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High temperature resistant silicon molybdenum ferritic nodular cast iron for steam turbine and its preparation process

A nodular cast iron and preparation technology, applied in the field of nodular cast iron and its preparation technology, can solve the problems of increasing casting production risk, increasing production cost, prolonging production cycle, etc., and achieve the effects of shortening production cycle, saving resources and reducing production cost

Inactive Publication Date: 2018-02-27
上海宏钢电站设备铸锻有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] The silicon content in this material is high, which can easily cause brittle castings and increase the risk of casting production; at the same time, aging stress relief annealing treatment is required to prolong the production cycle and increase production costs.

Method used

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  • High temperature resistant silicon molybdenum ferritic nodular cast iron for steam turbine and its preparation process
  • High temperature resistant silicon molybdenum ferritic nodular cast iron for steam turbine and its preparation process
  • High temperature resistant silicon molybdenum ferritic nodular cast iron for steam turbine and its preparation process

Examples

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Embodiment Construction

[0042] The product in the following examples is the medium-pressure outer cylinder of a double-reheat steam turbine of Shanghai Electric. Its main wall thickness is 60-350 mm, partly 500 mm, and its pouring weight is 64.0 tons.

[0043] The material is a kind of high temperature silicon molybdenum ferrite ductile iron for steam turbine, the mass percentage of each component is as follows:,

[0044] C 3.0~3.5%, Si 2.8~3.2%, Mo 0.5~0.8%, Mg 0.040~0.055%,

[0045] Sb 0.004~0.008%, Mn<0.2%, P<0.040%, S<0.015%,

[0046] Re<0.010%, the remainder is iron and residual elements.

[0047] The following table is the composition value of each embodiment:

[0048]

[0049] The preparation process steps of the high temperature resistant silicon molybdenum ferrite nodular cast iron product for above-mentioned steam turbine are as follows (asfigure 1 shown):

[0050] a. Furnace charge ratio: 50 parts by weight of pig iron, 30 parts by weight of carbon steel scrap, 20 parts by weight of ...

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Abstract

The invention discloses a high-temperature-resistant silicon-molybdenum-ferrite nodular cast iron for steam turbines and a preparation process thereof. The nodular cast iron is composed of 3.0-3.5% C, 2.8-3.2% Si, Mn<0.2%, P<0.040%, S <0.015%, 0.5-0.8% Mo, Re<0.010%, 0.040-0.055% Mg, 0.004-0.008% Sb, and the remainder is iron and residual elements. The preparation process includes: burden ratio; melting in an intermediate frequency induction furnace; spheroidization treatment, adding ferrosilicon for primary inoculation; controlling the content of each element; pouring into a plug sprue box for secondary inoculation; pouring molding. The ductile iron obtained by the present invention has better overall performance and lower cost, its spheroidization rate reaches more than 80% specified in GB / T9441-2009 "Metallographic Examination of Ductile Iron", and the ferrite content is greater than 90%. The mechanical properties meet the requirements of production.

Description

technical field [0001] The invention relates to a metal material and a preparation process thereof, in particular to a nodular cast iron and a preparation process thereof. Background technique [0002] Due to its good casting performance and low production cost, ductile iron has been widely used in the field of equipment engineering, such as steam turbine cylinders, bearing housings, etc. Nowadays, high power, high parameters, high reliability, high thermal efficiency and clean environmental protection have become the development direction of steam turbine technology. The application of the steam turbine reheating technology makes the reheating temperature of the unit reach 625°C, the pressure is 35MPa, and the operating temperature of the outer cylinder reaches 350-450°C, which has a significant impact on the strength, creep characteristics, oxidation resistance, and fatigue resistance of the material. more stringent requirements. The service temperature of ordinary ducti...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C37/10C22C33/08
Inventor 蒋毓良王强吴铁明戴月良曾海明蔡娟朱广忠徐德民张伟寿洪苗
Owner 上海宏钢电站设备铸锻有限公司
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