Update of Standard for Carbon Steel Parts in Investment Precision Casting

Update of Standard for Carbon Steel Parts in Investment Precision Casting

JB/T5100-1991 "Technical Conditions for Carbon Steel Parts in Investment Casting" is a widely used standard in the domestic investment casting industry, which has been in use for more than 20 years. With the expansion of China's foreign business exchanges and the entry of a large number of foreign casting enterprises, the differences between JB/T5100-1991 Technical Conditions for Carbon Steel Castings in Investment Casting and ISO standards and other foreign standards are becoming increasingly prominent, often causing discrepancies between the supply and demand sides in the determination of casting inspection results, which brings many disadvantages to Chinese enterprises. It is necessary to establish new standards to meet the actual needs of the current industry and enterprise development. Today, precision casting manufacturer Tianyao Metal will talk to you about the updated standards of JB/T5100-1991 "Technical Conditions for Carbon Steel Parts in Investment Casting".

The investment precision casting carbon steel parts standard prepared this time follows part of JB/T 5100-1991, absorbs the essence of the American ASTM standard, and strives to achieve a simple, clear and reasonable effect, in line with the domestic expression, understanding and application habits.

This standard is divided into 7 components. Compared with JB/T 5100-1991, the main revisions are as follows.

1、 Scope

This standard specifies the classification, grade, technical requirements, test methods, and inspection rules of investment cast carbon steel parts, as well as marking, packaging, transportation, and storage.

This standard is applicable to investment cast carbon steel parts for general engineering purposes.

2、 Normative reference documents

According to the drafting requirements of GB/T 1.1-2009 "Guidelines for Standardization Work Part 1: Structure and Writing of Standards", this standard has added normative references compared to JB/T 5100-1991.

3、 Classification and grade

Referring to GB/T 5613 "Method for Indicating Steel Grades" and following the principle of downplaying the process, the "R" representing investment casting process in JB/T 5100-1991 standard is removed, and "ZG" is uniformly used to represent cast steel. According to the working conditions and uses of castings, they are divided into three categories. Under the same casting category, investment casting carbon steel parts have five grades based on strength, including ZG200-400, ZG230-450, ZG270-500, ZG310-570, ZG340-640, etc.

4、 Technical requirements

Specific requirements have been put forward for chemical composition, mechanical properties, dimensional tolerances, surface roughness, surface defects, internal quality, physicochemical properties, casting repair, and heat treatment. Among them, compared to the JB/T 5100-1991 standard, this standard refines the dimensional and geometric tolerances of different processes such as water glass process, silica sol process, and water glass silica sol composite shell process, increases the technical requirements for internal defects, and proposes higher requirements for casting repair.

1. Chemical composition and mechanical properties

The chemical composition and mechanical properties of this standard refer to GB/T 11352. The vast majority of production raw materials for investment casting steel parts come from scrap materials of forging, stamping and other enterprises. Compared with JB/T 5100-1991 and American ASTM A732/A732-05 standards, the S and P components can be further controlled, increasing the Al or Ti content in the chemical composition of investment casting carbon steel parts. The residual element control is slightly different, but the total amount does not exceed 1.00%.

2. Dimensional tolerances

The dimensional tolerance of carbon steel parts in investment casting shall be in accordance with the CT4 to CT9 levels specified in GB/T 6414, and different processes shall be executed within different levels.

3. Geometric tolerances

The geometric tolerances of carbon steel parts in investment casting shall be executed according to ISO/CD 8062-2 CTG4~CTG8 levels, and different contour dimensions shall be executed within different level ranges. The geometric tolerance levels and corresponding tolerance values of castings have been added, or shall be executed according to the technical conditions specified in the drawings and purchase agreements.

4. Surface roughness

The surface roughness of carbon steel parts in investment casting shall comply with GB/T 15056, with a range of Ra3.2~12.5 μ m, and different processes shall be carried out in different grade ranges.

The most obvious aspect of internal quality and casting repair is the combination of the characteristics of the times, the popularization of relevant testing technologies, and customer requirements for high performance products. This has increased the internal quality technology and testing requirements for Class I and II products. Compared with JB/T 5100-1991 standard, internal inspection and testing methods (including magnetic powder, ultrasonic, radiographic, and penetration testing) have been added, which are executed in accordance with GB/T 9444, GB/T 7233.1, GB/T 5677, GB/T 9443, and HB 6573, respectively. For different types of castings, the allowable defect level in the designated X-ray inspection area should comply with the provisions of Table 6. Non designated areas should be executed according to the provisions of the lower level casting category, or according to the technical conditions specified in the drawings and purchase agreement.

Detailed descriptions have been added around casting repair, the limit values for non machined surface porosity defects in Class I castings have been modified, provisions have been added to allow repair glue to repair Class III products, and technical requirements for welding repair of castings have been modified.

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