The equipment supervisor of a chlor-alkali enterprise in Jiangsu encountered practical problems when promoting the alkali evaporator lining project, Drawing specification is N4 nickel plate, Some suppliers quote directly on N6 nickel plate.The price difference between the two materials is about 15 yuan per kilogram, Seemingly able to reduce procurement costs, But the carbon content of N6 nickel plate is relatively high, Under long-term high temperature and concentrated alkali working condition, Graphite embrittlement is easy to occur.if that condition match incorrectly, It will cause premature damage to the equipment, The replacement cost of the complete evaporator will be much greater than the cost of material savings.
N6 is one of the most frequently used industrial pure nickel plates., The selection decision logic is consistent with N4/N6 nickel rods, The core differences focus on carbon content and impurity control indicators.N4 grade nickel + cobalt total content is not less than 99.9%, carbon content control within 0.02%;The total nickel + cobalt content of N6 nickel plate shall not be less than 99.5%, and the upper limit of carbon content shall be 0.10%.The difference in purity between the two is only 0.5%, But under the condition of high temperature and concentrated alkali, Different material choices, The actual life cycle of the equipment will be significantly different.
Based on the chemical composition,, N4 belongs to ultra-low carbon and high purity nickel, in addition to that major element of nickel and cobalt, iron, copper, silicon, The control range of various impurity elements of manganese is stricter.N6 as a conventional industrial pure nickel, the allowable range of various impurity indicators is relatively relaxed.When the operating temperature exceeds 315℃ for a long time, Graphite is precipitated gradually from carbon in nickel matrix., initiation of grain boundary graphitization embrittlement, N4 relies on ultra-low carbon content, This type of failure risk can be mitigated.GB/T 5235‑2021 shall be implemented at the national standard level, N4 shall correspond to American standard Ni201 (UNS N02201), N6 shall correspond to American standard Ni200 (UNS N02200), and the plate inspection shall refer to ASTM B162 standard.
Combined with the working conditions, the two brands have corresponding applicable scenarios.Chlor-alkali industry alkali evaporator lining, Vacuum furnace internals, Long-term exposure to heat above 315℃, N4 nickel plate is preferred, Avoiding graphitization embrittlement riskElectroplated nickel anode plate, The tab of electronic battery is mainly under normal temperature condition, Choose N6 nickel plate, Balance conductivity and molding requirementsThe lining temperature of chemical reaction kettle is between normal temperature and 300℃, Priority given to N4, N6 is selected after evaluating operating conditions under budget constraintsHydrometallurgical electrolytic bath temperature below 60℃ weak acid electrolyte, select N6 nickel plate;Food and medicine high soda washing equipment, strict control of impurity precipitation, it is recommended to use N4 nickel plate.Simple selection judgment logic: temperature is greater than 315℃ and long-term heating, select N4;Normal temperature ‑300℃ alkali resistance can be selected according to needs;Electroplating, battery, hydrometallurgy normal temperature conditions, select N6.
terms of specifications, Nickel plate is divided into thin plates 0.5‑4mm, Middle plate 4‑20mm, Heavy forged plate greater than 20mmCommon width 1000mm, 1219mm, 1500mm, length includes 2000mm, 2500mm, 3000mm;Surface state can be divided into black skin, pickling, polishing, sandblasting.The price will fluctuate with the electrolytic nickel plate market. The thin plate range N4 refers to 220‑250 yuan/kg and N6 refers to 200‑235 yuan/kg.Medium plate N4 reference 200‑235 yuan/kg, N6 reference 185‑220 yuan/kg, N4 compared with N6 per kilogram price difference of approximately 15‑20 yuan;Forged plate prices will rise further, zero shear, Further processing services such as polishing will incur additional processing costs, The purchase volume reaches more than 5 tons, Corresponding purchase discounts can be negotiated.The material price difference is limited, and the equipment loss cost caused by the mismatch of working conditions is often higher than the material price difference itself.
