JB/T 2980.2-1999 This standard is a revision of JB 2981-81 "Test Method for High Temperature Bending Strength of Investment Casting Shell". During the revision, only editorial changes were made according to relevant regulations, and the main technical content remained unchanged. This standard specifies the method for determining the bending strength and deformation value of standard shell specimens under loading in the range of room temperature to 1200℃. JB/T 2980.2-1999 Test Method for High Temperature Bending Strength of Investment Casting Shell JB/T2980.2-1999 Standard download decompression password: www.bzxz.net

JB/T2980.2
This standard is an editorial revision of JB2981-81 "Investment Casting Shell". The main technical content has not changed. This standard replaces JB2981-81 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Foundry Standardization. The drafting units of this standard are: Shenyang Foundry Research Institute and Tsinghua University. 464
Machinery Industry Standard of the People's Republic of China
Test method for high temperature strength ofinvestment casting shell
JB/T2980.2-—1999
Replaces JB2981-81
This standard is applicable to the determination of the bending strength and deformation value of the standard specimen of the shell under loading at room temperature 1200C. 2 Instruments and Equipment
The testing instrument is a high-temperature bending strength tester for mold shells. 2.1 The instrument works in a clean environment without strong magnetic and electric fields, strong vibrations, etc. 2.2 The heating element of the high-temperature furnace of the instrument is an iron-chromium-aluminum resistance wire, and its maximum operating temperature is 1250℃. 2.3 The measuring accuracy of the instrument is 1.5%.
3 Preparation of Samples
3.1 The shape and size of the sample are shown in Figure 1. bZxz.net
3.2 Use the wax mold with eight recesses as shown in Figure 2 to prepare the sample according to the production process or according to the test requirements. Each time a layer is applied, the multiple layers of paint outside the recess are scraped off until the recess is filled. The last layer is only coated with paint without sand. 9'0 at 9
3.3 After the sample is dewaxed, it is kept at 110C for 2h and dried. 3.4 The bottom and side surfaces of the sample should be flat, with clear edges and corners, and no stratification is allowed. Figure 2
3.5 The thickness of the sample should be 6mm ± 0.5mm. When measuring, each sample should be measured 3~~5 times at the thinnest part in the middle of the sample and the average value should be taken. The measurement accuracy is ± 0.1mm.
4 Test steps
4.1 Align the upper and lower blades of the shell high temperature bending strength tester; then put the qualified sample on the lower blade in the furnace, heat it to the test temperature, and start the test after keeping warm for 0.5h. When testing continuously, each sample must be kept warm at the test temperature for 10min. 4.2 When measuring the static bending strength of the sample, the loading speed is generally 5~6mm/min. 4.3 After the specimen touches the upper blade, it enters the loading state, and the lower blade continues to rise until the pressure rises until the specimen breaks. The deformation and the applied load value P are read by the XWC-200 potentiometer. 4.4 The broken specimen is moved to the non-test area behind the furnace for storage, and then taken out from the back door of the furnace. 5 Calculation of results
5.1 Substitute the load value measured for each specimen into formula (1) to calculate the bending strength value of the specimen: 3LP
0称= 2ahz
武中: L
Bending span, mm;
PThe load borne by the specimen, N
a---specimen width, mm;
Specimen thickness, mm.
5.2 The bending strength value should be the average value of the test results of no less than 5 specimens. 6 Test records
（1）
The test records shall include: specimen name, specimen number, specimen size, test temperature and its corresponding load value P, specimen bending strength value. , test date, and test personnel.
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.