is millimeter (mm);..t--wavelength, unit is millimeter (mm); n-----circumference ratio. E.4 When testing forgings with center hole, gaining numerical value requires improving is calculated according to formulate (E.2): A= }.,T -101 g mi.2 g R (E.2) Where R----Outside diameter of the tested part, unit is millimeter (mm); r--inside diamet~r of the tested part, unit is millimeter (mm). 19