김정우
2008-08-27 14:36:00
3
494
안녕하세요.
Carbon and Alloy steel자재로 열처리가 요구 될시에는 UCS-85에 따라 test specimen이 요구 되는데,
Sstainless steel(A240-316)자재로 Head forming후에 Solution annealed이 요구 될시 Test specimen이 요구 되는지 궁금 합니다.
Carbon and Alloy steel자재로 열처리가 요구 될시에는 UCS-85에 따라 test specimen이 요구 되는데,
Sstainless steel(A240-316)자재로 Head forming후에 Solution annealed이 요구 될시 Test specimen이 요구 되는지 궁금 합니다.
First of all, UCS-85 which is for mechanical test (i.e., tensile test, impact toughness, etc) is not for stainless steel. The change of mechanical properties of austenitic stainless steels is not much expected before/after solution heat treatment (SH) of hot-formed heads. As far as I know, there is no requirement for test specimen after SH in UHA (high alloy steel) of ASME Sec.VIII-1.
However as Mr. Lee mentioned, the corrosion resistance of the head may be greatly different before/after the SH.
In order to prove the corrosion resistance, we may be able to consider two different specimens, such as pre-qualification (simulation) test and production test. For the simulation test, it may not be easy to get the identification between the test coupon and actual head components because the identified simulation of formed condition may not be possible. So the production test may be considered. However it may neither be easy to get the test coupon from the knuckle part of the head which has thermally stressed.
Therefore the following suggestions are advised under your client’s approval.
1. To do the production test from the crown radius part, knuckle part or flange section. And/Or
2. To prepare the reasonable ITP (inspection and test plan) including head forming and SH procedure.
If you have some experience and good SH facilities, you may take an approval of above No.2 proposal from your client.
However as Mr. Lee mentioned, the corrosion resistance of the head may be greatly different before/after the SH.
In order to prove the corrosion resistance, we may be able to consider two different specimens, such as pre-qualification (simulation) test and production test. For the simulation test, it may not be easy to get the identification between the test coupon and actual head components because the identified simulation of formed condition may not be possible. So the production test may be considered. However it may neither be easy to get the test coupon from the knuckle part of the head which has thermally stressed.
Therefore the following suggestions are advised under your client’s approval.
1. To do the production test from the crown radius part, knuckle part or flange section. And/Or
2. To prepare the reasonable ITP (inspection and test plan) including head forming and SH procedure.
If you have some experience and good SH facilities, you may take an approval of above No.2 proposal from your client.
공지사항
Solution Annealing은 급냉의 과정인데, 이게 수냉일 경우에는 수증기에 의한 단열효과가 발생하고 강제 공냉일 경우에는 냉각 속도의 지연으로 인해 S.A의 효과가 감소하고 조직내에 Carbide를 형성할 가능성이 높지요.
그래서 Code나 Spec.의 요구에 무관하게 별도의 시편을 통해 건전성을 확인하자는 요구는 지극히 당연하다고 봅니다.