Effect of Postweld Heat Treatment Conditions on Microstructure of 9Cr-1Mo-V Steel Welds for Pressure Vessel

2017 ◽  
Author(s):  
Hidenori Terasaki ◽  
Tomohiro Tanaka ◽  
Masamitsu Abe ◽  
Mitsuyoshi Nakatani
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Weld Metal ◽  
Postweld Heat Treatment ◽  
Pressure Vessels ◽  
Dislocation Network ◽  
Precipitation Behavior ◽  
Treatment Conditions ◽  
Scanning Transmission ◽  
The Difference

We investigated the effects of post-weld heat treatment conditions on the microstructure of the multi-pass submerged arc weld metal of 9Cr-1Mo-V steel used in pressure vessels. The microstructural properties were analyzed under three conditions (as-weld, Larson-Miller parameter (LMP) = 21.38 × 103, and LMP = 21.99 × 103). The precipitation behavior was observed using scanning electron microscopy, and the difference in precipitation behavior in the “as-welded” and “reheated” regions of the prepared multi-pass weld metal was clarified at the different LMP values. The precipitate was analyzed using scanning transmission electron microscopy. An oxide and two types of precipitates were identified, and a dislocation network pinned by MX-type carbides was visualized under the low-LMP condition. The effects of LMP on the effective grain size and dislocation amount were also evaluated using electron back-scattering diffraction. All microstructural change along the LMP had a positive effect on the toughness of weld metal.

Heat Treatment Effects on Distortion, Residual Stress, and Retained Austenite in Carburized 4320 Steel

2014 ◽  
Vol 783-786 ◽  
pp. 692-697 ◽  
Author(s):  
Andrew Clark ◽  
Randy J. Bowers ◽  
Derek O. Northwood
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Retained Austenite ◽  
Compressive Residual Stress ◽  
Surface Residual Stress ◽  
Depth Profiles ◽  
Size And Shape ◽  
Austenite Content ◽  
Treatment Conditions ◽  
The Difference

The effects of heat treatment on distortion, residual stress, and retained austenite were compared for case-carburized 4320 steel, in both the austempered and quench-and-tempered condition. Navy C-ring samples were used to quantify both size and shape distortions, as well as residual stress. The austempering heat treatment produced less distortion and a higher surface residual stress. Both hoop and axial stresses were measured; the difference between them was less than seven percent in all cases. Depth profiles were obtained for residual stress and retained austenite from representative C-ring samples for the austempered and quench-and-tempered heat treatment conditions. Austempering maintained a compressive residual stress to greater depths than quench-and-tempering. Quench-and-tempering also resulted in lower retained austenite amounts immediately beneath the surface. However, for both heat treatments, the retained austenite content was approximately one percent at depths greater than 0.5 mm.

A Thermal Stress Mitigation Technique for Local Postweld Heat Treatment of Welds in Pressure Vessels

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Chunge Nie ◽  
Pingsha Dong
Keyword(s):  
Heat Treatment ◽  
Thermal Stresses ◽  
Postweld Heat Treatment ◽  
Pressure Vessels ◽  
Cylindrical Vessel ◽  
Spherical Vessel ◽  
Novel Method ◽  
Bull's Eye ◽  
Recommended Guidelines ◽  
Postweld Heat

This paper introduces a novel method for effectively mitigating high thermal stresses caused during local postweld heat treatment (PWHT) of welds in pressure vessels on which traditional heating method such as bull's eye heating arrangement has been proven difficult in meeting Code requirements for avoiding “harmful” temperature gradients. The method involves the use of a secondary heat band (SHB) that strategically positioned at some distance away from primary PWHT heat band (HB) in terms of vessel characteristic length parameter Rt, where R is vessel radius and t wall thickness. The basic principles associated with the SHB based technique are first demonstrated on a simple straight pipe girth weld configuration. Then, applications for treating nozzle welds in more complex spherical vessel, cylindrical vessel, and at end of cylindrical vessel are presented. Finally, a set of recommended guidelines are provided for defining both the SHB size and location for performing local PWHT on welds in three major nozzle/vessel weld configurations.

