Ti-Containing Fe-Ni-Cr Alloy Composition for Clean Slit Cut Surfaces
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Solution Overview
Problem
Ti-containing Fe—Ni—Cr alloys used in cladding tubes for sheathed heaters and pipe layouts face challenges in achieving superior slit cut surface quality due to issues like burrs, nips, and concave-convex portions, which affect welding workability and reliability, especially during high-speed welding processes.
Innovation Solution
A specific alloy composition with controlled titanium nitride sizes and numbers, along with optimized annealing conditions and production methods, is developed to improve slit cut surface quality, ensuring a small border line departure area and fine crystal grain diameter, enhancing welding properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional slitting is performed on Ti-containing Fe—Ni—Cr alloys, then production efficiency is maintained, but the slit cut surface quality deteriorates due to burrs, nips, and concave-convex portions
Solution Approach 1:
The invention changes the chemical composition parameters of the steel plate by strictly controlling the content ranges of Ti (0.03-1.50%), Al (0.05-1.00%), and their ratio (0.05-1.50 when Ti×100/Al), along with other alloying elements. This parameter optimization prevents the formation of excessive titanium nitrides and improves the uniformity of the material structure during slitting, thereby reducing burrs, nips, and concave-convex portions on the cut surface while maintaining production efficiency
2Productivity
If high-speed welding is performed on poor quality slit surfaces, then productivity is improved, but welding reliability deteriorates due to defects
Solution Approach 1:
The invention performs preliminary action by optimizing the steel plate composition and controlling the titanium nitride distribution before the slitting and welding processes. By pre-controlling the alloy composition (Ti, Al, and their ratio) and the size distribution of titanium nitrides (95% or more with equivalent circle diameter of 0.01mm or less), the material is prepared in advance to produce high-quality cut surfaces that enable reliable high-speed welding without defects
3Strength
If titanium nitride size is increased to improve strength, then material strength is improved, but slit cut surface quality deteriorates due to larger departing portions
Solution Approach 1:
The invention optimizes the parameters of titanium nitride size distribution by controlling the equivalent circle diameter of 95% or more of titanium nitrides to be 0.01mm or less, while maintaining appropriate Ti and Al content ratios. This fine control of nitride particle size prevents large departing portions on the cut surface (keeping the area ratio to 10% or less) while still providing adequate material strength for the application
Data Source
AI summary
Alloy compositions, structures, and production methods for an appropriate slit cut surface shape improve productivity by increasing welding speed and stabilizing quality during high speed welding in Ti-containing Fe—Ni—Cr alloy production. The Ti-containing Fe—Ni—Cr alloy contains, hereinafter in weight %, C: 0.001 to 0.03%, Si: 0.05 to 1.25%, Mn: 0.10 to 2.00%, P: 0.001 to 0.030%, S: 0.0001 to 0.0030%, Ni: 15 to 50%, Cr: 17 to 25%, Al: 0.10 to 0.80%, Ti: 0.10 to 1.5%, N: 0.003 to 0.025%, O: 0.0002 to 0.007%, Fe as a remainder, and inevitable impurities, and when the number and size of titanium nitrides contained in material are evaluated in a freely selected field of view of 5 mm2, the titanium nitrides having sizes of not more than 15 μm are not less than 99.3% of total of the titanium nitrides.