Vermicular cast iron of valve material

Vermicular cast iron of valve material

This scale defines the terms and definitions, grades, technical requirements, sampling and test blocks, test methods, maintenance rules, casting identification, packaging, storage and transportation requirements. The production method and chemical composition of vermicular cast iron are to be determined by the supplier to ensure that the required material grade and function conform to this scale. When vermicular cast iron has special uses and requirements, the chemical composition and heat treatment can be agreed by both parties. Vermicular cast iron should be observed to have at least 80% vermicular graphite on its two-dimensional polished plane, and the remaining 20% should be spherical graphite, clumped graphite, and flake graphite should not be allowed.

range

This scale defines the terms and definitions, grades, technical requirements, sampling and test blocks, test methods, maintenance rules, casting identification, packaging, storage and transportation requirements.

This scale is suitable for use in mold forging of vermicular graphite cast iron with sand mold or with thermal conductivity commensurate with sand mold. The coil cast iron produced by other forging methods can be used as reference.

Normative reference document

The following documents are essential for the application of this document. For dated references, the dated version is applicable to this document. The version of an undated referenced document (including all amendments) shall be used for this document.

GB/T 228 Metallic materials — tensile test method at room temperature (GB/T 228-2002,eqv ISO 6892:1998)

Metallic materials — Brinell hardness tests — Part 1: Test methods (GB/T 231.1-2009, ISO 6506-1:2005, MOD)

GB/T 5611 Forging terms

GB/T 5612 cast iron grade representation method (GB/T 5612-2008, ISO 15931; 2004, MOD)

Sample forging surface (GB/T 6060.1-1997,eqv ISO 2632-3:1979)

Dimensional tolerances and Machining allowances for Castings (GB/T 6414-1999,eqv ISO 8062:1994)

GB/T 11351 casting weight tolerance

GB/T 26656 vermicular cast iron metallography repair

Terms and definitions

The terms established in GB/T 5611 and the following terms and definitions are used for this document.

Vermicular cast iron

Carbon is mainly in the form of vermicular graphite precipitated from cast iron in the metal matrix.

Creep treatment

A process in which a creep agent is added to liquid iron to precipitate wormlike graphite during solidification.

Casting main wall thickness

The main wall thickness of casting refers to the thickness of the section of the mechanical function of casting materials or the thickness of the main working part of the casting, which is agreed by both parties.

brand

The material grade shall be represented in accordance with the specification of GB/T 5612.

In this scale, vermicular graphite cast iron is divided into 5 grades according to the mechanical classification of the samples processed by single cast or with cast test blocks (see Table 1 and Table 2).

Order information

Brand of casting material required by Demander.

The main wall thickness of the casting function as agreed by both parties.

Other special requirements agreed by both parties.

Production and manufacturing

The production method and chemical composition of vermicular cast iron are to be determined by the supplier to ensure that the required material grade and function conform to this scale. When vermicular cast iron has special uses and requirements, the chemical composition and heat treatment can be agreed by both parties.

Technical requirement

Mechanical properties of single cast sample

The mechanical properties of single cast samples of vermicular cast iron should conform to the delineation in Table 1.

Generally, 0.2% yield strength Rpo is not used as the basis for acceptance. When the demander has special requirements, it can also be determined.

Table 1 Mechanical function of single cast sample

The mechanical function of the cast specimen

The mechanical properties of vermicular cast iron samples shall conform to the delineation in Table 2.

0.2% yield strength Rpo is generally not used as the basis for acceptance. When the demander has special requirements, it can also be determined.

Table 2 Mechanical function of the cast sample

Mechanical function of casting body sample

The position of vermicular cast iron with test blocks on the casting shall take into account the shape of the casting and the structure form of the pouring system, so as to avoid adverse effects on the functions of the adjacent parts, and the principle is not to affect the structural function of the casting, the appearance quality of the casting and the density of the test blocks. The test block shall be taken from the sexual part of the casting. In order to determine the size of the sample, the buyer shall indicate to the supplier the important section of the casting. If the demander has no bias opinion, the supplier can set the cutting position on the casting and determine the diameter of the sample.

Mounting: vermicular cast iron for Valve materials (I)

With cast test block

The castings to which the test block is attached are also all castings of the same batch having a similar wall thickness.

Generally, when the weight of the casting is more than 2000kg, and the wall thickness is 30mm~200mm, it is preferred to attach the casting test block. When the casting weight is more than 2000kg and the wall thickness is 200mm, the attached casting test block is used. The size and position of the cast test block shall be agreed by both parties.

Unless otherwise specified by both parties, the shape and size of the attached cast test block are shown in the figure

The position of the supplementary casting test block on the casting should take into account the shape of the casting and the structure form of the pouring system, so as to avoid adverse effects on the functions of the adjacent parts, and do not affect the structural function of the casting, the appearance quality of the casting and the density of the test block as the principle.

All test blocks should be marked prominently to ensure that the casting quality can be tracked throughout the process.

When castings require heat treatment, the attached castings shall be separated from the castings after heat treatment unless otherwise agreed by the parties. stretch

Explanation:

Sand eating capacity of test block casting: type Ⅰ, Ⅱa and Ⅱb are 40 mm smaller; Type Ⅲ small 80mm

Note: For thin-wall or metal castings, the sample may be taken from u12.5mm test block, and the mechanical function can be agreed by both parties.

The size units of the I and U blocks are millimetres

Explanation:

Test block cast eating tray: type I, type II small 40mm; Type Ⅲ Small 80mm,

Note: For thin-walled or metallic castings, the sample may be taken from u

Body test block

The mechanical function of the specified part of the casting shall be agreed by both parties. These functions shall be measured from a sample cut from a specified part of the casting. Sample diameter shall be agreed by both parties. The size of tensile sample is shown in FIG. 4 and Table 6

The test block shall be taken from the sexual part of the casting. In order to determine the size of the sample, the buyer shall indicate to the supplier the important section of the casting. If the demander has no bias opinion, the supplier can set the cutting position on the casting and determine the diameter of the sample.