研究了一种超高强度低合金钢与环境裂纹敏感性（ EAC）有关的拉伸微屈服行为。宏观屈服强度为1120 MPa，拉伸应力近700 MPa开始微屈服的超高强度低合金钢，其化学成分（质量分数，％）为0．22C-0．25Si -0．70Mn-3．40（Cr＋Ni＋Mo）-0．13（V＋Nb＋Ti）。用这种钢制作的深水系泊链环经1273 K 淬火和873 K回火，原位中子衍射测量结果表明，对其光滑圆柱试样施加拉力，至应力500 MPa，良好地符合线弹性应变；至700 MPa时，（200）晶面族晶粒优先出现非线弹性应变；至800 MPa，（110）晶面族晶粒也呈非线弹性应变。随着拉力的进一步增大，（200）晶面族晶粒的非线性弹性应变量逐步增加，而（211）晶面族晶粒仍停留在线弹性应变阶段。%Micro yield behavior connected with environment assisted cracking ( EAC) for an ultra-high strength low alloy steel was investigated .The chemical composition of ultra-high strength low alloy steel , which has macro yield strength of 1120 MPa and exhibits micro yield when tensile stress is near 700 MPa, is 0.22C-0.25Si -0.70Mn-3.40(Cr+Ni +Mo)-0.13(V +Nb +Ti)(mass fraction,%).In-situ neutron diffraction results show, as the smooth cylinder specimens taken from deepwater mooring chain made of above-named steel and quenched from 1273 K and tempered at 873 K is subjected to tension stresses , that the specimen offers a good linear elastic deformation when subjected to the stress up to 500 MPa, and the grains of (200) family of crystal planes exhibit a non-linear elastic strain over all others when subjected to the stress up to 700 MPa , as well as the the grains of (110) family of crystal planes also offer a non-linear elastic strain when subjected to the stress up to 800 MPa.As the tension stress become greater , the non-linear elastic strain amount of the grain of (200) family of crystal planes will increase progressively , but yet the grains of ( 211 ) family of crystal planes are still in the linear elastic deformation stage .
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