【導(dǎo)讀】為是造成在前奧氏體晶粒邊界形成雜質(zhì)[1-4]的原因。示[5]，不僅有這些進程，而且有其他進程，像在500-600℃淬火鋼有助于回火脆性在發(fā)生。在這項工作的關(guān)注是淬火鉻鉬合金，以防止在釩和磷的含量RTB的鋼回火脆化。米厚的板材被切斷他們。另外，在一個100公斤的感應(yīng)爐加熱熔化。釩被添加到在一個重達16公斤的鑄塊中，它被鍛造、軋制成10毫米厚的金屬板。從板淬火和在100-760℃回火10. 小時后制備樣品。Tso的確定是通過5×5×毫米的切口1毫米深（根半徑）沖擊試驗樣品。Tso被認為是在斷裂50％纖維下的測試溫度。拉伸強度通過5個直徑為3毫米的樣品確定的。更改影響回火鋼的穩(wěn)定的情況下釩濃度，因為不含釩的鋼的強度會下降至約500°。熱件1開始時回火溫度大約300℃，Tso的增加達到500-600度的最高值。對峰值相比增加了100℃?；鼗饻囟冗M一步提高，Tso會下降，這與削弱開始相吻合。在730℃后的Tso鍛煉價值與。顯微條件后，在600℃回火，對應(yīng)于對強度特性極值邊緣與Tso高峰在760°的回火之后，

　　

【正文】 follows. With increasing tempering temperatures cementite begins to coalesce, precipitating at 250350 176。. In steels containing more effective carbideforming elements than iron the formation of nuclei of special carbides begins around 350 176。, especially MC3 [8]. Precipitating evenly throughout the volume on disloca tions, lowangle boundaries of martensite laths, and highangle boundaries of colonies of laths, they strengthen the matrix and weaken (embrittle) the boundaries. It is probable that the boundaries are weakened most with the maximum density of carbides coherent with the matrix or with their precipitation, ., at secondary hardening temperatures. Such elements as vanadium, promoting refining of carbides and thus increasing secondary hardening [8], increase the embrittlement. With precipitation and coalescence of carbide phase, occurring simultaneously with polygonization of dislocations, the boundaries bee more perfect and the matrix is weakened. Both these effects lead to a drop of the ductilebrittle transition temperature, which is in fact observed. CONCLUSIONS 1. Steels of the 15Kh3MFA type are susceptible to embrittlement, which reaches a peak at a given tempering temperature. The upper limit of the peak (Tso) coincides with the temperature at which the material begins to weaken. 2. The height of the peak and the tempering temperature corresponding to it increase almost linearly when the vanadium concentration is raised from 0 to %, but they are independent of the phosphorus concentration within limits of %. 3. Temper brittleness of the steel investigated depends on the change in the carbide phase (from cementite to special carbides) that occurs with retention of the dislocation arrays preferentially in the boundaries of fragments. LITERATURE CITED . M. Utevskii, Temper Brittleness of Steels [in Russian], Metallurgizdat, Moscow (1961),p. 138. 2. P. B. MikhailovMikheev, Thermal Embrittlement of Steels [in Russian], Mashgiz, MoscowLeningrad (1956), p. 56. 3. J. Hollomon, Trans. ASM, 36, 473 (1946). 4. E. Houdremont, Special Steels [Russian translation], Vol. I, Metallurgiya, Moscow (1966),p. 455. 5. V. A. Korablev, Yu. I. Ustinovshchikov, and I. G. Khatskelevich, Embrittlement of chromium steels with formation of special carbides, Metalloved. Term. Obrab. Met., No. I,16 (1975). 6. A. P. Gulyaev, I. K. Kupalova, and V. A. Landa, Method and results of phase analysis of hlghspeed steels, Zavod. Lab., No. 3, 298 (1965). 7. J. Heslop and N. Perch, Phil. Mag., ~, No. 34, 1128 (1958). 8. V. V. Rybin et al., The mechanism of hardening of sorbitehardening steel and the possibility of determining it theoretically and experimentally, in: Metal Science [inRussian], No. 17, Sudostroenie, Leningrad (1973), p. 105. 9． L. K. Gordienko, Substrucutral Hardening of Metals and Alloys [in Russian], Nauka, Moscow(1973), p. 64. 10． E. E. Glikman et al., Nature of reversible temper brittleness, Fiz. Met. Metalloved.,36, 365 (1973). 11. Oliver WC, Pharr GM (2020) J Mater Res 19:3 12. Kim JY, Lee BW, Read DT, Kwon D (2020) Scr Mater 52:353 13. Kim JY, Lee JS, Lee KW, Kim KH, Kwon D (2020) Key Eng Mater 326–328:487 14. Kim JY, Lee JJ, Lee YH, Jang JI, Kwon D (2020) J Mater Res 21:2975 15. Kim JY, Kang SK, Lee JJ, Jang JI, Lee YH, Kwon D (2020) Acta Mater 55:3555 16. Dowling NE (1993) Mechanical behavior of materials. Prentice Hall, Englewood Cliffs 17. Kim JY, Lee KW, Lee JS, Kwon D (2020) Surf Coat Technol 201:4278 18. DIN 1717579 (1979) Seamless steel tubes for elevated temperatures 19. Ahn JH, Kwon D (2020) J Mater Res 16:3170 20. Dieter GE (1988) Mechanical metallurgy. McGrawHill, Singapore