Titanium forgings: forging ratio 4:1 is watershed-below this value
Published by Engineering Team, Shaanxi Qianyi Tuoda Technology Co., Ltd on 2026-07-22
Titanium forging ratio 4, 1 is the critical performance watershed, The blanks below this ratio are easily misjudged as qualified forgings, Essentially the internal structure is close to the casting.The products with forging ratio less than 4 times are liable to fatigue failure within 1 to 2 years of service.The impact toughness decreases by 50% after β brittle phase precipitation, and the machining hardening layer will form stress channels, which will bury the hidden danger of fracture.This paper systematically explains titanium forging material principle, production process, implementation standards and selection points, and recommends collection.
Titanium forgings are titanium and titanium alloy blanks, hot forging, cold forging forming, matching annealing, machining made of blank parts.According to the molding method is divided into free forging, die forging, die forging, extrusion forging, ring forging and other categories.Common titanium forgings include cake forging, diameter range Φ100-1500mm, refer to GB/T25137, AMS4930 standards;The outer diameter of ring forging can reach Φ200-3000mm, and AMS4928 and AMS4960 shall be executed;Stepped shaft forging;Flange forgings shall comply with ASTM B381 and GB/T25137.
Compare titanium castings ZTA2, TA2titanium barmaterial, TC4 free forgings and TC4 forgings, Shrinkage is easy to exist in titanium castings, loosen, blowhole defects, Low impact toughnessThe tensile strength of TC4 free forging and die forging parts can reach 895MPa or more., Forgings require forging ratio not less than 4, Local forging ratio of aviation key parts shall not be less than 3.In terms of size accuracy, the machining allowance of castings is the largest, the size accuracy of die forgings is the best, and the machining allowance is the smallest.Price, titanium castings about 300-450 yuan per kilogram,titanium barMaterial 180-280 yuan per kg, TC4 free forging 450-650 yuan per kg, TC4 forging 650-1200 yuan per kg.
typical application scenarios, C919 landing gear strut uses TC4 forging, Replacement of conventional castings and bar machined parts, Fatigue life increased to more than 20 yearsDN600 Large caliberTitanium flangeIt adopts integral ring forging instead of steel plate coil welding structure, and its service life can reach 15 years.Corrosion resistant reaction kettle adopts titanium free forging blank, effectively avoiding pitting corrosion problem;TC4 ELI die forgings are selected for medical artificial joint femoral stem, which has better long-term implantation stability.
According to the statistics of China Aviation Industry Association Forging and Casting Branch, The domestic titanium forging market size in 2024 is about 3.5 billion yuan, Annual growth rate of 22%, aviation, maritime work, The three major medical fields account for 70% of the market demand.Large-diameter titanium ring forgings with an outer diameter greater than 2000mm are the fastest growing category, The C919 program drives an annual increase of more than 30% in the demand for landing gear forgings.
1. Failure mechanism of titanium forging core: forging ratio, β brittle phase and mechanical hardening
Titanium forgings purchase unit price is several times higher, But the service life can be increased by 5 times, The core value comes from sufficient forging ratio.For the same material, the properties of blank with forging ratio 2:1 are inferior to those of high quality titanium casting.The forging ratio ≥6:1 can obtain stable and reliable forgings, and the fatigue life can be doubled by increasing the forging ratio.Most of the scrap problems of titanium forgings are not macroscopic cracks, but three major process hidden dangers.
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Insufficient forging ratioForging ratio = blank weight/raw material weight.Forging ratio less than 4, 1 o 'clock, Internal porosity does not allow adequate welding, Even if the ultrasound test is temporarily qualified, Fatigue crack initiation occurs at the loose position during service, 1-2 Breaks occur during the year.
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beta brittlenessTC4 α+β titanium alloy, slow cool after heat for a long time in beta phase interval above 995 DEG C, α-phase precipitated at grain boundary to form β-brittle phase, Impact toughness directly drops by 50%.Aviation forgings are forged in α+β phase region, combined with solid solution aging process to avoid β brittleness risk.
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machining hardeningAfter machining, the surface of titanium will form a hardened layer of 0.05~0.2mm, which constitutes a stress channel.Residual stress superimposed external load, Easy to induce stress corrosion from machined surfaces, Shot peening is generally used to eliminate hardened layer in aviation forgings.
Second, titanium forging classification and material selection
Forming process is divided into free forging, suitable for large-scale cake, ring, shaft blank;Die forging is mostly used for aviation precision structural parts;Die forging adapter flange, valve blank;Ring forging for large diameter flanges, bearing rings;Extrusion forging for pipe fittings, T-shaped components;Precision die forging belongs to near net forming process, which is used for high demand parts such as aviation aligning shaft and wing beam.
