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2004-07-08 16:04:39
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오스테나이트-페라이터 강인 DUPLEX 강(ASTM A182-F51)의 열처리에 대하여
물어볼게 있습니다.
저희들이 DUPLEX강을 수입하였는데 열처리 상태가 ANNEAL(1060 C/1 H. Quenched in water.) 라고 되어있더라고요...
근데 저의 owner에서 받은 spec에서는
aging heat treatments are prohibit. 라고 되어있습니다.
시효열처리가 뭔지 잘 몰라서 그러는데 이 수입소재를 사용해도 되는지 모르겠네요. 좋은답변 부탁드립니다.
물어볼게 있습니다.
저희들이 DUPLEX강을 수입하였는데 열처리 상태가 ANNEAL(1060 C/1 H. Quenched in water.) 라고 되어있더라고요...
근데 저의 owner에서 받은 spec에서는
aging heat treatments are prohibit. 라고 되어있습니다.
시효열처리가 뭔지 잘 몰라서 그러는데 이 수입소재를 사용해도 되는지 모르겠네요. 좋은답변 부탁드립니다.
"Aging heat treatments are prohibit." It can be interpreted that (1) a 2nd heat treatment with longer time and lower temperature compare to the previous (main) heat treatment (quenching @1060 deg.C) shall not be done or (2) the main heat treatment shall not be done with long time and/or low temperature.
This requirement is to prevent from the formation of the intermetallic phases (e.g., σ, γ, Cr2N) during long time heat treatment (not quenching) because they can have the following frailties;
1. Decrease corrosion resistance
2. Decrease toughness (low temperature impact absorbing energy)
3. Decrease mechanical properties (TS, YS); It is not a big deal if the values are over than MSTS or MSYS.
Some client spec say this kind of prohibited clause but a little bit.
Your MTR (Anneal-1060 C/1 H. Quenched in water) does completely meet the owner requirement. I am sure the metal was not treated any aging treatment (it is normal practice).
Please refer the following definition.
====Definition====
Aging: Describes a time (longer than the previous heat treatment-Quenching of Duplex SS) -temperature (lower than the previous heat treatment-Quenching of Duplex SS) -dependent change in the properties of certain alloys. Except for strain aging and age softening, it is the result of precipitation from a solid solution of one or more compounds whose solubility decreases with decreasing temperature. For each alloy susceptible to aging, there is a unique range of time-temperature combinations to which it will respond.
Annealing: A term denoting a treatment, consisting of heating to and holding at a suitable temperature, followed by cooling at a suitable rate, used primarily to soften, but also to simultaneously produce desired changes in other properties or in microstructure. The purpose of such changes may be, but is not confined to, improvement of machinability; facilitation of cold working; improvement of mechanical or electrical properties; or increase in stability of dimensions. The time-temperature cycles used vary widely both in maximum temperature attained and in cooling rate employed, depending on the composition of the material, its condition, and the results desired. When applicable, the following more specific process names should be used: Black Annealing, Blue Annealing, Box Annealing, Bright Annealing, Cycle Annealing, Flame Annealing, Full Annealing, Graphitizing, Intermediate Annealing, Isothermal Annealing, Process Annealing, Quench Annealing, and Speroidizing. When the term is used without qualification, full annealing is implied. When applied only for the relief of stress, the process is properly call stress relieving.
Good luck,
Thomas J.C. Eun, P.E.
NACE Corrosion Specilist
NACE Materials Selection/Design Specialist
This requirement is to prevent from the formation of the intermetallic phases (e.g., σ, γ, Cr2N) during long time heat treatment (not quenching) because they can have the following frailties;
1. Decrease corrosion resistance
2. Decrease toughness (low temperature impact absorbing energy)
3. Decrease mechanical properties (TS, YS); It is not a big deal if the values are over than MSTS or MSYS.
Some client spec say this kind of prohibited clause but a little bit.
Your MTR (Anneal-1060 C/1 H. Quenched in water) does completely meet the owner requirement. I am sure the metal was not treated any aging treatment (it is normal practice).
Please refer the following definition.
====Definition====
Aging: Describes a time (longer than the previous heat treatment-Quenching of Duplex SS) -temperature (lower than the previous heat treatment-Quenching of Duplex SS) -dependent change in the properties of certain alloys. Except for strain aging and age softening, it is the result of precipitation from a solid solution of one or more compounds whose solubility decreases with decreasing temperature. For each alloy susceptible to aging, there is a unique range of time-temperature combinations to which it will respond.
Annealing: A term denoting a treatment, consisting of heating to and holding at a suitable temperature, followed by cooling at a suitable rate, used primarily to soften, but also to simultaneously produce desired changes in other properties or in microstructure. The purpose of such changes may be, but is not confined to, improvement of machinability; facilitation of cold working; improvement of mechanical or electrical properties; or increase in stability of dimensions. The time-temperature cycles used vary widely both in maximum temperature attained and in cooling rate employed, depending on the composition of the material, its condition, and the results desired. When applicable, the following more specific process names should be used: Black Annealing, Blue Annealing, Box Annealing, Bright Annealing, Cycle Annealing, Flame Annealing, Full Annealing, Graphitizing, Intermediate Annealing, Isothermal Annealing, Process Annealing, Quench Annealing, and Speroidizing. When the term is used without qualification, full annealing is implied. When applied only for the relief of stress, the process is properly call stress relieving.
Good luck,
Thomas J.C. Eun, P.E.
NACE Corrosion Specilist
NACE Materials Selection/Design Specialist
공지사항
쉽게 설명드리면 석출물이 발생하여 금속을 강하게 해주어야 하는 데, 이를 위해 적당한 시간과 온도가 필요하게 됩니다.
이런 강종은 추후에 열처리나 용접과정등에 의해 기계적 특성의 변화가 발생할 수 있습니다.
따라서, 강재의 선정과 적용에 주의가 필요하게 되지요.
Duplex강과는 거리가 있는 얘기입니다.
다른 규정이 없다면 Vendor에서 제시한 조건 그대로 사용해도 좋을 것으로 판단합니다.