ISO TR 4956:1984 download free.Wrought steels for use at elevated temperatures in engines.
1 Scope
1.1 This Technical Report covers tech.iical delivety iequirernenLs and technical information for wrought steels supplied for parts such as bolts, blades, discs or casings in stationary or non-stationary turbines required to withstand relatively high mechanical trcss at elevated temperatures (above about 400 °C) and additionally corrosive attack by hot gases.
NOTE — Other steel types exist which are used mainly for large engine parts; these steel types are not covered by this Technical Report, since they are sold mainly to pcopnetoc specifications only.
1.2 Unless otherwise stated, this Technical Report is applicable to blooms, billets, bars, forgings, strip, sheet, plates and wire in the delivery conditions given in 4.2.
1.3 International Standards exist for heat-resisting steels (see ISO 4955)1), valve steels for internal combustion engines (see ISO 683/15), and steels for use on and with pressure vessels and boilers (see ISO 2604/1 to 6).
2 References
ISO/R 79, Bnnell hardness test foe’ steel
ISO/R 81, Vickers hardness test for steel (load 5 to 100 kgfJ.
ISO 82, Steel- Tensile testing.
ISO 88, Steel- Tensile testing of sheet end sttip less than 3 mm and not less than 0,5 mm thick.
ISO 89, Steel- Tensile testing of iwe.
ISO 148, Steel-Charpy impact rest (V-notchl. ‘
ISO/R 377, Selection and preparation of samples and test pieces for vwought steel.
ISO 404, Steel and steel products – General technical dekvery requieinents.
ISO/R 783, Mechanical testing of steel at elevated temperatures — Determination of lower yiefd stress and proof stress and
proving test.
3 OrderIng
3.1 The purchaser shall state in his enquiry and order
a) the steel type (see table 2);
b) the product form and the dimensions and tolerances of the product (see 48);
c) the treatment condition induding surface condition (see 4.2);
d) the quantity to be delivered;
e) the req uiement class (see table 1);
fI the required type of document (see 5.6).
3.2 Certain options in ordering are permitted by this Technical Report and the purchaser may also state in his equiry and order his related requirements as shown below.
a) whether a product anaIyss is required (see 4.4,2);
b) whether the mechanical properties for other dimensions than according to table 4 are to be specified;
ci in cases Ni which tensile end Impact properties are to be verified on reference test pieces and in cases in which more than one heat treatment Is indicated In tables 4 and 5 for the typ. of steel concerned, the heat treatment to be applied (see 5..3.3); dl In cases in which minimum proof stress at elevated temperatures is to be verified, the testing temperature selected from tab4 6 (see 5.4.5);
a) the machining allowances (see 4.7.2).
3.3 The relevant dause of ISO 404 is valid.
4 Requirements
4.1 Manufacture of the steel end of the product
Unless otherwise agrccd in the order, the processes used in making th. steel and the product are at the manufacturer’s dlscr.tion When he so requests, the user shall be informed what steelmaking process is being used.
4.2 Treatment condition at the time of delivery
4.21 The surface nd heat-treatment condition at the time of dehvery is to be agreed at the time of enquiry and order.
4.2.2 Products which are not determined for further hot- or cold-forming operations are usually delivered in the heat-treatment conditions indicated In table 5.
Products intended for further forming operations are usually delivered in the following conditions:
a) in the case of mertens,tic stoats: “annealed on a hardnoes <270 HB”; bi In the case of austenitic steels: “treated for further forming operations”.
4.2.3 The steels are delivered by casts.
4.3 Requirement classesl
The steels covered by this Technical Report shall be ordered and delivered in accordance with one of the requfrement dasses given in table 1.
4.4 Chemical composition
4.4.1 The chemical composition of the steels, as given by the cast analysis, shell be in accordance with the spectfications in table 2.
The cast analysis, if called for In the order, shall be provided by the manufacturer.
4.4.2 The permissible deviations between the values specified in table 2 and the product analysis are given in table 3. II a product
analysis is required by the purchaser, this shall be stated .n the enquiry and order.
4.5 Mechanical properties
4.5.1 When ordering according to the requirement class 1 a, 9 or 10 and according to a heat-treatment condition given in table 5. the hardness values specified In table 4 apply for the product In the delivery condition.
4.5.1 When ordering according to the requirement class 1 a, 9 or 10 and according to a heat-treatment condition given in table 5, the hardness values specified In table 4 apply for the product in the delivery condition.
4.5.2 When ordering according to the requirement class 5 or 8 and according to a heat-treatment condition given in table 5, the twid arid impact prupertiaa spedfiod iii table 4 apply for the pwduct in the delivery condition.
4.5.3 When ordering ucwrdirig to requirement claas 7, 8, 9 vi 10, the tesisile and irnpott pioperues specifiød i,. table 4 apply fur reference test pieces which were prepared in accordance with 5.3.3.3.
4.6.4 When ordering steels according to requirement class 6, 8 cc 10, the elevated temperature yield or proof stress values specified in table B apply either for a test piece In the delivery condition (requirement class 61 or for a reference test piece (requirement dass 8 Or 10) (see 5.3.3.4).
4.6 Further material characteristics
There are some further material characteristics for which however It is impossible at the time being to formulate dear requirements. As far as appropriate arid possible, annex A gives technical informations for these characteristics.
