Fracture toughness studies in different regions of weld heat affected zones on a C-Mn steel

1984 ◽  
Vol 3 (6) ◽  
pp. 512-514
Author(s):  
Ahmet Aran ◽  
Sefik G�le�
Keyword(s):  
Fracture Toughness ◽  
Mn Steel ◽  
Weld Heat

Evaluation of the Fracture Toughness of a C-MN Steel Using Small Notched Tensile Specimens

2009 ◽  
pp. 513-513-10
Author(s):  
B Marini ◽  
S Carassou ◽  
P Wident ◽  
P Soulat
Keyword(s):  
Fracture Toughness ◽  
Mn Steel

Alternative Approach for Qualification of Temperbead Welding in the Nuclear Industry

2012 ◽  
Author(s):  
Steven L. McCracken ◽  
Richard E. Smith
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Alloy Steel ◽  
Nuclear Power ◽  
Post Weld Heat Treatment ◽  
Nuclear Power Industry ◽  
Low Alloy Steels ◽  
Low Alloy Steel ◽  
Alloy Steels ◽  
Weld Heat

Temperbead welding is common practice in the nuclear power industry for in-situ repair of quenched and tempered low alloy steels where post weld heat treatment is impractical. The temperbead process controls the heat input such that the weld heat-affected-zone (HAZ) in the low alloy steel is tempered by the welding heat of subsequent layers. This tempering eliminates the need for post weld heat treatment (PWHT). Unfortunately, repair organizations in the nuclear power industry are experiencing difficulty when attempting to qualify temperbead welding procedures on new quenched and tempered low alloy steel base materials manufactured to modern melting and deoxidation practices. The current ASME Code methodology and protocol for verification of adequate fracture toughness in materials was developed in the early 1970s. This paper reviews typical temperbead qualification results for vintage heats of quenched and tempered low alloy steels and compares them to similar test results obtained with modern materials of the same specification exhibiting superior fracture toughness.

Commentary on Recent Changes in ASME B31.3 Post Weld Heat Treatment Requirements and the Effectiveness of Weld Preheat

2017 ◽  
Author(s):  
Phillip E. Prueter ◽  
Katelyn J. Smith ◽  
Brian Macejko ◽  
Kraig S. Shipley
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Brittle Fracture ◽  
Master Curve ◽  
Post Weld Heat Treatment ◽  
Impact Testing ◽  
Mandatory Requirement ◽  
Section Viii ◽  
Weld Heat

The 2014 Edition of ASME B31.3, Process Piping [1], introduced significant changes to the post weld heat treatment (PWHT) requirements for P-No. 1 carbon steel materials. In particular, PWHT is no longer a mandatory requirement for any wall thickness provided that multi-pass welding is employed for wall thicknesses greater than 5 mm (3/16 of an inch) and a minimum preheat of 95°C (200°F) is implemented for wall thicknesses greater than 25 mm (1 inch). Detailed fracture mechanics analyses have shown that the lack of a mandatory PWHT requirement for thicker P-No. 1 components may result in a significant increase in risk for brittle fracture failures due to near-yield level weld residual stresses. Given the concern throughout the pressure vessel and piping community regarding potential brittle fracture failures, this updated PWHT guidance is examined. Impact testing requirements and exemption curves were introduced in the 1987 Addenda [2] of ASME Section VIII Division 1 (VIII-1) [3] in Paragraph UCS-66 and extended into ASME Section VIII Division 2 (VIII-2) [4]. During the VIII-2 rewrite in 2007 [5], the available technical and historical basis for the UCS-66 exemption curves was examined and improved to reflect modern fracture mechanics standards. The result of that effort was a systematic approach that can be modified for particular geometries and assumed flaws, if desired. The method used the most modern, fracture mechanics approach for welds in API 579-1/ASME FFS-1, Fitness-For-Service, (API 579) [6] based on the failure assessment diagram (FAD). As a result of explicitly accounting for weld residual stress, two separate sets of exemption curves are provided in VIII-2 [4]; one set for as-welded components and another set for PWHT components. In this paper, a similar approach is summarized to generate exemption curves by establishing newer as-welded and PWHT curves using the Fracture Toughness Master Curve (Master Curve) as documented in upcoming Welding Research Council (WRC) Bulletin 562 [7]. The increased propensity for brittle fracture in as-welded components versus PWHT components is clearly highlighted using this approach. The Master Curve, in conjunction with the elastic-plastic fracture mechanics employed in API 579 [6] provides a means to develop exemptions curves anchored in state-of-the-art fracture toughness technology that can be directly tied to different reference flaw sizes. Additionally, commentary on the appropriateness of the current ASME B31.3 [1] PWHT requirements is offered and the effectiveness of using weld preheat in lieu of PWHT as permitted in the National Board Inspection Code (NBIC) [8] is examined using simplified computational weld analysis.

Temper-Bead Weld Heat-Affected Zone Properties in A516-70 Steel

1987 ◽  
Vol 109 (2) ◽  
pp. 157-163 ◽  
Author(s):  
Y. J. Kim ◽  
J. W. Prince
Keyword(s):  
Fracture Toughness ◽  
Heat Affected Zone ◽  
Fracture Toughness Test ◽  
Test Results ◽  
Weld Repair ◽  
Metallographic Examination ◽  
Series Of Experiments ◽  
Hardness Values ◽  
Welding Technique ◽  
Weld Heat

A temper-bead welding technique has been developed to provide an alternative weld repair method in which the application of a high temperature post-weld heat treatment (PWHT) can be avoided. In order to assess the integrity of temper-bead weld repairs, a series of experiments were carried out on a simulated temper-bead weld made on A516-70 steel plate. Metallographic examination of the weld repair shows that the temper-bead technique can produce a grain refined heat-affected zone (HAZ) microstructure with acceptable hardness values. The JIC fracture toughness test results show that the HAZ exhibited equivalent or greater fracture toughness than the base metal.

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