The Experimental Statistical Analysis Study Of New Low-carbon Bainitic High Strength Steel Welding Defects

Due to its good weldability, low-temperature toughness and impact resistance, the welding structure of high-strength low-carbon bainitic steel has been widely used in the field of machinery, aviation, hydropower, construction and so on. It is called the green steel in the 21st century. The welding defects is the main factors in affecting the safety and durability of welding structures. We consider that the study in the field of new high-strength low-carbon bainitic steel welding defects statistical analysis is not sufficient.There are significant engineering and economic meaning to study on it.First of all,WDB620, ADB610 steel welding defects data are obtained through non-destructive testing experiments. The experimental data is recorded in the form of X-ray film.Then finding the main causes of welding defects with the help of causal diagram and giving the advise of prevention.We draw histograms of the welding defect data. to predict the distribution types of the welding defects.In order to fit the distribution of WDB620 and ADB610 welding defects. The most commonly used statistical distribution functions in reliability design are programmed in MATLAB,which includes the distribution characteristics of normal distribution, exponential distribution, three-parameters and two-parameters Weibull distribution function, the parameter estimation and distribution fitting tests, Drawing out the linear regression picture of distribution function.Regarding the experimental data as random variables.Using a varity of mathimatics model such as normal distribution, exponential distribution, three-parameters and two-parameters Weibull distribution to fit the distribution of WDB620 and ADB610 welding defects.Estimation parameters were calculated for each distribution and using the correlation coefficient and K-S test method to test the fit extent of the distribution. Drawing out the linear regression picture of distribution function.Finally,we concluded that the distribution of the welding defect obeys exponential distribution.In view of the impact of different welding method,. We contrast the welding defects of gas shielded arc welding and manual welding.First of all,we contrast welding defects type with ordered diagram.And we believe there is significant difference in welding defects type between the two kinds of welding methods, then we tested the hypothesis with T test method.With the rank sum test method we conclude the average welding defects size of gas shielded arc welding is smaller than the Manual welding.At the same time analyze the welding defects of different thickness and different materials to find out their impact on welding defects. We believe that there is no significant difference between the welding defects of WDB620 and ADB610 steel plate at the same thickness. Meanwhile, there is no significant difference in the same kind of steel plate when the thickness is closing. When the thickness difference is significant, the welding defect size tend to increase with the thickness of the steel plate.Finally, on the basis of statistical analysis, get the results with a certain reliability. We give out the interval estimation with 95% confidence level of welding defects which obeys exponential distribution.