块状铁素体

低中碳合金钢的中温块状铁素体组织

Middle temperature transformation of massive ferrite in low or medium carbon alloy steels

并得出这种中温块状铁素体具有以下的相变特征：（1）无浮凸效应。

The massive ferrite of intermediate-temperature transformation has some characteristics : ( 1 ) There is no surface relief .

焊缝柱状晶区的组织由沿柱状晶界分布的先共析铁素体+侧板条铁素体+块状铁素体+针状铁素体组成；

The microstructure of weld seam columnar grain are composed of proeutectoid ferrite 、 FSA 、 massive ferrite and acicular ferrite .

结果表明，焊缝金属主要由柱状、针状、条状和块状铁素体构成，也含有少量的贝氏体和珠光体。

The weld metal is mainly for columnar , blocky , acicular and stripferrites , and it also contains a small amount of pearlite and bainite .

在低、中碳合金钢的中温区内，除板条状铁素体转变外还存在块状铁素体转变。

The transformation of the massive ferrite , besides the lath one , was observed in the low or medium carbon ahoy steels under middle temperatures .

含碳量低，减少块状铁素体，细化组织有利于提高管材抗应力腐蚀的能力。

Based on the above study , low carbon content , reducing massive ferrite and refining structure are good for increasing the ability to resist stress corrosion cracking of pipelines .

热丝焊接的堆焊层组织则由垂直于熔合线的柱状铁素体、块状铁素体、粒状珠光体、少量贝氏体等组织构成。

The microstructure of cladding layer by hot-wire welding composed by cylindrical ferrite which was perpendicular to the fusion line , massive ferrite , granular pearlite and a small amount of bainite .

此外，显微组织中网状、块状铁素体的存在以及螺纹表层脱碳使连接螺栓疲劳强度下降也是造成断裂的重要原因。

The existence of reticulation and mass shape ferrite , decarbonization at the screw thread surface layer which induced decline of fatigue strength of connecting bolt were also the important reasons of fracture .

此粒状珠光体由两部分构成：一部分来自块状铁素体或奥氏体中直接析出的粒状的不连续渗碳体；一部分来自等温过程中片层状渗碳体的不断熔断。

The granular pearlite consists of two parts : one part is from the discontinuous granular cementite which precipitated directly from ferrite matrix ; another part is from the " fusing break " of the lamellar cementite during isothermal treatment .

结果表明，（1）不同的焊接工艺参数对焊缝和热影响区的组织均一性有较大影响。因为热输入及冷却条件的差异会使焊缝中形成粗大的块状铁素体；

It was shown that : ( 1 ) The different welding parameters have considerable effect on the microstructure homogeneity of welding seam and the HEZ as result of block ferrite in certain weldings by different heat inputs and cooling conditions .

打底焊缝中心奥氏体晶界为大量块状铁素体而且晶内针状铁素体较粗大，观察到的热裂纹大多在块状铁素体中产生并沿奥氏体晶界扩展。

Austenite grain were made up of many massive ferrites on boundaries and intragranular coarse acicular ferrites in the backing weld center , and most of the hot cracks observed generated in the massive ferrites and extended along the austenite grain boundaries .

焊缝显微组织主要是回火马氏体和块状δ铁素体组织。

The microstructure of the weld metal was found to be tempered martensite with a little of delta ferrite .