Mechanical behavior characteristics of metal materials at high temperature

Due to the increase of atomic diffusion ability at high temperature, the increase of the number of vacancies in the material and the change or increase of the grain boundary slip system, the high temperature strength of the material is very different from the room temperature strength. When considering the high-temperature strength of materials, in addition to the two most basic factors of temperature and mechanics, the influence of time and medium factors must also be considered. Under high temperature conditions, the deformation mechanism of the material increases, and plastic deformation is prone to occur, which is manifested by the decrease of strength, the weakening of deformation strengthening, and the increase of plastic deformation. The strength decreases with the increase of temperature, and the plasticity increases with the increase of temperature.

Under high temperature conditions, materials bear different loads, and the time required for their fracture is also different. Not only does the time to fracture decrease with increasing stress, but the form of fracture also changes. The trend of grain boundary strength and grain strength decrease with increasing temperature is different, and the intersection point corresponds to temperature T. (called isointense temperature), the material changes from transgranular fracture to intergranular fracture.

1. The strength decreases with the increase of temperature, while the plasticity increases with the increase of temperature.

2. The mechanical behavior and performance are closely related to the loading duration;

3. Even if the stress at high temperature is less than the yield strength at this temperature, the material will undergo slow and continuous plastic deformation as the load time increases, that is, the material will undergo creep.

4. At high temperature, the plasticity will decrease significantly with the increase of bearing time, the notch sensitivity of the material will increase, and the fracture will often be brittle.

5. Temperature affects the microscopic fracture mode of the material.

6. The corrosion effect of the environmental medium on the material is intensified as the temperature increases, thus affecting the mechanical properties of the material.

Therefore, the room temperature mechanical properties of the material cannot reflect its behavior under high temperature loading, and a special high temperature performance test must be carried out to determine the high temperature mechanical properties of the material;

Temperature and time are important factors affecting the high-temperature properties of Hollow Titanium Ball, so the relationship between temperature, stress and strain and time must be studied to study the high-temperature mechanical behavior of metals.

Advantages of hot die forging and conventional forging of titanium alloys

Like isothermal forging, hot die forging of titanium alloy processing technology is also a promising precision forging process. The difference is that the mold temperature of hot die forging is higher than that of ordinary forging, but lower than that of isothermal forging. Typical hot die forging die temperature is 110-225°C lower than the billet temperature. Compared with isothermal forging, the reduction of mold temperature can make a wider selection of mold materials, but the ability to form very thin and complex-shaped forgings is slightly worse.

Compared with conventional titanium alloy flange, hot die forging has the following advantages:

(1) Reduce the material consumption of forgings. During hot die forging, the chilling of the die contacting the blank and the work hardening of the material are reduced, and the forgeability of the material is improved, so the forgings are allowed to have a smaller fillet radius and a smaller draft The inclination and small forging allowance greatly reduce the quality of forgings. For example, a Ti-6Al-4V alloy structural part has a mass of 28kg. The mass of forging produced by conventional forging process is 154kg, while the mass of forging produced by hot die forging process is 109kg. The difference between the two methods is 45kg.

(2) Reduce the number of forging operations and improve the working capacity of the press. During hot die forging, the mold temperature is higher and the temperature drop of the billet is less. Conventional forging requires two fires, three fires or more fires to form forgings. Hot die forging Only one time, as many as two fires can be completed. And because of hot die forging, the deformation resistance of the metal is low, which relatively increases the working capacity of the equipment.

(3) Reduce the amount of machining of forgings Because the forgings produced are close to the weight and contour size of the parts, compared with the forgings produced by conventional forging, the amount of material removal in machining is reduced.

(4) The uniformity of the product is better. During the forging process, the temperature gradient is greatly reduced, and the uneven deformation caused by the temperature gradient is easy to reduce. Therefore, the uniformity and consistency of the structure and performance of the product are better than those produced by conventional forging. , but less than forgings produced by isothermal forging.

During hot die forging, although the billet has a temperature drop, it is still in the forging temperature range, and the deformation resistance does not rise as sharply as in conventional forging. The strain rate used in hot die forging varies within the range of 0.05-0.2s-1. If the strain rate is too low, the blank temperature may decrease.

