發(fā)布時間：2018-05-29 17:32

  本文選題：12%Cr鐵素體不銹鋼 + 高頻焊接　； 參考：《天津工業(yè)大學》2017年碩士論文

【摘要】：12%Cr鐵素體不銹鋼是一種碳含量和鉻含量均很低的經濟型鐵素體不銹鋼,不僅價格低廉,而且具有良好的焊接性,研究該鋼種的焊接性對提高我國鋼鐵制造行業(yè)生產效率具有實際意義。本課題采用高頻焊接工藝將12%Cr鐵素體不銹鋼鋼板制成高頻焊管,觀察分析焊接接頭的宏觀形貌和顯微組織變化及機理。改變焊接速度、氣體保護和焊后熱處理條件,結合組織變化和力學性能特點,分析不同焊接工藝對焊接接頭的影響,為實際生產提供理論指導。觀察分析焊接接頭的形貌和組織,高頻焊接熱影響區(qū)呈現腰鼓形,寬度hn為 0.6～0.75mm,約為管壁厚度 3mm 的 1/4～1/3,h≈hi≈1.3～2.2hn,fo≈fiv1.3～3fn,均符合理想的焊縫結構參數,熱影響區(qū)尺寸隨著焊接速度的增大而減小。12%Cr鐵素體不銹鋼母材基體組織為單相鐵素體,其平均晶粒尺寸約為30μm。經過高頻焊接后,焊縫熔合線的組織由δ鐵素體、粗晶板條馬氏體和少量殘余奧氏體組成,晶粒大小約為80Oμm～100μm;熱影響區(qū)的組織由均勻分布的黑色塊狀馬氏體和白色鐵素體基體組成,晶粒大小約為20μm～50μm,低于850℃的區(qū)域雖受熱源影響,但不發(fā)生相變,最終組織與母材基本一致。高頻焊接過程中某些合金元素會以化合物的形式析出,對焊接接頭質量產生影響,應嚴格控制微量合金元素的含量。對焊接接頭進行力學性能測試,結果表明,焊接過程產生大量高硬度馬氏體組織,提升了材料的強、硬度和耐磨性,增加了材料的區(qū)域淬硬性,降低了焊接接頭的沖擊韌性。熱影響區(qū)晶粒粗大、存在雜質析出相等因素,會對材料的沖擊韌性造成不利影響,降低材料的使用性能。焊接速度增大,熱影響區(qū)寬度減小,高硬度、低韌性區(qū)寬度也會隨之減小;焊后熱處理工藝可以細化晶粒,使組織更加均勻化,提高材料的綜合力學性能;焊接過程中若無氣體保護條件,會產生大量氧化物夾雜,且不易被排出,容易引起熱裂紋等缺陷。12%Cr鐵素體不銹鋼進行高頻焊接的過程中必須進行焊接氣體保護和焊后熱處理,在保證獲得理想焊縫結構參數的前提下,焊接速度越大越好。同時應適當加入一些微量合金元素來控制其含量,獲得理想的焊接接頭。
[Abstract]:12%Cr Ferritic stainless steel is an economical ferrite stainless steel with low carbon content and low chromium content. It is not only cheap but also has good weldability. It is of practical significance to study the weldability of this kind of steel for improving the production efficiency of iron and steel manufacturing industry in China. In this paper, 12%Cr ferrite stainless steel plate was made into high frequency welded pipe by high frequency welding technology. The macroscopic morphology, microstructure change and mechanism of welded joint were observed and analyzed. The effects of different welding processes on welded joints are analyzed by changing welding speed, gas protection and post-welding heat treatment conditions, combined with microstructure changes and mechanical properties, and providing theoretical guidance for practical production. The morphology and microstructure of the welded joints were observed and analyzed. The high frequency welding heat affected zone showed a waist drum shape with a width of 0. 6 ~ 0. 75mm, about 1 / 4 / 1 / 3 h of the thickness of the pipe wall 3mm 鈮，

本文編號：1951790