Collapse-Type Shrinkage’s Characteristics in Both Eucalyptus urophylla and E.cloeziana Wood under Heat-Treatment Conditions

2010 ◽  
Vol 297-301 ◽  
pp. 1016-1021
Author(s):  
Yi Qiang Wu ◽  
Kazuo Hayashi ◽  
Ying Chun Cai
Keyword(s):  
Heat Treatment ◽  
Eucalyptus Urophylla ◽  
Permanent Set ◽  
Treatment Conditions ◽  
Shrinkage Process ◽  
Continuous Heat Treatment ◽  
The Difference ◽  
Heat Treatment Regimes ◽  
Increasing Temperature ◽  
Continuous Heat

In order to explore the formation process of collapse-type shrinkage of eucalypt wood, the collapse-shrinkage properties in Eucalyptus urophylla and E.cloeziana wood under different heat-treatment conditions were systematically investigated by using frozen drying, and simultaneously creative assessments on their collapse-type shrinkage process were conducted based on the novel concepts of both transient collapse and maximum transient collapse advanced for the first time. The results indicated that, for lower-density E.urophylla, total shrinkage and residual collapse under both heat-treatment regimes increased with increasing temperature. As compared to intermittent heat treatment, the above two indices at three levels of temperatures in continuous heat treatment displayed relatively larger values, and exhibited down-open-parabola type; For higher-density E.cloeziana, only higher collapse phenomenon in the part near to the pith were observed, and similar to E.urophylla, while almost slight and /or no collapse occurs in the middle heartwood and sapwood, and shrinkage and collapse in continuous heat treatment is slightly larger than those in intermittent heat treatment, and both shrinkage and collapse take on up-open-parabola type. Trends of radial variation of both parameters for both species in continuous heat treatment were consistent with those in intermittent heat treatment. It can be speculated that the mechanism of the difference in collapse-type shrinkage characteristics between two heat-treatment patterns are that the more types of cells and the more number of cells participated in the collapse development, and the more transient collapse, especially maximum transient collapse, is transformed into the permanent set to develop the residual collapse for continuous heat treatment than the intermittent heat treatment. Therefore, it is very crucial for lower-density susceptible-collapse eucalypt to manage to prevent maximum transient collapse from being transformed into permanent set in the process of drying.

Numerical Simulation of CrMo Steels Thick Welds Intermediate Postweld Heat Treatments

2005 ◽  
Author(s):  
Maryline Clerge´ ◽  
Christian Boucher ◽  
Sylvain Pillot ◽  
Philippe Bourges
Keyword(s):  
Heat Treatment ◽  
Complex Shape ◽  
Heat Treatments ◽  
Pressure Vessels ◽  
Post Weld Heat Treatment ◽  
Treatment Conditions ◽  
Stress Relieving ◽  
Creep Resistant Steels ◽  
Postweld Heat ◽  
Hydrogenation Treatment

During manufacturing, complex shape welded pressure vessels are submitted to numerous intermediate heat treatments after each weld (de-hydrogenation treatment - DHT and/or intermediate stress relieving treatment - ISR) before final Post Weld Heat Treatment (PWHT). The present study aims at analysing and optimising the intermediate heat treatment conditions regarding the resulting mechanical properties (tensile strength and impact. strength) of CrMo and CrMoV creep resistant steels. Hydrogen behaviour in weld metal and HAZ, and residual stresses evolution have been assessed by numerical modelling and experimental measurements on welded specimens representative of big pressure vessels: butt welds and set in nozzle welds of 150 mm wall thickness. The optimised conditions are compared to usual construction codes and buyer’s requirements.

The cheesemaking potential of milk concentrated up to four-fold by ultrafiltration and heated in the range 90–97 °C

1990 ◽  
Vol 57 (4) ◽  
pp. 549-557 ◽  
Author(s):  
Margaret L. Green
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Whey Protein ◽  
Protein Interactions ◽  
Heat Denaturation ◽  
The Difference

SummaryProperties of interest to cheesemaking were investigated with milks concentrated by ultrafiltration and heated at 90 °C or 95–97 °C for 15 s. The effects of light homogenization before concentration and of addition of CaCl2 after heating were assessed. No changes in casein–fat or casein–whey protein interactions were detected by electron microscopy. The heat denaturation of whey protein increased linearly as the milk became more concentrated. Coagulability by rennet after heat treatment increased with concentration to close to the unheated value in 3·5 to 4-fold concentrates. The decrease in curd firming rate by heat treatment was slightly affected by concentration and addition of CaCl2 restored some of the difference. Heat treatment reduced the rate of whey loss and slightly improved the curd structure but did not affect fat losses. Light homogenization slightly reduced heat denaturation of whey protein and whey loss.

scholarly journals Effect of Aging Heat Treatment Conditions on the Mechanical Properties and Microstructure of Base and Weld Metal of Alloy 282 Superalloy