In hot die forging of titanium alloys, forging heating temperature, strain rate, microstructure of preform and holding time are extremely important factors, which play a decisive role in the dimensional accuracy and microstructure of formed parts. Usually lower strain rates and longer dwell times increase the possibility of precision forming. However, the microstructure of the preform has a direct impact on the flow stress and superplasticity of the material, especially on the microstructure after forging. It cannot be attempted to completely eliminate the defects and uneven grains in the raw material through isothermal forging or hot die forging.

At present, whether titanium alloys and high-temperature alloys use hot die forging technology mainly depends on the total cost of forgings or the need for uniformity and consistency of products. The development trend of this process is to use conventional forging preforms, and finally carry out isothermal or hot die final forging.

Matters needing attention in the cutting process of titanium tube

titanium heat exchanger tube are generally divided into two types, one is an extruded type called seamless titanium tube; the other is welded type called welded titanium tube. The Huayu titanium tube manufacturer summarizes the matters needing attention in the cutting process of titanium tubes.

1. If it is semi-automatic cutting, the guide rail should be placed on the titanium tube plane, and then the cutting machine should be placed on the guide rail, and the order should not be reversed.

2. The cutting parameters should be appropriate, and should be reasonably determined according to the thickness of the titanium tube, so as to obtain a good cutting effect.

3. Check whether the cutting gas is unobstructed. If there is a blockage, it should be unblocked in time.

4. Before cutting, the surface should be cleaned and some space should be left, which can facilitate the blowing out of slag.

5. The distance between the cutting nozzle and the surface of the titanium tube should be appropriate, too close or too far is not good.

6. Preheating should be sufficient so as not to affect the cutting process.

7. If cutting workpieces of different sizes, the small ones should be cut first, and then the large ones.

Performance requirements of titanium containers and titanium alloy tubes for petrochemical industry

Titanium and titanium alloys have very good stability in organic compounds, except for five organic acids (formic acid, acetic acid, oxalic acid, trichloroacetic acid and trifluoroacetic acid) at higher temperatures. Therefore, titanium is an excellent structural material in petroleum refining and petrochemical industry, and can be used to make various reactors, pressure vessels, heat exchangers, separator piping, distillation tower top condenser linings, etc.

In oil and gas drilling and production, the UK used titanium drilling and production equipment in a 600m deep, 262°C containing 5% H2S and 25% NaCl. The former Soviet Union adopted titanium pumps, titanium valves and medical titanium plate flushing brine equipment. In order to solve the corrosion of 600-700atm high-temperature H2S, C02 and water vapor at the wellhead of natural gas in my country, Ti-6Al-4V valve plate, valve seat and valve stem are used, and the long-term use effect is very good.

Offshore oil and gas production must endure seawater corrosion and stress corrosion for a long time. Ti-6Al-4V is widely used abroad as oil platform pillars, rope supports, high-pressure pumps, risers and couplings of seawater circulation pressurization systems. Because Ti-6A1-4V is not only resistant to seawater corrosion, but also has high toughness, high yield strength and high fatigue limit. Recently, titanium prestressed oil production pipe joints are selected abroad. This joint is easy to assemble, light in weight, and maintains elastic sealing. Titanium is the best preferred material. my country's offshore oil industry is entering a stage of large-scale development. Currently, the structural parts, key components and equipment of the platform are all imported from abroad, and domestic materials are rarely used. But it can be expected that titanium will find a broad market here.

Classification of medical titanium alloys

Grade 5 Ti-6Al-4V Titanium Bar can be divided into α-type titanium alloys (such as pure titanium series), α+β-type titanium alloys (such as Ti6Al4V, etc.), β-type titanium alloys (such as Ti12Mo6Zr2Fe, etc.) and TiNi shape memory titanium alloys according to the type of material microstructure. There are four types of alloys. Compared with medical stainless steel and cobalt-based alloys, they have the characteristics of small specific gravity, high specific strength, low elastic modulus, corrosion resistance, easy cutting and good biocompatibility.

According to professional standards for surgical implants and orthopedic devices, titanium alloy materials can be classified as "metal materials" in "materials for surgical implants", while Titanium Threaded Forged Fitting materials are used in non-active surgical implants and active surgical implants. In the three major categories of medical devices, implants and orthopedic devices, they can serve as cardiovascular, bone and joint, bone joint, spine, orthopedic devices, cardiac pacemakers and defibrillators, cochlear implants, neurostimulators and other implants The raw material of the product.

