이동묵
2004-06-03 16:18:14
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321SS 에 대한 Stabilization Heat treatment에 대하여 설명해 주시고,
열처리 방법에 대하여 설명해 주시기 바랍니다.
열처리 방법에 대하여 설명해 주시기 바랍니다.
1. Survey of ASTM A376-01a
para. 6.2.3; 321SS & 347SS shall be solution heat treated at min. 1900 deg.F (1040 deg.C). (Mandatory Requirement)
S.9 ; Subsequent (stabilization) heat treatment shall be done less than the solution heat treatment in para. 6.2. The stabilization heat treatment temperature shall be decided as agreed upon between the purchaser and vendor.(Supplementary Requirement)
2. Metallurgical Review and Conclusion
2.1 Stabilization heat treatment (Normally at min. 1650 deg.F = 899 deg.C, holding time 2~4 hours/inch thickness) of S9 is not mandatory requirement in ASTM and ASME. Please check the client`s spec.
2.2 Rapid cooling for 321SS or 347SS in stabilization/solution heat treatment is not critical. Slow cooling is more recommended for the coarse grain practice in high temperature service.
2.3 Stabilizing effect for 321SS or 347SS can be fully obtained by stabilizing heat treatment (at min. 1650 deg.F = 899 deg.C) as well as solution heat treatment (at min. 1900 deg.F = 1040 deg.C.)
2.4 Sometimes the stabilizing heat treatment for products (not material) is required in high chloride environment in client`s spec. Please check the client`s spec.
Hope this helps,
Thomas J.C. Eun
para. 6.2.3; 321SS & 347SS shall be solution heat treated at min. 1900 deg.F (1040 deg.C). (Mandatory Requirement)
S.9 ; Subsequent (stabilization) heat treatment shall be done less than the solution heat treatment in para. 6.2. The stabilization heat treatment temperature shall be decided as agreed upon between the purchaser and vendor.(Supplementary Requirement)
2. Metallurgical Review and Conclusion
2.1 Stabilization heat treatment (Normally at min. 1650 deg.F = 899 deg.C, holding time 2~4 hours/inch thickness) of S9 is not mandatory requirement in ASTM and ASME. Please check the client`s spec.
2.2 Rapid cooling for 321SS or 347SS in stabilization/solution heat treatment is not critical. Slow cooling is more recommended for the coarse grain practice in high temperature service.
2.3 Stabilizing effect for 321SS or 347SS can be fully obtained by stabilizing heat treatment (at min. 1650 deg.F = 899 deg.C) as well as solution heat treatment (at min. 1900 deg.F = 1040 deg.C.)
2.4 Sometimes the stabilizing heat treatment for products (not material) is required in high chloride environment in client`s spec. Please check the client`s spec.
Hope this helps,
Thomas J.C. Eun
공지사항
이유는 열교환기가 당연히 고온에 적용되기 때문이지요.
아시는 바와 같이 Stabilized된 강종이라고 해도 용접이나 고온 사용으로 인해 입계예민화가 발생할 수 있기에 이를 예방하는 차원에서 초기 Solution Annealing을 실시한 온도 바로 아래에서 열처리를 실시하는 것입니다.
이의 목적과 정의에 대해서는 다음의 내용을 참조하세요
1. ASTM A213 등의 Code상에 언급된 내용
S2. Stabillzing Hear Treatment
S2.1 Subsequent to the solution anneal required in Sec-tion 6, Grades TP309HCb, TP310HCbN, TP321, TP321H, TP347, TP347H, TP348, and TP348H shall be given a stabilization heat treatment at a temperature lower than that used for the initial solution annealing heat treatment. The temperature of stabilization heat treatment shall be at a temperature as agreed upon between the purchaser and vendor.
==> 원문에 소개된 바와 같이 그 온도는 발주처와 협의하여 정의하도록 되어 있습니다.
2. 열처리 기술 문헌에 따른 언급
Thermal stabilization treatments at 900C (1650F) minimum for 1 to 10 hours are occasionally employed for assemblies that are to be used in the 400 to 900C (750 to 1650F) temperature range. Thermal stabilization is intended to agglomerate the carbides, thereby preventing further precipitation and intergranular attack (IGA). As with 815 to 870C (1500 to 1600F) stress relief, it is best to test for susceptibility to IGA per ASTM A262.
==> 이 내용에 따르면 Stabilized 열처리에 추가하여 응력 제거를 해주면 가장 좋다고 되어 있지요. 아마도 이런 내용을 감리자 혹은 발주처에 보여주면 제작자는 정말 머리 아프겠지요.
도움이 되시길 바랍니다.