PS44 Effect of Oxide Scale in Small Punch Creep Specimen on Creep Rupture Life

2010 ◽  
Vol 2010 (0) ◽  
pp. 143-145
Author(s):  
Masahiro KANEKO ◽  
Ken-ichi KOBAYASHI ◽  
Hideo KOYAMA
Keyword(s):  
Oxide Scale ◽  
Rupture Life ◽  
Creep Rupture ◽  
Small Punch ◽  
Creep Specimen

Influence of Testing Environment on SP Creep Rupture Lives

2013 ◽  
Author(s):  
Ken-ichi Kobayashi ◽  
Sho Takei
Keyword(s):  
Oxide Scale ◽  
Residual Life ◽  
Rupture Life ◽  
High Vacuum ◽  
Creep Rupture ◽  
Test Duration ◽  
Destructive Testing ◽  
Creep Tests ◽  
Testing Environment ◽  
High Temperature Components

Small Punch (SP) Creep test has been recognized as a semi destructive testing method to examine residual life of creep in high temperature components. Employing 2.25Cr-1Mo steel (SCMV4), SP creep tests were conducted at 600°C both in air and in high vacuum to examine the influence of oxidation on the long-term rupture life of the SP creep tests. As a test result, the creep rupture life in air was shorter than that in vacuum when the rupture life was less than 1000 hours. Reduction of rupture lives in air was approximately a half of them tested in vacuum. However when the creep rupture life was longer than 1000 hours, little difference emerged even if the testing atmosphere was different. A thickness of the oxide scale formed on SP creep specimens in air increased with the test duration. The experimental test results showed that the oxide scale affected on a coefficient of friction between the loading ball and the SP creep specimen. Furthermore the oxide scale formed in air did not always peel off from the test specimen, and the thick oxide scale endured a part of applied load in the longer life test.

Influence of Testing Environment and Radius of Die Shoulder on SP Creep Rupture Life

2011 ◽  
Author(s):  
Ken-ichi Kobayashi ◽  
Masahiro Kaneko ◽  
Hideo Koyama ◽  
Gavin C. Stratford ◽  
Masaaki Tabuchi
Keyword(s):  
Oxide Scale ◽  
Rupture Life ◽  
High Vacuum ◽  
Creep Rupture ◽  
Test Duration ◽  
Creep Life ◽  
Destructive Testing ◽  
Creep Tests ◽  
Testing Environment ◽  
High Temperature Components

Small Punch, hereinafter designated as SP, creep test has been proposed as a semi destructive testing methodology to examine the residual creep life of high temperature components. Employing low alloy steel, a series of SP creep tests were conducted on disc specimens at 600°C in air and in high vacuum to investigate the influence of oxide scale on the creep rupture life. Thickness of the oxide scale on disc specimens in air increased with the test duration, e.g., about 30μm in thickness after 400 hours. The creep rupture life in air reduced to a half of the life in vacuum due to an increase in the actual stress in the disc thickness. In addition, the magnitude of radius of a lower die shoulder affected the SP creep rupture life. The influence of this radius on the SP creep life was also studied experimentally and numerically. The creep rupture life with the die radius of 0.5mm had twice longer than that with 0.6mm. This fact was also demonstrated by the FE analysis.

EFFECT OF BORON ON CREEP DUCTILITY AND CREEP RUPTURE LIFE IN 9CR-1.5MO STEEL

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2490-2495 ◽  
Author(s):  
BUMJOON KIM ◽  
JIWOO IM ◽  
MOON K. KIM ◽  
JONGHOON LEE ◽  
BYEONGSOO LIM
Keyword(s):  
Creep Test ◽  
Rupture Life ◽  
General Concept ◽  
Creep Rupture ◽  
Displacement Rate ◽  
Boron Addition ◽  
Creep Ductility ◽  
Small Punch ◽  
Uniaxial Creep ◽  
The Relationship

In this study, the relationship between the creep ductility and rupture life of 9 Cr -1.5 Mo steel with boron addition at 600°C was investigated by small punch (SP) creep test from the viewpoint of the modified Monkman-Grant relation. The amount of boron addition ranged from 0.0076wt% to 0.0196 wt%. The general concept of Monkman-Grant ductility for uniaxial creep was introduced and then particularly modified for the SP creep. The microstructure of the steel was observed to analyze the effect of boron addition on the creep ductility and rupture life. Based on the modified Monkman-Grant ductility for SP creep, it was found that the boron addition improved the creep ductility and rupture life of the 9 Cr -1.5 Mo steel. Also, the relationship between the minimum creep displacement rate and the amount of boron addition was analyzed.

