钢结构设计

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查阅了一下，钢结构设计规范，发现这个规范NORSOK N-004 非常详细完全可以当，设计手册来用。里面给了多的数据，各种修正系数之类的。比国标严谨和详细几十倍。

随便问下焊接问题，焊接有个系数叫做prEN=C+Si/30+(Mn+Cu+Cr)+Ni/60+Mo/15+V/10+5B,
冷裂系数。

这个公式前面的系数，是不是可以理解为每个元素的使马氏体能力值， B最厉害，C次之。

Fluid

https://wwu.lanzoub.com/iKjs407ocfaj  密码:5ah1

大侠厉害哦

山东土狗

在低碳钢的焊接中 Boron 元素达到 100ppm的量级就可以促使低温贝氏体产生，抑制了珠光体和高温贝氏体的产生，微观结构产生了很大的变化，因此toughness下降。同时B会促进铁素体在凝固胞体边界和奥氏体边界的析出。

山东土狗

感谢分享。
在welding metallugry里面也有这种公式，深层原理不明白。

2266998

要先读那个元素的东西，深读到金属徤，这个牵扯分子力，

还是那句话，读‘凝固’，所有金属问题之本，不能略过，

leftwall

作为一名资深伸手党，我有话要说

山东土狗

The Boron hardenability effect
An outstanding feature of boron steels is the improvement in hardenability produced by the addition of even a minute quantity of boron. It is generally accepted that a hardenability peak is reached when the quantity of boron is between 3 and 15 ppm. In an excessive amount of boron (>30 ppm) is present, the boron constituents become segregated in the austenite grain boundaries, which not only lowers hardenability, but also may decrease toughness, cause embrittlement and produce hot shortness. The affect of boron on hardenability also depends on the amount of carbon in the steel. The effect of boron increases in inverse proportion to the percentage of carbon present.

Boron must be in its atomic state to improve hardenability, which means that care must be taken during steel production for the boron to be effective. Boron may also become ineffective if its state is changed by incorrect heat treatment. For example, high austenitizing temperatures must be avoided as well as temperature ranges where certain boron precipitates occur.

Hardenability is highly dependent on the behavior of oxygen, carbon and nitrogen present in steel. Boron reacts with oxygen to form boron oxide (B2O3); with carbon to form iron boroncementite (Fe3(CB)) and iron boroncarbide (Fe23(CB)6); and with nitrogen to form boron nitride (BN). Loss of boron by oxygen is presented by making the boron addition to silicon-aluminum killed steels and by using good ladle and mold practices. Strong nitride formers (titanium, aluminum, and zirconium) protect the boron from reaction with nitrogen. For example, if nitrogen is fixed by using titanium, satisfactory hardenability is obtained in the temperature range up to 1830°F (1000°C) provided that the steel contains about 5-20 ppm of boron.

The hardenability of boron steel is also closely related to austenitizing conditions and is generally said to decrease by heating above 1830°F (1000°C). Boron steel must also be tempered at a lower temperature than other alloy element steels of the same hardenability.

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山东土狗 发表于 2020-12-22 15:03
The Boron hardenability effect
An outstanding feature of boron steels is the improvement in hardenab ...

焊接板材，质量LEVEL 1