OBRABOTKAMETALLOV technology Vol. 25 No. 4 2023 is provided by the International Welding Institute and is commonly used for simple carbon and carbonmanganese steels. In Europe, Pcm, the critical parameter of the metal, denoted by Pcm, is calculated. CE Pcm is taken from the documents of the Japanese Society of Welding Engineers. CE Pcm was proposed specifically to test the weldability of high-strength steels. + + = + + + + + + % % % % % % % % 5 ; 30 20 60 15 10 cm Si Mn Cu Cr Ni Mo V P C B + + + = + + + % % % % % % % . 6 5 15 IIW Mn Cr Mo V Cu Ni CE C The API piping specification states that CEIIW restrictions will be taken into account if the mass fraction of carbon exceeds 0.12 %. CE Pcm is used when the mass fraction of carbon in steel is less than or equal to 0.12 % (American Petroleum Institute, 2012). In addition to metal alloying, thermal cycles play an important role in changing the microstructure, as well as cooling rates during welding. Before predicting the behavior of steel during and after welding, it is also necessary to take into account the welding materials used and the conditions for preparing and conducting the welding process. The requirements of API 5CT for pipe steels for mechanical properties during tensile testing are shown in table 4. API 5CT requirements for pipe steels of a strength group K55 for mechanical properties during tensile testing are as follows: σy = 379–552 MPa, σu ≥ 655 MPa, minimum elongation, е, expressed as a percentage, should be determined by the following equation: = 0,2 0,9 A e k U , Ta b l e 4 API 5CT requirements for pipe steels for mechanical properties in tensile tests Pipe grade Minimum yield strength, MPa Maximum yield strength, MPa Minimum ultimate tensile strength, MPa Maximum ultimate tensile strength, MPa Х42 290 496 414 758 Х46 317 524 434 758 Х52 359 531 455 758 Х56 386 544 490 758 Х60 414 565 517 758 Х65 448 600 531 758 Х70 483 621 565 758 Х80 552 690 621 827 Х90 625 775 695 915 Х100 690 840 760 990 Х120 830 1,050 915 1,145
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