heat treatment-2

Alloy heat treatment delivery status of special steel materials (HY-industry technical centre)

1. Hot rolled state

heat treatment-2The steel is no longer subject to special heat treatment after hot rolling or forging, and is delivered directly after cooling. It is called hot rolling or hot forging. The end temperature of hot rolling (forging) is generally 800 to 900 ℃, and then generally in the air Natural cooling, so the state of hot rolling (forging) is equivalent to normalizing treatment. The difference is that because the termination temperature of hot rolling (forging) is high or low, unlike normalizing, the heating temperature is strictly controlled, so the fluctuation of steel structure and performance is greater than that of normalizing. At present, many steel companies use controlled rolling. Because the temperature control of the final rolling is very strict and forced cooling measures are taken after the final rolling, the grains of the steel are refined, and the delivered steel has high comprehensive mechanical properties. It is the reason that the cold-rolled wire rod without twist control is superior to the ordinary hot-rolled wire rod. The steel delivered in the hot-rolled (forged) state has a certain corrosion resistance due to the surface covered with a layer of oxide scale, so it is stored and stored The requirements are not as strict as the steel delivered in cold drawn (rolled) state. Large and medium-sized steel and medium-thick steel plates can be stored in the open-air yard or after being covered.

2. Cold drawn (rolled) state

Cold-drawn, cold-rolled and other cold-formed steel materials are delivered directly without any heat treatment, which is called cold-drawn or cold-rolled state. Compared with the hot rolled (forged) state, the cold drawn (rolled) state steel has high dimensional accuracy, good surface quality, low surface roughness, and has higher mechanical properties. Due to the cold drawn (rolled) state, the steel is delivered The surface is not covered with oxide scale, and there is a lot of internal stress, which is extremely susceptible to corrosion or rust. Therefore, the cold drawn (rolled) steel has strict requirements for packaging, storage and transportation, and generally needs to be kept in the warehouse. And should pay attention to the temperature and humidity control in the warehouse.

3. Normalizing state

Steel is heat-treated by normalizing before leaving the factory. This delivery state is called normalizing. Since the normalizing heating temperature (Ac3+30-50°C for hypoeutectoid steel and Accm+30-50°C for hypereutectoid steel) is more strictly controlled than the hot rolling termination temperature, the structure and properties of the steel are uniform. Compared with the annealed steel, due to the faster normalizing cooling rate, the amount of pearlite in the steel structure increases, and the grains of the pearlite lamella and steel are refined, so it has higher comprehensive mechanical properties and is conducive to improvement The Wei structure of low carbon steel and the cementite network of hypereutectoid steel can prepare the structure for further heat treatment of the finished product. Carbon-bonded steel and combined steel are often delivered in normalized condition. Certain low-alloy high-strength steels such as 14MnMoVBRE and 14CrMnMoVB steel also require normalized delivery in order to obtain a bainite structure.

4. Annealing state

Steel is annealed and heat-treated before leaving the factory. This delivery state is called the annealed state. The purpose of annealing is mainly to eliminate and improve the structural defects and internal stress left over from the previous process, and to prepare for the organization and performance of the subsequent process, alloy structural steel, structural steel to ensure hardenability, cold heading steel, bearings Steels, tool steels, steam turbine blade steels, steel wire-type stainless heat-resistant steels are usually delivered in annealed condition.

5. High temperature tempering state

heat treatment-1Steel is subjected to high temperature tempering heat treatment before leaving the factory. This delivery state is called high temperature tempering state. The high tempering temperature of high temperature tempering is conducive to completely eliminating internal stress, improving plasticity and toughness. Carbon structure, alloy steel, and structural steel with hardenability can be delivered in high temperature tempering state. Some martensitic high-strength stainless steels, high-speed tool steels and high-strength alloy steels are often tempered after quenching (or tempering) due to their high hardenability and strengthening effect of alloying elements. Medium carbides are properly aggregated to obtain coarse tempered sorbite structure with carbide particles (similar to spheroidizing annealing structure). Therefore, the steel in this delivery state has good cutting performance.

6. Solution treatment state

Steel is solution treated before leaving the factory. This delivery state is called the solution treatment state. This state is mainly applicable to the treatment of austenitic stainless steel before delivery. Through solution treatment, a single-phase austenite structure is obtained to improve the toughness and plasticity of the steel, create conditions for further cold working (cold rolling or cold drawing), and also prepare the structure for further precipitation hardening.Most superalloy raw materials are delivered in solid solution.Same like Nimonic 80AInconel 600,Inconel 718 etc.

7. Aging treatment status

After solid solution treatment, cold plastic deformation or casting, after forging, the steel is placed at a higher temperature or room temperature, and its performance, shape and size change with time after heat treatment process to achieve the delivery state of the established mechanical properties.Most superalloy parts are delivered in an aging state.Same like inconel 718,mp35n,17-4PH etc.

HY-industry is qualified  Nickelalloy&cobalt alloy materials supplier.

We have more than twenty years experience in kind of High temperature alloy production.

Inconel 718, Monel 400,Stellite 6,Stellite 12,Incoloy 800ht,Incoloy 901,Nimonic 80A,Kovar,Invar 36,Inconel 625,Hastelloy C276, Incoloy 825 are mature productes of us.

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