【作者】 赵建华；

【导师】 王笑川；

【作者基本信息】 重庆大学 ， 材料加工工程， 2008， 硕士

【摘要】 在焊接过程中热源沿焊件移动时,焊件上某点温度随时间变化的过程称为焊接热循环,它可以描述焊接过程中热源对母材金属的加热过程。焊缝及近缝金属组织及性能的变化取决于母材金属的化学成分和焊接过程中的热循环特点。尤其在焊缝附近的热影响区(HAZ)受焊接过程热循环(加热和冷却)的作用,相当于经历了一次“特殊的热处理”过程一样。焊缝及热影响区各部分由于离焊缝距离不同而被加热到不同的温度,焊后冷却时又以不同的冷速冷却下来,使该区域的组织及性能变化非常复杂。因此,对焊接过程温度变化进行测试研究、分析具有重要的理论及实际意义。焊接热循环参数主要有加热速度、加热峰值温度、相变温度以上停留时间及冷却速度等,这些因素都会影响焊后组织和性能。因此,通过建立一套先进的焊接热循环的测试与分析计算系统,可以为分析焊接接头组织性能变化及焊接缺陷生成机理提供重要依据及技术手段。也可指导和改进焊接工艺设计、改善热循环过程,进而达到提高焊接质量的目的。本文采用计算机软、硬件技术并结合适当的数据处理方法,研究和开发了一套基于LabVIEW编程语言的焊接过程温度测试及分析系统。该系统由热电偶、温度变送器、数据采集卡和微机等组成,集焊接热循环温度数据采集、存储、处理和分析功能于一体。整个系统具有多通道温度信号采集、热循环曲线实时显示、数据存储、数据回放、曲线打印输出等功能。该系统与传统的X-Y函数记录仪测试方法相比,具有精度高、实时性好、使用方便、界面友好、功能强等优点。本文还采用16Mn低合金钢进行了焊接测试实验。通过对测得的焊接热循环曲线,以及焊接HAZ微观组织的分析,所得试验结果与传统焊接CCT图吻合较好。说明依据测得的热循环曲线并参考焊接CCT图,能够对HAZ组织进行预测,进一步证实了本系统的实用性和可靠性。更多还原

【Abstract】 In the course of welding, thermal resource moving along the welding seam, at every point of which temperature varies at any time, all of these phenomena is called welding heat cycle.It is also the circulation which thermal resource heats the basic metal.The transformation of metallurgical texture and the development of strss in the welding seam and its neighborhood lie on metallic chemical constitution and welding heat cycle.Especially,welding HAZ of near welding seam will meet with the (heating or cooling )process of welding heat cycle, it’s the same to experience a specific heat processing .The every portion of welding seam and welding HAZ was heated different temperature,and was cooled different cooling temperature after welding cooling so the HAZ texture and performance was changed very complicated.Consequenctly, it’s an important theory and effective meaning to test and analyse the temperature change of welding process.Parameters of welding heat cycle maily include heating velocity, heating maximal temperature, length of staying above phase transition temperature and cooling velocity. Any of these parameters will affect metallic performance after welding. Therefore,through based a set of advanced test and calculation of welding heat cycle are very important to analyze the change of welding joint texture and performance, reasons of welding defects.By improving welding procedure and process of welding heat circulation,we can improve the quality of welding products very well.Adopt the hardware and software of computer and connected with appropriate data processing. With studying and exploiting the testing system research on welding process temperature base on LabVIEW. The system employs computer technology which can collect and process data conveniently. It consists of electric thermo-couples, A/D interface board and a microcomputer.The system is the interger of data collecting, data processing and analyzing. With the system, we can the some paths acquisition of temperature signal、heat cycle graph real-time indication、data storage、data playback and graph printing and so on. The system has some avantages: high precision, esay usage, friendly interface and high ratio of quality to price than X-Y functional recorder.The article adopts the welding test of 16Mn alloy of low percentage steel. Throught testing welding heat cycle graph and analyzing the microcosmic tissue of welding HAZ, the testing result is very anastomosed than the traditional CCT. According to testing welding CCT graph and consulting welding CCT graph, we can forecast the texture of welding seam, and the authenticity and reliability of the system is even more approved.更多还原