Material selection: TA1, TA2 pure titanium suitable for chemical weak stress corrosion resistance conditions;TA10 is suitable for seawater and chloride ion corrosion environment;TA18 is mostly used for aviation pipelines;TC4 is the main material of aero main bearing component.TC4 ELI high purity titanium alloy is used for medical implants;TC11 and TC18 are used for high-load components such as aeroengines and landing gears.
TC4 alloy matrix is titanium, aluminum content is 5.5~6.5%, vanadium is 3.5~4.5%, impurities are strictly controlled, hydrogen content is controlled ≤0.015%, medical TC4 ELI is further reduced to ≤0.012%.Mechanical properties Tensile strength ≥895MPa, yield ≥825MPa, factory state is solid solution aging state.
Three, titanium forging manufacturing process points
The biggest difference between titanium forging production and steel forging lies in forging ratio control, β Phase Zone Insulation Control, Vacuum annealing and solution aging treatment.Complete process flow: vacuum meltingtitanium barRaw Material → Homogenization Annealing → Blanking Cutting → α + β Phase Interval Multi-pass Forging, Total forging ratio ≥4, Aviation parts ≥6, 1→ intermediate stress annealing → final forging → solution aging strengthening → rough and fine machining → nondestructive testing → marking packaging, and warehousing under the protection of nitrogen.
Core Process Control, Forging heating temperature control 940~980℃, The total residence time of β phase interval shall not exceed 30 minutes, Prevention of β brittle phase precipitationSpecial tools and lubrication are adopted for machining, cutting speed is controlled, and work hardening is avoided;Products require 100% ultrasonic UT and penetrant PT nondestructive testing;Shot peening removes machining hardened layers.
IV. Implementation of standard system
Domestic common standards include GB/T25137 General specification for titanium and titanium alloy forgings, GB/T16598 titanium cake and titanium ring standard, HB5435 aviation TC4 titanium forgings, GJB 2744A military titanium forgings, medical implants GB/T13810.International standards include ASTM B381 Basic Specification for Titanium Forgings, AMS 4928 Aviation Titanium Forgings, AMS 4930, AMS 4960 Standard for Cake Rings and Die Forgings, ASTM F136, ASTM F620 for Medical Implantation Forgings.
Selection Reference Order, Project conditions → domestic GB/T25137 or American standard ASTM B381→ AMS series for aviation, HB Military Standard, ASTM F Series → Complementary Nondestructive Testing Standards, Finally, special technical requirements for the project are added.The forging ratio, β-phase holding time and UT+PT detection must be stipulated in the aviation procurement contract.Medical forgings require ISO13485 quality system, and the whole process of single piece can be traced.
V. Application Scenarios and Selection Procurement Avoidance
Titanium forgings are widely used in aviation landing gear, cartridge receiver, Medical femoral stem hip joint, Chemical reactor flange, Marine ship propeller, nuclear power, Petrochemical equipment, etc.
Six-step selection: the first step to determine the operating environment;secondly, selecting a titanium alloy grade;thirdly, determining the forming process and the lowest forging ratio;The fourth step is to determine the size, weight and surface roughness;The fifth step is to agree on physical and chemical and nondestructive testing items;The sixth step is to formulate heat treatment and β brittle phase control scheme.
Procurement contract must be clearly identified, forming process, forging ratio, size tolerance, heat treatment system, β phase insulation limit, test item, Lot traceability and warranty period.Procurement focuses on preventing seven quality risks, Insufficient forging ratio, β brittle phase precipitation, machining hardening stress channel, NDT missed detection, Omit shot peening, Insufficient solution cooling rate, Hydrogen permeation pollution in machining.
Domestic titanium forging industry chain mature, Stable supply of 0.5kg to 5000kg full specification forgings, Domestic products are more cost-effective, Aeroengine high-pressure rotor only, There is a premium for imported products of oversized ring forgings.
VI. Industry development trend
Three major directions of the future industry: the demand for ultra-large ring forgings continues to grow, and ships and marine equipment are pulled;Precision near-net die forging gradually popularized, greatly reducing machining allowance;Digital simulation simulates forging process and realizes online monitoring of forging process.
Relying on the advantages of Baoji China Titanium Valley Industrial Cluster, Shaanxi thousand billion Tuoda technology can supply TC 4 titanium forging parts, TA18 Titanium ring forging, TC4ELI Medical Titanium Forgings, Supporting material certificate, Physico-chemical and non-destructive testing report, adaptive aviation, medical treatment, chemical engineering, Offshore titanium forging project.
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disclaimer, the proces parameters herein, Material selection content for technical reference only, aviation, medical treatment, Selection of key components of pressure equipment, Must be reviewed by professional engineers in conjunction with project conditions.