Work Item
ASTM WK14922
New Practice for Determination of Fracture Toughness of Ferritic Steel Welds
1. Scope
1.1 This practice provides methods for preparing specimens from welds in metallic materials and interpreting subsequent test results when used in conjunction with standards E 1290 and E 1820 for the determination of fracture toughness. The fatigue pre-cracking procedures included in this practice may also be used to aid in preparing straight pre-cracks for weld specimens in accordance with standard E 1681. 1.2 This practice draws heavily from ISO 15653: Metallic materials Method of test for the determination of quasistatic fracture toughness of welds. All references to ISO 12135 in that test method should be replaced with the applicable ASTM test method (E 1820, E 1290 or E 1681). 1.3 The recommended specimen is a single-edge bend [SE(B)] with width, W, equal to twice the specimen thickness, B. An alternate SE(B) specimen with W/B equal to one and a span, S, to W ratio of 4 may be used but may produce different toughness values. A compact tension [C(T)] specimen may be used if it can be demonstrated that the analysis of results properly accounts for weld-to-base metal strength mismatch effects on fracture toughness. 1.4 The recommended limitation on weld-to-base metal yield strength ratio is 0.5 Weld Yield Strength/Base Metal Yield Strength 1.5 . Undermatching within this limitation leads to conservative estimates of fracture toughness, while overmatching may lead to an overestimation of the fracture toughness by upwards of 10%.
Keywords
ferritic steel welds; fracture toughness; weldment; residual stresses; fatigue precracking; local compression; step-wise high R ratio; reverse bend
Rationale
The proposed standard will provide guidance on how to prepare specimens from welds for fracture toughness testing, and how to account for the unique characteristics of welds in the interpretation of results. The standard itself does not include fracture toughness testing; it refers the user to other established standards for actual testing. Users for this standard would be anyone that is concerned about structural integrity and fitness for service of welded structures.
The title and scope are in draft form and are under development within this ASTM Committee.
Work Item Status
Date Initiated: 03-26-2007
Technical Contact: Stephen Graham
Item: 001
Ballot: E08.07 (07-01)
Status: Will Reballot Item
Item: 021
Ballot: E08 (11-01)
Status: Ballot Item Approved