Fe-Ni Welding Wire Composition for High-Temperature 800H Joints
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Solution Overview
Problem
The heat transfer tubes of steam generators in nuclear power units, made from 800H alloy, experience early failure of welded joints due to reduced tensile strength at high temperatures when using existing welding wires like Inconel 82, posing a safety risk.
Innovation Solution
A Fe—Ni based alloy welding wire with specific chemical components (C: 0.05-0.10%, Si: ≤1.0%, Mn: ≤1.5%, Ni: 29.0-32.0%, Cr: 17.0-19.0%, Nb: 0.35-0.45%, Mo: 1.50-2.50%, Al: 2.5-3.0%, N: ≤0.03%, B: ≤0.01%, S: 0.002-0.008%, P: 0.008-0.009%, and balance Fe) is developed, which maintains high tensile strength and elongation at both ambient and high temperatures through a preparation method involving vacuum melting, casting, forging, hot rolling, and drawing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If existing welding wires are used for welding 800H alloy, then welding process is simple, but welded joint reliability deteriorates due to early failure at high temperature
Solution Approach 1:
The patent modifies the chemical composition parameters of the welding wire to achieve both high reliability and ease of manufacture. By optimizing C content (0.04-0.08%), adding Nb (0.03-0.06%), Ti (0.02-0.05%), and Al (0.04-0.08%), the welding wire maintains good weldability while ensuring welded joint reliability at high temperatures through enhanced mechanical properties.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The Fe—Ni based alloy welding wire achieves superior tensile strength and elongation at high temperatures, outperforming existing 800H base metal and Inconel 82 welding wires, ensuring safer operation of nuclear power units by preventing early failure of welded joints.
Implementation Method 1
subjecting the resulting raw material mixture in sequence to a vacuum melting, a casting, a forging, a hot rolling and a drawing
Implementation Method 2
the hot rolling is carried out at a temperature of 1150-1200° C. with a rolling speed of 61-91 mm/min
Data Source
AI summary
The present disclosure belongs to the technical field of welding materials, and in particular relates to a Fe—Ni based alloy welding wire for welding 800H alloy and a preparation method thereof and a method for welding 800H alloy. The Fe—Ni based alloy welding wire for welding 800H alloy provided by the present disclosure has a reasonable chemical components, and after being used to weld 800H alloy, the obtained weld has a tensile strength of 557.6 MPa and an elongation of 37.5% at ambient temperature, and has a tensile strength of 420 MPa and an elongation of 17.25% at a temperature of 650° C.