4.7 Surface quality
4.7.1 All products shall have a workmanlike finish and shall be clean and free from surface imperfections likely to have an adverse effect.
4.7.2 Hot’rolled, forged, cold-drawn or rough machined products shall be delivered with a machining allowanc, for the removal, by machining or grinding of
a) surface decarburization. and
b) surface imperfections.
A long as no International Starwlard for the machining allowances of creep-resisting steels is available, the allowances shall be aqreed
at th, time of onquiry and order.
4.8 Dimensions and tolerances
4.8.1 The products shall, if possible, be ordered and delivered in accordance with existing International Standards for dimensions and tolerances (see list in annex B). The ordered dimensions must, where applicable, include the minimum machining allowances (see 4.7.2) and the undersize tolerance.
4.8.2 If corresponding International Standards for dimensions and tolerances are not yet avsilabla or if the tolerances given in the corresponding International Standard are not applicable for creep-resisting steels, then the dimensions and tolerances shall be agreed at the time of enquiry and order.
5 Testing
5.1 General
5.1.1 For all requirement classes, acceptance tests can be agreed.
5.1.2 If acceptance tests have been agreed the general conditions of ISO 404 regarding
— the place of acceptance,
— the submission for inspection,
— the rights of the Inspector,
— the acceptance,
and, furthermore, the conditions given in 5.2 to 5.6 (as far as these are applicable according to the ordered requirement class) are to be observed.
5.2 Test unit and number of sample products and tests
52.1 Che.nlcal composition
The cast analysis, if called for in the oder, shall be provided by the manufacturer. If a product analysis is required by the purchaser,
and if not otherwise agreed at the time of enquiry and order, one sample product shall be taken from each Cast.
5.2.2 MechanIcal properties
If. eccordinq to the ordered requirement class (see table 1) and the required type of document (see 5.6 and 5.1.21 the mechanical properties are to be verified, then the indications n table 7 apply for the test unit and the number of sample products and tests.
5.3 Selection and preparation of samples and test pieces
5.3.1 General
The general conditions given in ISO/B 377 for the selection and the preparation of samples and test pieces shall apply.
5.3.2 Product analysis
For product analysis, the selection and preparation of samples shall be carried out in conformity with the requirements of ISO/B 377.
5.3.3 Mechanical properties
5.3.3.1 For the hardness test, the surface of the sample product or of a test piece taken from the sample product in the delivery condition shall be prepared in accordance with the requirements in ISOIR 79 (BrInell hardness) or ISO/B 81 (Vickers hardness),5.3.3.2 If the tensile and impact properties at room temperature are to be verified on test pieces in the delivery condition (requirement dasses 5 and 61. the samples and test pieces shall be taken from the delivery In accordance with figure le or lb. and shall be prepared in accordance with the International Standards mentioned in figures 1 a or lb.
5.3.3.3 If the tensile and impact properties at room temperature are to be verified on reference test pieces (requirement classes 7, 8, 9 or 10), d.ti test sarriples shall be taken fruni the de{ivey in dccu.ddnce with figure 1 a or I b end shall be heat treated in accordance with the heat-treatment conditions indicated in table 5 for the relevant steel. If in this table more than one heat treatment is indicated for the steel concerned, the treatment to be applied shall be agreed at the time of enquiry and order.
After the heat-treatment of the samples, the test pieces shall be taken end prepared in accordance with the indications in figure 1 a or lb.
5.3.3.4 If the yield or proof stress at elevated temperatures as specified in table 6 is to be verified on test pieces in the delivery condition {roquirornont class 6) or on roforenco test pieces (roquircmcnt clasecs 8 or 10), a test piece according to ISOIFI 7 shall be taken undor conditions corresponding to those specified for taking the test pieces for the tensile tests at room temperature (see 5.3.3.2 and 5.3.3.31.
5.4 Test methods
5.4.1 ChemIcal analysis
In cases of dispute, the methods used for the chemical analysis shall be those establshed by the relevant International Standards. It no International Standards are available, the methods shall be agreed upon at the time of enquiry and order.
5.4.2 The Brinoll hardness test shall be made in accordance with ISO/R 79. The Vickers hardness test shall be made in accordance with lSO/R 81,
5.4.3 The tensile test at room temperature shall be made in accordance with the International Standards according to which the test pieces are to be prepared (see fIgures 1 a and bI.
5.4.4 The impact test shall be made in accordance with ISO 148 (V-nOtChl. Unless otherwise specified at the time of enquiry and order, the impact value shaH be determined by the arithmetic average of three test results.
5.4.5 The yield or proof stress at elevated temperature shall be determined in accordance with ISO/R 783 at a temperature selected from table 6 and agreed at the time of enquiry and order.
5.5 Retests
FOr retests, ISO 404 is valid.
5.6 Certification of the tests
ISO 404 is valid, acceptable documents being one of the following
— statement of compliance with the order;
— report based on quality control;
— works certificate;
— test certificate;
— certificate of acceptance.
6 RectifIcation, defects and reclaiming
If not otherwise stated in the foregoing, the conditions given In ISO 404 are valid for
— surface defects;
— rectification;
— Internal detects;
— dimensional tolerances;
— reclaiming.