机械工程学报
機械工程學報
궤계공정학보
CHINESE JOURNAL OF MECHANICAL ENGINEERING
2015年
6期
2-8
,共7页
韩一纯%陈学东%范志超%卜华全
韓一純%陳學東%範誌超%蔔華全
한일순%진학동%범지초%복화전
2.25Cr1MoV钢%焊接粗晶热影响区%热模拟%再热裂纹敏感性
2.25Cr1MoV鋼%銲接粗晶熱影響區%熱模擬%再熱裂紋敏感性
2.25Cr1MoV강%한접조정열영향구%열모의%재열렬문민감성
2.25Cr1MoV steel%welding coarse grained heat affected zones%thermal simulation%reheat cracking sensitivity
再热开裂曾多次在2.25Cr1MoV钢反应器的焊接粗晶热影响区(Coarse-grained heat affected zone, CGHAZ)部位发生，却很少在“斜Y型坡口再热裂纹试验”中出现。考虑两者之间的热输入差异，通过Gleeble热模拟试验研究热输入对2.25Cr1MoV钢CGHAZ再热裂纹敏感性的影响，并结合显微组织观察、硬度测定及断口分析，讨论热输入、组织和性能之间的关系。结果表明，在5～100 kJ/cm的热输入范围内，CGHAZ的再热裂纹敏感性随热输入的升高而增大，当热输入为35 kJ/cm时， CGHAZ在675℃对再热开裂“高度敏感”，限制热输入在25 kJ/cm以内，将有效降低其再热裂纹敏感性。综合分析发现，模拟CGHAZ的高温塑性与其在高温拉伸试验后硬度的变化规律之间存在良好的对应关系。当软化现象发生时，拉伸试样的断裂模式为穿晶与沿晶的混合型断裂，具有较高的断面收缩率(Reduction of area, RoA)，当二次硬化现象发生时，其断裂模式为均一的微孔聚集型沿晶断裂，RoA显著降低。试验结果从二次硬化的角度反映了高热输入条件下CGHAZ的再热脆化机理。
再熱開裂曾多次在2.25Cr1MoV鋼反應器的銲接粗晶熱影響區(Coarse-grained heat affected zone, CGHAZ)部位髮生，卻很少在“斜Y型坡口再熱裂紋試驗”中齣現。攷慮兩者之間的熱輸入差異，通過Gleeble熱模擬試驗研究熱輸入對2.25Cr1MoV鋼CGHAZ再熱裂紋敏感性的影響，併結閤顯微組織觀察、硬度測定及斷口分析，討論熱輸入、組織和性能之間的關繫。結果錶明，在5～100 kJ/cm的熱輸入範圍內，CGHAZ的再熱裂紋敏感性隨熱輸入的升高而增大，噹熱輸入為35 kJ/cm時， CGHAZ在675℃對再熱開裂“高度敏感”，限製熱輸入在25 kJ/cm以內，將有效降低其再熱裂紋敏感性。綜閤分析髮現，模擬CGHAZ的高溫塑性與其在高溫拉伸試驗後硬度的變化規律之間存在良好的對應關繫。噹軟化現象髮生時，拉伸試樣的斷裂模式為穿晶與沿晶的混閤型斷裂，具有較高的斷麵收縮率(Reduction of area, RoA)，噹二次硬化現象髮生時，其斷裂模式為均一的微孔聚集型沿晶斷裂，RoA顯著降低。試驗結果從二次硬化的角度反映瞭高熱輸入條件下CGHAZ的再熱脆化機理。
재열개렬증다차재2.25Cr1MoV강반응기적한접조정열영향구(Coarse-grained heat affected zone, CGHAZ)부위발생，각흔소재“사Y형파구재열렬문시험”중출현。고필량자지간적열수입차이，통과Gleeble열모의시험연구열수입대2.25Cr1MoV강CGHAZ재열렬문민감성적영향，병결합현미조직관찰、경도측정급단구분석，토론열수입、조직화성능지간적관계。결과표명，재5～100 kJ/cm적열수입범위내，CGHAZ적재열렬문민감성수열수입적승고이증대，당열수입위35 kJ/cm시， CGHAZ재675℃대재열개렬“고도민감”，한제열수입재25 kJ/cm이내，장유효강저기재열렬문민감성。종합분석발현，모의CGHAZ적고온소성여기재고온랍신시험후경도적변화규률지간존재량호적대응관계。당연화현상발생시，랍신시양적단렬모식위천정여연정적혼합형단렬，구유교고적단면수축솔(Reduction of area, RoA)，당이차경화현상발생시，기단렬모식위균일적미공취집형연정단렬，RoA현저강저。시험결과종이차경화적각도반영료고열수입조건하CGHAZ적재열취화궤리。
Reheat cracks have been detected many times in the welding coarse-grained heat affected zones(CGHAZ) of 2.25Cr1MoV reactor, but seldom been discovered after Y-groove reheat cracking test. Considering the difference of heat inputs between the two, the influence of weld heat inputs on reheat cracking sensitivity of CGHAZ in vanadium-modified 2.25Cr1Mo are studied by mean of Gleeble thermal simulation. Effect of heat inputs on microstructural, hardness, and high temperature ductility are discussed by microstructural observation, hardness test and fractographic analysis. The results show that the reheat cracking sensitivity of CGHAZ increases with increasing heat inputs within the range of 5~100 kJ/cm. CGHAZ with heat input of 35 kJ/cm is considered “highly susceptible” to reheat cracking at 675℃. The reheat cracking sensitivity is mitigated effectively by heat inputs limited to 25 kJ/cm. The comprehensive analysis reveals that the high temperature ductility of the simulated CGHAZ is closely related to the hardness change after high temperature tensile test. Relatively high reduction of area(RoA) is observed corresponds to softening phenomena, along with a mixed fracture mode of transgranular and intergranular. While the ductility of CGHAZ degraded obviously when second hardening occurs, along with a uniform fracture mode of intergranular microvoid coalescence.
