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Burst of water wall tube

Tensile test. As shown in Figure 1 the right side of the middle tube and a tube does not break the interception of the pipe, tensile test, the results shown in Table 2, the table also lists the corresponding mechanical properties of materials, 20g standard. The right side of the pipe can be seen testing the mechanical properties are standard, while the middle tube sections are much lower than the standard value, but their elongation rates are not changed. Because there is no interception of the right side of the pipe burst near the mouth of the original, received little impact on heat, so the mechanical properties not significantly reduced; and the middle pipe burst from the mouth close to the original,[link widoczny dla zalogowanych], highly heat of greater strength so dramatically on the tube downward trend. Yu Xiang, et al: Analysis of water wall tube burst Table 2 Tensile properties of water wall tube test results Tab. 2Tensilestrengthofwater-coolingtubes Note: 1) shown in Figure 1; 2) standard 20g. 2 Analysis and discussion of water wall tube break at the mouth of the original explosion was macroscopic plastic deformation, expansion diameter thick wall thinning at the pipe break circular cross-section has been turned into an oval. Away from the explosion at the mouth of the matrix structure of ferrite + pearlite, normalizing for the 20g normal tissue. The explosion at the mouth of the microstructure is ferrite + pearlite + bainite for subcritical quenching, indicating that the mouth of the hot blast temperature of the A ~ A. Hardness test showed that the explosion is much higher than the hardness of the mouth of the hardness of the matrix. These results show that the water wall tube is a short dramatic population explosion caused by overheating rupture the moment, not long hot cracking due to creep failure. Mechanical test results also show that received a very small heat affected the strength of the right pipe not significantly reduced; while those with greater impact on the middle of the heat pipe sharp decline in the intensity, which is the short sharp burst pipes caused by overheating of the main features of a . Microstructure observation did not see the inclusions,[link widoczny dla zalogowanych], composition analysis showed that the sulfur content of the material is not exceeded, although the carbon content is lower than standard, but the right side of the pipe yield strength and fracture strength are much higher than the standard value, indicating that the carbon content low and did not significantly reduce the strength of the material. Therefore, the burst water wall tube is mainly caused by short-term overheating dramatically reduces the strength of materials caused by high-temperature plastic deformation and cracking. These results indicate that short-term over-temperature water wall tube is probably due to water wall tube of small diameter (22.0mIn) caused by blockage. 3 Conclusions (1) wall of water wall tube blockage is likely caused by overheating. (2) water wall tube caused by overheating due to the rapid transient short break, not a long hot cracking due to creep failure. (3) The chemical composition of water wall tube basically qualified, the production of explosive population has no direct contact with the inclusions. References: E1] king aloof. Metal Materials Used in New International Manual [M]. Beijing: Beijing University Press, 1995:411. [2] GB6397-1986 metal tensile test specimen [S]. (Continued from p. 421) on. The metallographic examination, the organization of ferrite and pearlite, but the fine grain (up 12.5). Rolling process can be controlled through the adjustment to optimize the grain to improve the status of grains too small. This helps reduce the tensile strength and hardness. According to Morrison formula: tie a 5 / (10 + d / 2), through the improvement of grain size to increase the bar strain hardening index value. It is conducive to the best drawing formability. In the stamping process, this value is important not only because it is a measure of resistance to necking, and when the contingency occurs, the value of the steel bar with high strain redistribution in favor, so that the deformation uniformity. Through the laminar cooling cooling adjusted by the back-end front-end cooling, the strength of steel fell by 40MPa,[link widoczny dla zalogowanych], the grain size of 9 to 9.5, the effect is significant. (2) the dimensional accuracy of steel stamping and jumping on the quality and mold into parts consumption has a greater impact. If the plate thickness exceeds the allowed tolerance, such as steel too thin, not tight because the weight of the workpiece surface wrinkles, or a rebound is not the correct geometry; and have resulted in thick steel plate concave, convex mold gap is too small, with too tight, or even damaged parts caused by mold or crack. Therefore, to ensure dimensional accuracy of steel is to improve the performance of its punch another measure. (3) The direction of plate rolling and stamping performance related, continuous rolling of the vertical and horizontal large difference in performance, so users should be pressure washed bending direction perpendicular to the direction of rolling as possible. Reference: I-1] Song Weixi editor. Metallurgy EM]. Beijing: Metallurgical Industry Press, 1998. E23 Chen Jiyu,[link widoczny dla zalogowanych], bears in the real editor. Metal EM]. Beijing: China Material Press, 1986. [3], editor of the Shanghai Institute of Manufacturing Technology. Metallographic analysis fM]. Shanghai: Science and Technology Literature Press,[link widoczny dla zalogowanych], 1987.

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