Nickel plate market unit price is high, brand appearance recognition is low, procurement stage needs to do a good job of material verification.The first check material quality certificate, focus on confirming nickel and cobalt total content, carbon content two key indicators;Secondly, the peak value of N4 impurity detected by XRF spectrometer is lower than that of Fe, Cu and Si impurity elements.Third, check the plate steel seal logo, regular product label brand, specification, furnace batch number information;Fourth, the use of ultrasonic thickness gauge verification of the actual plate thickness, pay attention to the existence of plate negative tolerance stealing material on the market.
In the actual procurement process, there are several common types of risks that need to be avoided.Recycling remelted raw materials processing plate, element composition can not reach the brand standard;Some merchants use N6 engraved with N4 logo for high temperature working conditions, and embrittlement damage occurs in the later period;There are also N4 contract supply, actual delivery of N6 materials to earn purity difference;The actual thickness of the plate is lower than the nominal specification, affecting the strength of the equipment;Defective plates are polished to cover up surface problems and pitting occurs after use.Therefore, the procurement contract, Need a clear brand, size specification, thickness tolerance standard, surface states, And in the terms of the contract, it is stated that the warranty needs to provide nickel and cobalt, Carbon measured data, Reduce procurement risk.
processing links, Pure nickel plate has sticking tool, Features of fast work hardening rate, Machine plus recommendations for the use of large rake angle sharp coated carbide tools, With plenty of coolant.TIG argon arc welding is adopted for welding, Match ERNi‑1 pure nickel wire, Argon shield the back of the weld, Stress relief annealing after weldingThin plate laser, plasma cutting is easy to deform, early reserve clamping allowance.
Shaanxi 100 billion Tuoda Technology is located in Baoji, China Titanium Valley, N4 can be supplied, N6 nickel plate full specification products, Supports sizing and multiple surface finish requirements, Material accompanying spectral test data, Traceability of furnace lot number, Engineers can combine media, temperature, Thickness Multi-dimensional to assist in material selection, nickel rod if required, See N4/N6 nickel rod Technical Article.
Q: How to choose N4 nickel plate and N6 nickel plate? A: Take the operating temperature as the core judgment.Long-term heating above 315℃, high temperature concentrated alkali, vacuum furnace tooling selection of N4;N6 can be selected for alkali resistance, electroplating, battery and hydrometallurgy scenarios at room temperature ‑300℃.
Q: Which American standard does N4 correspond to? A: N4 corresponds to ASTM Ni201 UNS N02201, belonging to ultra-low carbon nickel;N6 corresponds to ASTM Ni200 UNS N02200 commercially pure nickel.
Q: What welding wire is used for nickel plate welding? TIG argon arc welding matching ERNi‑1 pure nickel welding wire, Argon shielding is required for welding back, Annealing stress relief is recommended after welding, And dissimilar steel welding needs to add nickel-based transition layer.
Q: How do nickel plate purchases avoid risks? A: Check the nickel, cobalt and carbon indicators in the warranty;Spectral sampling for impurities;Check the batch number of steel stamp furnace;Measured sheet thickness;The contract states all technical requirements.
This article refers to GB/T 5235‑2021 "Wrought nickel and nickel alloy designation and chemical composition", ASTM B162 Nickel and Nickel Alloy Sheet and Strip, Prices are industry reference ranges, Actual quotation subject to metal market on the date of order, The type selection needs to be comprehensively evaluated in combination with the actual working conditions of the project.
Understanding N4 nickel rod and N6 nickel rod: Grade Composition, Working Condition Selection and Procurement Pit Avoidance Guide
Key points of welding process and common defect treatment scheme for pure nickel materials
Baoji Titanium Valley Nonferrous Materials Custom Processing Service Introduction
The content of this paper is only a reference for the selection of pure nickel materials, Price of materials in this article, Suggestions on working condition selection are based on the experience of Shaanxi Qianyi Tuoda's past projects, Does not constitute engineering design, The direct basis for purchasing contracts.The price of metal raw materials fluctuates dynamically with market conditions, equipment material selection, The welding processing scheme shall be submitted to the project engineering technicians in combination with the site conditions., Design specifications for accounting verification, The enterprise shall not bear the engineering losses caused by the direct application of the contents of this article
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