25MnSi2Ni2MoAl的焊接性分析.doc

焊接冶金学课程设计25MnSi2Ni2MoAl的焊接性分析学院:机械工程学院专业班级:材料成型及控制工程10焊接班姓名:谭晓冬学号:1010100811指导老师:王辉虎副教授卜智翔讲师前言焊接冶金学课程设计目的:通过对指定材料(母材)的焊接性分析,选择合适的焊接材料,分析焊缝化学成分和HAZ组织要求: T图的分析方法初步分析材料的焊接工艺特点内容:查阅材料的成分、T对母材进行焊接性分析选用焊接材料,···············4 ···························································································································································································································································································(HAZ)的脆化·······························(HAZ)的软化·························································································································································································································································································································································1225MnSi2Ni2MoAl(HT-150类)【日】,屈服强度为1226MPa,是由调质结构钢发展起来的,合金元素总含量小于5%,其作用是保证钢的淬透性,提高马氏体的抗回火稳定性和抑制奥氏体晶粒长大,细化钢的显微组织。常用元素有Ni、Cr、Si、Mn、Mo、V等。通常在淬火和低温回火状态下使用,显微组织为回火板条马氏体,具有较高的强度和韧性。如采用等温淬火工艺,可获得下贝氏体组织或下贝氏体与马氏体的混合组织,也可改善韧性。表1-1:25MnSi2Ni2MoAl化学成分【1】化学成分(%)C(%)Si(%)Mn(%)S(%)P(%)Cr(%)Ni(%)Mo(%)Cu(%)AL(%)(Si):在炼钢过程中加硅作为还原剂和脱氧剂,-%,硅就算合金元素。硅能显著提高钢的弹性极限,屈服点和抗拉强度,故广泛用于作弹簧钢。-%的硅,强度可提高15-20%。硅和钼、钨、铬等结合,有提高抗腐蚀性和抗氧化的作用,可制造耐热钢。硅量增加,会降低钢的焊接性能。锰(Mn):在炼钢过程中,锰是良好的脱氧剂和脱硫剂。%以上时就算“锰钢”,较一般钢量的钢不但有足够的韧性,且有较高的强度和硬度,提高钢的淬性,改善钢的热加工性能,锰量增高,减弱钢的抗腐蚀能力,降低焊接性能。钼(Mo):形成硬度很高的碳化物,在回火时弥散析出,产生二次硬化,同时也能提高红硬性,硬度和耐磨性,提高钢的淬透性。可以阻碍马氏体分解,提高钢的挥霍稳定性。铝(Al):铝是钢中常用的脱氧剂。钢中加入少量的铝,可细化晶