GB/T 14999.1-2025 Test method for superalloys—Part 1：Macro-structures English, Anglais, Englisch, Inglés, えいご
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ICS 77.140.99 CCS H 40
NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA
GB/T 14999.1-2025
Replaces GB/T 14999.1-2012, GB/T 14999.2-2012, GB/T 14999.3-2012
Test Method for Superalloys-Part 1: Macro-Structures
Issued on August 29, 2025 Implemented on March 1, 2026
Issued by
State Administration for Market Regulation
Standardization Administration of China
CONTENTS
Foreword
Introduction
1 Scope
2 Normative References
3 Terms and Definitions
4 Sampling and Preparation
5 Testing and Result Presentation
6 Test Report
Test Method for Superalloys-Part 1: Macro-Structures
1 Scope
This document describes the types and characteristics of common defects and non-uniform structures in the macro-structures of wrought superalloys, as well as the types and features of longitudinal fracture porosity and fracture delamination. It also covers the sampling and preparation of test specimens, inspection and evaluation, methods for result presentation, and test reports.
This document is applicable to the inspection of macro-structures and defects in the longitudinal and transverse directions of wrought superalloy ingots, melt test samples, forged or rolled billets, and materials. Other products may reference this document for implementation.
This document is also applicable to the inspection of fracture porosity and fracture delamination in hot-rolled bars of wrought superalloys with a nominal diameter of not less than 16 mm. Other types of bars may reference this document for fracture inspection.
2 Normative References
The following documents contain provisions which, through reference in this text, constitute essential provisions of this document. For dated references, only the editions cited apply; for undated references, the latest edition (including any amendments) applies.
GB/T 6394 Test Method for Average Grain Size of Metals
GB/T 30067 Metallographic Terms
3 Terms and Definitions
Terms and definitions established in GB/T 30067 and the following apply to this document.
3.1
Slag Inclusion
A defect formed by foreign materials such as slag and refractory materials mixed into the alloy during smelting and pouring.
3.2
Heterometallic Inclusion
A defect caused by incomplete melting of alloy materials or mixing of foreign metals during smelting and pouring.
Note: On acid-etched test specimens, the color differs from the matrix structure, with no specific shape. Some have clear boundaries with the matrix, while others have unclear boundaries.
3.3
Residual Shrinkage
A defect caused by insufficient cutting of the alloy ingot head, leaving some shrinkage cavities on the billet.
Note: On transverse acid-etched low-magnification test specimens of the alloy, it appears as irregular voids or cracks at the center; on longitudinal test specimens, it appears as a shrinkage pipe; on longitudinal fracture specimens, delamination occurs at the corresponding location of the residual shrinkage cavity, often accompanied by severe porosity, inclusions (slag), and composition segregation.
3.4
Porosity
A defect characterized by insufficiently dense structure due to inadequate feeding of the alloy liquid in the center of the ingot during final solidification.
Note: On transverse acid-etched low-magnification test specimens of the alloy, it appears as dark small spots and fine pores at the center; on longitudinal fracture specimens, it appears as layered or fibrous. Porosity at the filling end of the ingot may be accompanied by gas and inclusion accumulation.
3.5
Blowholes
Holes caused by gas failing to escape during alloy solidification.
Note: On transverse low-magnification test specimens of alloy ingots, blowholes appear as round holes; on longitudinal test specimens, they appear as spindle-shaped holes, sometimes as unevenly long silkworm-shaped grooves, often found at the bottom of electroslag remelted ingots; on transverse low-magnification test specimens of forged or rolled materials, they appear as irregular short "S"-shaped cracks; under higher magnification, they appear as inclusion-free cracks.
3.6
Crack
A defect characterized by metal separation in the form of stripes on the surface or inside of an alloy ingot, billet, or material due to various reasons.
Note: Common types of cracks include:
a) Cracks caused by improper control of smelting and pouring processes, leading to severe inclusions and segregation in the alloy ingot. During hot processing, cracks often occur at these locations, accompanied by inclusion chains and carbide segregation, usually with fine grain bands.
b) Cracks caused by low hot processing temperatures, especially during punching, expanding, pressing, rolling, and forging.
c) Cracks caused by high hot processing temperatures or prolonged heating and holding times, leading to oxidation or localized melting of grain boundaries, significantly reducing alloy plasticity.
d) Cracks caused by excessive deformation, uneven hammering, or too fast deformation rates.
e) Cracks caused by too high furnace loading temperatures, too fast heating or cooling rates, or localized overheating during grinding.
3.7
Overburning
A defect characterized by oxidation and localized melting of grain boundaries due to excessive heating of the alloy.
Note: Overburning can usually be seen as cracking and severe delamination on surface low-magnification test specimens.
3.8
Lamination
Note: On the inspection surface of the longitudinal fracture, there are longitudinal striated structures, but no granular metallic structure or metallic luster, and the metal continuity is disrupted. It generally appears grayish-white, light yellow, or brown-black. Three common types of delamination are:
a) Center delamination caused by secondary shrinkage cavities and foreign slag inclusions;
b) Subsurface delamination caused by blowholes and cold flow during pouring, irregularly distributed but always extending from the surface toward the center;
c) Minor delamination caused by fine chain-like inclusions from secondary oxidation, located on the material's fracture surface.
3.9
Carbide Aggregation
A form of interdendritic segregation.
Note: On longitudinal low-magnification acid-etched specimens, it appears as dark bands along the processing direction; on transverse specimens, it appears as slightly darker areas with curved or clustered short black lines.
3.10
Spot Segregation
A region where carbides and/or secondary phases accumulate.
Note: On transverse low-magnification acid-etched specimens, it appears as dark gray or black spots of varying sizes, more susceptible to corrosion than the matrix and recessed into it; on longitudinal specimens, it appears as bands along the processing direction, potentially forming fine cracks in severe cases.
3.11
Freckle
Positive segregation due to accumulation of carbides, carbonitrides, Laves phase, μ-phase, and other intermetallic compounds.
Note: Appears as dark areas on acid-etched specimens.
3.12
White Spots
Negative segregation due to reduced carbides or carbide-forming elements and strengthening elements.
Note: Appears as light-colored areas on acid-etched specimens.
3.13
Dendritic Structure
As-cast structure with incomplete fragmentation of dendrites in alloy ingots.
Note: On longitudinal and transverse low-magnification acid-etched specimens, it appears as dendritic-like structures; under high magnification, large primary γ/ phases and small amounts of γ+γ' eutectic structures are visible between dendrites.
3.14
Ingot Segregation
A segregation box formed at the solid-liquid interface due to columnar grain growth pushing low-melting-point components, gases, and segregating elements toward the uncondensed central liquid region.
Note 1: A product of alloy ingot solidification. The segregation box contains excessive impurities that fail to diffuse evenly into the remaining liquid or toward the riser before solidification.
Note 2: On transverse acid-etched specimens, it appears as deeply etched segregation zones composed of dense dark spots, typically box-shaped or circular depending on the ingot mold.
