High-temperature-resistant silicon molybdenum ferrite nodular cast iron for steam turbine and preparation technology therefor

A technology of ductile iron and preparation process, applied in the field of ductile iron and its preparation process, can solve the problems of increasing the production risk of castings, increasing the production cost, brittleness of castings, etc., and achieving the effects of shortening production cycle, saving resources and reducing plasticity

Inactive Publication Date: 2015-09-16
上海宏钢电站设备铸锻有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

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 ferrite nodular cast iron for steam turbine and preparation technology therefor
  • High-temperature-resistant silicon molybdenum ferrite nodular cast iron for steam turbine and preparation technology therefor
  • High-temperature-resistant silicon molybdenum ferrite nodular cast iron for steam turbine and preparation technology therefor

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 ductile iron product for the above-mentioned steam turbine are as follows (such 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...

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Abstract

The invention discloses high-temperature-resistant silicon molybdenum ferrite nodular cast iron for a steam turbine and a preparation technology therefor. The nodular cast iron comprises components: 3.0-3.5% of C, 2.8-3.2% of Si, less than 0.2% of Mn, less than 0.040% of P, less than 0.015% of S, 0.5-0.8% of Mo, less than 0.010% of Re, 0.040-0.055% of Mg, and 0.004-0.007% of Sb, the balance being iron and residual elements. The preparation technology comprises furnace charge matching; intermediate frequency induction furnace fusing; spheroidizing and addition of first inoculation ferrosilicon; control of contents of elements; pouring into a pulling runner box for secondary inoculation; casting moulding. The obtained nodular cast iron has good combination properties and a low cost, the nodularity reaches more than 80% of the nodularity prescribed by GB/T9441-2009 nodular cast iron metallographic examination, the ferrite amount is more than 90%, and normal temperature and high temperature mechanical properties meet production requirements.

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 Applications(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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