Effects of microstructure and lattice misfit on creep life of Ni-based single crystal superalloy during long-term thermal exposure

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wenyan Gan ◽  
Hangshan Gao ◽  
Haiqing Pei ◽  
Zhixun Wen
Keyword(s):  
Single Crystal ◽  
Rupture Life ◽  
Precipitation Amount ◽  
Lattice Misfit ◽  
Thermal Exposure ◽  
Phase Evolution ◽  
Creep Rupture ◽  
Simultaneous Increase ◽  
Creep Life ◽  
The Matrix

Abstract According to the microstructural evolution during longterm thermal exposure at 1100 °C, the creep rupture life of Ni-based single crystal superalloys at 980 °C/270 MPa was evaluated. The microstructure was characterized by means of scanning electron microscopy, X-ray diffraction and related image processing methods. The size of γ’ precipitates and the precipitation amount of topologically close-packed increased with the increase in thermal exposure time, and coarsening of the γ’ precipitates led to the simultaneous increase of the matrix channel width. The relationship between the creep rupture life and the lattice misfit of γ/γ’, the coarsening of γ’ precipitate and the precipitation of TCP phase are systematically discussed. In addition, according to the correlation between γ’ phase evolution and creep characteristics during thermal exposure, a physical model is established to predict the remaining creep life.

Long Term Creep Properties of a Die-Cast Mg-Al-Ca Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 163-166
Author(s):  
Yoshihiro Terada ◽  
Tatsuo Sato
Keyword(s):  
Creep Rate ◽  
Magnesium Alloys ◽  
Cast Alloy ◽  
Rupture Life ◽  
Testing Temperature ◽  
Creep Rupture ◽  
Die Cast ◽  
Cast Magnesium Alloys ◽  
Term Creep ◽  
Cast Magnesium

Creep rupture tests were performed for a die-cast Mg-Al-Ca alloy AX52 (X representing calcium) at 29 kinds of creep conditions in the temperature range between 423 and 498 K. The creep curve for the alloy is characterized by a minimum in the creep rate followed by an accelerating stage. The minimum creep rate (ε& m) and the creep rupture life (trup) follow the phenomenological Monkman-Grant relationship; trup = C0 /ε& m m. It is found for the AX52 die-cast alloy that the exponent m is unity and the constant C0 is 2.0 x 10-2, independent of creep testing temperature. The values of m and C0 are compared with those for another die-cast magnesium alloys. The value m=1 is generally detected for die-cast magnesium alloys. On the contrary, the value of C0 sensitively depends on alloy composition, which is reduced with increasing the concentration of alloying elements such as Al, Zn and Ca.

Reliability assessment of creep rupture life for Gr. 91 steel

2013 ◽  
Vol 51 ◽  
pp. 1045-1051 ◽  
Author(s):  
Woo-Gon Kim ◽  
Jae-Young Park ◽  
Seon-Jin Kim ◽  
Jinsung Jang
Keyword(s):  
Rupture Life ◽  
Reliability Assessment ◽  
Creep Rupture

scholarly journals CREEP RUPTURE LIFE OF PRE-STRAINED SUPERALLOY N07080

2021 ◽  
Vol 9 (10) ◽  
pp. 1167-1176
Author(s):  
Omer Beganovic ◽  
Keyword(s):  
Stress Concentration ◽  
Grain Boundaries ◽  
Rupture Life ◽  
Warm Rolling ◽  
Creep Rupture ◽  
Cavity Nucleation ◽  
Standard Heat ◽  
Creep Cavity ◽  
Heat Treated

The creep of the pre-strained superalloy N07080 is described in this work. The pre-strain was achieved by warm rolling at 1050 oC.-The warm rolling was performed due to additional strengthening, i.e increasing of the superalloy hardness.-The pre-strain drastically reduces the creep rupture life of the superalloy compared to the creep rupture life of the standard heat treated superalloy.-The drastic reductionof the creep rupture life is result of rapid creep cavity nucleation on stress concentration sites along primary grain boundaries of the pre-strained superalloy.-Recrystallization eliminates potential sites for rapid cavity nucleation and prolongates the creep rupture life.

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