High-Chromium Ni-Cr Alloy Strip With Ductile Powder Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for producing nickel-chromium (Ni-Cr) alloy strips with high chromium content (>33 wt.%) are difficult to work due to brittleness, limiting their ductility and formability, which is essential for applications like flux cored welding consumables, necessitating additional chromium additions to the welding wire core, increasing costs.
Innovation Solution
A process involving roll compaction of nickel and chromium powders, followed by sintering and cold rolling, to produce a Ni-Cr alloy strip with a chromium content of 33 to 50 wt.%, achieving sufficient ductility and formability without the need for melting, thus eliminating the requirement for additional chromium in the welding wire core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional melting and casting methods are used to produce Ni-Cr alloy with high chromium content (>33 wt.%), then the alloy achieves high chromium content for improved corrosion and wear resistance, but the alloy becomes difficult to work due to brittleness and insufficient ductility
Solution Approach 1:
The invention changes the production method from conventional melting and casting to a powder metallurgy process involving roll compaction and sintering. This parameter change in the manufacturing process enables the production of Ni-Cr alloy strip with >33 wt.% chromium that maintains adequate ductility and formability, resolving the contradiction between high chromium content for corrosion resistance and workability
Solution Approach 2:
The invention utilizes phase transitions during the sintering process to achieve densification and bonding of powder particles without melting. The controlled heating and cooling through phase transitions enables the formation of a ductile microstructure even at high chromium concentrations, avoiding the brittle phases that form during conventional casting
2Quantity of substance
If conventional casting methods are used for high chromium Ni-Cr alloys, then the alloy achieves high chromium content, but segregation during casting results in large volumes of brittle chromium phases that reduce ductility
Solution Approach 1:
The invention segments the alloy production into discrete powder particles that are individually controlled for composition and size. By starting with homogeneous metal powders and maintaining that homogeneity through roll compaction and sintering, the process avoids the macrosegregation that occurs during conventional casting, ensuring uniform chromium distribution throughout the final product
Solution Approach 2:
The invention introduces metal powders as an intermediary material between the raw elements and the final alloy product. This powder intermediary enables controlled composition and uniform distribution of chromium throughout the alloy, preventing the segregation that occurs during direct melting and casting
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 resulting Ni-Cr alloy strip exhibits improved ductility and formability, enabling its use as a sheath in flux cored welding consumables, reducing manufacturing costs by eliminating the need for extra chromium additions and avoiding the formation of brittle phases associated with high chromium content alloys made by conventional casting processes.
Implementation Method 1
roll compacting the powder charge to form a green strip
Implementation Method 2
sintering the green strip to form a sintered strip
Implementation Method 3
cold rolling and annealing the sintered strip to form the alloy strip
Implementation Method 4
cold rolling and annealing the sintered strip to form the alloy strip
Data Source
AI summary
A nickel and chromium alloy having a combined wt. % of nickel and chromium of at least 97 wt. %, wherein the chromium accounts for 33 to 50 wt. % of the alloy. The alloy may be provided in strip form and has adequate ductility for the manufacture of various products, such as sheaths for flux cored welding electrodes. A method of making the alloy strip includes forming a powder charge that is 97 to 100 wt. % of nickel and chromium combined and the chromium accounts for 33 to 50 wt. % of the charge, roll compacting the powder charge to form a green strip, sintering the green strip to form a sintered strip, and cold rolling and annealing the sintered strip to form the alloy strip.