Publishing Service

Polishing & Checking

Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

2017 Vol.18 No.11 P.871-881

A load-holding time prediction method based on creep strain relaxation for the cold-stretching process of S30408 cryogenic pressure vessels

Feng-qing Xiao, Ying-zhe Wu, Jin-yang Zheng, Cun-jian Miao, Xiao-bo Zhu

Institute of Process Equipment, Zhejiang University, Hangzhou 310027, China; High Pressure Process Equipment and Safety Engineering Research Center of Ministry of Education, Hangzhou 310027, China; State Key Laboratory of Fluid Power and Mechatronic Systems, Hangzhou 310027, China; Zhejiang Provincial Special Equipment Inspection and Research Institute, Hangzhou 310020, China

xiaofq@zju.edu.cn, yzwu@zju.edu.cn, jyzh@zju.edu.cn, miaocunjian@zju.edu.cn

Abstract: Austenitic stainless steel (ASS) has been widely used for cryogenic pressure vessels. Its high strain hardening characteristic allows cold-stretching. In the cold-stretching process, the load-holding time is a critical operating parameter which affects the final deformation of the material. In this paper, a load-holding time prediction method for the cold-stretching process of S30408 cryogenic pressure vessels is proposed, based on room-temperature creep strain relaxation. The proposed correlation has only one variable, the maximum circumferential stress applied to the cylindrical shell, which can be easily obtained by finite element analysis. Consequently, the strain rate measurement during the cold-stretching process is significantly simplified. The prediction method and the strain rate measurement were verified by experimental measurements conducted on two vessels manufactured via the cold-stretching process. The measured strain relaxation times accurately matched the calculated values and the load-holding time for the process was well predicted.

Key words: Cold-stretching; Room-temperature creep (RTC); Austenitic stainless steel (ASS); Cryogenic vessels

Chinese Summary  <23> 一种基于蠕变应变弛豫的S30408深冷容器应变强化保载时间预测方法

目的：奥氏体不锈钢（ASS）在深冷压力容器中应用广泛。ASS较高的应变硬化特性有助于其产生应变强化。在应变强化过程中，保载时间是影响材料最终变形量的关键参数。基于室温蠕变应变弛豫理论，本文旨在提出一种S30408深冷压力容器应变强化过程中的保载时间预测方法。
创新点：1. 根据室温蠕变应变弛豫理论，保载过程即为材料在室温蠕变中应变速率逐渐减缓、材料结构逐渐稳定的过程；本文据此获得了保载时间的计算模型。2. 结合材料试验与容器试验，将计算模型中涉及的多个微观变量转换为唯一宏观变量--圆柱壳上的最大环向应力，可为常规工业生产提供定量的、具有实际可操作性的技术支持。
方法：1. 根据室温蠕变应变弛豫理论，建立蠕变本构关系，得出保载时间计算模型。2. 通过材料试验，考虑实际生产中的特定条件，将保载时间计算模型的多个微观变量简化为唯一宏观变量。3. 通过在多个工业规模的容器上进行实验，比较验证所提计算方法的可靠性。
结论：1. 室温蠕变应变弛豫理论可以用于描述应变强化保载过程中的材料变化。2. 容器保载时长，即材料应变弛豫时长，与其所承受的最大应力有关。3. 所提出的保载时间计算方法可以为容器保载时间提供可靠预测；其平均绝对误差为7.53%，且绝大部分情况下偏于保守。

关键词组：应变强化；室温蠕变；奥氏体不锈钢；深冷容器


Share this article to： More

Go to Contents

References:

<Show All>

Open peer comments: Debate/Discuss/Question/Opinion

<1>

Please provide your name, email address and a comment





DOI:

10.1631/jzus.A1600798

CLC number:

TH49

Download Full Text:

Click Here

Downloaded:

3403

Clicked:

5186

Cited:

0

On-line Access:

2017-11-06

Received:

2016-12-30

Revision Accepted:

2017-04-14

Crosschecked:

2017-10-11

Journal of Zhejiang University-SCIENCE, 38 Zheda Road, Hangzhou 310027, China
Tel: +86-571-87952276; Fax: +86-571-87952331; E-mail: jzus@zju.edu.cn
Copyright © 2000~ Journal of Zhejiang University-SCIENCE