박헌주 일반적으로 carbon steel인 경우, carbon steel로 만든 제품이(ex.formed head) 재결정온도(730 C ) 이상으로 열처리 되어진다면, forming전에 그 plate에 simulation test을 하는데, stainless steel(SA240-304L)이 forming후에 고용화열처리가 된다면 이 경우도 forming 전에 simulation test을 해야 하나요?
참고로 저는 화공압력기기 제작업체에서 근무하고 있습니다
참고로 저는 화공압력기기 제작업체에서 근무하고 있습니다
The simulation test is not a mandatory requirement of codes (e.g., ASME) and standards (e.g., ASTM). However some company specifications have the requirement for simulation test of base metal (and its weldment) when the fabrication and/or maintenance are in significant condition, such as heat treatment at the higher temperature than normal, long (or several) time of heat treatment, heavy wall thickness, special materials, or special weld joints.
As you know, the purpose of simulation test is to prove and confirm that the degraded conditions (e.g., in tensile/yield strength, impact test requirement, grain size, creep-rupture, fatigue, microstructure, precipitation, etc.) anticipated by means of fabrication and/or maintenance shall be met the requirement of the applicable codes and specifications.
1. Simulation test for formed head of carbon steels
The test is not normal requirement for formed head however if the forming temperature is too high (e.g., over than 930 deg.C for normalized steels), it may be a reasonable requirement.
I have some questions below;
(1) What is based on the limitation of 723deg.C? heat treatment of pressure vessel or head forming temperature
(2) Is the 723 deg.C heat treatment (or forming temperature) a fixed value or abnormal (unexpected) condition? Because the simulation test should be done at mill shop before forming of the head, your answer is very important in a sequence point of view.
Anyway I think you may apply it selectively if you send me the specification and the answers.
2. Simulation test and Solution Heat Treatment for formed heads made of stainless steel
(1) Need of Simulation test
All austenitic stainless steel products will be solution heat treated according to Material Standards (ASTM, ASME, etc.) at the mill manufacturing shop. Therefore the simulation test for the solution heat treatment of formed heads is not required. Also if it is required because of the unstable solution heat treatment of formed heads, it will be very difficult situation (or impossible) for the feasibility of 3D shape at the mill shop (plate = 2D).
(2) Need of Solution Heat Treatment
If you can keep the hot forming time less than about 30~50 hours, the 304L formed heads may be exempt from the solution test requirements.
I can give you additional information about the exemption of simulation test and/or the requirement of solution heat treatment if you send me the specification.
Thanks,
Thomas Eun
thomaseun@hanmail.net
1-780-713-3199
As you know, the purpose of simulation test is to prove and confirm that the degraded conditions (e.g., in tensile/yield strength, impact test requirement, grain size, creep-rupture, fatigue, microstructure, precipitation, etc.) anticipated by means of fabrication and/or maintenance shall be met the requirement of the applicable codes and specifications.
1. Simulation test for formed head of carbon steels
The test is not normal requirement for formed head however if the forming temperature is too high (e.g., over than 930 deg.C for normalized steels), it may be a reasonable requirement.
I have some questions below;
(1) What is based on the limitation of 723deg.C? heat treatment of pressure vessel or head forming temperature
(2) Is the 723 deg.C heat treatment (or forming temperature) a fixed value or abnormal (unexpected) condition? Because the simulation test should be done at mill shop before forming of the head, your answer is very important in a sequence point of view.
Anyway I think you may apply it selectively if you send me the specification and the answers.
2. Simulation test and Solution Heat Treatment for formed heads made of stainless steel
(1) Need of Simulation test
All austenitic stainless steel products will be solution heat treated according to Material Standards (ASTM, ASME, etc.) at the mill manufacturing shop. Therefore the simulation test for the solution heat treatment of formed heads is not required. Also if it is required because of the unstable solution heat treatment of formed heads, it will be very difficult situation (or impossible) for the feasibility of 3D shape at the mill shop (plate = 2D).
(2) Need of Solution Heat Treatment
If you can keep the hot forming time less than about 30~50 hours, the 304L formed heads may be exempt from the solution test requirements.
I can give you additional information about the exemption of simulation test and/or the requirement of solution heat treatment if you send me the specification.
Thanks,
Thomas Eun
thomaseun@hanmail.net
1-780-713-3199
I really appreciate your kind and detail answer on my question.
we usually order the mill maker(e.x POSCO) to product the plate(carbon steel) as simulated condition when the head and shell is heattreated as normalizing after forming. Because the formed plate is heattreated over its transformation point(723 C).
However, for the stainless steel(e.x 304L), i just wondered whether the plate which is to be solution heattreated after forming should also be simulate tested or not at mill maker shop.
we usually order the mill maker(e.x POSCO) to product the plate(carbon steel) as simulated condition when the head and shell is heattreated as normalizing after forming. Because the formed plate is heattreated over its transformation point(723 C).
However, for the stainless steel(e.x 304L), i just wondered whether the plate which is to be solution heattreated after forming should also be simulate tested or not at mill maker shop.
공지사항
지금 말씀하신 내용은 발주처의 Requisition에 어떻게 규정되어 있는 가에 달려있습니다.
열처리 전후의 조직 변화와 기계적 및 화학적(부식성) 특성의 변화를 확인하기 위해 ASME Code에 제시된 Supplimentary Requirement를 적용할 경우가 있습니다.
이런 경우에는 반드시 Simulation Test를 실시해야 하겠지요
하지만 그리 흔한 일을 아닙니다.