2020 ◽  
Vol 58 (8) ◽  
pp. 540-549
Author(s):  
Jinhyeok Bang ◽  
Yongjoon Kang ◽  
Namkyu Kim ◽  
Seong-Moon Seo ◽  
Sanghoon Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Weld Metal ◽  
Base Metal ◽  
Aged Condition ◽  
Creep Life ◽  
Aging Heat Treatment ◽  
Treatment Conditions ◽  
One Step ◽  
The One

The effect of aging heat treatment conditions on the mechanical properties and microstructure of the base and weld metal of Alloy 282 superalloy was investigated. The aging heat treatment conditions employed in this study were as follows: two-steps (1010 °C for 2 hours plus 788 °C for 8 hours) and one-step at 788 °C, 738 °C, and 688 °C for 4 hours. The base metal with the one-step aged condition exhibited lower hardness but longer creep life than that treated with the two-step aged condition. The base metal subjected to the two-step aging exhibited the highest hardness and the shortest creep life, mainly due to the precipitation of Mo-rich M6C-type carbides and coarse <i>γ</i>' (Ni3(Al,Ti)) phase. For the weld metal, regardless of aging heat treatment conditions, creep elongation and life decreased significantly compared to the base metal, due to the coarse effective grain size and inhomogeneous distribution of <i>γ</i>' precipitates.

Characterization of Microstructure and Mechanical Properties of AA2219-O and T6 Friction Stir Welds

2019 ◽  
Vol 969 ◽  
pp. 205-210 ◽  
Author(s):  
D. Venkateswarlu ◽  
Muralimohan Cheepu ◽  
P. Nageswara Rao ◽  
S. Senthil Kumaran ◽  
Narayanan Srinivasan
Keyword(s):  
Heat Treatment ◽  
Welding Process ◽  
High Strength ◽  
Friction Stir ◽  
Microhardness Distribution ◽  
Treatment Conditions ◽  
Heat Treated ◽  
The Difference ◽  
Aluminum Alloy 2219 ◽  
Failure Location

In the present study, aluminum alloy 2219 of two different heat treatment states were selected and welded using the friction stir welding process to evaluate the effect substrate on the joint properties. The microstructural observations have exhibited the difference in their characteristics between two heat treatment conditions of 2219-O and T6 conditions. The tensile strength of the AA2219-T6 joints much higher than the AA2219-O joints. Consequently, the microhardness distribution across the different zones varying with two different heat treated conditions. The failure locations and fracture surface features are revealed the significant differences among these two heat treated conditions with the change in their failure location and the fracture morphologies. The optimal welding conditions were analyzed to determine the high strength of the welds with excellent metallurgical properties of the welds.

scholarly journals PENGARUH PENDINGINAN MEDIA AIR DAN OLI PADA HEATTREATMENT SAMBUNGAN LAS METODE SMAW TERHADAP KEKUATAN LOGAM YANG DIHASILKAN

2018 ◽  
Vol 8 (2) ◽  
pp. 196
Author(s):  
Asep AR Ruchiyat
Keyword(s):  
Heat Treatment ◽  
Weld Metal ◽  
Cooling Water ◽  
Welding Process ◽  
Raw Material ◽  
Natural Phenomenon ◽  
Free Air ◽  
Mechanical Ability ◽  
The Difference ◽  
Cooling Media

Abstract Welding is a method of metal extension that utilize the Penetration of heat produced. Heat and the freeze of a metal extension is a natural phenomenon, where that process works based on the difference of temperature. The cooling temperature that work so fast creating diverse structure as the result that the mechanical ability of a metal changes.                This research purpose is to find out to what extent heat treatment with water and oil cooling media gives effect to the result of SMAW weld, considering processes changes in metal are very sensitive towards mechanical ability.                 Hardness testing in raw material that has been done gives result of 46.9 with an average hardness in the normal welding process of 48 HRB or increased by 2.34%. This value indicates that the welding process will have an impact on the increase in hardness of the weld metal. Then the weld metal heat treatment process at 850oCwith normal cooling of free air decreases the weld metal hardness by 43.5 HRB or 7.24% under raw material. While the quenching process carried out with water and oil cooler has an impact on increasing the hardness above heat treatment, normal cooling is 4.36% and 3.19% lower to the raw material. From this description it can be concluded that quench accelerates the rate of cooling and increase hardness by 4.36%. Key words: welding SMAW, heattreatment, cooling water and oil, hardness metal   

Sign in / Sign up

Export Citation Format

Share Document