Heat-Affected Zone (HAZ)
Engineering definition, metallurgical mechanisms, standard testing specifications, and manufacturing guidelines for closed-die forgings up to 50 kg.
Quick AnswerFeatured
The portion of the base forging metal adjacent to a weld seam that has not melted but whose microstructure and properties have been modified by the intense heat of welding.
Technical Explanation & Metallurgical Principles
During welding of forged flanges and pipe elbows, the adjacent base metal reaches temperatures ranging from ambient to near-melting. This creates multiple microstructural zones: coarse-grained HAZ (risk of low impact toughness), fine-grained HAZ, intercritical HAZ, and subcritical tempered zone.
Key Engineering Specifications & Parameters
| Technical Parameter / Metric | Engineering Benchmark / Value |
|---|---|
| Critical Hardness Limit | ≤ 248 HV10 (22 HRC) for NACE MR0175 sour service |
| Mitigation | Control of heat input (kJ/mm) and preheat temperature |
Application at Jayesh Forge (Rajkot Plant)
Our low carbon and micro-alloyed forging chemistry is specifically tailored to prevent untempered martensite in the HAZ when customers butt-weld our products in the field.
Related Materials, Standards & Products
Engineered Product Lines
Related Metallurgical & Testing Terms
Carbon Equivalent (CE / CEV / CET)
An empirical mathematical formula that converts the combined hardening effect of various alloying elements into an equivalent carbon percentage to evaluate weldability.
Weldability of Forged Steels
The capacity of a forged metal to be joined by thermal fusion welding processes into a reliable joint that satisfies specified service mechanical criteria.
NACE MR0175 / ISO 15156 Sour Service Standard
The international standard defining material requirements for metallic equipment used in oil and gas production environments containing corrosive hydrogen sulfide (H2S).
Questions Regarding Heat-Affected Zone (HAZ)
Hardnesses above 22 HRC (248 HV) in the presence of wet H2S gas are acutely vulnerable to Hydrogen-Induced Stress Corrosion Cracking (HIC/SSCC).
Request a Forging Quote with Heat-Affected Zone (HAZ) Compliance
Our Rajkot metallurgy desk is ready to review your technical drawings, testing protocols, and delivery schedules for custom closed-die forgings strictly up to 50 kg.