The difference between titanium and titanium alloy

Titanium is a single substance, and titanium alloy is a mixture. Therefore, titanium alloys have more diverse properties and wider uses.

Titanium alloy Concept definition: The alloy composed of titanium as the base and other alloying elements is called titanium alloy. Titanium alloy has the advantages of low density, high specific strength, good corrosion resistance, and good process performance, and is an ideal structural material for aerospace engineering.

Research scope: Titanium alloys can be divided into structural titanium alloys and heat-resistant titanium alloys, or α-type titanium alloys, β-type grade 5 titanium sheet, and α+β-type titanium alloys. The research scope also includes forming technology of titanium alloy, powder metallurgy technology, rapid solidification technology, military and civilian use of titanium alloy, etc.

Titanium alloy is a new type of structural material, which has excellent comprehensive properties, such as low density (~4.5g cm-3), high specific strength and specific fracture toughness, good fatigue strength and crack growth resistance, and good low-temperature toughness. Excellent corrosion resistance, some titanium alloys have a maximum operating temperature of 550ºC and are expected to reach 700ºC. Therefore, it has been widely used in aviation, aerospace, chemical industry, shipbuilding, and other industrial sectors, and has developed rapidly. The relationship between (σ0.2/density) and the temperature of light alloys, steels, etc., the specific strength of ASTM F67 Gr2 Titanium Plate is higher than that of other light metals, Steel, and nickel alloys, and this advantage can be maintained up to about 500ºC, so some titanium alloys are suitable for making gas turbine components. About 80% of titanium production is used in the aviation and aerospace industry. For example, titanium alloy accounts for about 21% of the body structure materials of the US B-1 bomber, which is mainly used to manufacture fuselage, wings, skin, and load-bearing components. The body structural material of the F-15 fighter jet uses 7000kg of titanium alloy, accounting for about 34% of the structural weight. In the structural parts of the Boeing 757 passenger plane, titanium alloy accounts for about 5%, and the amount is up to 3640 kg. In the DC10 aircraft produced by Mc-Donnell-Douglas, the amount of titanium alloy is 5500kg, accounting for more than 10% of the structural weight. Titanium consumption in chemical and general engineering fields: the United States accounts for about 15% of its production, and Europe accounts for about 40%. Due to the excellent corrosion resistance, good mechanical properties, and qualified tissue compatibility of titanium and its alloys, it is used to make biomaterials such as prosthetic devices.

0.01mm - 0.5mm ASTM F67 Gr. 23 Titanium Foil

 

Basic Info

Model NO.

ASTM F67 Gr. 23

Surface Treatment

Polished, Pickled

Packing

Plywood

MOQ

20 Kgs

Delivery Time

5-15 Days

Trademark

Allotech

Transport Package

as Per Customer′s Requirement.

Specification

Customzied

Origin

China

HS Code

8108902000

Product Description

Our commitment to providing grade 1 titanium foil products with the highest quality is the cornerstone of our success. Allotech strives to provide our customers with personalized material solutions designed to suit their needs and manufacturing processes.

Processing	Cold rolling, Annealed
Standard	ASTM B265, ASTM F136, ASTM F67
Thickness	0.01 mm - 0.5 mm
Width	20-600mm
Length	As Your Required
Grade	Gr1, Gr2, Gr3 , Gr23, etc.
Surface	No burr No oil spots
Packaging	Wooden cases

Applications:
Grade 2 Pure Titanium Foil in the coil is mainly applied to electron, chemical industry, horologe, glasses, ornaments, sports good, mechanical equipments, galvanizing apparatus, environmental protection, golf, medical, precision processing industry and so on. 

Features:
Corrosion resistance
Low modulus of elasticity
Good heat-exchanger performance
Non magnetic
Suction performance
Bear high & low temperature, etc
Nonmagnetic and Non-toxic

Detection:
Visual inspection to check surface quality, ensuring without any flaw, black and any other defects.
Chemical Composition Detection, making sure all chemical components can meet your demands.
Mechanical Features testing, making sure all titanium foils have satisfying mechanical features before delivery.

Quality Assurance:
According to globally recognized standards, such as ASTM, AMS, ASME, JIS, MIL.
Chemical composition, Mechanical properties, making sure no defects inside the products.
ISO Quality Management System.